Console power supply voltages off

Is the transformer a center-tap design?

Are they adjustable?

Look at the +/-24V pins first to see if those are off as well. If not, then see if P2 is turned too far to one side or another. If not, then it might be a case of testing each resistor to make sure none of them have drifted over time. I guess you should also make sure that each cap on the output is still good. Your DMM set to DC might not read AC ripple very well if the caps are bad.

I had a console that was left on once when I was gone and it rained and the roof leaked. Came back and water had dried on the surface, but there was about an inch of water in the pan.  Basically worked, but the solo logic was all out of whack. Same exact thing. +/- rails way out of whack. Re-adjusted them to +/- 15v and all was fine.

As you see in the schematic there are no "regulators" per se.  The design is partially discrete and the "regulators" are made of all those components you see on the schematic page.  

Did you measure the +/-24V?  What did you see? (since this is the first thing I asked you to look at after you asked for help looking at it..)

Where are you measuring the +/-15V?  Are you measuring right at the power supply output or are you measuring inside the console itself?  If you're measuring at the console, stop and measure the power supply output without the console or cable attached.   Not sure how stable it might look even in a normal working state since it has a distinct lack of output capacitance or decoupling.

"Regulators" don't go bad due to age.  Caps can go bad by drying out, either by leaking over time or by being overheated over time.  If you leave this thing on for a while does the voltage change?

It's still likely either not regulating properly due to drifting carbon resistors or even a bad common connection.  Have you tried reseating the A-M connections, specifically the A-D connections to make sure it's not a corrosion/connection issue?

It looks like it employs some kind of external feedback through the "Sense" pins.  It might need those pins connected to their respective outputs in order to regulate properly.  Are you using the same cable for both supplies?  Have you pinned out the cable to make sure all conductors are continuous?

So you're getting both +24 and -24?

Which is kinda strange since those are the source voltages for +15 and -15 respectively, so you shouldn't be able to read 26V with 24V source unless it's oscillating or something.  You'd need an oscilloscope to see.

I guess things are getting confused.


If you look at the schematic of the power supply, there are BOTH +24/-24 outputs (points 7 and 9) as well as +15/-15 outputs (points 1 and 3).  What are the voltages you are measuring at the +24/-24 points?

Ok, so it's pretty much the regulation that's gone off the reservation.  I'd try hooking the sense inputs to their respective outputs and see if the voltages align.