Hi,
Recently just fixed an HP Officejet G85 which had the dreaded "Scanner failure" message on the screen whenever it was asked to copy, scan or fax, or whenever it went onto power save. When it got the error message, it would sometimes still print, but often it "locked solid", and none of the buttons on the front even beeped like they normally do.
I solved the problem, and thought I'd share a diganosis guide with you since a lot of other people seem to have this problem and no solution.
In summary, common problems are: dirty mirrors dirty glass (bottom) failed bulb wonky alignment strip jammed head bad belt failed motor.
Do each suggestion below, and after each test it and see if the problem still occurs.
First, press the # key and the 6 key at the same time as plugging in the power cord and switching it on. This will do a full reset, and may fix the issue.
Next have a look inside the scanner through the glass while you turn it on or while pressing copy. Do you see the scanner head move? If you don't, then there's a problem with the motor or it's jammed - see below. Do you see the light come (evenly across the whole length)? If you don't, you probably need a new scanner bulb. Do you hear any "grinding" noises while it's moving? If you do, see below. If you havn't got any of those problems, it will be worth trying the procedure below as well, because dirt inside can often stop it working.
Next we're going to take it apart. It's quite easy to get apart as long as you're careful, although If you're not sure about dismantling things, print this page out and ask someone techy to do it... As always, I can't guarantee it won't be broken by you doing this, but I fixed mine this way, and you havn't got much to loose taking apart an already pretty useless thing (out of print, copy, scan and fax, only print works). You will need a set of torx screwdrivers.
To take it apart, fully lift up the scanner lit and lift it off. There's a cable attaching it to the main scanner base you'll have to unclip and unplug.
Next, remove the piece of plastic on the button pannel - you should be able to do that with your fingernails round the edge. It has lots of clip-like things, so you need to pull quite firmly to detach it.
Next fully remove the buttons themselves. Do that by pushing back the clip at the bottom edge of the button panel and sliding the whole pannel left, then lifting it out. Remove the little wire attaching it, remembering which way round it fits in.
Now you need a torx screwdriver (this is a special type of screw, so if you havn't got the right type of screwdriver you won't be able to undo it) to get the scanner glass off. Remove the two screws at the back of the scanner, down two deep holes on the top surface. Now unclip the front edge of the top surface, with the two large clips down where the buttons were (these are hard to unclip - use a small screwdriver to "lift" each clip while lifting the surface a bit). Now lift the entire surface off and put it somewhere it won't get damaged. While you're at it, clean both the top and bottom with glass cleaner.
Now you're in. Check all these things:
On the scanner glass, there is an alignment strip glued to it. Check this is exactly parallel with the edge of the glass. If it's at an angle with one edge more than about 3 mm out, the scanner won't work. If it's not, remove the glass from the plastic and heat the strip with a hairdryer and peel it off. use glass cleaner to remove the glue, and then put the strip back on where it was, but straight. Do not reglue it with new glue, because the middle of the strip is intentionally not sticky so the scanner can calibrate colours better without the glue getting in the way.
Check that the scanner "head" isn't rubbing on anything. It should move from end to end freely when you rotate the wheel on the little motor. Watch out for it touching the white pulley at the rightmost end - this will cause it to misalign, and can be fixed with a tiny piece of folded paper under the right end of the metal bar to raise it slightly. If you came here because the scanner head wasn't moving at all, but yet it didn't seem to be rubbing on anything, it may be the motors failed. Check all it's connections, or otherwise you may need to get a new one. Alternatively, a failed motor driver in the lower half of the scanner could also cause that, but thats out of the scope of this guide.
Make sure that the little clear plastic wheel on the motor (back left of the scanner) is very clean. Clean it carefully with a kitchen towl. If it's got printer ink on (quite likley), clean it off with a slightly damp kitchen cloth, but don't let anything get wet. Also clean the little sensors either side of the wheel. This wheel is used for detecting the position of the scanner, and if it's dirty it won't work.
If you found anything bad and fixed it, now would be a good time to put it together and test it before delving deeper as to why it doesn't work. Otherwise carry on with taking apart the scanner "head".
To remove the scanner head, de-tension the belt by moving the white leaver at the back right (on the "floor" of the scanner bed). by slightly lifting the leaver you can detension it a lot. Now remove the belt from both pulleys. If the belt has any badly worn parts (ie. where it is no longer toothed), then you'll need a new one, which should fix the problem.
Next remove the flat white data cable from the head. Do do that, unclip the top cover with the clips at either end of it, and carefully pull the white cable out of the circuit board. Now you should be able to fully remove the head, complete with metal bar, to a new place to work on it.
If you came here to find out how to fit a new bulb, this is the place to fit it. unplug the bulb from the smaller circuit board, and remove the whole bulb assembly by carefully rotating it to get it free of the black plastic housing. the bulb itself can be wiggled out of the aluminium, but it's very fragile. The reflector is supposed to have black edges - thats not a defect.
Otherwise, you next want to take off the bottom of the "head". You'll need a normal cross head (maybe philips) to do that. When you're in, you should see a load of pieces of glass. they're mirrors, and they must be squeaky clean. If any aren't, then clean them carefully. They can easily get dirty, as the printer below puts a lot of ink dust into the air, which drifts into the scanner section.
If your scanner suffers from light leakage (where copying a portrait black sheet would give it coloured or white vertical bands), then solve it by filling the gaps round (a) the mirror thats visible from the outside of the scanner head (the shortest one), and (b) the back edge of the aluminium housing for the light, with black tape.
You can also take off the circuit board and clean the actual scanning sensor, but It seems fairly sealed, so I don't think it would get dirty.
Next put everything back together, doing the above instructions in reverse, making sure every wire is firmly plugged in, and test. When you're testing, if you don't touch it, you can switch it on while it's apart. The whole scanner, with the exception of the flourescant light, is a safe low voltage. Note that the light and motor should work with everything apart, but it will still come up with the scanner error since it can't find it's alignment mark on the scanner glass. To fully test you need to reassemble at least the scanner glass, and it should then copy. You don't need to put the hinged lid back on. You do need the buttons plugged in for all tests so you can switch it on.
If the above guide helped you, reply or email me so I know peple actually read and use these guides I make, to encourage me to write more.