LaserJet 2420 grey background - posted on behalf of AlanHK

[tsbservice]

LaserJet 2420 grey background
Here's part of a page printed below.

Most of the left side of the page has a greyish irregular background, maybe 10% grey. The text is a bit faded and sometimes broken up.
I got this printer a few months ago, Has 207,000 pages on the clock.
I had another printer, same model, that was having a lot of jamming issues, so I took its 90% full toner cart for this and it printed perfectly.
The fold out "tray 1" was damaged though, so I took the tray from the other printer. To do that I had to take off several panels and take the toner cart out. I did try to protect it. Cleaned dust out of the printer while I was at it. The print seemed to be still OK, then. I disposed of the old printer (no room for it). But shortly after this grey vertical bands appeared. I made a couple of the cleaning pages and ran the clean cycle, but made no obvious improvement.
Is this some damage I did to the toner cart when doing the repair & clean? Can it be fixed, or will a new cart fix this?

Note:
posted on behalf of AlanHK

[AlanHK]

Re: LaserJet 2420 grey background - posted on behalf of AlanHK

Thanks tsbservice.
Could not start a new thread myself so needed an assist.

Note: posted on behalf of AlanHK

[blackcat4866]

Re: LaserJet 2420 grey background - posted on behalf of AlanHK

Did you use air to blow out the printer. It's just not a good idea to blow around toner. It has a way of settling down in hard to find places. I would start by cleaning the laser slit glass, and if that didn't help, I'd clean the laser mirrors and polygon mirror surfaces. =^..^=

[slimslob]

Re: LaserJet 2420 grey background - posted on behalf of AlanHK

The last time I saw background like that on an HP it was refilled cartridges.

[AlanHK]

Re: LaserJet 2420 grey background - posted on behalf of AlanHK

The last time I saw background like that on an HP it was refilled cartridges.

It's not a HP cart, but not a refill. I'd done a thousand pages in the old printer with it over 18 months and quality was perfect.
Done another 500 or so since then hoping it would come good, but not happening.
It's 90% full, but if it's the problem I'll replace it.

Did you use air to blow out the printer. It's just not a good idea to blow around toner. It has a way of settling down in hard to find places. I would start by cleaning the laser slit glass, and if that didn't help, I'd clean the laser mirrors and polygon mirror surfaces. =^..^=

Didn't blow anything; wiped, but might have messed it up nonetheless.

Just took out the cart and found the metal plate above it rather dusty with toner, wiped that.
Below image of the drum-- obviously has streaks of toner on it. Any point in wiping that? Or would it make it worse? I though it should self clean. Use a cloth with alcohol?

Looked in the service manual, only mention of a mirror is "the mirror in the laser/scanner might be dirty. Replace the laser/scanner".
Not really encouraging for maintenance.
Presumably the laser slit is on this unit? Do I need to take it out to get to the slit?

[slimslob]

Re: LaserJet 2420 grey background - posted on behalf of AlanHK

It's not a HP cart, but not a refill. I'd done a thousand pages in the old printer with it over 18 months and quality was perfect.
Done another 500 or so since then hoping it would come good, but not happening.
It's 90% full, but if it's the problem I'll replace it.



Didn't blow anything; wiped, but might have messed it up nonetheless.

Just took out the cart and found the metal plate above it rather dusty with toner, wiped that.
Below image of the drum-- obviously has streaks of toner on it. Any point in wiping that? Or would it make it worse? I though it should self clean. Use a cloth with alcohol?

Looked in the service manual, only mention of a mirror is "the mirror in the laser/scanner might be dirty. Replace the laser/scanner".
Not really encouraging for maintenance.
Presumably the laser slit is on this unit? Do I need to take it out to get to the slit?

You should have provided that picture with your original post. That looks like you have a problem with drum cleaning. Could be a damaged cleaning blade, paper scrap on the blade or a build up of toner lint.

Edit: If the laser shield glass were dirty you would get light streaks, possibly even blank stripes.

[blackcat4866]

Re: LaserJet 2420 grey background - posted on behalf of AlanHK

... Just took out the cartridge and found the metal plate above it rather dusty with toner, wiped that.
Below image of the drum-- obviously has streaks of toner on it. Any point in wiping that? Or would it make it worse? I though it should self clean...

The only situation in which you might want to clean a drum is if it had label adhesive on it. I use paraffin lamp oil on a Q-tip, and clean only the smallest affected area, then again with alcohol. Otherwise, yes, the drum IS self cleaning and if it doesn't you'll need another cartridge.

... Looked in the service manual, only mention of a mirror is "the mirror in the laser/scanner might be dirty. Replace the laser/scanner".
Not really encouraging for maintenance.
Presumably the laser slit is on this unit? Do I need to take it out to get to the slit?

