To add to the last post. This waveform is shown in the Service Manual here, and it shows that it's supposed to have a symmetrical top portion. Also of note is that the DC voltage on the output of Pin 5 is called out as 4.6V in the SM, but it measures 8VDC with a DMM.
The output of Pin 7 is also incorrect; it's a smooshed sawtooth looking thing and nothing like what it is supposed to be. I have to assume something is wrong either on the input side (Pins 1&2) or the output side (between Pins 7 and 5, or further downstream from 5).
I see the basically correct symmetrical 6.4VDC on pins 1&2 (SM says 6.5, but that's pretty close I think), but the parabola is driven by current and not voltage, so I'm not sure if just having those two correct voltages is enough, and I'm not sure how to tell if there is imbalance in the current draw (or what to do with that information if I had it).
I've followed the output as far as the last set of transistors in the Pincushion circuit (which control the Pin Balance), and the voltages at those transistors appears to be correct.
10-05-2024, 11:47 AM
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