Lister Start O Matic SL1 (1965)

[Lister owner]

I have an one of the above which has been running perfectly till recently. The voltage has now dropped to 200v. The engine is running at the right speed. Is there an adjustment to one of the resistors in the Alternator control box which I can make? or is it likely to be one of the windings or commutators that is the problem?

[hotater]

Welcome Lister owner.  Somebody with a lot more electrical sense than I will be along shortly to expound on an answer likely to be:

1)  Correct
2)  Argued over just short of forever.

Please be patient.

  Lets' see some pictures of a working SOM, please!

Bye the way...  If the engine is at proper speed it's the generator that's gone wrong.  The CS is still doing it's job perfectly.
 

[bitsnpieces1]

What hotater says.
and:
What is the rated voltage?  210/220/240
It should have an adjustable regulator somewhere to get the volts right.  If it dropped all of a sudden (or quickly) it might be a bit of trash or oxidation on a contact or possibly a connection beginning to come loose. 

[dieselgman]

Clean slip rings,
check Rectifier MR or MR1,
adjust main field Rheostat FR1 or FR3

There are many SOM variations so these suggestions from the SOM instructions may require adjustment.

Best of luck with your machine, feel free to email me if you would like more details or parts.

Gary
diesel-electric.us

[listerdiesel]

Bye the way...  If the engine is at proper speed it's the generator that's gone wrong.  The CS is still doing it's job perfectly.
 

It's an SL1 Gary....

Peter

[dieselgman]

I got the SL1 prime mover part... plenty familiar with those.

The generator model is what is needed for exacting diagnosis and repair from the standpoint of component identification and adjustments.

Gary
diesel-electric.us