You do not need to remove the the laser to clean the slit glass. It is vertically directly above the drum and is covered with a mechanical shutter. Remove the toner cartridge and move aside the shutter to clean the glass. Use glass cleaner or alcohol on a shortened Q-tip

To clean the laser you must remove the top cover. The laser is right on top. It removes with a few screws and a few harnesses. Take care with the ribbon cables. It comes apart easily to clean the mirrors, especially the polygon mirror surfaces. NOTE: Do not remove the mirrors from the laser! Clean them in place. It's not as difficult as it sounds.

=^..^=

[Blizzoo]

Re: LaserJet 2420 grey background - posted on behalf of AlanHK

PCR Roller inside toner cartridge (if a compatible HP cartridge) must be shot

[copier tech]

Re: LaserJet 2420 grey background - posted on behalf of AlanHK

All you need to do is simply replace the toner cartridge.

Only use genuine HP & you will never have this issue again.

[AlanHK]

Re: LaserJet 2420 grey background

PCR Roller inside toner cartridge (if a compatible HP cartridge) must be shot

Yeah, that seems likely. I asked in the manuals forum for some docs on the cartridge and got a remanufacturer's manual.
That included a list of common problems:

Dirty or Bad Primary Charge Roller (PCR): This will show on the test print as vertical gray streaks down the page, as a gray background throughout the page, or as ghosting where part of a previously printed area is repeated.

Which describes the printout pretty much.
I assume the dirty drum is consistent with this.

Since this happened after I moved the previously good cart to a "new" machine my assumption was that the problem was the printer. But I guess transferring the cart somehow damaged it. Maybe a poor electrical contact.Though I've taken it in and and out of the first printer dozens of times to clear jams.

I've had a few carts broken out of the box, but none that have failed in service before.

You do not need to remove the the laser to clean the slit glass. It is vertically directly above the drum and is covered with a mechanical shutter. Remove the toner cartridge and move aside the shutter to clean the glass. Use glass cleaner or alcohol on a shortened Q-tip

This shows the slit glass, I think? On the top of the cart; no shutter though. The only shutter is on the bottom, over the drum.
A smear of toner on the left. Cleaned it but print quality not improved. Still plenty of toner marks on the drum. So this is a symptom, not a cause.

So: seems clear the problem is the cartridge, so will replace.
If my wife allowed me to keep the old printer and its cart I would have been able to swap it in to confirm, but such are the constraints of working from home...

Might try to crack the cartridge. Probably can't fix it without new parts but it will be educational.

All you need to do is simply replace the toner cartridge.
Only use genuine HP & you will never have this issue again.

I'm sure that's true, but the HP cartridge is A$379.97. Compatibles are $25-$35. In 30 years I've only had a few issues with non-HP carts, so I accept the risk. Larger businesses may have a different calculation.
But found someone local reselling a genuine HP cart almost as cheap, so will see if I can get that.

Thanks all for the advice.

[slimslob]

Re: LaserJet 2420 grey background

This shows the slit glass, I think? On the top of the cart; no shutter though. The only shutter is on the bottom, over the drum.
A smear of toner on the left. Cleaned it but print quality not improved. Still plenty of toner marks on the drum. So this is a symptom, not a cause.

No, I think that is the opening in the cartridge that the laser projects through. The laser shield glass would be in the main body of the printer above that opening when the cartridge is inserted.

[AlanHK]

Re: LaserJet 2420 grey background

No, I think that is the opening in the cartridge that the laser projects through. The laser shield glass would be in the main body of the printer above that opening when the cartridge is inserted.

There's a slot above the cart, as image. No shutter or visible glass though. The laser unit is inside so presumably has the shield as part of it.
Won't go into there unless the new cart doesn't fix it. Need to take off most of the covers to get into that, and every time I do that I cringe, thinking the plastic tabs may snap off.
15 year old plastic gets brittle. I used to have a 2100, held the case and doors together with duct tape for the last year or so as it crumbled away.

[slimslob]

Re: LaserJet 2420 grey background

There's a slot above the cart, as image. No shutter or visible glass though. The laser unit is inside so presumably has the shield as part of it.
Won't go into there unless the new cart doesn't fix it. Need to take off most of the covers to get into that, and every time I do that I cringe, thinking the plastic tabs may snap off.
15 year old plastic gets brittle. I used to have a 2100, held the case and doors together with duct tape for the last year or so as it crumbled away.

The shield glass serves one purpose, keeping toner and dust from getting into the laser unit.You can clean it by wiping it with a lint free dust clothe, but doing so will not help the problem you have. A dirty shield glass causes light images and void streaks.

[AlanHK]

Re: LaserJet 2420 grey background

Still can't see a shield on the slot, or several mm inside it. No mention in the service manual.
But hopefully the problem is just the cartridge.

[tsbservice]

Re: LaserJet 2420 grey background

Still can't see a shield on the slot, or several mm inside it. No mention in the service manual.
But hopefully the problem is just the cartridge.

As others said your problem is in cart not in Laser unit. Also check inside printer for bent contacts especially where they mate with cartridge contacts.