HP M476dw Horizontal Line across the page every 2 1/2 inches

[atadikohp]

I just ran into this issue today. The print out has horizontal black bar across the sheet and every 2 1/2 inches down the sheet.
I did a latest firmware update ==> issue still there
Change another OEM black toner cartridge ===> no help
The ITB look clean since the printer is not that old.

Any one here cross this problem before? Please advise. TIA
PS: Attachment is the sample print out

[Pafasa]

Re: HP M476dw Horizontal Line across the page every 2 1/2 inches

I think you are on the right track. I notice Cyan in the center of the top band of black. I would try a cyan cartridge also. Not sure if this machine is using oem or rebuilt cartridges. Often, rebuilt ones have a lower quality drum and the drum actually arcs through to the transfer belt.

[atadikohp]

Re: HP M476dw Horizontal Line across the page every 2 1/2 inches

I think you are on the right track. I notice Cyan in the center of the top band of black. I would try a cyan cartridge also. Not sure if this machine is using oem or rebuilt cartridges. Often, rebuilt ones have a lower quality drum and the drum actually arcs through to the transfer belt.

Thank you for your help. The customer had changed the entire OEM color toner set before the call. I pretty sure that this is some kind of irregular current out put to the between ITB and cartridges bur could not pin point where the issue is. I hate it to have to drive 4 hrs one way to customer site to bring the printer back to the shop to troubleshoot

[Pafasa]

Re: HP M476dw Horizontal Line across the page every 2 1/2 inches

Its interesting that the problem repeats so regularly. Is 2 1/2 inches apart the exact measurement or an estimate. The exact measurement in millimeters would help in troubleshooting this.

[atadikohp]

Re: HP M476dw Horizontal Line across the page every 2 1/2 inches

Its interesting that the problem repeats so regularly. Is 2 1/2 inches apart the exact measurement or an estimate. The exact measurement in millimeters would help in troubleshooting this.

The distance is 55 millimeters apart. Each bar is 8 millimeters thick. I did ask the customer to make a blank copy, the result is still there with those horizontal black bar with some color. This definite some type of current issue. I was thinking between high voltage PS and DC controller

[BaconSteve]

Re: HP M476dw Horizontal Line across the page every 2 1/2 inches

...or, possibly internal to the ITB itself. ?

[Pafasa]

Re: HP M476dw Horizontal Line across the page every 2 1/2 inches

55mm doesn't correspond to any roller in the machine except maybe the fuser film which is 57mm. Hard to imagine the fuser film causing what you are seeing. Does this happen when printing an engine test? About 3 inches below the right front corner of the scanner, there is a hole in the cover. Ask your customer to press a plastic tool in there to press the engine test button. If you get a good print with no bands, then you can eliminate mechanical issues and most of the process control components, ie power supply, dc controller, hv board, leaving the formatter as the likely culprit.

I like what BaconSteve is thinking too. Wouldn't hurt to pull the ITB and check the alignment of the pressure mechanisms. They should both be in the same state and the alignment guides should be set for both black and color.

There are some raised marks that you can use to make sure everything is in the correct position. I rotated each coupler clockwise until it hit the correct position, but then it would jump a bit past it, so I then changed to counter-clockwise and turned very slowly. You can feel it drop into position if you pay attention. I marked the raised marks with black sharpie so they can be easily seen in the pic. There are two pressure mechanisms in the belt. One for black and one for the three colors. Each mechanism is rotated by the machine through a + shaped coupling. Each pressure mechanism has three raised marks that must be aligned properly before installing the belt in the machine. You can see these marks in the pic because I "sharpied" them. When these marks are aligned properly, the + shaped coupling should be straight up and down. Not rotated off center at all. At this point, handle the transfer unit carefully and insert it into the machine. To be sure nothing falls out of position, move the locking pins in and up to their locked position right away after installing the belt. Then go back and insert the two connectors and screw the two locks down under the fuser.

Hope this helps.....