Bad News: On May 2, 2007, while moving peripherals around, I dropped my 10 year old HP 5p and it crashed to the floor breaking the scanner glass. I thought that I could repair it with a new piece of glass, but the bulb was broken too. Contrary to popular belief, I do not know where to get a replacement bulb, so I guess it's a candidate for the trash.  I have since replaced it with a Canon 4400F (it was cheap and does what I need), besides, I now free up a new PCI slot, since the 5p's SCSI card can go.
I'll keep this site up for those of you that still have the models listed, but I will not be adding any more to it, or adding to the repair count which stands at 150.5 this date.
Thanks for all the fish!

A 'one' Scanning Tip 

Although the instructions here apply to an HP 5p scanner, the remedy has worked for other models and makes including the HP II cx, 4p, 5p, 3200, 5100, 5110, 5200, 5300, 6200, 6250, 6300, and 6350. the MicroTek 4800 and X12USL, the UMAX Astra 610, 1220, 2000, and 2100, and an Epson Expession 800, and perhaps other unknown makes and models. All scanner photos are of the HP 5p (the only scanner I own and have access to) with comments, submitted by viewers, for other models. 

My Hewlett Packard 5p scanner was a couple of years old (now 6 years old) and I had noticed that there were vertical colored streaks beginning to show up on scanned images (see banner image above). It first looked like it could be a printer problem, but these streaks showed up in images opened in Paint Shop Pro before they were printed. It wasn't too noticeable at first or on dark scans, but as time went on, they became more and more prominent. I had to move the images around on the glass to avoid that area, and in some cases, I had to make two half scans of the same image using only the unstreaked parts of the glass and then stitch them back together in PSP.  I had taken the top off the scanner once before and cleaned the bulb, but it didn't help. I figured the scanner was beginning to go and soon it would be time to replace it.  One day I got ambitious again, and since I had decided that I was going to buy a new scanner anyway, it wouldn't be a problem if I screwed this one up. 

Since the streaks extended the full length of the image, I reasoned that something with the scanning head was causing the streaks and not something on the glass itself, so it was off to clean the scanning head, which would require that I remove the top shell of the scanner. 

Before going through this disassembly, try this easy fix that is posted on the HP web site.
http://h10025.www1.hp.com/ewfrf/wc/genericDocument?lc=en&cc=us&docname=bps05270
<Quote>
Step 1: Re-homing the scanning carriage
The scanning carriage in the scanner may have lost the home position and needs to be reset.
1. Shut the computer system off, then disconnect the scanner from the power source. Leave the scanner disconnected from the power source for at least one full minute.
2. Reconnect the power, then restart the computer system.
3. When the computer system has fully restarted, try scanning again. If the scanner functions normally, there is no need to continue with the other steps in this document. </Quote>

The reset for the HP scanning head has been reported to have worked for some UMAX models. 

If  that doesn't work, then continue below.
 
The Cause:

HP Glass cleaning recommendations from the site above

Cleaning supplies
Lint free cloth
Glass cleaner
 

Recommended glass cleaners
Cinch Glass Cleaner
Spic and Span Glass Cleaner
Sparkle Glass Cleaner
Glass Plus Glass Cleaner
Or any Isopropanol and Butoxypropanol based cleaners
 

Cleaners to avoid
Any cleaner containing ammonia (Windex)
Any cleaner that leaves a film, haze, or streaks

Other HP warnings on cleaning the undersides of the glass.

Clean the glass using a soft, lint-free cloth sprayed with a mild glass cleaner.
CAUTION: Use only glass cleaner. Avoid abrasives, acetone, benzene, and carbon tetrachloride, all of which can damage the scanner glass.  Avoid isopropyl alcohol because it can leave streaks on the glass.  Do not spray the glass cleaner directly on the glass.  If too much glass cleaner is applied, it could pool and run to the edges. This would render your scanner useless and would require sending it in for repair.
Dry the scanner glass with a dry, soft, lint-free cloth.  

and...
CAUTION: Do not spray the glass cleaner directly on the glass.  Do not allow the cleaner to seep between the glass and the plastic.  If liquid gets between the glass and the plastic it could stain the calibration strip (the white strip under the glass) and render your scanner useless.  If the cleaner gets in the calibration-strip area, the scanner must be sent to HP for repair.  

In the pic above, the long white calibration strip under the 5p's glass near the rear of the scanner top case (outlined in green here for clarity). You may want to look for similar ones under your scanner top case.

Here are step by step instructions for removing the top of a HP 5p scanner, with user supplied notes for other models. 

HP 5p, 5100, 5200: (See below for other models) First thing is to remove the lid which is easily accomplished by lifting the cover to the vertical position and then just lifting it straight up and out of the case. There are two T-15 torx screws on either side of the upper case where the cover hinges slip into the upper case.  Remove these two torx screws. If you don't have a T-15 torx screwdriver or a torx screw bit, a 3/32" SAE hex key (aka Allen wrench) will work (Thanks to Helen Jost for this tip). I found that Metric hex keys are either too small (2 MM) or too big (2.5 MM). If you are in the US, you may have a couple of these SAE hex keys laying around in a drawer or toolbox somewhere. You can also try removing the screws with a pair of pliers, grabbing the edges of the screw head with the ends of the plier tips. If they are in too tight to remove with the pliers, and you don't have the torx or hex key, stop here and take a drive down to the hardware store and get one of those multi bit screwdriver kits which has a T-15 torx bit included.

