Lister Engine Forum
Lister Engines => Original Lister Cs Engines => Topic started by: vegoil on January 24, 2019, 06:38:12 PM
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my startomatic has stopped working it has been starting and stopping when a load is switched on or off.
now it will not auto switch on. the only way that I can get power from the old Lister CS8/1 is to hold up the exhaust lifter put the switch on the control panel to manual and push the start button if you get what I mean.
I think that it may be a capacitor 50uf 350v DC
has anyone had this happen to you?
I will try to put on photos!
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That cap looks in rough shape, so a replacement would be the first thing. But I don't know if it's in the starting circuit with that high of a voltage rating.
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Throw that Cap away and replace it with a new one. That cap stops the start relay from chattering while it is running and burning out the contacts. Replace it with with a 50 uF 400 volt cap.
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Can I put in a AC/DC or AC or dose it have to be DC only
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Either is fine but a DC electrolytic will be cheaper and can do the job. An AC rated (metal film- motor run type) cap will be much larger and more expensive.
I don't have a SOM, and don't have a wiring diagram for it. The question might be why did that cap fail...if it's what's causing it to not start now.
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I think the reason that it failed was old age and damp, the control box had been stored in a leaky damp out building for many years before I bought it. The other possible reason is the engine house that it all lives in now heats up to 40*C. maybe a combination of the Two.
all the points in the control box look in good order.
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Hi Vegoil, sorry I didn`t get involved in this conversation earlier. There are several reasons why an SOM does not auto start. None of them involve the large rectifier and associated capacitor.
For these to start 12 volts has to flow through the detection circuit and closes the small relay, this triggers the start up sequence, the switch must be on Auto and there must be a load. Once the generator is up to speed and making 240 volt AC, the large rectifier and capacitor turn some of this 240 volts AC into 350 volt DC. This DC voltage is used to close the large relay switching 240 volt AC to the load and switching over the 12 volt DC detection circuit to a rectified 12 volts generated across the wire wound toroidal core.
Once the load current stops flowing the rectified 12 volt also stops, opening the small relay and triggering the shut down sequence.
If you manually close the small relay (don`t use your fingers!) does this trigger the start sequence? With a load applied does the generator sustain generation if you manually close the small relay? (Switch in Auto position)
There should be two old rectifiers in the control panel, strongly recommend you replace these with modern diodes, the smoothing capacitor on mine is only 4 micro-farad so 25 would be fine, it must be rated at no less than 400 volt. When working with large capacitors like this always short across the terminals before handling, 400 volts DC will give you a nasty shock!
Please also clean and adjust Line contactor 2 on the large relay.
Bob
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thanks for the advice .
I have turned the switch to auto closed the small points on the small coil (marked with the letter D) the engine stated with 24 volt once up to speed it switched over to 230v and also was putting a charge back into the batteries after a while I released the small points the engine stopped.
for some reason the photos have come out side on!
cheers
John
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Sounds like both the 12v autostart detection circuit isn't working, and the ac current sensing isn't working either. Something common to both is perhaps out. Hopefully Bob can get you sorted. I have printed out your wiring diagram and will study it.
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Thank you John for posting the wiring diagram. Yours varies considerably from my later model SOM, however the basic concept is the same.Current flows from the battery +ve through the battery fuse, it then runs down the drawing until it hits PC/2 (normally closed contact on the main relay). It then runs through J/1, PC/4 (normally closed contact on main relay) and DR (wire wound resistor) from there it travels to the solenoid coil D and a capacitor. It cannot flow through the rectifier R because the rectifier will only allows current to flow in the opposite direction. The current should then flow through the solenoid coil , at the same time it will also charge the capacitor. The current will then flow through IS/2, through the load (whatever you have connected to the generator) and then back to the neutral on your battery, completing the circuit. The current flowing through this circuit energizes the solenoid coil D causing the relay D/1 to close beginning the starting sequence.
Since the generator starts and generates when you manually closed D/1 (small solenoid relay)we can not rule out the rectifier and capacitor as these provide the DC voltage which power the solenoid coil on the small relay once the unit starts to generate. we also need to check the normally closed relay contacts PC/2 and PC/4 on the large relay, J/1 and DR (wire wound resistor), the the solenoid coil D and finally the switch IS/2. Sadly I have no idea what is inside of J as my SOM has transistorized switching rather than a relay mechanism.
