If it seems to turn on normally, with the speaker relay coming on after the
usual delay, and just no display, there is a chance that only the -30 volt
line for the display is down (or some other section of the power supply).
There is a 100 ohm fusible resistor on the power board, R901, near the large
connector which goes to the main board. This resistor could be bad.

There is also a separate fuse board, and there could be bad fuses there -
don't recall if you said you had checked those.


Mark Z.

I actually checked the "hidden" fuses on the power supply board above
the transformer a while back. I went ahead and removed the power
supply from the stereo again tonight, removed the fuses again and they
checked ok for continuity. I then checked the resistors on the board
and they seemed to check within tolerance - one of these was the R901
you speak of. I went ahead and checked the switching diodes (they
seemed ok) and the two 1N002 diodes. One of the 1N002's (D902) tested
kind of odd so I pulled one leg out and it checks out the way it
should. When I put it back in the board it cheked out the same as
before across the ends - ".051" and it didn't matter which way I had
the black and red leads of my DMM. As you probably already know these
should ideally check between .4 - .6 one way and "OL" the other. So I
am not sure why this diode is reading this way, but I did notice one of
the traces is going to a small transistor Q901, but I do not recognize
this as one I know how to check/ meter out The numbers on it are C107
(top line) and M131 (bottom line). On the same trace going the other
way it leads to an OMRON 5VDC black box (not sure if its function).
Does this diode reading sound suspicious or like soemthing else on the
board is causing this goofy reading? Considering I pulled one leg out
and it read ok I beleive the diode to be good. Other than this, I
don't readily see anything that looks out of the ordinary. Any other
ideas for me to try? I will leave the power supply on my bench
overnight. Thanks for your help this far. John