I just finally got to the bottom of it...
After 1 whole day of changing parts, it ended up being the engine board.
Printing looked like the attached PDF
There were 2x c4300 in very recent memory when the call came in. Yesterday, I exchanged the laser assembly with all 4 from a donor thinking that would be it. But the image was un-changed. I disassembled the k laser motor from the housing and spun it with my fingers, and it felt rough.
Then I cleaned the charge roller.
Inspected the drum carefully.
The developer coating was beginning to show through ever so slightly, but it rotated fine as did the developer spacer rollers.
Then I changed:
The drum/developer set with new parts
The transfer belt
Then I swapped the yellow/black laser assemblies to re- rule-out the LSU. Problem remained on black.
During a printout of the maintenance report it gave grey bands on a couple of pages, where the black image was "magnified" inside the grey area. My guess is the laser motor was being driven slower, so the video feed was slowed to maintain sync.
I tried to print on "thick" paper , and got more lines than the faster feed which told me that the issue was electronic not mechanical. I wish I had done that hours earlier...
Then I changed the lvpsu - no improvement, then finally the engine which restored proper operation.
After 1 whole day of changing parts, it ended up being the engine board.
Printing looked like the attached PDF
There were 2x c4300 in very recent memory when the call came in. Yesterday, I exchanged the laser assembly with all 4 from a donor thinking that would be it. But the image was un-changed. I disassembled the k laser motor from the housing and spun it with my fingers, and it felt rough.
Then I cleaned the charge roller.
Inspected the drum carefully.
The developer coating was beginning to show through ever so slightly, but it rotated fine as did the developer spacer rollers.
Then I changed:
The drum/developer set with new parts
The transfer belt
Then I swapped the yellow/black laser assemblies to re- rule-out the LSU. Problem remained on black.
During a printout of the maintenance report it gave grey bands on a couple of pages, where the black image was "magnified" inside the grey area. My guess is the laser motor was being driven slower, so the video feed was slowed to maintain sync.
I tried to print on "thick" paper , and got more lines than the faster feed which told me that the issue was electronic not mechanical. I wish I had done that hours earlier...
Then I changed the lvpsu - no improvement, then finally the engine which restored proper operation.
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