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Synaux
02-23-2019, 05:13 AM
This seems to only happen on Thick 1 and up. Apparently, this never happens on plain paper.
41802

Random and relegated to black.
That picture says leading edge, but it is the tail end of a 11x17. The leading edge is barely noticeable (have to use a jewelers scope to see it). Second side gets worse, but corrects itself one end. I got lucky with this sample as it happened once when I calibrated all trays/paper types for "centering" and "lead edge" and the only example of a duplexed print shown to me.
All these details are somewhat moot, because I have been shown other examples on 5.5x8.5 prints just as bad, if not worse--throughout.

Figures:
MFP ~375k
Fuser: 250k
Belt: 375K
K rotation time: 12k m
Serviced machine when it arrived on location ~6mo ago used (install, clean, calibrate etc) looks like some things were swapped or replaced.

Synaux
02-23-2019, 05:33 AM
EDIT: It LOOKED like k only at first blush, ...but upon closer inspection it is M and C (probably Y) and probably not K. It is very difficult to tell without pulling my microscope out. I will try to post a picture, but having issues getting a good photo.... and have it look like anything....:mad:

allan
02-23-2019, 06:31 AM
Should then get a code like P21?
Check that shadow for color dots to make sure.

Synaux
03-02-2019, 05:04 AM
Should then get a code like P21?
Check that shadow for color dots to make sure.

I stopped by today just to pickup the print to use microscope and maybe get a decent picture--they are definitely C/M dots. I cannot see any Y (or K) until breaking out the scope.
No P21s
Looked at the my notes while there. I had completely forgotten that there were 100+ P-14 codes, no others--cleared 6mo ago--no reoccurring (dismissed as dirty IDCs).
I will approach like it is P-14 related and report back!

Thinking Skew Adj, PHRB (ICP 3) and/or PH (G3 lens)....belt...
A curious and perhaps goofy workaround might be running 1200DPI:


To be compatible with the high speed printing system, a seven sided polygon mirror and two beam array LD is used.
In 600 dpi writing, two lines are scanned with two laser beams emitted from two LD elements (LD1 and LD2) arrayed vertically through a single surface of the polygon mirror.
The LD elements of the two-beam array LD are spaced for 600 dpi use, so that the LD cannot be used for 1200 dpi writing.
In 1200 dpi writing, one line is scanned with LD1, while LD2 controls the SOS signal.
To enable 1200 dpi writing, the paper feed speed in the sub-scanning direction is made slow to thereby narrow writing intervals.

blackcat4866
03-02-2019, 04:59 PM
I'll be interested in your results. =^..^=

icemanhi
07-01-2020, 11:47 AM
Any update? Fighting the same problem for a long time....


I stopped by today just to pickup the print to use microscope and maybe get a decent picture--they are definitely C/M dots. I cannot see any Y (or K) until breaking out the scope.
No P21s
Looked at the my notes while there. I had completely forgotten that there were 100+ P-14 codes, no others--cleared 6mo ago--no reoccurring (dismissed as dirty IDCs).
I will approach like it is P-14 related and report back!

Thinking Skew Adj, PHRB (ICP 3) and/or PH (G3 lens)....belt...
A curious and perhaps goofy workaround might be running 1200DPI:


To be compatible with the high speed printing system, a seven sided polygon mirror and two beam array LD is used.
In 600 dpi writing, two lines are scanned with two laser beams emitted from two LD elements (LD1 and LD2) arrayed vertically through a single surface of the polygon mirror.
The LD elements of the two-beam array LD are spaced for 600 dpi use, so that the LD cannot be used for 1200 dpi writing.
In 1200 dpi writing, one line is scanned with LD1, while LD2 controls the SOS signal.
To enable 1200 dpi writing, the paper feed speed in the sub-scanning direction is made slow to thereby narrow writing intervals.

Synaux
07-18-2020, 10:17 PM
Any update? Fighting the same problem for a long time....

Actually, yes, just a week ago.

They got a good deal on a transfer belt, which seems to have cleared it up (the problem is the randomness--I was unable to duplicate the issue). If you look at the Theory of Operation section with image processing (or whatever it is called), this makes some sense. Seems like a timing chain like issue in a vehicle for a loose example.

I cannot see anything wrong with the old one--not a scratch--super mint condition and everything seems to be moving perfectly.

Perhaps a worn bushing somewhere? I dunno.

I never did get get the microscope on the prints because...well...I had bigger and cheaper things to do :rolleyes:

Synaux
10-07-2020, 04:35 AM
Actually, yes, just a week ago.

They got a good deal on a transfer belt, which seems to have cleared it up (the problem is the randomness--I was unable to duplicate the issue). If you look at the Theory of Operation section with image processing (or whatever it is called), this makes some sense. Seems like a timing chain like issue in a vehicle for a loose example.

I cannot see anything wrong with the old one--not a scratch--super mint condition and everything seems to be moving perfectly.

Perhaps a worn bushing somewhere? I dunno.

I never did get get the microscope on the prints because...well...I had bigger and cheaper things to do :rolleyes:

I know I had written a retraction on this... I never got any feedback and upon review, I apparently must not have hit "submit reply."

Transfer belt replacement did NOT fix this issue. I sincerely hope I did not make anyone purchase a transfer belt needlessly.

The issue resurfaced again only on thick 1-4 some time ago (same scenario). I was unable to duplicate the issue on plain paper.
It seems that the K is distorting/stretching ever so slightly.

K Dev unit was replaced some months ago, transfer belt replaced, fuser inspected visually with ~75% life left, K drum is about half life, but I intend to try a swap soon. This was the machine I tried to to do the version up on...so if anyone remembers that post, it has new FW as well (lol).

Attached is a microscope pict of--if I recall correctly--is it the void between a "V" at maybe at ~10point font size. This anomaly will appear in a wave-like manner throughout prints.

Dropbox - Microscope.jpg - Simplify your life (https://www.dropbox.com/s/bw32q091zvyutvn/Microscope.jpg?dl=0)

Synaux
02-12-2021, 05:40 AM
Just an update, replaced K drum unit and the issue has not resurfaced for a few months.

I wanted to make sure this was the fix before posting because of how random the issue was.

Cheers!

Bix
02-12-2021, 09:26 AM
Thanks for sharing!
it's crazy how many problems a drum can cause.

Synaux
02-13-2021, 05:02 AM
Thanks for sharing!
it's crazy how many problems a drum can cause.

I dont know how this could happen. I half-expected to see a degraded tooth on the gear spline on the drum itself, thus creating a timing issue (even know it somehow self-corrects). Those units are fairly barebones, so I do not know what could cause this at this point. I kept it anyways, because it would still be useful for K production only.

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