Mp 9000 random smudge... I'm gone mad!

[Mark Bbb]

Plus one with that one.
My unproven theory is that it is caused by change of temperature and humidity over night while the drum sits in one place with a poor air flow over its surface. The straight line is caused by the cleaning blade blocking the air flow. We see the same often on copiers with drums nearing the end of their life, usually as a blurred patch that comes and goes and occasionally a dark patch like yours.
The only remedy is a new drum and filters then change the filters when they should be changed at every PM around 300k.

Well, how big is the fluctuation of the temperatire in the copyshop?

[trc]

Clean, inspect the contact between drum shaft ass´y and the electrode plate........

[luca72]

Hello guys
I have an Mp9000 thats driving me crazy... It seems the machine is possesed by the devil. Randomly a smudge appears on the first copies /prints.... Ever on the same height on the sheet but not on the same place, then after two or three xopies/prints the smudge disappears for days or sometimes for weeks..... I've swapped the following from a working machine : drum, cleaning assy, development unit, pcu frame, laser diode, polygon motor, transfer unit...... But the problem still occurs....

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Try cleaning / scraping the corona wires gently with a flat-head screwdriver to remove the hardened toner + clean / replace the air filter near the corona c. unit ... and while you're at it clean the main filters as well ... clean / scratch the first 15 centimeters of the drum axis (where the internal contacts of the drum rest) to improve grounding, good work

[Codex]

Well, how big is the fluctuation of the temperatire in the copyshop?

About 10-15 degrees Celsius

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[Codex]

Since i opened this thread there was no problem on this machine..... It's more then a week now

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[NeoMatrix]

Try cleaning / scraping the corona wires gently with a flat-head screwdriver to remove the hardened toner + clean / replace the air filter near the corona c. unit ... and while you're at it clean the main filters as well ... clean / scratch the first 15 centimeters of the drum axis (where the internal contacts of the drum rest) to improve grounding, good work

Re. Clean corona wires.

Spring hook works the best. I clean all corona wires religiously every service. You can feel where the dirt/rust/rubbish is located along the corona wire as you scrap along it with the spring hook.

The Canon guys will argue that scraping removes the gold coating from the wires, and so it does but, the gold coating is removed in a uniform state and the corona wires work perfect still. Well they did when I use to work on Canon many moons ago...

[slimslob]

Re. Clean corona wires.

Spring hook works the best. I clean all corona wires religiously every service. You can feel where the dirt/rust/rubbish is located along the corona wire as you scrap along it with the spring hook.

The Canon guys will argue that scraping removes the gold coating from the wires, and so it does but, the gold coating is removed in a uniform state and the corona wires work perfect still. Well they did when I use to work on Canon many moons ago...

Just make certain that you have new wire with you for when the wire breaks.

[JDYAL]

I find that using a pencil eraser with a just a tiny bit of pressure removes most build up. Plus I always have plenty of wires on standby.

[NeoMatrix]

Just make certain that you have new wire with you for when the wire breaks.

Fairly rare to break a tungsten or gold coated corona wire. The corona wire tension spring does stretch a marginal distance before the wire breaks. In saying that I have broke the very rare corona wire while in a hurry. I have replace miles more corona wire than I ever broke.

You don't have to clean round the total circumference of the corona wire. The wire only has to be cleaned on the top side/outer side facing the drum or copy paper. The rest of the corona wire can stay dirty which makes for insulation.

Don't use the hook end of your spring hook; scrap the corona wire clean using the "U" shape end of the spring hook. If you keep your spring hook long enough; continuous wire cleaning will ware a slotted track in the "U" end of your spring hook, which makes for better wire cleaning.

[blackcat4866]

I've refined my corona cleaning technique:

I pour 1/4 cup of alcohol in a small glass jar. I dip wood handled cotton swabs and swab out the housing. Glass cleaner can short out the blocks, doesn't clean off the ozone as well as I'd like, and does not evaporate as well as alcohol. Then I dip another cotton swab and run it along the edge of the housing under the wire, back and forth 3 times. Then on top of the wire (resting on the edge of the housing) 3 times. Flip the unit lengthwise and again 3 times under the wire, 3 times over the wire.

Next, I lay down a section of newspaper with the grid on top. Dip a toothbrush in the alcohol and scrub the grid in the direction of the diagonal grid pattern, usually left handed on the inside, right handed on the outside. Move the scrubbed grid onto a fresh/clean section of the paper and using your forefinger squeegee the alcohol off of the grid, both sides. If there are any wrinkles or burned marks that the alcohol won't remove, you can stop right there. It's not worth continuing to clean a damaged grid. You won't get an even halftone.

I know it sounds a bit complicated, but you can clean a corona unit in about 6 minutes with a little practice. You'll see a surprising amount of ozone on the newspaper when the alcohol dries. =^..^=