sb@pnet91.cts.com (Stephen Brown) (06/16/91)
I have just acquired an Apple Monitor IIc. It is unwell. I don't have the
schematic, and I don't know where to get it.
The problem (actually symptom) is that it blows the INTERNAL (motherboard
mounted) 1.5 amp fuse. This fuse is after the voltage regulator and before the
monitor circuitry itself. I guess you'd call it (in old terms) B+.
I measured the current though the fuse: 2.3A. The voltage is about 11 volts to
ground. (At 2.3 amps, not surprising that the fuse blows) Before the fuse
blows, the monitor seems to work perfectly, except
(a) the neon bulb on the base pc of the picture tube is on, BRIGHT
(b) there is that "warm" smell that you aren't supposed to get
(c) just before it goes, there is the faint sound of corona (arcing) but none
is visible. The sound is coming from a region between the high voltage
"cage" and the edge of the pc near the focus control.
There is nothing visible wrong (ie. nothing fried). A quick check of the
diodes and resistors in the area suggests them to be good. Of course, these
are not while operating voltages are applied. I suspect something fishy in the
horizontal output/driver circuit, near the flyback. Any ideas???
Dazed and Confused, but NOT Electrocuted.
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| Stephen Brown Toronto, Canada |
| Internet: sb@pnet91.cts.com UUCP: utzoo!pnet91!sb |
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| Apple II Forever !!! |
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