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Laserbeam
02-17-2015, 01:27 PM
Hello at all,

a bizhub 421 in a copy-shop shows following symptom:

Only when print double-sided, after approximately 500 sheets, one side shows grey backround. The other side is perfect. The backround-side in the paper-tray from the finisher points towards the floor (It would be the second printed page, isn't it or I'm thinking wrong?).
If the machine stands still for a longer time, the first double-sided prints are back in order. Then the problem starts again anew.

Single-sided printing makes no gray background.

Life Counter: Drum 130k, Developer 70k

My first action was to clean all ground-contacts from the charging- and transver/sep. corona, drum- and developing unit, ground-contacts in the right side-door, etc., but unfortunately without success!!!
In my opinion it would be a potential-problem, not an overtoning-problem. Otherwise, the other side would be gray, too.

Yesterday I got a call from the owner of the copy shop, the neighbour-machine, a bizhub 501, now has exactly the same problem!!!!
This problem might be a weak point of this series of KM????

Greetings from (C)Old-Germany :)

Synaux
02-17-2015, 03:36 PM
Hello at all,

a bizhub 421 in a copy-shop shows following symptom:

Only when print double-sided, after approximately 500 sheets, one side shows grey backround. The other side is perfect. The backround-side in the paper-tray from the finisher points towards the floor (It would be the second printed page, isn't it or I'm thinking wrong?).
If the machine stands still for a longer time, the first double-sided prints are back in order. Then the problem starts again anew.

Single-sided printing makes no gray background.

Life Counter: Drum 130k, Developer 70k

My first action was to clean all ground-contacts from the charging- and transver/sep. corona, drum- and developing unit, ground-contacts in the right side-door, etc., but unfortunately without success!!!
In my opinion it would be a potential-problem, not an overtoning-problem. Otherwise, the other side would be gray, too.

Yesterday I got a call from the owner of the copy shop, the neighbour-machine, a bizhub 501, now has exactly the same problem!!!!
This problem might be a weak point of this series of KM????

Greetings from (C)Old-Germany :)
Is the power good? Are they on line conditioners??
Remember the first side is the second sided image.

This might give you some ideas:

TAUS0703844EN*
Description
C2801 (C-2801) code possibly accompanied by agray background on copies.
Solution
PROBABLE CAUSES:
1. The HVPS has failed.
Replace the HVPS (p/n 50GA84010). [appears to be the same for both the 421 and 501.]
SPECIAL NOTE : Solution contribution by Tom Kelly, Workgroup/SSD

2.A TCR output abnormality; the TCR output is in excess of 3.0V DC. This is usually due to a severe undertoning or a failed TCR sensor. It is possible to run
the Toner Auto Condition mode under the Service Mode =>Image Adjust Mode. Running this setting will automatically add toner to the developer if
depleted. If the Auto Toner Condition mode fails to correct the issue, the developer and the TCR sensor should be replaced.
Replace thedeveloper and TCR sensor (p/n 26NA-8804-1).Be sure to reference the attached Field Service Manual pagesand perform all adjustments
associated with developer replacement.

EarthKmTech
02-17-2015, 09:23 PM
ive had this many times ever since the first 420/500 machines came out and only ever changed the developer to solve the problem.

If the customer is using bad paper that ends up shedding a lot of paper dust it will not last the 250k service cycle. I dont know how or why but it has always been the second side that starts to show the problem first.

Laserbeam
03-09-2015, 08:23 AM
Last week I changed the developer with an new one and all was fine :) !! The customer prints several hundred double-sided pages and no toner-backround occurs.

But today he called me again, because the old problem returns again :(:confused::mad:.


I think it's a problem of this model, which can not be solved with simple methods. I think it's best if we replace the machines.

allan
03-09-2015, 01:41 PM
Try changing the developer unit.

The charge and grid voltage could be tampered with.

Do you use the list of adjustment items if you replace the developer?

Did you reset the drum counter after replacing the drum?

Laserbeam
03-11-2015, 07:13 AM
Hello allan,

thank you for your quick response!
Our company used for this machine toner from Katun, no original toner. Could this be the reason for this problem?
When I replaced the developer, I only performed the TCR adjustment. :(

This week I will start a last attempt with exchange of the following components:

1. Drum and Blade-unit
2. Developer and Developer-unit (Dev.-unit from a used machine with a total count about 130K)
3. Charging- and Transfer/Sep. Corona unit (both have a duration of about one million)

Then I will perform the following adjustments:

1. TCR
2. Toner density
3. Laser diameter
4. LD1 Offset
5. LD2 Offset

I hope this will fix the problem, otherwise I have no other idea. :confused:

blackcat4866
03-12-2015, 02:35 AM
Hello allan,

thank you for your quick response!
Our company used for this machine toner from Katun, no original toner. Could this be the reason for this problem?
When I replaced the developer, I only performed the TCR adjustment. :(

This week I will start a last attempt with exchange of the following components:

1. Drum and Blade-unit
2. Developer and Developer-unit (Dev.-unit from a used machine with a total count about 130K)
3. Charging- and Transfer/Sep. Corona unit (both have a duration of about one million)

Then I will perform the following adjustments:

1. TCR
2. Toner density
3. Laser diameter
4. LD1 Offset
5. LD2 Offset

I hope this will fix the problem, otherwise I have no other idea. :confused:

Oh yes! Look no further. Change to OEM if you care about the image quality. =^..^=

Laserbeam
03-12-2015, 08:25 AM
Hello blackcat 4866,

thankyou for your response!

At first I will vacuum all Katun-Toner and replace it with original one.

blackcat4866
03-12-2015, 11:58 PM
Hello blackcat 4866,

thankyou for your response!

At first I will vacuum all Katun-Toner and replace it with original one.

It will take some time to consume the remaining Katun toner from the developer mix. It should only take a few days to consume it and replenish with OEM. Copy quality will gradually improve. =^..^=

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