Q596 generates an alternate sync pulse. There was a pulse on the base but not on the collector. The transistor tested good. Turns out that line to J2-2 was grounded effectively killing the pulse.
The alternate switch when switched out does ground out the sync pulse. But when alternate mode is selected the sync pulse is supposed to be applied to the base of Q338. That wasn't happening. Line was still grounded. I suspected at the time that the alternate switch was bad but in order to get to it the vertical pre-amp board had to be removed. Decided at the time this would wait until I was good and bored. Removing that board is no simple task.
Last week I was bored so I decided to tackle the mess. Took a few hours to remove the board. And lo and behold testing the alternate switch revealed it was fine. Works as intended. Grounds the line when switched out and allows the signal to pass when switched in. So.....spend the hours re-installing the vertical board. So now I know that line is shorted to ground somewhere. But where? After much poking around today I finally found it and I caused it. See following pix.
When I re-capped the PSU somehow I caused a solder bridge from the large pad with "CR1412" to the right of it to that thin trace to the left of the pad which is the alternate sync pulse line. That pad is a ground for one of the PSU capacitors. I tried removing the solder bridge with an iron and an X-acto knife but was unsuccessful.
So I cut the trace at two points where I could get easy access with a dremel and restored the circuit with a wire. Yep, it's a giant bodge but really had no choice.
Giant bodge or not it fixed it. Now have alternate trace mode.
