If you pull the plug on top of page 24203e that connects those transistors you should be able to check them in situ with a dmm diode tester.
Hi cncjerry -
I am not sure what you mean about "page 24203e". However, I do have some good progress to report on the repair.
First off, I found a bunch of bad parts. It looks like some very high voltage or over-current situation happened on one or both of the output channels. I found a bunch more bad parts. And I'm not speculating when I say "bad". I mean they measured bad in-circuit, I removed them and they still measured bad.
So far this is the tally:
Resistors burned in half: R107, R108, R102, R103, R185,
Resistors, no visible damage but resistance way off: R138 (pot, just damaged on one end of the range), R101 (marked 12K, measured 20K), R120 (marked 10K, measured 17k).
Transistors: Q103, Q104, Q106, Q115, Q116
Also I was wrong when I said 24V regulator (QA201) was OK - that and the op-amp (QA-202) being used to generate the "virtual ground" for the +/- 12V supply were both bad.
This last issue was what really confounded me on the repair. I would measure various voltages in the circuit, but everything was way off. There would be no logical change in voltage at the appropriate test point as I adjusted the KV range switches. This turns out to be because the buffer op-amp I used to replace QA-202 did not have enough current drive. I had convinced myself there was another bad component dumping too much current into this net and causing the problem, but after carefully reviewing the schematic, and doing some testing out of circuit, I came to the conclusion that the op-amp just didn't have enough drive.
I've ordered something from DigiKey that should work better, but being impatient, I decided to just whip up a little circuit of my own. I used a 741 op-amp (it's what I had laying around) and a couple of transistors in a push-pull configuration to create a beefier virtual ground. After wiring this in, I can see a very steady ground node for the +/-12V supply - it changes less than a uV as I change the range selector and output selector switches. And wonder of wonders, I can actually see the KV divider working now.
So, I am waiting on a replacement for Q104, and then I will put that in, reconnect the +/- 130V rectifier and give the whole thing another try. My only real concern at this point is that all the transistor replacements will not turn out to really be a good match for the parts they replaced, and there will be some problems created because of that.