HP 3550 printout way too light after 59.99 error repair

[melvinzill]

Hi, first of all let me apologise for my poor English im from Germany and this is my first post. Both of my 3550s had issues with Error 59.99. Unit 1 was decommissioned after if died out of the blue with 59.99, the other had it occasionally. I followed @Davidzuts advice (https://h30434.www3.hp.com/t5/LaserJet-Printing/CLJ-3550-quot-59-99-Printer-Error-quot/td-p/5888283) and followed the service manual to remove the assembly and repaired the sticky solenoid.

And what happened to 59.99? Its gone! Both printers now print consistently and reliably. Great.

Until I saw the first printout. It's far too light and looks terrible (see image). The test page looks bad too. I first thought this was due to Unit 1 having some other issue (wouldn't have surprised me because its been in storage for about ten years), but I did the same to Unit 2 and it shows the exact same symptoms. I calibrated numerous times, and the 4 toners (and yes it has a 3700 toner fitted but it's been like that for a while, this isn't the issue!) and transfer kit are known good.

At the point I am completely stuck. I don't know where I f***ed up these printers, as everything appears to be working.

Both trays work smoothly and there are no weird sounds... 

If anyone has even the slightest of clue, tell me.

It would help a lot. 

Thanks so much in advance, 

-Melvin-

[melvinzill]

Oh and just a small addition, on the bottom of the page it looks a bit better.

[Repairatrooper]

2 most common causes of light print light this would be dirt on the scanner lens or bad high voltage power supply. You should be able to see the scanner lens when you open the front door and remove the cartridges.

[melvinzill]

Hi, thanks so much for your reply. But I personally doubt either is the issue. On Unit 1, yeah maybe. But number 2 was fully working before I took the assembly out. Printouts looked great. I think something else is going on here, I mean how likely is it the I got the lens dirty in the exact same way on both or killed both HV boards? 

best regards,

melvin