I'm having difficulty getting an N72 to work. This is my first SCA kit build.
Q1 through Q3 are all measuring within .2 volts of what the table says they should. Q4 measures about 6v on the collector, which is about a volt higher than prescribed. Base and emitter are at .8v and .2v respectively. Q5 shows 22.4v on the collector, 6.2v on the base, and 5.7v on the emitter. Q6 is 22.4v collector, 4.4 base, 3.8 emitter. When I adjusted R39 for 22.2v on Q6, I had 4.4v at R40. Readjusting R39 for 3.75v at R40 resulted in .2v more at the Q6 collector. Otherwise, it seems like power is getting to where it's supposed to.
I tried following a signal from a tone generator with a signal probe, and the thing that's stumping me is that it doesn't seem to be getting out of the input transformer. Continuity between the transformer pins and the PCB seems fine, but it seems like I ought to detect some kind of signal coming out of pin 7 of the transformer, and I don't. Any tips on how to troubleshoot the I/O?
One additional note about this build: when I first finished it, it calibrated fine, then I put the chassis in my rack to try to use it, and found that it didn't pass signal. When I got it back on the bench, I found that I was no longer able to get the Q6 collector to measure correctly, and I eventually traced that to a dead short in R40. I replaced the part and was able to get everything calibrated again. I'm including this detail in case it's a clue about anything.
P.S. I recently noticed the precaution about not letting the Q6 heat sink come into contact with the chassis. As far as I can tell, that heat sink doesn't conduct electricity. Is that warning still applicable to the latest revision?