hardware failure - HP Printer Jamming during Pick-up

Self-Explanatory Videos

1. Jamming during Pick-up: Front View


2. Debug: Rear View without Duplex Unit

Issue Description

Consider the following printer:

• HP OfficeJet Pro 8000 (A809n)


• with duplex unit


• no modifications from factory (ie: no dispenser nor bulk installation)


• no major problems during its lifetime (nor jamming issues)

Then, suddenly (24hrs ago), it started to jam every time it picks-up a paper. Video 1 exemplifies this malfunction, briefly:

• cancel button pressed for 3 secs in order to print a test page


• paper jams just after the main tray (not even entering the duplex unit nor arriving at the printhead)


• this process can go on forever

Unfortunately, HP no longer provide technical assistance for such model and alternative repair shops are hesitating to accept this service due the lack of spare parts. Therefore, find someone to repair it is not an option.

Questions

1. What is the cause of such failure?


2. Is it possible to solve it?


3. In technical terms, how to fix this printer?

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Notes

• Brief explanation of video 2: Without the duplex, the pick-up rollers correctly move the paper from the main tray to the rear part. Additionally, if you insert the paper directly from the rear (caution: this can damage your printer), the printing will continue just fine.


• The pick-up rollers were already cleaned with distilled water (according the procedures of HP Printer Support), however there was no improvement and the malfunction still persist.

Answer

To my experience working as a service engineer there is some piece in the paper path that affected the position of the tray rollers. The abnormal sound of the carriage proves that.

I noticed that that paper is jammed in U form that means that the paper is picked up with a pick-up roller and moved inside to the middle. Then it stops in the paper path but the bottom pick-up roller still moving it forward. That means that something in the middle of the paper path is the wrong position.

To my memory there are so called plastic 'flags' used to detect where each moving part is at every moment. They are moving up and down during the paper move. I saw they are often put in the wrong position and act abnormally providing printer CPU wrong information. As the result cartridge carriage is moving left-right in the wrong time slots (it should be in the most right position when paper reaches it).

Also, from the sound of the carriage I can conclude that it's not moving like it should in full scale. The carriage is driven by a drive with a toothed belt. I saw issues when the belt is damaged and the carriage is slipping on it.

It's not a rubber of the rollers definitely - in the case it would not just move the paper forward.

You definitely need to disassemble the device to fix it. That's all can be said remotely.