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New developments: On the bad machine, the control signal's duration is much longer on the positive half-cycle than on the negative half-cycle with the machine in PLAY mode. About 2 and a half times as long. Eject the tape, and it goes back to the correct symmetrical 30 Hz signal. Also, it looks like my service manual was written before this serial number, as the FM PRE board near the head drum is completely missing, with the wiring going instead to the Audio 3 board - which only contains about 30% of the circuitry as the Audio 3 board on the good machine. Looks like they replaced a lot of discrete circuits with some kind of microprocessor - somewhere.
So now I'm not sure if the same check/alignment procedures would apply. Both my good 822's have the optional Time Code boards installed. Time to check the manual supplement for more clues.
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