K density faded c550/650

[Synaux]

First let me just shoot out there that I am well aware of most if not all of the IU fixes/mods/issues discussed on numerous older threads. That being said, I feel inadequate having to post this, but still hopeful.

There are 3 machines with the same general behavior ONLY on black:
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< - - - - - - -Untitled-3.jpg

This scan is not great and a little washed out, but this halftone print (from Service Mode) is perfect on the dark end; however, it exponentially lightens towards the back on the machines/prints.

HV contacts cleaned, PH cleaned, switched around tranf rollers/belts and fusers. Played musical chairs with the IUs and even manually replenishing toner.

Ran/reran Reset/Stabilize & Gradation.
Then I messed around with TCR 3, DMax +10 and ran 250 sheets with almost no coverage and reduced the fade by about 50% on one machine.

I then installed a new IU that immediately exhibited the same results on the two machines I have tried it in so far.
At that point it was time to go home.

Table Numbers:
VDC-K:
399 Machine #1
333 Machine #2
410 Machine #3

VG-K
~490 Machine #1
~450 Machine #2
~500 Machine #3

Level History = Good
IDC Output = Good
All machines in a decent environment with ESP protectors (2 machines are at the same location and the other elsewhere).


Thats about everything my scrambled brain can recall right now.

Thanks in advance!

[Rolandito]

Re: K density faded c550/650

I think the IU K is not seating correctly.
There is a fix for that...Try to give more pressure on iu unit ...

[mascan42]

Re: K density faded c550/650

Also make sure that there isn't developer spilled onto the print head window. I see that A LOT on C550s that didn't have the IU making good contact.

[Synaux]

Re: K density faded c550/650

I think the IU K is not seating correctly.
There is a fix for that...Try to give more pressure on iu unit ...

Thanks for the reply
I have the bracket mod installed and even wrapped some tape around them to make them more robust.

Also make sure that there isn't developer spilled onto the print head window. I see that A LOT on C550s that didn't have the IU making good contact.

Again thanks for the reply
I cleaned the PHs.

I seriously doubt that this is an issue of dirty machines as it is replicated on three machines (and I keep the machines I work on immaculate). Either way, I will remove a PH and inspect it.

I have not been back yet, but what really freaks me out is that the new IU did what the old ones were doing. I have been thinking about this and the only thing I can think of is that the new IU was an OCE IU chipped for konica; however, the old IUs were OEM konica...?

Its possible, but three bad HV1 boards...? Possible, but unlikely.

[Printer People]

[EarthKmTech]

Re: K density faded c550/650

stupid question, but are you sliding these iu's in straight out of the box ?

I've found repeatedly if you do this without agitating the settled contents by rocking / shaking the iu before installation as instructed they fail within a week to a couple days.

[Etech]

Re: K density faded c550/650

Is this the same with the other colours ? if so tbu might be suspect ?

[Synaux]

Re: K density faded c550/650

stupid question, but are you sliding these iu's in straight out of the box ?

I've found repeatedly if you do this without agitating the settled contents by rocking / shaking the iu before installation as instructed they fail within a week to a couple days.

Do not shake the black imaging unit"

I am still unsure to what exactly happened, but I tossed that new IU and swapped the HV board from a parts machine in the first machine I used the black IU in. So far, things are going well...

[Synaux]

Re: K density faded c550/650

Is this the same with the other colours ? if so tbu might be suspect ?

Only on black...color me stupid, but what the heck is a tbu??

[Etech]

Re: K density faded c550/650

Only on black...color me stupid, but what the heck is a tbu??

Glad you got it sorted tbu is, transfer belt unit.

[Synaux]

Re: K density faded c550/650

Glad you got it sorted tbu is, transfer belt unit.

Oh lol

[GTgosu]

Re: K density faded c550/650

i have the same problem so Synaux i try to
replace:
transfer belt
HV board 1/2
Toner supply section
Developer in IU
Drum in IU

after that i bought a new IU, after 2k copies problem returned.
I don't have any idea how to fix this.