konica c550 very light

[acsolutions]

Hi, I have a c550 light, transferbelt image good fill, sec. transfer problem! new transfer roller. In service mode, state confirmation ATVC 2nd is at it's lowest value which is 300 and the value should be between 300 and 5000. all the other machines I have looked at sit around 1500 and 1700. I'm caught between the print controller and the hvt! Any suggestions would be helpful.

[tech51]

Your not going to like this but it could be the service eeprom board (PWB-EE) has failed. If this is the case you have to replace the eeprom board, all four toners,all four IU`s, waste box, transfer belt, fuser unit and ozone filter. You must then carry out all the adjustments as detailed in the manual (pages 175 & 176 in my copy). Its not a quick and cheap fix I`m afraid...

[acsolutions]

can I just rechip everything, and why the waste toner box? when I reboot the machine then go into the service mode and check ATVC 2nd it is at 0 then when I run my first copy it goes to 300, so it's not locked up so why do you suspect the PWB-EE board.

[tech51]

I don`t know. The solution comes from KM direct. You may be ok or you may not. Wether you rechip or not you must do the adjustments as detailed in the manual to put new values into the service rom....

[Stirton.M]

Description
Image density is light on single-sided copies and prints.
Solution
CAUSE: Secondary transfer adjustment is set to 0 in the Tech Rep mode by default.
SOLUTION: This should only affect serial number range between A00K0100000001 through A00K010000135. To change the secondary transfer for first
side:
1. Access Tech Rep mode.
2.Press Utility => Meter Count => Check details => Image Process Adjustment => Transfer output Fine Adjustment => Secondary transfer
adjustment => First side => Plain paper.
3. Change the setting from 0 to 3 by using the plus sign on the screen.
--------------------------------------------------------------------------------------
Description
When copying or printing originals the color density drops off. This is especiallynoticeable with large jobs.
Solution
CAUSE: Copying/printing with a very high fill rate.
SOLUTION: To increase the density perform the following:
1. Enter Tech Rep Mode.
2. Press Image Processing Adjustment.
3. Select TCR Level Supply.
4. Increase CMYK to +1.
----------------------------------------------------------------------------
When first powering up the machine in the morning, the following image failure is generated:
Carrier adhesion (Black and possibly Magenta)
Low image density/images are almost not printed
Uneven image density
Solution
CAUSE: Poor contact between the main body and the Black Imaging Unit. As for Magenta, since the failure occurrence ratio is quite low, there may not be an
issue.
SOLUTION: Apply either rubber or a harder urethane foam on the fixed lever control part of the Imaging Unit, and press it down on the back side of the IU.
This should ensure better contact. A terminal plate has been added in production so that the terminal of the Black Imaging Unit will certainly contact with the
pin located on the main body.
-----------------------------------------------------------------------


Those are just a few TSB entries related to low image density.

There could be other factors at play.

Are you getting a P-27 code? If not, the ATVC section is not at fault and your low image densities could be related to something else. Just because you are at the low end of the scale does not mean a thing. The machine is adjusting based on age of the consumables (drum and belt) in the case of the ATVC-colour entries, or it is adjusting according to the 2nd transfer requirements...thick paper vs normal for example. I am not sure if the level history will allow you to run a test print from that screen using anything but plain paper. I know this is true of most tech rep test screens, but I cannot be certain specific to this as I have not occasioned to try it.

A determinant is to print a solid on a large page, but force a jam condition as the paper enters the 2nd transfer area. Pull the transfer belt out and inspect the toner transfer on the belt from the drum units. If the density looks good there but the paper still shows poor transfer, it is possible that the bias connections for the 2nd transfer might be at fault and worth investigating.

And just in case, make sure you clean the IDC sensors, and of course the very obvious, make sure you select the proper thickness setting for the media you are printing to. Coated stock for example should be thick 4 through bypass.

[acsolutions]

Thanks Stirton,
Yes the image density on the transfer belt looks good! All colors! I was concerned with the bias connection and it is very difficult to tell if it is getting good contact so I ran a jumper from the HVT to the metal tab with no change in density.

The only other thing I can think of is that another tech. had replaced the yellow imagine unit and the customer said the problem started that day!

Sorry, no P-27 code!

[mrwho]

If you put back the old yellow IU, does the problem persist? It's a long shot, but maybe the new IU is defective and is shorting something on the machine. It's worth a try - I'd do it.

[Stirton.M]

Yep, a defective IU is possible.

As to bias, it could possibly be a failing HV, though I doubt this. Have you tried adjusting 2nd transfer values in tech rep? Did that at least help?

[acsolutions]

Thanks guy's! Yeah, the last guy who installed it said he tossed it! I'll try to borrow one from one of my customers. I also tried the adjustments in the service mode (2nd transfer) going both directions + and- made no difference!

[Stirton.M]

Those adjustments sometimes require you to fully restart the machine to force a stabilize on the new adjustment.