help with power supply

[mark532011]

I wasn't sure if I should post this in newbie or here. Please move if it should be there!

I recently purchased an old 1979 Star Trip cocktail pinball table http://www.ipdb.org/machine.cgi?id=3605
It is pretty fun looking but doesn't work right yet. When turned on, the lights come on and the main processor board runs through its self diagnostics ok, but since none of the solenoids will fire, I assume it is either a dead solenoid board or the power supply.

I've checked the power supply and *some* of the DC voltages are coming out at 1/2 of what they should be (the 7 and 28V) and one is ok (12V).

A fellow pinballer posted the circuit diagram and parts layout for my board, see https://img-f.pinside.com/201504/2417079/397716.jpg and https://img-f.pinside.com/201504/2417079/397731.jpg

and here are some pics of the board inside the unit: http://pinballrepairandlife.blogspot.com/2015/04/pics-of-star-trip.html - Yes, the parts are screwed into a piece of plywood and hardwired together!

I can find the hot end of a soldering iron (at least by the 2nd try) but this is beyond me. Does anyone have any suggestions on how to proceed? I am assuming something ought to be replaced but I am not good enough at reading the diagram to know which thing.
Mark

[mark532011]

So perhaps the power supply is actually ok. Another person posted to me:

The two voltages which are half is to be expected since the fuses are on one leg of the bridge rectifier.

(i had checked the voltages by touching ground and the fuse) - does this sound correct?

i'm guessing what I need to do is check that the voltages at the connectors to the other boards?

[pebe]

Bearing in mind that the machine is over 30yrs old, it is almost certain that one or more of the electrolytic capacitors has dried out. That would give the symptoms you have.

I would change them in turn, starting with the large cap marked 7 on the power board layout (unregulated 12V supply).