HP 4350 lines across pages

[psteelers]

Hi all. I've got a HP 4350 that prints horizontal lines across pages down entire page. Lines are 1/4" apart with random splotches on the lines down entire page. The actual printed image is very faint in the background. If you print an Engine test, the lines that normally run vertical, only print at top of page, then fade quickly. The horizontal lines are still there on Engine test. Same spacing and splotches. Tried different toner cartridge with no change. Tried different transfer roller, no change. I thought the toner ground spring was bent out of position as they had said removing toner was difficult at best. Found toner tension spring on left side to be very loose. Tried re-bending it and also total tear down to try to repair it. No change.
Question is: It could be the LVPS/HVPS unit or the DC Controller (which I think is aka Engine board), I just don't know which or if there is something else like a broken spring contact I can't see.
Any ideas?
Thanks

[walterman]

Have you checked the laser unit shutter and made sure it is fully opening? Sometimes the shutter assembly breaks and the shutter does not fully open and it could cause this issue. I would think, that if the printer was not getting the proper voltage, it would trigger a possible code, 41.x, etc.

[Printerdude]

Are the toner cartridges remanufactured or new OEM?

[1stcavvet]

I say there's a grounding problem with the cartridge, block the ground with a piece of tape and see if it doesn't go completely black, the wierd part is the pattern, are the lines evenly spaced? that would mean something ticking something, gear moving somthing, some wiggle. check the wiring on the board on the right side. GOOD LUCK

[psteelers]

First. Thanks all for replying. Here's a follow up. Tried new Transfer Roller, bending contact spring under block where it contacts the HVPS, Engine test with and without Formatter installed, a known good DC Controller, a known good Laser/Scanner (I even removed the shutter altogether, that's for you Walterman) and different toners, and unfortunately, yes they are aftermarkets Printerdude.
Still get the same lines horizontally, but on some toners, the lines go away and are replaced with a blotches down pages. Looks like hundreds of small bubbles jumbled together. Any ideas? 2.JPG1.JPG

[walterman]

If I'm reading correctly on your, follow up, you mentioned the cartridges are aftermarket, have you tried an OEM toner cart.? Have you checked the wall voltage and ground?

[psteelers]

If I'm reading correctly on your, follow up, you mentioned the cartridges are aftermarket, have you tried an OEM toner cart.? Have you checked the wall voltage and ground?

This hospital doesn't use OEM's. I"ve never had this issue with them before and I did try a working one from another location. Wall voltage is good and a loaner printer is working fine in same spot. Tomorrow I may try to continuity test the contact springs. Thought of it too late for today.
Thank you.

[walterman]

Wow, I'm stumped, the only other thing I could think of is swapping out the 110 power supply board (PN- RM1-1173). Let us know what you come up with.

[blackcat4866]

I've seen primary charge problems plenty of times and this looks like primary charge. IIRC the high voltage is on the power supply. That, and those dreaded aftermarket cartridges. Just for my peace of mind I would install an OEM, just this once. =^..^=

[Printerdude]

Wow! Printed pages looks like a toner cartridge issue. Make sure the toner cartridge guide are intact and toner cartridge fully seated. You can try removing the power supply and clean the contacts on the power supply and springs. Try a OEM toner cartridge, I never trust a remanufactured toner cartridge before eliminating parts first. Could be the power supply needs replacing.