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Author Topic: startomatic  (Read 5775 times)

vegoil

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startomatic
« on: January 24, 2019, 06:38:12 PM »
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!
« Last Edit: January 24, 2019, 07:08:28 PM by vegoil »

mike90045

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Re: startomatic
« Reply #1 on: January 25, 2019, 01:44:04 AM »
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.

oldgoat

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Re: startomatic
« Reply #2 on: January 25, 2019, 01:12:41 PM »
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.

vegoil

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Re: startomatic
« Reply #3 on: January 25, 2019, 01:32:52 PM »
Can I put in a AC/DC or AC or dose it have to be DC only

BruceM

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Re: startomatic
« Reply #4 on: January 25, 2019, 05:01:53 PM »
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.

vegoil

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Re: startomatic
« Reply #5 on: January 25, 2019, 06:12:33 PM »
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.

ajaffa1

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Re: startomatic
« Reply #6 on: January 25, 2019, 09:10:08 PM »
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


vegoil

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Re: startomatic
« Reply #7 on: January 25, 2019, 11:31:26 PM »
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
« Last Edit: January 25, 2019, 11:54:11 PM by vegoil »

BruceM

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Re: startomatic
« Reply #8 on: January 26, 2019, 12:15:59 AM »
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.

ajaffa1

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Re: startomatic
« Reply #9 on: January 26, 2019, 06:25:56 AM »
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

BruceM

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Re: startomatic
« Reply #10 on: January 26, 2019, 08:03:32 AM »
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?










ajaffa1

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Re: startomatic
« Reply #11 on: January 26, 2019, 09:59:33 AM »
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

vegoil

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Re: startomatic
« Reply #12 on: January 26, 2019, 04:28:35 PM »
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

ajaffa1

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Re: startomatic
« Reply #13 on: January 26, 2019, 10:42:11 PM »
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

vegoil

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Re: startomatic
« Reply #14 on: January 26, 2019, 10:56:43 PM »
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
« Last Edit: January 27, 2019, 01:50:19 PM by vegoil »