[CQ] HP CLJ4600 magenta background on backside only

[blackcat4866]

Most of the time it's just swap the cartridge, then out the door, except today.

The first thing I do is swap the cartrdge from the machine down the hall. Now both machines have good CQ. Swap the cartridges back to their original location, and the CQ issue returns to machine1. I thought this was odd, so I open a fresh compatible. Same CQ problem. I don't know what to make of this.

Next I swapped the transfer belt assy. No change.

After some searching I discover that the developer shift rack along the back frame of the printer is broken at the left, and the right side rack is doing all the lifting. As far as I can tell from the manual this is not available as a seperate part, so I get to do some "field engineering". I got the left rack repaired, and re-installed.

At this point the problem is 90% gone. If you look very closely you can see some very faint magenta background every 3rd page. I figure that I'm on the right track since the problem continues to improve.

Next I look at the part of the cartridge that contacts the developer shift rack. There are two little posts at the left and two posts at the right that are melted/mushroomed to a specific length (6.5 mm from the flat). C Y & K cartridges all look basically the same, but on M those posts have been busted off at 5.0 mm. So I look at the other M cartridges. Three out of four M cartridges have these posts damaged in some way. The simple fix is to superglue on a chunk of plastic and dremel it down to 6.5 mm (15 minutes, once I knew what to look for).

This might help you save a few of these failing magenta compatibles.
prntrfxr: Is that rack available as a seperate part? Does it have a part number?

=^..^=

[prntrfxr]

We're getting a number of calls this week about it. We've been researching it. Causes the machine to dump magenta toner on the belt and deposit it to next pages. Additionally causes one side of the page to be blank or print light. I'm working on a service note. It's called the Cartridge Alienation Plate Kit, Q3668-67925. It comes with instructions and part list. We have one in stock right now. Now that I know what it looks like (I've been researching it and couldn't find a photo of what you actually get), we will be ordering more. I will add a picture from home. I took it with my digital camera and it's too big to edit at work (too big to attach too). There are 4 black plastic pieces in the kit. 2 small and 2 long. This does not have the white pieces that are on the metal shaft. So if that's what is broken this kit won't help you. I am still trying to find the part # for those pieces.

[fixthecopier]

not sure if this is the same, but I have had these dumping magenta for years and was told by tech support that the dc control had a to do with it. needed to change and throw out the old magenta.

[blackcat4866]

I'll be interested in seeing the pictures of that "Cartridge Alienation Plate Kit, Q3668-67925".

It's one of my better field repairs, so I have confidence that it is durable. The cam system is OK, it's the rack portion that provides the color developer shift. The left and right racks appear to be identical by all appearances.

Thanks for looking into it. =^..^=

[prntrfxr]

The magenta dumping is actually caused by more than one thing, but since Blackcat determined that the parts behind the cartridge were broken when he posted, it kind of eliminated the other two. Blackcat, you should probably check the other things anyway.

Causes:

1) Setting the tray 1 settings to Any will cause the printer to put more toner on the belt to cover larger sizes of paper. This causes the waste toner bins in the cartridges to fill up before toner runs out in the cartridge. Result: cartridge leaks toner and excessive toner on ITB. Resolution: set the printer and the driver settings to letter or whatever size the customer is printing. (remember any settings in the driver will override the printer configuration.) Replace leaking cartridge

2) Defective cartridge. Broken tabs, faulty shutter, or poor quality of 3rd party cartridges. (Do not mix and match OEM cartridges with 3rd party. The OEM have firmware in them that will degrade quality. Use all one type.)

3) Replace transfer belt. If it does not clean itself properly, toner gets redeposited to the pages.

4) Verify the printer has Version 2 of the DC Controller. Yes, HP made a correction to their boards due to cartridge leaking issues

5) Since these printers are getting older the plastic parts wear out. No surprise, then that these plates which move up and down with a white cam attached to a shaft, can get broken. The Cartridge Alienation Plate Kit is an HP kit and I have attached a photo of it. The small ones are the ones in the black cartridge position and tend to get broken more frequently. Since the magenta is the next one down, it is the one that usually leaks. These same parts work on the HP 4600/4610/4650

6) We know the part numbers of the white cams and brackets. I am checking to see if those can be purchased from HP (they came out of the Canon service manual). If they can, I will post the part numbers.

Hope this helps you guys.

[blackcat4866]

#5 was my situation. And those are the parts in the photo. If my repair doesn't hold up you'll be the first to know. =^..^=

[prntrfxr]

we have the cams and shaft supports on order so we can get them. FYI will are making a kit that will have the HP kit and the cams and shaft supports in it.

[Wild Bill]

Re: HP CLJ4600 magenta background on backside only

Question I dont under stand how to tell dc controller version; It says on mine Printer number 62


Verify that Printer Number (located on the Configuration Page under Printer Information) is less that 6D.
NOTE: If the Printer Number is equal to or greater than 6D, this service advisory does not apply.

6D? how does that work?