If you have a multi-meter please check the resistances across all of these(recommend you disconnect the battery before doing this). It is also possible that there may be a damaged or broken wire somewhere so please check the continuity of the yellow/pink wires connecting all these components together. When testing the rectifier it should only pass electricity in one direction so please check the resistance one way and then reverse your probes and check it the other way. Please get back to me with what you find.
Bob
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Well done, Bob. I could not figure out the Lister diagram shorthand until you talked us through coil D/1 driving relay D/1. Having a legend for all the symbols would have helped, I didn't even find the battery until your description helped me find it.
I am in fact a lousy electrical technician; good ones can leave me in the dust in sorting out someone else's design and notations.
The use of a relay coil for sensing the DC current is the sort of thing you just don't see much in modern designs. How the D/1 coil manages to cope with the with the high voltage rectified AC as well as 12 or 24 VDC is rather baffling to me. But I also don't know what the mysterious A is, as well as many other mysteries in this diagram.
I don't suppose Lister provides a legend for the many symbols?
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Hi Bruce, the drawings pasted into the back of the control panels are not designed for people who understand electrical diagrams. They can be a bugger to decipher, but are actually for the use of the average mechanic, they have more in common with plumbing diagrams than electrical drawings. I guess that`s how they did it 50+ years ago.
The mysterious A is an amp meter on the front of the control box telling you if you are drawing or feeding current to your batteries.
The solenoid coil D only has a resistance of about 6.2 ohms on my setup, however there is a resistor in line with it (DR) which is designed to keep the current to the absolute minimum required to open relay D/1.(on my SOM this is an adjustable wire wound rheostat allowing for fine tuning).
Now we get to the bit you know all about, the toroidal core(choke)and the AC windings around it produce a back EMF that is rectified to produce around 9 volt AC, this is rectified and smoothed to give around 12 volt DC this feeds the solenoid coil D and keeps D/1 open.
This is a beautifully simple system, however I would not ever recommend trying to start one of these by plugging in your Iphone or any other piece of sensitive equipment. Please use something simple like an incandescent light bulb to trigger generation. Once it`s generating, plug in what ever you like.
Bob
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Hi Bob
I have taken the large capacitor ( 50uf 350volt) out from the board and I have tested the capacitor and it is dead. no reading from + to - or - to + but dead short from neg to the case.
I have ordered a replacement hopefully it will be here next week
Is there an ease way to test the rectifier without soldering it from the wires. I am hoping that it was just the capacitor that is faulty!
cheers John
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Hi John, The rectifier will only allow current to flow in one direction. Test the resistance across it, then reverse your meter probes and test the resistance across it again.You should get a low resistance reading one way and a very high or no circuit resistance the other. If it is defunct it can easily be replaced with a modern IN4004 diode using a terminal block connector. I would recommend you do this anyway as the old selenium rectifiers break down over time. The diodes are available on Epay for about $2 for a pack of ten.
Bob
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thanks for the help I will order the diodes right now. I will test the old rectifier tomorrow and let you know what I find. even if it is all right I will have the diodes for a backup.
Cheers
John
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John, When selenium rectifiers are failing they start to give off a garlic smell. This is mildly carcinogenic so please don`t take a big lung full. When you start to smell garlic it`s time to swap out the rectifier.
Bob
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Hi I have had a ohm meter on it and I get 1.3 ohm each way so am I right it thinking that it is Dead.
cheers
John
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Yes, it's kaput; the ohm meter test both ways is reliable. The failed diode caused the cap to fail.
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I have ordered the other capacitor the brown one 1uf 250v I suspect it may be blown as well would you be able to tell what way round it goes on the board as there are no + - markings on it. there is a small raised band around the left hand end. Is it the same as the blue one 50uf 350vDC + to the right hand side. If you look at some of the other photos.
cheers
John
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In the diagram there is only one other capacitor, marked "C". It's only a contact arc suppressor, which is consistent with it being a 1 uF metal film type capacitor. It's not involved in the diode and larger cap failure. If you do replace it, it must be a metal film type, not an electrolytic.
I don't have a SOM and only have your diagram to go on. Bob might be able to fill you in better.
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thanks for the advice.
Cheers John
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Hi John, Sorry to see that the old rectifier has turned it`s toes up. That said I wonder how much of our modern electrical equipment will still be working 50+ years from now.
