Problem with 9V/12V

From: MagerValp (
Date: 2005-12-06 23:26:44

First off, the 6526:s arrived today, thanks Ruud!

Unfortunately I forgot the package at work, so I sat down and tried to
figure what was wrong with another C64. The symptoms are the classic
LED on, black screen. I replaced the fuse, which was blown, but the
machine still won't power up. To summarize:

  * 250407 board.
  * PSU is fine, I measure 9.4 VAC at the power connector, and 5 V on
    the user port.
  * With the fuse removed, I measure 9.4 VAC across C21.
  * With the fuse in place, I measure 2.0 VAC across C21, but this
    fluctuates a bit (0.6 - 2.1 VAC).
  * With the fuse in place, I measure 0.15 V across pins 2 and 3 on VR1,
    the 7812, and this also fluctuates a little.
  * I tried removing the VIC and the SID, which I believe are the only
    9/12V ICs, and it didn't have any effect.

I don't have any other 250407 boards on hand, so I don't have anything
to compare with. I also kinda suck at analog stuff :) So, does anyone
have a clue as to what's going on?

PS: after taking inventory, I realize that I could use a couple of
    1541-II/1581 PSUs, and maybe a couple of C64s too (especially with
    250407 and BN/E boards). If you have spares and are interested in
    trading or selling, send me a mail off list. Oh, and 230 V/PAL
    only :)

    ___          .     .  .         .       . +  .         .      o   
  _|___|_   +   .  +     .     +         .  Per Olofsson, arkadspelare
    o-o    .      .     .   o         +
     -       +            +    .

       Message was sent through the cbm-hackers mailing list

Archive generated by hypermail pre-2.1.8.