Hp CP5525 Missing colour issues

[Ian Stevens]

Hi I'm new on this site. Got a mega problem with above printer. Prints out first page of pantone pages fine but all other pages come out in mono but apart from the missing colour are fine. Print a demo page and get a bit of colour lead edge but then goes to mono (see example) I also uploaded a demo page of what it should look like from another printer. The colour that you get lead edge is normally cyan but is sometimes green fading to yellow. You do a config mono print, first page is ok but second page is ok until halfway across then most of print missing. Engine test page normally just shows black without colour stripes but occasionally we get about 10cms of colour stripes that fade out across the page and over to one side. Stopped print half way through and observed image on ITB and its missing as per problem on pages. This leads me away from thinking second transfer section as well as the fact that on the second config page with print missing, the print that is there is in exactly the same place on all second pages. If it print wasnt transfering properly I would expect it to be random. With this in mind I'm thinking Formater PCB or DC Control. Changed both and no difference. Have since then changed Main HVT PCB, Primary ITB HVT, Laser assembly, Low voltage PCB, Transfer roller section but not whole door assembly. ITB assembly, All drum units. I have swapped these items both ways with another printer and they have all worked fine on other machine but not improved situation on this one. I thought it looks like a problem with ITB charge rollers that use a cam mechanism to push them in and out to give contact with the correct drum but that all looks fine. I'm now thinking it must be a drive assembly issue but that is a hell of a job to take apart and I dont really want to remove it from their working machine incase I cock that one up to with a timing issue or something. The shutters below the drum units seem a bit wobbly but from what I can work out are moved back and forth by the drive assembly. Ive not changed the secondary transfer HVT PCB or the whole right hand door assembly but might give it a go on Monday even though it goes against my reasoning about print in exactly the same place of second config page. I read up about drum alienation but I would have thought if there was a problem in this area we would get a code. The red herring I had when I first looked at the machine was the secondary charge roller was not fitted correctly. The little white plastic retainer was bent back on itself under the roller and therefore not allowing the roller to seat properly. However by correcting this it didn't improve the problem. Ive attached four pages one of a correct demo page, one that I'm getting off this machine and first and second config page. Any help would be really appreciated.

 

[LaserRick]

The pics clearly show there is impedance in the high voltage system. It may be that the ground (located on the cartridge access door) are not making proper contact. Try running a ground wire to the drum of the black toner and see if the print improves. If so, trace the grounds on the door to their source and make sure it is properly connected.