[sci.electronics.repair added]
On Wed, 30 May 2007 18:44:45 -0700, Jim Thompson
wrote:

Anyone know how to dismantle and clean an hp3970?

I've developed a foggy looking coating on the _inside_ :-(

Never worked on HP scanners, but I've fixed Canons & various other
brands plenty of times, & the usual steps to dissasemble go something
like this:

* Hold lid by sides & lift until the supports pop out of the slots.

* Look for a retaining strip in the area that was covered by the hinge
of the lid.

* If present, unscrew / unclip to reveal one end of the glass lid.
CAREFULLY lift open end above case & slide out.
* Goto: CLEANING.

* Otherwise, place scanner upside down on SOFT SURFACE, grab a torch,
& look under unit for round screw slots or square/rectangular
retaining-clip slots. Remove screws or 'pop' clips with long,
flatblade screwdriver.

* If it uses clips, it's usually neccessary to apply a little tension
between the halves of the shell while 'popping' the clips/hooks to
keep them released. I use tongue-depressers or similar to keep the
halves from 'clicking' back together while I'm doing the other clips.

When the case is split, it should be easy to figure out how the cover
glass is being retained. Wearing clean gloves, remove glass
*CAREFULLY*.

CLEANING:

* Put on a pair of lint-free white cotton gloves, or a pair of clean
rubber gloves.
* Place glass on clean towel, folded several times.
* Spray Windex or similar ammonia-based glass cleaner on a clean lens
cloth or similar soft, *lint-free* cloth.
* Clean top side with damp cloth, dry with a *different* cloth.
* Flip glass, touching only the sides.
* Clean this side, as above.

* Slide glass slowly & carefully back into the case, in exactly the
reverse of the way you removed it. With some cases, it can be useful
to tie a ribbon or similar around the glass first, so you can support
it with your other hand, so it can't fall inside the case if you slip,
etc. Using your gloved finger, make sure the glass is seated solidly,
& flat, as it's not always obvious, & a bad fit will give you poorly
focussed/blurred scans.

* Without removing your gloves, reassemble the unit.

* Test. (Duh.)

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