Firstly, I appreciate the comments immensely. I had been using the rear BNC A-Gate signal as sync for my bench rig while observing other waveforms earlier in the repair so I am familiar with those. I¡¯ll try to explain what I¡¯ve found on those BNC jacks. The photos posted are pretty much what I see, sans any waveform movement via R1110 (Front panel ¡®Delay Time Position).
Regarding the waveform from the A-Gate and the B-Gate, when A sweep and B sweep knobs are locked, the waveforms at A and B are identical, +5.5 volts with active negative-going pulses and are varied by the sweep setting. (I say ¡®negative but they actually only go to zero.) When the knobs are unlocked the A is as described above but the B waveform changes to zero volts with active 5 volts pulses. These high going pulse change width with the B timebase changes. Higher sweep speeds narrow the pulses as expected. However, the ten-turn pot, R1110 does nothing to this waveform. I believe this is significant...
Regarding S1120, this switch is directed via the four interlocking switches in the ¡®A LOCK KNOBS¡¯ assembly behind the A7 board coincidently also labeled sheet <7>. Not easy to access but they have been cleaned and assumed to be functional. Though I understand the why¡¯s behind the board number vs sheet number, it does make things confusing at times when they don't match... which is most of the time. <Grin>
I wanted to get back in touch with everyone as soon as I was able, so I am sending the results of the rear A-Gate and B-Gate BNC jacks now, later tonight I am going to dig deeper into the comparator and I¡¯ll include those results in a later post. Hopefully, I will have some useful data to share so further debugging will be fruitful.
Saying sections interact is an understatement¡ hehehe <more silly grinning>
I appreciate everyone¡¯s thoughts~!~
Michael - AF7U