13 Mar
2005
13 Mar
'05
6:25 a.m.
At 03:59 AM 3/13/05 +0000, you wrote:
BTW, there are 4 LEDs on the control board, visible through a slot in the
cover. These should all be on -- they're connected to the +ve and -ve PSU
control board supplies (I can't rememebr if before or after the
3-terminal regualtors) and one supply derrived from each main chopper.
That's interesting! They're not mentioned in the service manual and
they're not shown in the schematic. Are they visible without taking the IPC
apart? I should take a close lot at mine and see if they have them.
Joe
If
either of the former are out (in which case the 2
choppers will also shut
down), there;s a fuse on the PSU mainboard for them, a 3AG cartridge for
the +ve rail, a picofuse for the -ve rail. If those supplies are OK and
both choppers have shut down, then it's possible the protection cicuit,
based round all 12 comparators in the LM339s on the control board, has
triggered.