Lister Engine Forum
How to / DIY => Generators => Topic started by: Alexdick on November 12, 2018, 04:56:43 PM
-
I have a manual for an SDA + SDT Generator (see below) if anyone wants a copy I will scan a PDF over to you.
also I have de-magnetised it by shutting down whilst it was still powering my house! Help, how do I re-magnetise it? I am a TOTAL novice so two questions:-
1. Is there an idiot's guide to doing this job myself (photo of generator plate below) or;
2. Can anyone recommend someone in the Berkshire (UK) area to do it for me?
Many thanks
Alex l(http://)
-
http://www.dieselduck.info/machine/03%20electricity/flashing_generator.htm
you need to re-flash the generator
https://www.stationaryengineparts.com/st-alternators-instructions-for-operation-and-maintenance-1926-0.html
instructions:
To stop
1, Remove the load(s) from the output by opening the output switch(es).
2, Stop the prime mover.
Cautions:
Be very careful not to allow short circuits at the output of the generator. This can damage the rectifier diodes in the voltage regulating circuit.
Before stopping the generator, remove all output electrical loading first before turning off the prime mover. If you turn off the prime mover while the generator is under load, the resulting spin-down and gradually reducing electric fields may erase the residual magnetism in the rotor that allows the generator to start self excitation.
If the residual magnetism in the rotor is too weak to start self-excitation, the rotor will need to be re-magnetized.
Problems and Troubleshooting
First, verify that all internal and external connections are correct. Once this has been verified, if there is no voltage output then possible causes are:
Loss of residual magnetism
The rotor’s residual magnetism, which enables self-excitation, may be lost over time if the generator is unused for a long time or suddenly if the alternator’s prime mover is turned off while the electrical load is still connected to the generator.
To re-magnetize the rotor, flash connect a 12V storage battery to the field winding terminations F1 and F2 observing the polarity while the generator is rotating. Do not connect the battery in the reverse polarity and only connect the battery momentarily.
-
Hi Alex, Mike is absolutely right sbout how to flash an ST head. Sadly you have a Brush head which is very different. In an ST head the AC windings are stationary and the field is rotated by the diesel motor, the field is energized by feeding it DC voltage via the slip rings.
In a Brush head the field windings are stationary and the AC windings rotate, 240 volt AC is collected from the slip rings.
To complicate things further the generator also acts as a starter motor requiring further dc motor windings and a commutator ring, it also works as a dynamo to provide 12/24 volts to charge the batteries.
I believe that what you need to do is flash the auxiliary field windings. Please see the photo attached and the rather poor quality circuit diagram.
You will need to remove the cover on the back of the generator to access the rectifier and rheostat shown in the photo. Flash the field by connecting a pair of jump leads to a 12 volt battery, very briefly (half a second) touch one jump lead to either end of the rheostat shown on the left of the photograph. Doing it this way you do not need to worry about the polarity as the bridge rectifier will only allow current to flow in the correct direction. Please see drawing.
Good luck, let us know how it goes,
Bob
-
Hi Alex, further to my previous post, it is probably safer to disconnect the wire from one end of the rheostat, wouldn`t want to fry the rheostat.
Bob
-
When I had to flash mine, I used a automotive tail light bulb in series with the battery, to limit amps, just to not burn anything out. And just one zap is all it takes to refresh the mistake.
I added the ST head instructions, the reiterate the "remove loads" before stopping the engine, it's a universal requirement.
-
Hi Alex, Mike is absolutely right sbout how to flash an ST head. Sadly you have a Brush head which is very different. In an ST head the AC windings are stationary and the field is rotated by the diesel motor, the field is energized by feeding it DC voltage via the slip rings.
In a Brush head the field windings are stationary and the AC windings rotate, 240 volt AC is collected from the slip rings.
To complicate things further the generator also acts as a starter motor requiring further dc motor windings and a commutator ring, it also works as a dynamo to provide 12/24 volts to charge the batteries.
I believe that what you need to do is flash the auxiliary field windings. Please see the photo attached and the rather poor quality circuit diagram.
You will need to remove the cover on the back of the generator to access the rectifier and rheostat shown in the photo. Flash the field by connecting a pair of jump leads to a 12 volt battery, very briefly (half a second) touch one jump lead to either end of the rheostat shown on the left of the photograph. Doing it this way you do not need to worry about the polarity as the bridge rectifier will only allow current to flow in the correct direction. Please see drawing.
Good luck, let us know how it goes,
Bob
Bob
Thanks for this. Please see photo below....I assume that is the rheostat I have marked up and just need to remove one wire then touch either end with the jump lead as indicated with the red and blue circles?!
Again, many thanks for your help
Alex
-
Hey Mike, no criticism of advice offered and you are right about removing all loads before shutting down any generator. Alex doesn`t tell us how he came to be in this situation, but I suspect he ran it out of diesel and it wouldn`t produce electricity once he restarted it.
Like your idea of a light bulb, very simple and idiot proof, will magnetize the iron core without doing any damage to sensitive items. The residual magnetism required is very minimal as the field voltage will ramp up as it starts to generate, even if it starts from next to nothing.
Lets hope he understands the principals we are trying to explain to him and asks for help if he is confused.
Hope he gets it going without any further problems.
Bob
Bob
-
OK I did turn off the generator without switching off the load as I noticed the starting handle was still in it from years ago, was flying around and I was worried it would fly off and hit one of my children.....a few lessons learned!
So, Bob, I assume my photo above in response to yours is ok? I will add the light bulb into the equation too.....I assume i just connect it to the + and - wires from my battery? Or is the light bulb solution separate from the one Bob suggests with the rheostat.
Apologies for the crazy questions but I am a TOTAL novice!
Thank you for your help, I really appreciate it.
Alex
-
Hey Alex, Yes disconnect one wire from the rheostat you have highlighted. connect a battery between those two wires and you should be good to go. Even a small 9 volt torch battery should be OK.
Depending on the age of your equipment and if it has been modified/repaired since manufacture you may find that it has a more modern silicon bridge rectifier or even an automatic voltage regulator.(please see photos) If it is very different from the photos I posted earlier please get back to me.
Bob
-
Hey Alex, Yes disconnect one wire from the rheostat you have highlighted. connect a battery between those two wires and you should be good to go. Even a small 9 volt torch battery should be OK.
Depending on the age of your equipment and if it has been modified/repaired since manufacture you may find that it has a more modern silicon bridge rectifier or even an automatic voltage regulator.(please see photos) If it is very different from the photos I posted earlier please get back to me.
