15 Jun
2003
15 Jun
'03
7:56 a.m.
My Jupiter Ace, BTW, is almost repaired. I've got
the 16K RAM Pack, manual
and demo tape for it. The only thing missing is the power supply. If I can't
locate an original PSU, I'll build a one-amp linear regulated 9V PSU with a
"crowbar" overvoltage protection circuit. Yes, I'm paranoid enough to add
a
crowbar...
Fairly pointless. The only thing that 9V supply feeds is a 7085
regulator. If that fails, then the 9V will cook the chips anyway.
The original PSU is unregulated (just transformer, bridge rectifier,
smoothing cap). There's little point in regulating it -- the 7805 will
stand up to 35V on the input IIRC (it may well go into thermal shutdown
if you give it excessive voltage, but it shouldn't short). No sensible
fault in a simple unregulated linear PSU will make the output go up by a
factor of 4 or so.
If you want to add a crowbar, put one set to trip at a little over 5V
across the 5V line on the Ace's PCB...
I try and replace as little as possible. If a chip has
failed and I've got
both a replacement chip and a replacement board, I'll fit a socket and use
the chip. If I need to, I will repair damaged tracks on the board.
Me too. And I also regard sockets as a sensible modification. But I only
ever used turned-pin (machined pin) sockets now. Yes, they're expensive,
but so is my time in tracing bad connections.
with a solder-sucker. NEVER use desolder wick on
through-hole boards - it
eats pads and tracks for breakfast.
The only use I've found to solderwick is to clean up the pads on an
SMD-based board when replacing a component there. I never use it on
through-hole boards.
-tony