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Stored Sansui 881

OK, so I've gone and replaced a significant number of components on both the F-2437 and 2436 boards, as well as the filter caps. I swapped out the output transistors, the cement resistors as well as C18-21, and once this was done, without the driver board installed, was able to get the relay to click on. However with the driver board in, the relay would not click, so I did a halfway rebuild of that board, replacing a few of the capacitors, the variable resistors, a handful of resistors, and TR01-04. Regardless, the relay would not click on with it installed. I went and rechecked the machine with the driver board not installed, and now the relay does not click again. Intermittently it seems to click on startup, but when switching the power on off immediately after this, the relay will not respond. I checked the output transistors again for shorting, and they pass the multimeter diode check, and the original transistors appear to pass this test too... I am currently at a loss for this problem. I will report the current output transistor voltages.
 
Side note, upon the first minor repair of only the output transistors and the filter caps being replaced, I booted it up to see if anything changed, and the relay switched on and immediately switched off a millisecond later. It only did that once, and now I am faced with the behavior described. I'll get those voltages now.
 
TR701
E: -3.9V
B: -0.1V
C: +46.5V

TR702
E: +0.7V
B: 0V
C: +46.5V

TR703
E: -46.5V
B: -46.1v
C: -3.9V

TR704
E: -46.5v
B: -46.1
C: +0.8V
 
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