Bob
Bob
You are a star! thank you. I will try tonight when I get home. It was all installed in the early 1970s so no, I don't think there are any of the mods you mention!
Alex
-
Hi Alex, there is a very good reason I mentioned modifications, the thing in my original photo, that looks like an old fashioned school radiator, is an old selenium bridge rectifier. They have a life expectancy of around fifty years, yours is due to fail. It will smell of garlic when it does start to fail, please don`t breath this in as it can cause cancer.
It s a very easy fix to replace the selenium rectifier with a more modern silicon rectifier and heat sink, all the parts are available on fleabay for about ten quid. No, I am not trying to sell you something and no, I can`t come and do the work for you. I live in Northern New South Wales , Australia. I live in the middle of nowhere and rely on a old 1970`s Lister/Brush generator for back-up power. If you rely on your generator for primary power you should replace the selenium rectifier before it fails.
Where in Berkshire do you live? I was unlucky enough to go to school in Pangbourne, Berkshire.
I completely understand your concerns regarding starting handles. Many full grown men have been injured by these, children do not belong anywhere near them. If you are hand starting your generator please regularly grease the shaft and ratchet pin so you don`t get hurt.
Bob
-
Hi Alex, there is a very good reason I mentioned modifications, the thing in my original photo, that looks like an old fashioned school radiator, is an old selenium bridge rectifier. They have a life expectancy of around fifty years, yours is due to fail. It will smell of garlic when it does start to fail, please don`t breath this in as it can cause cancer.
It s a very easy fix to replace the selenium rectifier with a more modern silicon rectifier and heat sink, all the parts are available on fleabay for about ten quid. No, I am not trying to sell you something and no, I can`t come and do the work for you. I live in Northern New South Wales , Australia. I live in the middle of nowhere and rely on a old 1970`s Lister/Brush generator for back-up power. If you rely on your generator for primary power you should replace the selenium rectifier before it fails.
Where in Berkshire do you live? I was unlucky enough to go to school in Pangbourne, Berkshire.
I completely understand your concerns regarding starting handles. Many full grown men have been injured by these, children do not belong anywhere near them. If you are hand starting your generator please regularly grease the shaft and ratchet pin so you don`t get hurt.
Bob
Bob
It is a small world! I live about two miles away from Pangbourne!! We know quote a few people there as St Andrews (the school our children were add) is a local feeder for it!
I had better replace the rectifier and no doubt I will need advice on what/how at some stage! I will take some photos this evening. I only use the generator foe backup power if there is a power cut which, thankfully, is a fairly rare occurrence.
Thanks again
Alex
-
Alex, good luck and get back to me if it all goes to sh1t. Quarter past ten at night here so going to bed. will check the forum in the morning.
Bob
-
Hi Bob
No joy sadly. I removed the wire off the rheostat and sparked it with the main 12v battery (could I have fried it??) reattached the wire and fires it up. There is obviously a tiny charge getting to the house as the light on the heating control comes on dimly in the house but that’s about it! Maybe I fried the rheostat?!
Alex
-
Hey Alex. Did you flash the auxiliary windings or the rheostat? When you started it you say there is a dim light that comes on on the heating system, is this Generator a start-o-matic system that will self start when there is a load present? SOM systems use a 12 or 24 volt sensing circuit to trigger start up, this could explain the light on the heating controller. SOM generators have a control panel that looks something like the photo.
If it is not a SOM and you are getting a dim light on your heating controller then the generator is still producing electricity from residual magnetism, in which case I suspect the selenium rectifier is on the blink and not energizing the field windings.
Bob
-
Hi Rob
I flashed the thing shown in the photos which I think is the rheostat? I may have sparked it a little bit too much?!
Anyway, the light i refer to is in the house about 30m from the generator so a little bit of electricity is getting there from the generator but clearly not much as it is very dim. Any ideas? Should
I try and flash the rheostat again?
Thanks
Alex
-
If you are even getting a tiny bit of voltage, when you had none before, the flash was successful. Now there is something else preventing the voltage from becoming full.
Did you have any loads on the system when you shut it down again ?
Let it "build" voltage for a minute or 2 before you engage the breakers and loads.
-
Hi Alex. you need to flash the field not the rheostat. You need to connect your battery to the two wires connected to the rheostat after disconnecting one wire from the rheostat. This will cause electricity to flow through the selenium rectifier into the field windings and magnetize the iron core it is made of.
If that doesn`t work we will have to try and flash the main windings. Something I am hesitant to do because getting the polarity wrong could cause serious damage or injury.
Bob
-
Hi Alex, further to my previous post please ensure that all loads are isolated from the generator when attempting to flash the auxiliary field. You don`t want to feed 12 volt DC into your house.
Bob
-
Bob
Thanks for this.... you must think I am a total idiot!! I fully understand what I am meant to do now. I hope I didn’t damage the rheostat by doing what I did last night? I’ll get on the case when I return from work tonight and let you know how I get on.
Thanks again.
Alex
-
Hi Alex, no I do not think you are a total idiot, I actually think you are a very useful mammal for trying to fix and understand things for yourself. Most people would phone an electrician or go buy a new one.
Good luck,
Bob
-
Hi Bob
No joy sadly :(
Alex
-
Hi Alex, I will have to take the covers of my Brush head and take some more photos. I will also get some resistance measurements with a multi meter so we can compare them with yours to try to track down where the problem lies.
When you start your generator, how do you do it? What does your control panel and top box look like? Does the control panel have a wiring diagram pasted to the inside? A couple of photos would be very helpful.
Bob
-
Hi Bob
Apologies for the slow reply.
Sadly, no joy last night when I tried....
I start the generator using 2 x 12v batteries.
I attach some photos of the top box....I don't have a control panel? the feed to the house comes out of the top panel and the to the house where there is a junction box Mains - Off - Generator
The light in the house i have mentioned which is the timer on my central heating system still (next to the junction box) still flickers dimly when I turn the generator on so there is something getting through albeit next to nothing!
Thanks!
Alex
-
H Alex, sorry not to get back to you sooner. I completely forgot that I had a board meeting to attend yesterday. It sound very posh and important being on the board of directors for the local camping and canoeing center. Let me assure you it isn`t. This is a not for profit organisation and all the board members do it for free. We provide outward bound training for kids and etc as well as certificated training for rescue personnel. I spent most of yesterday in meetings and all of today doing the same.
I will try to get some multi meter readings for you in the morning so that you can compare your readings and hopefully we can identify the issue and get it resolved. Do you have a multi meter, or could you borrow one from a neighbor or friend? You could probably pick up a perfectly serviceable one at the local hardware store for 10 to 20 quid. It needs to do volts AC and DC and ohms (resistance)
Thank you for the photographs, I will try to work out some sort of wiring diagram based on them.