Replacing the rectifier with a diode is an easy fix as is replacing the blown capacitor. Have you checked the resistance of the small solenoid coil? If it is also burned out I can talk you through how to rewind it.
Why do you think the other capacitor is damaged? It is not a part of the same circuit. You can test it with your multi-meter, set it to the lowest Ohms range; now place the black probe to the neutral (orange wire going to small rheostat) and the red probe to the other end. The readout on your meter should briefly scroll as the capacitor charges. If the read out scrolls the capacitor is OK, if it doesn`t, replace it. The negative end is the one connected to the small rheostat (variable resistor).
Bob
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Hello Bob,Just got back home, de-soldered the wires from the small capacitor and it is fine. de-soldered the wires from the small coil and it was 100 ohm
cheers
John
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Hi John, not sure what the resistance should be but if you`ve got continuity it`s probably fine.
looking forward to you having it running again.
Bob
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Hello Bob, I made a school boy error, tried to test without de-soldering but quickly realised my error!
I am hoping to have the parts later this week.
Cheers
John
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Hi John, just went and measured the resistance of my small solenoid coil. I got 106 ohms so I think your reading of 100 ohms is close enough.
Bob
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by the way what way round dose the IN4004 diode go. I mean the silver end to the brown or the yellow wire. just so as I know before it arrives.
again thanks for all the help and advice without yourself and the forum I would have found this kind of repair very difficult.
you must be very patient having so many people throwing questions at you.
Cheers
John
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Hi John, the end of the diode with a silver ring around it is the negative so in your set up the silver ring connects to the yellow and the +ve end to brown. The easiest way to do this is with a terminal connector block screwed to the frame. Something like the photo.
I`m probably the most impatient person you`ll ever meet. I had a very serious car accident just over 2 years ago. I broke my neck and some other bones, had to sit in a chair watching TV for nearly six months. Drove me nearly mad. If I never ever see another episode of Dr Phil or Judge Judy. it`ll be too soon. I eventually got the nod from my doctors saying I could start doing stuff again, so I did and promptly had a heart attack. I now have to be very careful about what I do. If I do too little my neck stiffens up and I loose the use of my hands(trapped nerves), if I do too much I risk another heart attack and my neck stiffens up and I loose the use of my hands. I can`t win. Next month I have to go and see a surgeon about trying to release the nerves.
This forum is the only thing that keeps me sane, I take anti depressants but I find talking people through their mechanical/electrical problems much more therapeutic, so please feel free to ask away. I get huge satisfaction out of helping others do what I no longer can.
Bob
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I have ordered the other capacitor the brown one 1uf 250v I suspect it may be blown as well would you be able to tell what way round it goes on the board as there are no + - markings on it. there is a small raised band around the left hand end. ....
It's marked DC working voltage, so I suspect it is an electrolytic style.
Generally the minus side is marked, arrows, band or whatever. Perhaps you can check the polarity of the voltage present before you remove it. Also with such a large value 1uF , it would be unusual for it to be a film or mylar cap without it being very large. A 250V rating is large, and I would not get a replacement that is any less than that.
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As I recall, the 1 uF cap is the one marked C on the schematic, and on the cap it says metal film. As I had already stated.
Electrolytic caps are too high ESR (effective series resistance) to work well for contact arc supression. There are plenty of DC only rated metal film caps also, they are smaller than the AC ones of similar rated voltage. 1 uF metal film caps for 250VDC are not too big.
I would not recommend using an electrolytic for this cap C.
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Not seeing any scale on the size of the cap, I'll defer to BruceM's recommendations.
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Sorry Mike, I also concur with Bruce, go for as close as you can get to the original.
Bob
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Hello to everyone that helped with the Lister electrical problem. I received the Diode and the capacitor today got them fitted tonight switched on the heating in the house and the old Lister started up first time on automatic so all is well ( her in doors is happy )
Cheers
John
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Well done John, amazing what a little cooperation and knowledge sharing can achieve.
Bob
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yes, its all down to the good people that takes part on the forum to help one another out when they have a problem.
Cheers
John
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you are very welcome, I am happy that you can now generate your own power and flick the bird to the greedy, corrupt corporations. Probably time for you to investigate alternative fuels which will allow you to flick the bird to the greedy government.
Bob
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I am already running on WVO the Lister starts up and shuts down on WVO.
cheers
John