9 Sep
2004
9 Sep
'04
10:18 a.m.
The SX is
_very_ modular and comes apart into official FRUs in about
10 minutes.
Actually, so does the IIISi - once you know how. But it's more like
half an hour to 45 minutes if you have no reference and no experience.
Anyway, I believe I've now found the offending bit.
By the time I got it down to the point where anything more would mean
some pretty major mechanical work - I'd pulled apart all the
obviously-accessible electronics, and anything more is either more
electrical than electronic (eg, motors) or very delicate stuff I am not
about to mess with (eg, the driver circuitry for the laser) - by the
time I reached this point, I'd failed to find anything obviously fried.
So I put it back together but with one side tipped down, in the hope I
could see something. It's possible to reassemble it electronically
without completely reassembling it physically - in particular, it's
possible to have most of the electronics in view.
Yes, it's possible to get most laser printers into a state where all the
mechanical stuff is together (and interlocks are closed, etc) but you can
still get to the testpoints, etc. I've done this on both the CX and SX...
Then I extracted the relevant PCB and inspected that
spot closely. It
appears that an electrolytic cap has sprayed some black substance out
from between the cap and the board, coating everything in the vicinity
(which fortunately is not much - just another similar cap and some
incoming wires).
Ouch!. You want to clean that stuff off before it corrodes the traces,
etc. I would check all PCB traces and vias in the vicinity of that
capacitor for open-circuit problems.
-tony