I`ll post my reading tomorrow.
Bob
-
Looking at the photos I would turf out those old selenium rectifier bridges and replace them with modern silicon bridges probably cost you $30 and save a lot of grief later. If you have a multimeter turn it to ohms and actually see if you have continuity where you are applying your batteries
-
H Alex, sorry not to get back to you sooner. I completely forgot that I had a board meeting to attend yesterday. It sound very posh and important being on the board of directors for the local camping and canoeing center. Let me assure you it isn`t. This is a not for profit organisation and all the board members do it for free. We provide outward bound training for kids and etc as well as certificated training for rescue personnel. I spent most of yesterday in meetings and all of today doing the same.
I will try to get some multi meter readings for you in the morning so that you can compare your readings and hopefully we can identify the issue and get it resolved. Do you have a multi meter, or could you borrow one from a neighbor or friend? You could probably pick up a perfectly serviceable one at the local hardware store for 10 to 20 quid. It needs to do volts AC and DC and ohms (resistance)
Thank you for the photographs, I will try to work out some sort of wiring diagram based on them.
I`ll post my reading tomorrow.
Bob
Thanks Bob, I look forward to hearing from you. I have a multi-meter ready! See pic...
-
Looking at the photos I would turf out those old selenium rectifier bridges and replace them with modern silicon bridges probably cost you $30 and save a lot of grief later. If you have a multimeter turn it to ohms and actually see if you have continuity where you are applying your batteries
Thanks, will check later
-
Hi Alex, please see the revised wiring diagram attached.
What I would like for you to do is isolate the generator from the house. Set your multi meter to ohms, place the black probe on the terminal for the black wire in the connector block and the red probe on the terminal for the red wire in the connector block. Please tell me how may ohms it reads. (mine reads 12 ohms)
Bob
-
With the ohms set to 2k it reads 0.07 and with it set to 20k it reads zero .this is on the red and black terminals in the top box.
As an aside the batteries are set to deliver 12v not 24v
-
Hey Alex 0.07 on a 2000 ohm scale equates to 140 ohms, not ideal but not too surprising considering the age of the selenium rectifier in the circuit. The good news is that we have a circuit, which suggests that the AC winding, carbon brushes, bridge rectifier and the auxiliary winding are intact.
The next thing I would like for you to do is to flash it again. This time I would like for you to connect a wire from the positive battery terminal to the same red wire in the connector block, just touch it very briefly and let me know if you get a spark
Bob
-
No spark positive to positive
-
Ok , let us assume that some current flowed through the circuit, 12 volts through a resistance of 140 ohms equates to only 0.085 amps so wouldn`t produce much of a spark.
In the hope that this will have provided enough residual magnetism please start the generator and set your multi meter to Volts AC. Very carefully check the voltage between the red and black wires in the connector block. (if this is live you are looking at 240 volts and a possible 30 Amps, do not touch anything but the plastic handles on the multi meter probes!)
Bob
-
It say 11.6 !!!
-
Wow, I wasn`t expecting that. I have to conclude that the problem lies with the bridge rectifier having died. I suspect that you should also replace the charging circuit diode. I am very concerned that the voltage you are showing is very similar to to the battery voltage and you could have some sort of a leak between the AC and the DC side of things. I will have to take a whole load more resistance tests in the morning and ask you to compare your readings with mine.
I guess that when all else is eliminated what remains must be the truth (Sherlock Holmes)
Bob
-
Thanks Bob .... sounds complicated! I really appreciate your help with this. Thanks.
-
No worries, I`ll try to post resistance figures tomorrow.
Bob
-
Bob I’m thinking now might be the time for me to go shopping and buy a new set of things that need or could do with replacing anyway. It’s 45 years old so I think it deserves the expenditure.... I just need to find a good supplier and some advice on what to do. Good plan? Alex
-
Looked up bridge rectifier on your local ebay 1000piv 50 amp cheap as chips
-
It’s a family heirloom so I am keen todomit and replace whatever is needed. I guess I just need to know exactly what to buy!
-
At 2pounds 60 p that is the one you need
-
Hi Alex, 240 Volt AC is a sine wave it swings from +380 volt to -380 volt. Get a Bridge rectifier that is good for 1000 volt. I personally prefer ones with screw terminals, something like this would be ideal https://www.ebay.co.uk/itm/1600V-Single-Phase-Diode-Bridge-Rectifier-Power-Module-60-100-150-200-300-400A-G/142636237023?hash=item2135c840df:m:mHdv3EQvIAK-AnA4EtBmkeQ:rk:10:pf:0
You will also need a heat sink, a piece of 6 mm x 50 mm x 150 mm aluminium would be ideal.
The Selenium diode in the top box can be replaced with a modern silicon diode, something like this should be fine https://www.ebay.co.uk/itm/1N5408-Diode-Silicon-Rectifier-Bridge-Diode-3A-1000V/201950776806?_trkparms=aid%3D555017%26algo%3DPL.CASSINI%26ao%3D1%26asc%3D20160706105120%26meid%3D2e29568a7e32460eb9b9b0afffde8b2c%26pid%3D100508
You will need to be very careful to mark the wires connected to the old bridge rectifier to ensure polarity is right when fitting the replacement. Take lots of photos as you go. You may find that the lugs on the old wiring are the wrong size to fit the screws on the new rectifier. You will probably need to solder on some new lugs. Yes I use solder, I do not trust crimp connectors on any wiring supposed to handle 240 Volt at 30 Amps
When you mount your new bridge rectifier it should look something like the photo
Bob
-
Hi Alex, 240 Volt AC is a sine wave it swings from +380 volt to -380 volt. Get a Bridge rectifier that is good for 1000 volt. I personally prefer ones with screw terminals, something like this would be ideal https://www.ebay.co.uk/itm/1600V-Single-Phase-Diode-Bridge-Rectifier-Power-Module-60-100-150-200-300-400A-G/142636237023?hash=item2135c840df:m:mHdv3EQvIAK-AnA4EtBmkeQ:rk:10:pf:0
You will also need a heat sink, a piece of 6 mm x 50 mm x 150 mm aluminium would be ideal.
