hp laser 1600

[Saji]

I have a HP Laserjet 1600 printer, when printing color copies it only prints black and blue, ialready changed all catridges, what could be the prob?plz help

[prntrfxr]

There are 4 main possibilities:

1) dirty transfer belt - Clean by blowing out with compressed air. Especially the top where the sensors are located.
2) defective transfer belt - check the event log for 54 errors. If any are present, replace the transfer belt. If they are not present you probably have dirty scanner lenses.
3) dirty scanner lenses - follow the cleaning procedure below as it's only going to cost you time to do
4) defective laser scanner - this is not common

Laser Scanner lens cleaning procedure:
I assume you're a technician. I say that because you need to be one before you attempt what I'm going to tell you. What I think the problem may be is dirty laser scanner lenses. This machine has a 4-in-1 type laser scanner. There are no shutters, so toner tends to get in there and make the print faded until it disappears. Blowing compressed air into the scanner slits will not clear the problem, trust me. You have to remove the scanner, hold it up to a good light source and thoroughly clean it. The service manual does not have instructions to get to the laser scanner, so you will need to know something about handling electronic boards and cables (if you are not a tech don't try this):

1) Remove the cover over the rear of the tray
2) Remove the tray
3) Remove the cartridges and leave the front door (with transfer belt) open
4) Remove all screws securing rear cover (there are 9 of them)
5) Remove the rear cover
6) Unplug 16 connectors and 4 screws securing DC Controller, then remove it (take care when removing ribbon cables)
7) Unplug 6 connectors from the Formatter (take care when removing ribbon cables)
8) Remove 4 screws securing the formatter and remove it

This is as far as the service manual goes. The rest I'm doing by memory so it is possible I may have forgotten something. Use your common sense here.

9) Unhook all the harness track guides from the upper portion of the frame. I was able to remove the metal plate the formatter and DC controller are attached to without removing the cables from these guides. The purpose is to access screws behind them and remove the plate without disconnecting all the cables.

10) Remove all screws securing the metal plate. I don't remember how many there are, only that there are a lot of them as HP likes to put screws every 1 1/2". It is also important to note that there are at least 2 screws on the left and right sides that secure this plate. Be careful with the ribbon cables as those go to the laser scanner. There is also a hole toward the bottom of this plate that is for a power cable and another connector or 2. Make sure you pay attention to where the cables are and how they are routed because you won't have any guide in where to put them when you reassemble.

11) Remove the metal plate

12) You should now be able to see the laser scanner. Rotate the printer and let it set on it's side. There are 2 metal leaf springs on the bottom that hide screws. Remove them and remove the screws.

13) Return the printer upright and remove any other screws securing the laser scanner. Remove the laser scanner.

14) Hold the scanner up to light and use a swab to clean the lenses. Do not use alcohol or any other clean on them.

If you have a defective scanner, this will not work, but 90% of the time this works (I've only had to replace one due to it being so dirty it wasn't cost effective to clean). I've only had to replace 1 transfer belt too. Hope this helps you.

[Saji]

Thank you prntrfxr, i fixed the problom, by cleaning the laser unit mirrors,and once i again i thank you for explaining it so well.