Running a startomatic as a push button generator

[CS Dave]

Hello, I have a 1963 Lister 8/1 startomatic 4.5 KVA which is a little poorly at the moment

It was starting well, once a bulb was switched on (as it should), it was a bit flickery though.  I loaded it up a bit (easily within the limits of the unit) only to find smoke pouring out of the upper control box. I immediately removed the load but the damage was done and, at this time, I can't find out what's gone wrong.  I did see sparking across the blue finned device in the middle of the box (is that the rectifier). I read somewhere that's a common failure point, what should I replace it with please?

While I am working out what's happened, can I run the unit as a push start generator?  where would I connect the load (I am assuming in the lower box that's fixed to the generator?)

The unit fires up fine and runs fine with the wedge inserted in the solenoid

Thanks 

 

[George A]

Don't use your generator until you've determined the problem!

I'm no expert on StartOMatics by a long shot, but you described smoke coming from a finned device in the control box. That almost has to be a selenium rectifier, an early device used to convert AC to DC and may very well supply exciter current for the generator field. The problem with them is when they get old, their performance gets worse and they break down..........finally smoking and possibly damaging other components "down stream". In your case, it sounds like it began to fail supplying current to the generator and the output suffered. I'm currently rebuilding a 1955 Kohler generator, and that selenium rectifier was the FIRST thing I replaced!

First of all, locate a good schematic for your unit. If you have trouble reading it, find an electrician or someone who works on old radios. They'll have the knowledge to explain everything to you and maybe help with the repairs.

You need to find out what voltage and amperage that selenium rectifier was designed for and replace it with a modern diode rectifier mounted in a heat sink. The diode should have a rating that is HIGHER than the expected load. Such diodes are pretty inexpensive these days and are a far better choice than the old selenium rectifiers.

[CS Dave]

Hi George A, thank you for your reply.  Things have moved on quite a bit since my post.  I was told by others that the rectifier needed replacing and I did that, replacing it with a modern equivalent. I also replaced a capacitor that had taken a hit (one that's also part of the detection circuit). 

My SOM has a new issue now.  In manual mode the engine fires up as it should and the generator produces power. In automatic mode, when a lightbulb is switched on, the system detects the load as it should and goes into its start up routine.  The solenoid on the engine operates and the engine starts and cranks up to full speed - its at that point of the engine hitting full power, when the main relay should operate and switch the engine from its starting mode to producing full power that there's still a fault manifesting itself.  The main (multi contact) relay bounces and never fully settles, causing sparks across its contacts.  Clearly (in my mind) there's still a damaged component somewhere, that's not allowing the system to settle into fully operational automatic mode.

I have decided that I don't know enough to take this issue any further myself and I also don't want to damage any other components.  Given we are in lockdown, its not possible to get anyone to come and take a look, so for now, I will continue to run the engine in manual mode. 

If you have any thoughts of what other compolents I could test or just simply replace, that would be very helpful.

[oldgoat]

I would have a look at the engine speed switch which is supposed to operate the main contactor or check the contactor coil for continuity.