The Selenium diode in the top box can be replaced with a modern silicon diode, something like this should be fine https://www.ebay.co.uk/itm/1N5408-Diode-Silicon-Rectifier-Bridge-Diode-3A-1000V/201950776806?_trkparms=aid%3D555017%26algo%3DPL.CASSINI%26ao%3D1%26asc%3D20160706105120%26meid%3D2e29568a7e32460eb9b9b0afffde8b2c%26pid%3D100508
You will need to be very careful to mark the wires connected to the old bridge rectifier to ensure polarity is right when fitting the replacement. Take lots of photos as you go. You may find that the lugs on the old wiring are the wrong size to fit the screws on the new rectifier. You will probably need to solder on some new lugs. Yes I use solder, I do not trust crimp connectors on any wiring supposed to handle 240 Volt at 30 Amps
When you mount your new bridge rectifier it should look something like the photo
Bob
Thanks Bob, I really appreciate this. I will order the parts tomorrow. You mention ensuring polarity is right which I understand but what I don't know is which wires are positive and which are negative on the existing rectifier? also, which is the selenium diode in the top box? there are so many things there i don't know what's what.....
the journey continues!
thanks
alex
-
Hi Alex. If you look very closely at the photo you originally posted. there are six wires connected to the old selenium rectifier. The two larger wires nearest to us in the photo are AC, one goes to the slip rings and one to the neutral in the connector block. Also connected to the same lugs are two smaller wires which go to the rheostat. Polarity on these smaller wires does not matter.
The two other large wires, furthest from us in the photo, are the auxiliary winding wires. One has a red end the other is white. The red one should be positive but we will check later by comparing it to mine. We will also be checking the resistance across all these windings and comparing them to mine.
The selenium diode in the top box looks exactly the same as the one in the side cover except that it has only four vanes on it. Something like the photo attached.This should only have two wires attached to it. white and yellow. The white wire goes to the positive on your battery. The yellow goes to the charging circuit. We will replace this with a silicon diode using a new terminal block similar to the main connector block in your top box.
You will also need some new crimp connectors, as you can see from the photo, they come in different sizes for different wire thickness and to fit different terminal screw size. These will be soldered so do not worry about buying an expensive crimping tool. I can not tell you which lugs you will need as I do not know what size your new bridge rectifier screw terminals will be. You should also try to get some heat shrink, also shown in the photo, you will need red and black in around 6mm diameter. You local electrical retailer should have all of these items in stock for very little money.
We should also check the condition of the carbon brushes on the commutator ring and slip rings while we are about it.
Bob.
-
Like Bob, I once preferred soldered connection. Alas, the technical consensus today is that for many applications crimp connections are superior.
Solder does insure good connection, but also causes embrittling of copper wires since copper gets hardened by slow cooling, and softened or annealed by fast cooling. It's the opposite of steel and iron. So good quality crimping (with the proper crimp tool) is often a better choice, especially when vibration is present and the individual wire strands are not so large as to assure non-breakage with continued mechanical stress. With a soldered connection, there is a big mechanical stress riser right after the edge of the terminal, where the wires are no longer supported by the terminal. With vibration stress, this is where the wire/strands will break off over time as the heat hardened copper succumbs to stress cracking.
This is the reason you will find virtually no soldered connections in the automotive engine compartment. They crimp to reduce costly in-warranty troubleshooting and repairs.
It is strongly counter-intuitive to think that a crimp is better, but were there is vibration, it really is...just because of the very odd tempering characteristic of copper.
-
Hi Alex, 240 Volt AC is a sine wave it swings from +380 volt to -380 volt. Get a Bridge rectifier that is good for 1000 volt. I personally prefer ones with screw terminals, something like this would be ideal https://www.ebay.co.uk/itm/1600V-Single-Phase-Diode-Bridge-Rectifier-Power-Module-60-100-150-200-300-400A-G/142636237023?hash=item2135c840df:m:mHdv3EQvIAK-AnA4EtBmkeQ:rk:10:pf:0
You will also need a heat sink, a piece of 6 mm x 50 mm x 150 mm aluminium would be ideal.
The Selenium diode in the top box can be replaced with a modern silicon diode, something like this should be fine https://www.ebay.co.uk/itm/1N5408-Diode-Silicon-Rectifier-Bridge-Diode-3A-1000V/201950776806?_trkparms=aid%3D555017%26algo%3DPL.CASSINI%26ao%3D1%26asc%3D20160706105120%26meid%3D2e29568a7e32460eb9b9b0afffde8b2c%26pid%3D100508
You will need to be very careful to mark the wires connected to the old bridge rectifier to ensure polarity is right when fitting the replacement. Take lots of photos as you go. You may find that the lugs on the old wiring are the wrong size to fit the screws on the new rectifier. You will probably need to solder on some new lugs. Yes I use solder, I do not trust crimp connectors on any wiring supposed to handle 240 Volt at 30 Amps
When you mount your new bridge rectifier it should look something like the photo
Bob
Thanks Bob, I really appreciate this. I will order the parts tomorrow. You mention ensuring polarity is right which I understand but what I don't know is which wires are positive and which are negative on the existing rectifier? also, which is the selenium diode in the top box? there are so many things there i don't know what's what.....
the journey continues!
thanks
alex
Bob,
I guess the 60 Amp option is the one I want on the Bridge Rectifier available on the ebay link you sent me?
Alex
-
Hey Alex, yes the 60 Amp unit will be more than adequate for what you need, it`s also the cheapest. ;D
Bob
-
ok thats ordered....and 3 amps is ok for the modern silicon diode as shown in the ebay link you sent me? i assumed it would need to be bigger (30 amp?) ! thanks
alex
-
Hi Alex. the link I sent you was for a pair of 3 Amp diodes. The battery should only be charged at about 1 to 2 amps otherwise it will over charge and get hot. If you are concerned we will use both diodes in parallel which would give you six amps on the charging circuit.
Bob
-
Hi Bob
Good news, the parts are here (photos below) ! i need to find some 6mm wire today but, in the meantime, I guess i can get to work although I haven't got a clue what goes where!
Alex
-
Hi Alex, sorry I didn`t get back to you sooner but I had to go away for another round of medical tests and assessments. Total waste of time as the experts I visited didn`t have the results from any of the recent tests I had done. The Doctor I was seeing is the top Government assessor, I think he is really pissed that he didn`t have the most recent information in front of him and said he would be contacting the regional Judge to complain. Some one is going to get a reaming, bloody sure it`s not going to be me. :laugh:
Bob
-
Hi Alex, sorry about the confusion about when you wanted to make a start on this revamp, thought you were still waiting on parts.