Picture of a Stanley 66-801 multi-purpose screwdriver with the torx bit inserted (torx head in inset),
and two different 3/32" hex keys (hex head in inset)


HP IIc - 4 screws, two each front and back (back ones under little pop-out covers) (Thanks, Mac).
HP 5300 - 5370c: Two Phillips head screws near the hinges and 4 tabs near the front of the shell. After removing the screws, pry the back up slightly with your fingertips and pull to the rear to release the top from the tabs at the front. 
HP 4c - 4 screws. 2 at the back near the hinge, and 2 hidden with oval covers near the front. Slide the covers back to get to the screws.
Umax 3450: This model has a lighted top for transparencies, comes off by pushing the top towards the back of the scanner. The hinges are hooks which hold the two pieces of the shell together. Once the top is off a bit of gentle prying at the tabs frees the top so you can get at the guts. (Thanks, Dennis) 

HP 5p, 5100, 5200: After removing the two screws, look  through the scanner glass towards the front of the scanner and notice where the front of the scanner's upper case has molded tabs that surround the Green Scan button assembly inside the front of the scanner case. The lower ends of the tabs slip into slots in the black plastic piece. Note the position of these tabs because they have to placed correctly when reinstalling the cover.
HP IIcx There is no one-touch scan button on the IIcx, so you don't have to worry about that.
Umax Astra 610: There is an LED on the front of the upper case that is connected to the lower case by 3 wires. 

HP 5p, 5100, 5200: The top case has two plastic tabs at the front sides that slide under the metal base of the scanner and hold the front of the top case down. Gently lift the scanner top from the hinge end (where the screws were) and pull towards the front of the scanner and the top will come off. No wires or anything else have to be removed before lifting off the top cover.

Caution: Before you start moving or removing parts inside the scanner, it would be a good idea to note the positions of the parked head, belt tensioner, and other parts likely to be moved during disassembly, before you mess with them. Take digital pictures, or draw schematics.  Putting something back in the wrong position may cause more problems than dirty mirrors.

HP 5p, 5100, 5200: Looking at the scanner head, you'll notice a long white tube on the top, recessed into the scanner head. This is the scanning bulb. Check it for grime. This is probably not the cause of the stripes but since you have the case opened, you might as well clean it. Use a good glass cleaner on a paper towel and gently wipe as much of the bulb as you can from the top. Taking the top of the scanner head off to get to all sides of the bulb is restricted by one screw which is covered by the metal channel just behind the bulb on the right side in the pic below. It cannot be reached with a screwdriver no matter where I slide the scanner head. Taking the scanner head completely apart is not an option right now and it would require more expertise than I have to put it back together. ( Added: Barry VandenBergh e-mailed me on 1/9/2001 and said he corrected his problem using this tutorial and he also advised that there is a third mirror hiding inside below the bulb. Additionally, he was able to get to that one screw by removing two T-10 screws from the slide on the opposite side of the head from that screw and was therefore able to turn the head carriage to expose it. I don't have a T-10 bit at the moment and there is nothing warranting me taking the head apart at this time, so I haven't tried it (my scans came out streak-free by just cleaning the other two mirrors). Thanks, Barry). 
The third mirror can be accessed with a Q-tip, also known as a cotton swab, the kind that you clean your ears with. Don't clean your ears with the swab before cleaning the mirrors. Use a fresh one!
Just in front of the scanner bulb there is a full width slot. Look down in there and you will see the mirror laying at about a 45º angle (see diagram below). Stick your damp Q-tip down in there and wipe the length of the mirror.

Where I found the problem. 

Look on the front and rear of the scanner head. You will see two mirrors. The one on the front is about 3.5 inches long by 7/16 inches high and the one on the rear is about 7 inches long and the same height. Do they look clean? Mine did, but I decided to take them out anyway. Both mirrors are held in by metal clips on the ends of each mirror.

Picture of one of the spring clips. The back slides down into a hole on the plastic scanner head. The notch on the front rests against the mirror holding it in, and the tab on the bottom lays under the mirror edge.

Remove these clips by gently prying out the clip from the bottom until the bottom tab just clears the front of the mirror glass and then lifting the clip straight up. You may have to wiggle it a little or pry up the top to get it out of the hole. Don't be too aggressive with the prying, or else you might distort the clip. If you do, squeeze it back into the peoper shape before reinstalling it. Be careful that you don't break or scratch the glass, or let the mirror fall out. 

Note: Some scanners do not require that you take out the mirrors. They can be cleaned in place. On the HP IIc, you'll have to take off a top housing to get to all the mirrors and you won't have to actually remove the mirrors to get them clean using a Q-tip (cotton swab) and alcohol. Thanks to 'Mac' for providing all the info on the HP IIc.

