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

[Codex]

Thanks for the headsup....

You're talking about a Hydroscopic moisture type of effect . Given the warmth of the machine and cooling down at night
its an interesting probability.

Re. Drum Sweat Burn, Light Burn or Arc burn.
Wouldn't the smudge/blurb be a static constant and the exact same pattern on the drum every time for each copy?

It's interesting in that the blurb on the copy comes and goes over time with some type of regularity.

I wonder if they run a lot of labels or foils through the machine. It may account for aluminium or glue around the drum ?

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Like a well oiled TV soap opera, I'm waiting for the next exciting episode of this thread so I can find out what the fault was...

I've seen a lot of moisture in some machines... MPC2050, MP3350... but in the Mp9000 only around the duplex unit... The customer didn't use foil or labels... They print only on normal paper

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[Codex]

interesting phenomena!
Why was there no charge at that particular place at that particular time?
1. something came between drum and charge (piece of paper?) => unlikely
2. charge went away due to power supply unit or power pack failure. => possible
3. in wich conditions is the machine standing? In a normal office? What is temperature overnight?
What is the exact time when the dot is printed? Perhaps another big machine in the factory is than put to on...?

The machine is in a copyshop....

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[Mark Bbb]

The machine is in a copyshop....

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Perhaps there is something wrong at one particular time in the electrical circuit of the copyshop.
Bu than it would occur with other machines too.
It would be nice if customer take note exact when the problem occurs and which other machines are (put to) on or put to work.

I have had this a few times and it was always a piece of paper somewhere between this and that...

[mikadonovan]

I just remembered an issue I had with a C7501 years ago. The machine was experiencing similar quality issues, and it was due to a gigantic ghost turd floating around in the cavity area directly above the charger assembly. Replacing the charger did not help the issue, but removing the dust/hair ball fixed it.

[slimslob]

The fact that this occurs only on the first 1 or 2 copies after the machine has set tells me that it might be a pre-charge corona problem. Check your SC history. If there are any SC 312 or 313, check the setting of SP 2002-001. If it is 0, that is the cause of the problem. Fix whatever caused the SC then change SP 2002-001 to 2. Also clean the pre-charge corona. From the service manual: There is no mechanism to clean the pre-charge unit corona wire automatically.
However, the pre-charge unit corona wire can be cleaned manually. After the precharge unit has been removed, its cleaning pad can be pushed to the rear and front several times to clean the corona wire.
SC312 and SC313 signal a problem with the pre-charge unit. After either SC is issued, operation halts and the machine must be cycled off and on. When this occurs, the setting of SP2002 001 is automatically switched from "1" (On) or “2” (ON) to "0" (Off). The operator can use the machine, but the machine is allowed to operate with only the (main) charge unit operating. This will not seriously hinder operation of the machine.

[NeoMatrix]

I just remembered an issue I had with a C7501 years ago. The machine was experiencing similar quality issues, and it was due to a gigantic ghost turd floating around in the cavity area directly above the charger assembly. Replacing the charger did not help the issue, but removing the dust/hair ball fixed it.

Looking at the original scanned images posted to the forum: the halo(antialias) affect around the smudge lends me to believe it's and optics fault. Antialias would make it an A-to-D digital fault.
I would be inclined to search for a fluff ball (gecko, cockroach) floating around in the optics, but Codex has stated that the blurb also occurs on prints, which therefore rules out the optics.

Codex stated he's also said he's seen moisture in the machine, but only in the duplexer. Which has me leaning towards what Lagonda said.

[fadsamniote]

I want to see the real technical solving this issue

[Lagonda]

Having had a second look at Codex's samples I've suddenly realised its the same C/Q problem we used to get on the MP C4500 AP C1 range.
When autumn arrived each year and if the temperature dropped over the weekend we'd be flooded on Monday mornings with calls for copy quality. Copiers with drums that were about at 75% of their life just didn't like a sudden drop in temp and humidity. Usually by the time the tech got there at mid day everything had warmed up and the drums behaved themselves and the black mark had vanished but next morning it happened again. The only fix, a new set of drums.
Since Europe is now heading into autumn it could be a possibility.

[NeoMatrix]

Having had a second look at Codex's samples I've suddenly realised its the same C/Q problem we used to get on the MP C4500 AP C1 range.
When autumn arrived each year and if the temperature dropped over the weekend we'd be flooded on Monday mornings with calls for copy quality. Copiers with drums that were about at 75% of their life just didn't like a sudden drop in temp and humidity. Usually by the time the tech got there at mid day everything had warmed up and the drums behaved themselves and the black mark had vanished but next morning it happened again. The only fix, a new set of drums.
Since Europe is now heading into autumn it could be a possibility.

Re. Sudden cold snap in the weather.
Yes I know what you are saying. The cold snap in the weather causes the edge of the old drum blade to harden and not clean properly until the machine warms up.
I've seen that on the old MP C4500 series a few times. Had to convince the boss not to throw out 3/4 life span PCU's just because of a cold snap.

[Lagonda]

Re. Sudden cold snap in the weather.
Yes I know what you are saying. The cold snap in the weather causes the edge of the old drum blade to harden and not clean properly until the machine warms up.
I've seen that on the old MP C4500 series a few times. Had to convince the boss not to throw out 3/4 life span PCU's just because of a cold snap.

Sorry Neo but I have to disagree with you there, the cleaning blade isn't the problem, it's the drum surface not charging and discharging correctly.