Your fist job is to remove the selenium bridge rectifier and old rheostat from the plastic cover. Clean up the cover and fabricate a couple of L brackets to mount your heat sink. Then fit your new rectifier onto the heat sink. I found self taping screws worked very well into the aluminium heat sink. (see photo)
Second job is to disconnect the rheostat from the old selenium rectifier, give it a bit of a clean. If you are as obsessive as me you can give it a coat of high temperature spray paint (these get hot, exhaust pipe paint is ideal). Next is to refit it to the plastic cover and reconnect the wiring. You will need to fit new lugs to accommodate the larger screws in the new rectifier, use solder or quality crimp fittings (not the cheap sh1t they sell in auto centers), heat shrink is optional but I think it makes for a safer/more professional finish. The two wires connect to the side of the rectifier marked with a squiggle/sine wave symbol, the polarity does not matter for the rheostat. (see photo)
Third job is to remove the front plastic cover and clean up the larger rheostat found within, when you are done it should look like the photo.
Bob
-
Hi,
I read with interest about the selenium rectifiers. I have a SL SOM 4.5kva. The control box (on the wall) smells a bit like Garlic and the unit is 1960's - so I assume its about had its day! Is the SOM job similar to the one described in this thread? Also is the rectifier in the SOM in the wall box or the one on top of the head?
Cheers,
Jonny
Hi Alex, there is a very good reason I mentioned modifications, the thing in my original photo, that looks like an old fashioned school radiator, is an old selenium bridge rectifier. They have a life expectancy of around fifty years, yours is due to fail. It will smell of garlic when it does start to fail, please don`t breath this in as it can cause cancer.
It s a very easy fix to replace the selenium rectifier with a more modern silicon rectifier and heat sink, all the parts are available on fleabay for about ten quid. No, I am not trying to sell you something and no, I can`t come and do the work for you. I live in Northern New South Wales , Australia. I live in the middle of nowhere and rely on a old 1970`s Lister/Brush generator for back-up power. If you rely on your generator for primary power you should replace the selenium rectifier before it fails.
Where in Berkshire do you live? I was unlucky enough to go to school in Pangbourne, Berkshire.
I completely understand your concerns regarding starting handles. Many full grown men have been injured by these, children do not belong anywhere near them. If you are hand starting your generator please regularly grease the shaft and ratchet pin so you don`t get hurt.
Bob
-
Hi Jonny, could you please post some photo's of your control box internals. Want to see if it is similar to mine. I am also having battery charging issues on my SR2 SOM
-
Sure will, I'll try and get a few tonight.
It seems a common problem, many people plug in a battery charger; but I don't like to let it beat me!
Cheers,
Jonny
-
Hi,
See Pictures below of my unit internals.
One thing that worries me is that there appears to be a high voltage connection to the Fuel Control Solenoid, which i would expect to be 24v......
Any advice from anyone on how to improve safety of the unit appreciated.
Jonny
-
Bummer, totally different from my setup, but thanks for the shots.
-
Hi Guys, I`ve missed a bit of this thread because of very severe storms and flooding locally.
The fuel control solenoid should be 24 volt, it has two sets of windings in it. One high powered to open the rack and a second smaller coil to hold it open. There is a small relay built into the top of the solenoid to deactivate the high powered coil.
There is a third relay which releases the de-compressor levers, this one is a 240 volt unit and engages compression as the voltage ramps up during the starting cycle.
I sincerely hope the wiring has not been messed with and the 24 volt and 240 volt confused.
Bob
-
Thanks Bob, the decompression works correctly, so i must not be tracing the wires correctly at the junction box on the side of the engine.... I'll meter them and see if i can make any more sense of it.
On the charging problem, I've found the problem, the resistor is damaged. Any ideas on repair/replacement? Could i re wind it with resistor wire?
Cheers
-
Hi Jonny, have a look here for Power resistors they might have what you need or make you a special if you give them the specifications, could be expensive.
https://www.ohmite.com/catalog/power-resistors
If you can find the right gauge of resistor wire it would be very easy to rewind.
Bob
-
There are also adjustable wire wound power resistors in various wattages, see Digikey or Mouser.
-
I saw those Bruce, look like exactly what would be required, didn't find an exact match for resistsnce and power, though i need to confirm requirements first....
-
A rated wattage above your needs is not a problem. Once you get Bob's info on values, if you need help, let me know. You can always put resistance in parallel or series to get the values you need, either in resistance or wattage.
-
Hi Alex, sorry about the confusion about when you wanted to make a start on this revamp, thought you were still waiting on parts.
Your fist job is to remove the selenium bridge rectifier and old rheostat from the plastic cover. Clean up the cover and fabricate a couple of L brackets to mount your heat sink. Then fit your new rectifier onto the heat sink. I found self taping screws worked very well into the aluminium heat sink. (see photo)
Second job is to disconnect the rheostat from the old selenium rectifier, give it a bit of a clean. If you are as obsessive as me you can give it a coat of high temperature spray paint (these get hot, exhaust pipe paint is ideal). Next is to refit it to the plastic cover and reconnect the wiring. You will need to fit new lugs to accommodate the larger screws in the new rectifier, use solder or quality crimp fittings (not the cheap sh1t they sell in auto centers), heat shrink is optional but I think it makes for a safer/more professional finish. The two wires connect to the side of the rectifier marked with a squiggle/sine wave symbol, the polarity does not matter for the rheostat. (see photo)
Third job is to remove the front plastic cover and clean up the larger rheostat found within, when you are done it should look like the photo.
Bob
Bob
I have finally done the job! see photos below. What next? I guess i need to put the other wires on but what goes where?! Thanks for your help with this and a belated Happy Christmas and a very Happy New Year!
Regards
Alex
-
Hi Alex, happy new year to you and yours, welcome back. Congratulations on the quality of you work, very professional.
You should now have four blue wires hanging out of your generator. Two of them have black heat shrink on them. These two are the AC side of things and are connected to the rectifier using the same two lugs that your rheostat is connected to. (sine wave marks on rectifier) The polarity does not matter as these are alternating current.
Once those two are connected, you should now have two blue wires left one will have a red heat shrink on it, this is the positive and needs to be connected to the lug on the rectifier marked +.
The last wire should have a white heat shrink on it, this is the neutral and should be connected to the rectifier lug marked -.
You will probably need to fit new lug terminals to the wires coming out of the generator, as the screws in the new rectified are larger than on the original. Do these one at a time and replace the heat shrink to match the original color coding as you go, you do not want to get them muddled up.
Have fun,
Bob
-
To Jonnymac
On the charging problem, I've found the problem, the resistor is damaged. Any ideas on repair/replacement? Could i re wind it with resistor wire?
I have rewound a few of these resistors in the past and buy the wire from these people https://wires.co.uk This is the wire that I used Bare Constantan.
