Path: utzoo!mnetor!uunet!
From: prindle@NADC.ARPA (Frank Prindle)
Newsgroups: comp.sys.cbm
Subject: Re: Dead C128 in need of resurrection
Message-ID: <POSTNEWS11740@NADC.ARPA>
Date: 23 Feb 88 16:12:19 GMT
Lines: 18

Shorting the two 9V pins on the user port directly shorts the 9 Volt AC output
from the external power supply. The only components in the path are two
small RF chokes near the power connector and the power switch itself - it is
possible that one of those is fried, or that you melted a trace on the PC board;
Or the power supply might have blown a fuse. To check the power supply, measure
between DIN connector pins 3 and 5 (on the square-ish plug that comes from the
supply) for 9 to 15 volts AC, and between pins 1 and 4 on the same plug for 5
volts DC (pin 1 positive).  If either voltage is missing, the 128 cannot
function properly. One fuse on the C128 supply is externally accessible from
the bottom of the supply (you'd be amazed how many people never turned the
sucker over!). I'm not sure if the same fuse protects both outputs, or if there
is another fuse inside for the AC output.  The C64 had a fuse for the 9 VAC
lines *inside* the C64, but the C128 schematic doesn't show any (that doesn't
mean there isn't one)!

Sincerely,
Frank Prindle
Prindle@NADC.arpa