I've completed repairs on Hero's analog power board. I was unable to access RS232 communications because the -10VDC power line was out. It took a shotgun approach and I replaced a hand full of parts on the board. They were either capacitors or related to the operation of the switching power supply and 10 VDC charger pump circuit. The following is from the theory of operation manual:
NEGATIVE 10-VOLT SUPPLY
The ouput signal at the collector (C) of Q301 (replaced) is a square wave, which is derived from the on/off-pulses of Q31. These pulses are filtered and used to generate both the +5VCD and the -10VDC supplies.
C312,D302,D303 (all replaced and it was actually D302 that blew), C313 form a half-wave voltage doubler for the -10VCD supply.
Now I'm ready to put it all back together and give it a smoke test. Once I'm able to run Hero Basic I'll post some more info, photos and maybe some video.
I HAVE A HERO JR. AND HAVE A PROBLEM WITH THE PWR. SENSING BRD. THE SAME THAT YOU SHOW ON THIS PAGE. THE PROTECTION DIODE IS SHORTED AND BOUGHT A REPLACEMENT BUT I NEED TO KNOW WHERE THE 1N3317B IS LOCATED ON THE BRD. IS THERE ANY WAY YOU CAN E-MAIL ME A COPY OF THE SCHEMATIC AND THE LAYOUT OF THIS BRD. MY E-MAIL IS billcu69@verizon.net
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