2 Mar
2006
2 Mar
'06
10:28 a.m.
If this were a desktop system, I'd go for the
screwdriver first. However,
on portable systems, reassembly can sometimes get a little involved--at
least for my "all thumbs" hands!
SOmetime I forget that not everyone had a mis-spent childhood
re-assuembly clocks and ASR33s :-)
Let's not forget that the original poster knows
that the PSU puts out
+18vdc. It's EXTREMELY unlikely that the positive side of the PSU has a
direct connection with any signal pin!
I'ev got at least one cheap serial printer where the +ve side of the PSU
(about 10V regulated) is connected to the +5V line. There's a 7905
regulator, the output of which is the logic ground line. Then the
unregulated input formes a -5V-ish line for the (discrete transistor)
RS232 driver.
It's unlikely a computer would do the same thing, and it's unlikely that
you'd find the +5V line on a normal serial or parallel connector.
I would bet a sizeable amount that if yo u can find one side of the power
connector connected to a pin you know to be ground (e.g. pin 7 on a DB25
RS232 port) then that is the -ve side of the power connector.
-tony