Hi, I have a System 11 machine that I have never been able to play. It was DOA.
I have rebuilt the Power Supply with GPE kits (both caps and HV) and changed the headers and connectors.

The problem : I get ~+12V at the +5 outputs.

The signal flow :
About 10.5VAC at the transformer connector (3P1-10 to 12) - that's ok
Goes through F5 and F6 - ok
Goes through the bridge rectifier
I get +13.84VDC at TP3 and -14VDC at TP4 (directly connected to the bridge +/-) - i think that's ok
The + signal then goes to Q5's collector

And this is where it doesn't work anymore.

Q5 gets +13VDC at its base, from IC1, the voltage regulator. (I get +6.61VDC on another working machine)
And I get +12.60VDC at the emitter, instead of something around +5VDC.

I have changed Q5 with another one from a working machine and it's the same results.

Should I change IC1 or there is another possibility ?

Thanks

Thanks, helpful schematic. I'll check that after work.

Green is ok.
Red has 7VDC over what's written on the schematic.

circuit.png

Let's hope the TTL will forgive me for the 5 seconds of 12V I gave them...

89 cents later...
Fuck yeah!
I am so relieved...
IMG_20140404_231418.jpg

It seems, I get no error code. My mpu only had 12V for seconds, I figured something was fishy and turned off the power.
Other boards are not plugged yet, one thing at a time...

Thanks for chiming in John.
The machine booted fine, but I realized the displays are crap.
Lots of surprises, it's a machine I've never been able to play, DOA.
I just ordered a X-Pin set from you.