What's wrong with the scanner? I've fixed a whole lot of stuff over the
last 20 years or so and had a service manual maybe 0.5% of the time. It
helps, but most faults can be found without one. Even service manuals
for a lot of things don't go down to the actual component level. 90% of
the faults I see are either bad electrolytic capacitors or cracked
It's not troubleshooting I need the manual for. I think I know what the cause
is. (I posted the question re. this scanner elsewhere in this group earlier.
It's copied below.)
If the diagnosis is right (so says the Epson tech) I want to replace the flat
bed glass. And there's some kind of calibration afterward. At least that's
what I want to find out in the manual.
- - -
Epson Perfection 1640SU Office scanner with Auto Doc Feeder (ADF). The ADF
plugs into the back of the scanner via a DIN-8 plug. (The ADF is model EU-34,
The scanner will scan documents on the flat bed glass with no problems.
When the ADF is used, the paper feeds through the rollers smoothly. No jams
or other feed problems.
The resulting scan in ADF mode is all vertical lines. I tried different
resolutions and other settings. Also tried different applications. Same
A tech at a local Epson authorized repair facility said that this is a common
failure. There is a calibration strip at the "home" position on the bottom
side of the flat bed glass. Over time this white strip changes (it shrinks?)
and when calibration is done at power-on, incorrect calibration results.
The Epson tech says that this is a quite common failure mode and he does many
of these repairs on several different models. (I didn't ask if it was common
to other than Epson.)
How does this calibration work such that it succeeds for flat bed scans but
fails for ADF scans? Can someone explain?
The 'service manual' for a scanner is ... not much. Cleaning the
glass and maybe dusting the optics and especially the reference
(this is a black or white strip against which the scanner is
at startup) is about all the 'maintenance' there is, except for
lamp replacements and wallwart swaps.
You don't need the manual to replace a dead lamp.
If the scanner needs more than that, you throw it away and
Ye would think that. However I found the service manual for my LED based
Canon N650U scanner (free at fixdevice.com) incredibly detailed on
operation theory with 110 pages, for something that contains very few
parts, and not even a power supply (USB powered).
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