920 2nd side crappy transfer

[BigBob]

920, just shy of 6 million, new dv unit, dv, sep corona. Getting crappy txer on 2nd side, have followed all the bulletins, suggestions, bad advice, good advice, etc. Anybody got any ideas? Copies look wonderful when doing average (5-8%) coverage, but having a hard time reproducing halftones. Initially cleaned, then replaced drum sensors, new drum, just had a pm. Problem has been ongoing but have been able to work around it by having customer up density in service mode via dip switches when they do run a high coverage job, but even that's not working anymore.

[kon]

write unit will make a big difference as they go bad check your ld1 and 2 settings to verify

[otomatic]

we are having the same problem with our 920 at two mil
all kitted, new dev and drum but nothing has changed
test print 12 8'5 by 11 bond two sided
solid squares look great but the midtone screens are blotchy
the lead edge of the sheet is fine and most of side one is ok
side two is worse and gets worse toward the tail of the sheet
also the back half of the sheet is slightly more blotchy than the front half
and it sure seems odd that it gets worse from one end of the sheet to the other

I've tinkered with the transfer/separation volts and can get it look better but it still isn't right

does anyone know a good step by step method to fine tune all the volts?

[blackcat4866]

The way it was told to me, it's not a good idea to over-ride potential control. The only constructive suggestion is to make sure transfer assist is On and functioning. =^..^=

[methogod]

I would replace your 2 plastic recyling gears, it may not be time but at 4m, they get iffy, we change them often that screws up some major stuff... after that...

i would adjust LD 1 and 2 do to wearing / weaking laser unit. Then test test test...


if your clients are running different jobs all the time and not in the 5-10% coverage you need the INSTALL THE RECYCLING COLLECTION KIT OR YOU MAY HAVE ISSUES ALL THE TIME...


as machines get older the lasers get weaker, so you have to tuner them up (which is down), 255 is low, 1 is high, new machines start at 200-220 ish..

Now just to confuse you even more, sometimes the LD settings can get wonky, I know right, but its the word that describes it. I have seen some settings that don't make any sense, and this is over a good test period, not just a service call. Some unexplainable sh*t. The issues that i have seen are usual LD settings that are "too light" for the low number, even with a machine with 18 MILLION clicks, the LD is not much lower then 180. But i had an issue where i was playing around in the 100's to get it to darken on both sided. Knew it was off. But didnt hit me right away.

Finally thought it over and did a SYSTEM DATA RECALL (INSTALL POINT). you have to run all your adjustments again, but it did save me a hell of a head ache.


LD 1 and LD 2 are laser beams 1 and 2,,,, the number is the strength... Number should be very close together or you may have some other issues.






These machines i think are better then 1050's because they dont get beat up from over running themselves. If you run alot of the same %, you are in the sweet spot, as long as you dont expect C6501 quality blacks.

That wont clear even with firmware, you need to do a DATA RECALL back to norm (install) if you mess up the LD1/2 too much or you cant get it to make sense...

NEW BOX FROM FACTORY - 220 ( i think)
MOST DATA RECALLS - 220 - 210 ( MACHINE DEPENDENT)
RANGE- 255- 0
(SCALE IS REVERSED AS YOU MAY THINK)
100% IS 0, 0% IS 255)

this is not from a book, but my 120GB HD in my head, some info may be wrong please check before teaching others...

[otomatic]

The way it was told to me, it's not a good idea to over-ride potential control. The only constructive suggestion is to make sure transfer assist is On and functioning. =^..^=

I've recalled all the standard data
I've searched the manual and don't see any transfer assist to set
I did a test print 9 and side one is ok but has some dark banding but not bad
side two has more noticeable banding and random blotches

[methogod]

by chance do they have the paper settings right?

put some 20#copy paper in, staples red or blue, and test it.


Also you may need to verify the solenoid that opens the fuser plate for thicker stock is functioning.

there is a way to test paper settings see attached...EngIN_920_Process.pdf

[Chameleon]

We were just fighting the same issue when we had a 950 hit 2 mil. Replacing the HV unit for the transfer fix'd it. There was a way to check the output for that HV unit in service mode and it actually was showing values out of range.

[otomatic]

by chance do they have the paper settings right?

put some 20#copy paper in, staples red or blue, and test it.


Also you may need to verify the solenoid that opens the fuser plate for thicker stock is functioning.

there is a way to test paper settings see attached...EngIN_920_Process.pdf

thanks for the troubleshooting guide
I did get better results setting all the trays to recycled paper but still getting a lot of banding on side two
the bands are generally darker and sometimes have a pattern 1/2" apart

[methogod]

can you take a photo...

which pay main scan or sub?

to this day the worst i have seen with 20# paper is a hard jam into the cleaner unit, if its sticking to the drum something is really wrong. Would look to high voltage unit 1/2, whichever is up to, not that one below.

also i would investigate there electrical wiring. maybe there electrician ghetto rigged it. if you have 2 950s on that should be on dedicated 20amp circuits running a 1 30 or 40amp it will work just fine until you start having these weird electrical issues.

Found this out at a client, who was running 2 C650s on what they claimed was 2 dedicated 15amp lines, after a few too many boards for no reason, we told them one was down and disconnected it for a week, and like clockwork the other machine was working fine, so we called out electrician, couldn't believe what they did..