50g 0.71mm Copper Nickel Wire
Ref: CN0710-050
Price: £5.44 Exc VAT (£6.53 Inc 20% VAT)
50 gram reel of 0.71mm 22 SWG Bare Copper Nickel Wire (Copper Nickel = Constantan = Eureka)
Data: approx: 1.24 ohms per metre, 50g = approx 14 metres
This was correct for the resistor that I needed yours will probably be different. What I did is count the number of turns. Measured the diameter of the resistor calculate the circumference the multiply that by the number of turns to give the length of the wire needed. In my case it worked out to 8 meters of wire needed for 115 turns to give me the 12 ohms required. Also you need to measure the diameter of the actual resistance wire.
Nickel Chrome resistance wire is also available but would have only filled about half the resistor. But It might have been used in your case. This why you need to do a bit of maths so you don't get the wrong wire.
50g 0.71mm Nickel Chrome Wire
Ref: NC0710-050
Price: £6.75 Exc VAT (£8.10 Inc 20% VAT)
0.710mm 22 SWG Bare Nickel Chrome Wire (also known as Nichrome Wire / Hot Wire Cutter / Foam Cutter / Heater Wire / Element Wire)
Data: approx 2.7 ohms per metre, 50 gram = approx 15 metre
Mick
-
Nice to learn about Constantin alloy as a resistance wire, listeroil, thanks!
Might be very useful where very high currents demand lots of area of lower resistance heating wire.
-
Hi Listeroil, perhaps you can explain to me how these are wound as tight as they are without any insulation. Did they acid etch them or coat them with something to to stop them from shorting between the windings?
I have found that high temperature paints work for restoration but am curious about the original insulation.
Bob
-
Hi Alex, happy new year to you and yours, welcome back. Congratulations on the quality of you work, very professional.
You should now have four blue wires hanging out of your generator. Two of them have black heat shrink on them. These two are the AC side of things and are connected to the rectifier using the same two lugs that your rheostat is connected to. (sine wave marks on rectifier) The polarity does not matter as these are alternating current.
Once those two are connected, you should now have two blue wires left one will have a red heat shrink on it, this is the positive and needs to be connected to the lug on the rectifier marked +.
The last wire should have a white heat shrink on it, this is the neutral and should be connected to the rectifier lug marked -.
You will probably need to fit new lug terminals to the wires coming out of the generator, as the screws in the new rectified are larger than on the original. Do these one at a time and replace the heat shrink to match the original color coding as you go, you do not want to get them muddled up.
Have fun,
Bob
Bob
Many thanks for this. I have had a DISASTER!!! I went and cut the ends off without marking them before I put the new lug terminals on.... impossible to believe I know but I have done the unthinkable. The lesson for me is not to do something like this on New Year’s Day after a big night out!!! So I am now totally screwed....
Alex
-
Bob
further to my last....i have had a closer look and see two of the wires run to the shiny things in the photo below. Are these the ones that go to the sine screw on the rectifier? if so that accounts for two of the wires and just leaves the other two to work out.....
I have looked at the larger rheostat on the other side and see the copper band is broken. may be that caused the issue? can i just replace it with the one i took off the smaller rheostat that i cleaned up yesterday....it didn't have a wire off it so i assumed it wasn't needed....pics below.
thanks
Alex
-
Ok Alex, don`t panic. One wire on the AC side of things goes to the slip rings (shiny brass things in your photo) the other AC wire goes to the neutral in your top box, you should be able to identify them with your ohm meter. These two wires connect to the two Lugs marked with a sine wave, the same lugs that your rheostat are connected to, polarity does not matter.
Of the other two wires one should be about four inches longer than the other, The longer one is the neutral and the shorter one the positive.
The Copper band can be replaced with the unused one off the other rheostat. This rheostat feeds the main field windings and would certainly explain your lack of power generation, well spotted.
Hope you have recovered from the excesses of new years eve
Bob
-
Bob
Thanks for this! I’ll get the copper band done immediately...... it has slipped down so where should I put it on the rheostat?
Regarding the wires.... you mention checking the ohm readings but I don’t know what I am looking for. I have the four wires and an ohm meter.... what next? Sorry for being hopeless!
Thanks again
Alex
-
Actually I have worked it out now!!! I’ll revert ASAP!
-
Hi Alex, The main field rheostat ( the one in your recent photo) allows you to adjust the output voltage from your generator. A low resistance will push it up to 240 volts, while a higher resistance will drop the output to around 210 volts. If you can`t see where it was originally positioned stick it halfway and we can adjust it later.
Checking wires out with an ohm meter isn`t rocket science, I worked out how to do it and I`m as dumb as a brick. What you need to do is turn your meter to the ohms range, then touch the two probes together, the screen should show zero ohms. What that proves is that the two probes are connected to one another. Now if you put a piece of wire between those two probes it will also show 0 ohms resistance, proving that one probe is connected to the other probe via that wire.
So if you put one probe on the neutral terminal in your top box, one of your four wires will give a zero reading with the other probe. That wire is one of the AC wires and goes to one of the sine wave marked terminals. Now do the same by sticking one probe onto one of the shiny brass slip rings, use the other probe to identify which of the remaining 3 wires is connected to it. This is the other AC wire and should be connected to the other lug marked with a sine wave.
I explained the other two wires earlier but if you have any doubts I am happy to explain further.
Don`t feel intimidated or scared of this task, so far you are doing very well. It`s better and a lot cheaper to not know and ask, than to think you know and learn the hard way that you don`t!
Have fun,
Bob
-
Hi Bob
OK all done. I fired it up and checked the ohm reading on the red/black terminals on the top box and it says -1 .......!! can't seem to get any voltage readings anywhere either.
alex
-
Hi Alex, can`t do this tonight because it is black as pitch outside and well past my bed time. In the morning I will get some more ohm readings for you to compare and then talk you through flashing the main field windings. Photos of what you have done would help.
Bob
-
Bob
See photo below
The rheostat is connected to the sine screws as is the top box and the rotator arm.
positive and negative are, I believe, correct....the negative is the higher of the two where it goes into the windings.
thanks
alex
-
Bob
Further to my post above I’ve had a thought.... when I flashed the rheostat wires a few weeks ago, was the engine meant to be running? It wasn’t...
Alex
-
Bob
Further to my post above I’ve had a thought.... when I flashed the rheostat wires a few weeks ago, was the engine meant to be running? It wasn’t...
Alex
When I do mine, it's with all gear shut down. The flash provides some residual magnetization which allows the generator to produce power. Just disconnect loads before it spins down. Spinning down with a load, erases the residual mag.
-
Hi Alex, before anyone goes flashing anything, I want you to do a couple of resistance tests for me.