Stan wrote: In the IIcx, it is the small, forward mirror which has the interference pattern that needs to be cleaned. In fact, there is a hole in the aluminum frame below the mirror, and this is the only possible entry point for the condensing fumes from the circuit board. The hole is there for easy access to calibrating potentiometers on the circuit board; since this hole is where the fumes enter, this is a design error by HP. I also found condensed fumes (but less thick) on the totality of both mirror surfaces that in turn affect the total transmitted light, and therefore both mirrors need thorough cleaning to return the instrument to nearly the original spec after 10 years! Thanks, Stan.

Below: The front mirror. 

Below: The rear mirror reflecting the inside of the case. It runs between the two clips. Note the proximity of the green circuit board to the mirror. This could be one reason for the mirror discoloration.

On the backs of these mirrors is the mirror coating, a metallic film that provides the reflective qualities of the mirror. When I looked at the back of the long rear mirror, I saw some prism like rainbow discoloration in about the same location as I had determined the scanner was causing the streaks. 
Sorry, I didn't take a pic at the time, but the following pic was sent to me by MaMaT who had the same problem on a HP 5p. 

Using the same cleaning agent, I thoroughly but gently cleaned the discoloration off and then rinsed it off by running it under the faucet and then dried it by patting it with paper towels. I did not want to rub that mirror coating. I then removed, cleaned, and pat dried the front mirror although it didn't have the same discoloration. Make sure you remove all lint from the mirrors. 

I then replaced the two mirrors, with the glass side facing out and the mirror coating facing in. Be very careful here, the mirror coating is equally reflective on both sides and it is easy to put them in backwards if you are not careful.

A good way to tell which side is which is to look through the mirror at an angle. You can see through the bottom on the glass side (Green arrow), but not on the mirror coated side (Red arrow).

Place the back of the metal clip into the hole provided and then swing down the clip bottom and snap them into place. You may have to spring the front out a little bit to get the bottom of the clip below the glass so you don't scratch up the mirror glass.

Positioning the HP 5p belt spring tensioner.
If you removed the drive assembly and forgot where the belt spring tensioner should be located, here's a couple of pictures. The tensioner spring ends should be located on the belt where there are two rubber locating tabs built into the backside of the belt. Once that is in the correct position on the belt, you can move the belt and spring to the correct location in reference to the drive motor. There is a spot weld dimple in the steel by the slide rail next to the drive motor mounting plate, and a small phillips head screw on the right side of the drive motor mounting plate. The back end of the tensioner spring should be aligned with the dimple and the front end of the spring should be aligned with the motor plate screw.

Overhead view

Before you put the top shell back on, clean both sides of the scanner glass and remove any lint especially from the bottom where you won't be able to get it once the top case is screwed back on. 

Starting at the front of the case, replace the top by aligning the molded tabs on the inside front of the top case around the green button assembly as mentioned above. Then lower the rear of the upper case. Put the two torx screws back in and replace the cover and you are done. You should now have a clean scan. 

What caused that discoloration, I don't know for sure. It looks like it could have been some sort of heat discoloration, possibly from the circuit board below the mirror. Another cause, mentioned by someone else, could be tobacco smoke. I smoke a pipe, which throws off a lot more smoke than a cigarette and the scanner sits on the top of my desk hutch right over the monitor about 3 feet from my face.

My scanner makes noise or scans black or tinted colors now!
While disassembling your scanner, you may have moved or knocked something out of whack, such as the scanning head or head lock mechanism. If you get black or tinted scans, or there are grinding noises while scanning, see the fixes on these HP pages.
Grinding noises:
http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=bps01057&locale=en_US
Tinted scans: (this was mentioned and quoted at the beginning of my page above)
http://h10025.www1.hp.com/ewfrf/wc/genericDocument?lc=en&cc=us&docname=bps05270

Note to viewers:
I am not a scanning expert, nor do I repair scanners. Please don't e-mail me asking for scanner tips, or solutions to other scanner problems, or where to get replacement parts or bulbs, or advice on what brand or type of scanner you should buy.
If you are having any other scanner problems not mentioned here, I would suggest you seek professional service. Assuming you are out of warrantee, you might try contacting the scanner manufacturer for authorized repair facilities, or you can look in your yellow pages for computer repair shops and give them a call to see if they repair scanners. Make sure that the cost of the repair doesn't exceed the replacement cost of the scanner.
If you want to learn all there is to know about scanning, see Wayne Fulton's "A Few Scanning Tips".
You can also ask in the scanner newsgroups for a solution (if you weren't sent here from there):
alt.comp.periphs.scanner
comp.periphs.scanners

Number of people who have benefited from this page (or at least wrote me that they did!), since March 30, 2000, when it was put up. Count last updated May 5, 2007. It will not be updated any further.

Why the half in the count? Someone found the discoloration on the mirrors, but broke the scanner bulb in the process, so he couldn't test whether it solved the problem. 

Types of scanners reported to have been cured: 
HP II cx, 4p, 5p, 3200, 5100, 5110, 5200, 5300, 6200, 6250, 6300, and 6350.
MicroTek 4800 and X12USL
UMAX Astra 610, 1220, 2000, and 2100
Epson Expession 800
and perhaps other makes and models not specifically mentioned in messages.