HP Plotter DesignJet DJ500 - Printheads alignment error after belt/strip replacement.

[chania]

Hi everyone. I have a plotter HP DesignJet 500 (C7770B). I recently replaced both the belt and the strip because the belt was falling apart. Everything went well. I put every part back together, and I turned the plotter on - no problems there. It went straight to "ready" mode. I ran the troubleshooting mode, and it said "printheads require alignment". I run both the 4,5 and the 11 minutes alignment, but both ended in an "alignment error". It only does the first part of the alignment procedure, where it prints out the lines and the dots, then checks them, but then it just stops. Any suggestions as to what do I do next? Thanks in advance.

[Valsimot]

Can you scan or take a photo of the alignment sheet and post it here?

[chania]

Thank you for your reply.

The first scan is the alignment sheet. You can also see a scan of a print test i did, plus a photo of the error message the plotter shows, when the alignment procedure stops.

Alignment sheetPrint testError Message

[Valsimot]

That alignment sheet looks bad. The distance between the two columns of the dots in the same colour should be close to the same, you don't have that.
Did you lubricate the carriage rod, and the belt is tight? Calibration strip is clean, no finger marks or dirt?

[chania]

I lubricated the rod (light film of lubricant).
The belt seems tight, its spring is in the correct position (unlocked). In any case, i used two different belts (new belts, but not original HP, i bought them from China) in order to fix the issue, but it didn't work.

The strip (also new - original) is clean, I used a napkin with some warm water to clean it after installing it. 

[Valsimot]

The carriage moves freely when you move it with your hand, no bumps or something?

The encoder disk is on the left side under a small cover, use a wet cloth to push inside to encoder disc and to clean the encoder disc from both sides. You can use loaded paper to pull it to rotate the encoder disc while holding the wet cloth it will rotate and clean itself. 

[chania]

Yes, the carriage moves freely, no issues there.

Could you help me with some more information on how to locate that encoder disk you mentioned? i can't find it. Or could you send me a picture, so that I can understand what it looks like?

Thanks a lot.

[Valsimot]

You can get a free service manual, that would be the best help.