The first is the resistance between the two AC output connectors in the top box. Mine reads about 3 ohms.
The second is the resistance between the two slip rings, please insulate the four carbon brushes with pieces of paper as per the photo and then stick your ohm meter probes onto the two rings. Mine shows a resistance of between 0.6 and 0.7 ohms.
The third thing I want you to do is to disconnect one wire from the larger rheostat in the front of the generator. See photo. One of the two wires is connected to neutral and the other is connected to the main windings, we need to know which is which.Please put one of your probes onto a clean bolt or screw on the body of the generator, now touch the other probe onto each of the two wires in turn. One of them should give a reading of 0 ohms, this is the neutral wire. Please mark it with a piece of insulation tape so we know that is the neutral.
Next I want to know the resistance between those two same wires. Mine reads 8.2 ohms.
Please report back with your findings.
Bob
-
Hi Alex, I`m thinking we have got a couple of the wires on the rectifier muddled up. Please see the documents and edited photos attached. Please also disconnect the two radio suppression condensers from the slip ring brush holders before doing your tests, as these can play havoc with the readings.
Bob
-
Bob
Hi Listeroil, perhaps you can explain to me how these are wound as tight as they are without any insulation. Did they acid etch them or coat them with something to to stop them from shorting between the windings?
I did not consider insulation just wound it up as tight as I could and used it. It worked okay. However it makes sense to use insulated so I checked the website and they do sell oxidised wire and that appears to be insulated.One thing I will say is that all the resistors in Lister top boxes that I have seen have black windings and also a brand new one that I bought years ago. That one cost me £50 which is why next time I needed one I rewound it instead of being ripped off by Sleeman and Hawkins
Mick
-
Hi Alex, I`m thinking we have got a couple of the wires on the rectifier muddled up. Please see the documents and edited photos attached. Please also disconnect the two radio suppression condensers from the slip ring brush holders before doing your tests, as these can play havoc with the readings.
Bob
Bob
Can you tell me which numbers relate to what in the top box? The diagram is great but i don't know what is what! apologies for my ineptitude! many thanks
regards, alex
-
Hi Alex, I`ll try and add some more numbers and details to explain everything in the top box. I`ll also check what the resistances are so you can compare them with yours. Will try to post the results in the morning.
Bob
-
Hi Bob
Thanks....I am looking for 1,2,3,4,5,6,7,8,13 and 18
Regards
Alex
-
No worries Alex, most of the numbers you mention are inside the generator, rather then the top box but I`ll edit the photos and post them in the morning.
Sorry it takes so long but I live about 11 hours out of sinc with Berkshire, UK. Hope you don`t have any major power outages while we are getting this sorted.
Bob
-
Hi Alex please see the attached photos (with numbers and arrows) I have also attach an edited wiring drawing having adding a few more numbers. Please note that I do not know which of two wires is connected to lugs 2 and 6 on the drawing. Please put your black probe on 1 and the red probe on 2 it should read 0.1 ohms if it does not please put the red probe on 6 it should read 0.1 ohms if it does. please swap the numbers on the drawing to reflect that 2 and 6 are reversed. (it makes no difference with alternating current).
The extra numbers on the drawing are not relevant at the moment, but could you please also the resistance between 1 and 19 ( black probe on 1, red probe on 19) should read 0.1 ohm
Bob
-
Thanks Bob this is great. Sadly I won’t be able to do the test until the weekend but will get back to you as soon as I have done so! Thanks again. Alex
-
No worries Alex, get back to me when you can and hopefully we should be able to get her going again.
Bob
-
Bob
here are my readings, at last! i am worried about the amount of times i cam up withnothing! should i have lifted the brushes with cardboard?
thanks
alex
-
Alex
Sorry to butt in at this late stage but I have read through all the pages of this post and think you need to take a fresh look at your problem. I have been running these for 18 years and have rebuilt a few and this is a simple way of checking if your windings are ok.
When you start a generator with one of these dual function alternators you feed 24 volts into start windings which also feeds the main field winding as well which is the same as flashing the winding. So no need to flash the aux winding for any reason on these units.
What I would suggest is that you connect a 100 watt 240v incandescent light bulb directly to the 2 AC brush connections in the generator. Then start the engine and see what happens. The bulb should light up and stay lit when starter is released.
When I rebuild mine I do this before connecting the generator to the engine and use the starter function to spin the generator up. What happens is that as the revs increase the light get brighter and brighter as the revs build up. When I disconnect the start connection the bulb looses a bit of brightness but stays lit until the generator run down. If yours does this the windings are okay and your problem lies elsewhere.
Mick
-
Hi Mick, please don`t feel that you are butting in, any and all good advice that we can give to Alex will be appreciated.
Alex I will have a good look through your findings and get back to you this evening. From a very quick look I believe we have a pair of wires mixed up on the bridge rectifier. The good news is that you have continuity between the slip rings, so those windings are OK.
Bob
-
great, many thanks! I look forward to hearing from you.
Mick, I will give that a go to but would be grateful if you could let me know which the two AC brush connectors are! Thanks
Alex
-
Alex
The AC brush connections are the ones that go to the slip rings.
Mick
-
People like me who have a few gen heads but know nothing of their innards could learn a lot from this thread and it's digressions
I wonder if it is WOK material?
It seems to me there's good basic stuff here I might like to refer to later - so possibly others are in the same boat?
Cheers
-
Hi Mike, if I ever get the time it might be worth doing a complete strip down and rebuild of my Brush generator head. I could then post photos, wiring diagrams and resistance figures. There seam to be quite a lot of these generators still in out there.
Hi Alex, I was a little baffled by some of the readings you sent me. Having studied the wiring in your top box, the neutral and positive AC outputs on yours are different to mine, reversed. Thus 1 and 13 are reversed on your model. Please check the resistance between 13 and 2, also the resistance between 1 and 12 and get back to me.
The other thing that concerns me is that you do not have continuity between the slip ring (11) and the brush holder (12), could you please check the condition of the brushes, holders and wiring connections then check the resistance again.
Bob
-
Bob, that would be great, please find the time. From reading this thread, it would seem that the Brush unit is pretty much the same thing as my Hoffberg, and i would really like to know more and upgrade/modernise the thing.
-
Hi Dax021. I`m happy to do the disassembly and rebuild and document it for others. I just can`t do it any time soon due to the threat of rolling blackouts. Between the government, big business and environmental groups they have contrived to produce an electricity shortage in a country with the highest coal reserves on earth. High prices, low reliability and no investment for the future. The generating companies are coining it in, the government are doing the same. Small businesses are going belly up and house holders are footing the bill and sweltering in houses without power, large energy consumers like steel and aluminium smelters are being asked to shut down production.
I`m expecting to need my generator in serviceable condition for the immediate future. Happy to do the documentation once silly season has passed.
Bob
-
Bob
I look forward to this....I feel it wouold be best to strrip mine down as there is so much cr#p in it (dust etc) and some of the wires have been chewed. Perhaps I should do this anyway so we can get some decent resistance readings using the new wires, screws etc?! I might as well paint it at the same time! Mechanically it is fine and was generating electricity perfectly until i let it run down with the load still attached. I am not worried about powercuts so don't have to wait to do the job (and its not generating anyway as you know!)
Alex
-
Hi Alex, I feel like I have let you down somehow, we should have this sorted out by now but it is difficult to diagnose problems from the other side of the world. We will get there in the end. I am glad that the UK power supply is stable for the time being. The UK is currently importing large amounts of electricity from the continent and has ramped up it`s coal fired generation to deal with demand during the cold weather.
Nuclear power stations and coal fire plants are at the end of their useful lives so there is going to be a shortage, lack of government forward thinking has caused two nuclear projects to be canned. Just imagine how popular you will be when you are the only house in the street with power. :laugh:
Bob
-
Bob
Please do not feel that you have let me down.....quite the opposite!
I will get back ASAP with the resistance readings and we can take it from there.
thanks again
Alex
-
Hi Mike, if I ever get the time it might be worth doing a complete strip down and rebuild of my Brush generator head. I could then post photos, wiring diagrams and resistance figures. There seam to be quite a lot of these generators still in out there.
Hi Alex, I was a little baffled by some of the readings you sent me. Having studied the wiring in your top box, the neutral and positive AC outputs on yours are different to mine, reversed. Thus 1 and 13 are reversed on your model. Please check the resistance between 13 and 2, also the resistance between 1 and 12 and get back to me.
The other thing that concerns me is that you do not have continuity between the slip ring (11) and the brush holder (12), could you please check the condition of the brushes, holders and wiring connections then check the resistance again.
Bob
Bob
I have the readings.....between 13 and 2 is 1.9 ohms and between 1 and 12 is 0.5 ohms......
As the neutral and positive AC outputs are opposite to yours, could i have put everything back together back to front when i replaced the bridge rectifier etc?
I have checked between 11and 12 again...it shoots up to a reading between 107 and 170 ohms and then drop back to 1 ....
i am confused!
alex
-
Hi Alex thank you for your findings. I am a little confused by the resistance reading between 11 &12 (slip ring and slip ring brush holder), I suspect the brushes and slip rings may be a little dirty causing the anomalous reading.
I would like you to check the connections on the new rectifier.
What I would like for you to do is undo all the lugs on the new bridge rectifier. Remove the four large wires, you can leave the two small black wires that connect to the rheostat. Using your multi-meter, on Ohms, put the black probe on 13 and then touch the red probe on all of the four loose wires, one by one. One of them should read 0.1 ohms. Connect this wire to number 2 on your new rectifier, along with the wire to the rheostat. Please check that this terminal has the sine wave symbol next to it.
This leaves you with three wires please use your meter to test between these wires, two of them will make a circuit with a resistance of 0.3 to 0.4 ohms. These two are the auxiliary field windings, the longer of these two wires should be the +ve and needs to be connected to number 7 (please check it has a + sign). The shorter of these two wires is the -ve and needs to be connected to number 8 (please check it has a -sign).
This will leave you with only one wire this needs to be connected to number 6, along with the small wire to the rheostat.
Now please check the resistance between 1 and 13 you should have a circuit showing around 4 ohms.
Bob
-
Hi Bob and apologies for the delay in replying.
Ok, I have done everything you asked and the readings were slightly higher than yours. However, on the final task (measuring between 1 to 13) things go wrong. the meter jumps to about 26 ohms instantaneously and then drops back to 1 .....i feel the whole generator probably needs rewiring!?
thanks
alex
-
Hi Alex, nothing to panic about. The important thing is that you now have continuity between 1 and 13, so it should be able to generate electricity. The slightly odd reading you get might be caused by dirty brushes or slip rings, it could also be caused by the two radio frequency condensers if they are still connected or it might be that the very low voltages produced by a multi meter are not high enough to quickly trigger the diodes in a bridge rectifier rated at 400 volts 60 amps.
Could you please check the resistance between 13 and 14 (black probe on 13) should read 0.1 ohms, 13 and 15 (black probe on 13) should read 2.7 ohms, 13 and 16 (black probe on 13) should read 0.3 ohms and lastly 13 and 17 (black probe on 13) should read 0.1 ohms.
Let me know what you get, no surrender!
Bob
-
ok i have continuity between 13 + 14 but it is up at 112 ohms! 13 + 15jumps up to between 40 - 120 ohms then back down to 1 straight away. i can't get continuity between 13 + 16 and between 13 + 17....... I am beginning to wonder id i should strip it down and rewire it?! thanks. alex
-
Hi Alex, I think we are getting close to diagnosing the problem, You should have continuity between 13 and 16/17. Without it you will not energize the main field. Please confirm continuity between 13 and 19; please also confirm continuity between 22 and 16/17.
Bob
-
Hi Bob
no continuity between 13 and 19 (the battery negative input)
no continuity between 22 and 16 / 17
The engine turns over ok with the starter pressed down.
when the problem started originally it was generating fine but i let it shut down whilst still connected to the house so i feel everything is ok albeit a little antiquated? what do you think'?
thanks
alex
-
Hi Alex, I`m pretty sure everything on the output side of things is OK. Start it up and see what happens, the main field winding should be energized during the starting process. My only concern is the lack of continuity across that main field winding. The problem might be the connections on the wire wound rheostat.
Bob
-
Hi Bob
great news....it's working. I attached a lamp to the red/black outputs in the top box and the bulb is burning brightly! Thank you for all the help with this, I really do appreciate it. OK, my next project is to strip it down and rewire everything....it is filthy and some of the wires have been nibbled by mice so it is long overdue. What do you think? I can't see how to open it up for a start and, secondly, don't know which wire is should be looking to buy....
thanks
Alex
-
Well done Alex! I am so glad to hear the old family heirloom is back in action. You should certainly repair any wiring that has been damaged by mice or age. I would recommend that you try to find as close a match to the original wires as possible, When I did mine I found that some auto parts places had a very good range of different coloured wires in different gauges.
Looking forward to seeing the results.
Bob
-
Thanks Bob. One question, is there an easy way to dismantle it? I can’t see an obvious way of gaining access to the internals!