Konica 7255 Drum Wrap

[Bizhub]

Hi All

We have a 7255 that keeps wrapping paper around the drum. We have done the firmware, pickers, separation voltages AC and DC, set the drum voltage, checked the drum earth and stopped the wrap. Now we keep getting intermittant pale side 2 copies and if we re-adjust the separation voltages the drum wrap starts all over again.
K-M say it's damp paper but the 7272 next to it is working fine and has never had this problem
Any ideas?

Regards

[Luther]

Have you replaced the entire transfer/seperator assembly? I would try replacing it you may have a voltage leak from the blocks

[Bizhub]

Hi

Thanks for your reply, we have changed the transfer corona with no effect. To date the machine has had dev, drum + voltage set to 744vdc, new transfer assy + voltages adjusted loads of times, new firmware + paper decks set to recycle, user, thick, thin etc we have replaced the drum pickers, picker solenoid, drum earth checked need I say more.
What we find is that the paper A4C is flat on single sided, but on side two the paper rides up and hits the drum. A4R on both sides are flat, we would like to blame the paper but the 7272 next to it does suffer with side two riding up but it's never high enough to catch and jam.
We have even tried raising the height of the separation wire to improve the separation and stop the wrapping problem, but to no avail.

K-M have run out of ideas so its over to you guys

[CMB]

try different paper? run it a differnt direction-if possible.

[Luther]

If I'm not mistaken when the transport deck is installed it couples in the back to a suction fan for the aid in seperation,this is all from memory but thats why there are holes in the conveyance belts,check the fan operation, also heavy curl could be a bad lower pressure roller, just a couple of suggestions,good luck

[ebm]

How about the "decurler" roller in the fixing unit?

[Luther]

Could be, thats considered a consumable item, i would change it

[TonerMonkey]

You may find there is a firmware release to couteract this problem - version 16 control board if memory serves right.

[d7guitar]

We see this on 920's 750's and 600's. Not all them exhibit this problem???? Curious, did this start after a PM??? We have had excellent luck replacing the transfer wire with a non-KMBS wire. Order a spool of 70 micron wire, best they have, thicker gold plating. Before we found this (what appears to be) remedy, we were having some success (about 50k to 100k between calls) by moving both the transfer and the sep in the same direction +- by no more than thirty. That is only temporary and the CQ is affected. The wires we have been using for approx two months and have been VERY successful.

[Rudi]

Hi there , try setting your drum voltage lower i.o.w from 744 to say maybe 700 or lower if you can then set your bias voltage (it is normally under high voltage adjustment) to about 100 or lower depending on how low you take the drum voltage in order to avoid background.i Have not done it myself but i think it is worth trying.

[Bizhub]

Sounds like you might have something there !

Where do you get you 70micron wire from ?

We also found that the engineer did not check the soleniod, It was seized !

We cleaned it out and the problem has reduced but still does it on Mondays after the week-ends. The customer now takes the paper out of the machine on fridays and puts into the DI3510 and then loads a fresh pack on mondays into the 7255 and it works a lot better.
KM can't help so I will try anything.
Shame the salesman can't upgrade it.

[AusiTech]

Hi All

We have a 7255 that keeps wrapping paper around the drum. We have done the firmware, pickers, separation voltages AC and DC, set the drum voltage, checked the drum earth and stopped the wrap. Now we keep getting intermittant pale side 2 copies and if we re-adjust the separation voltages the drum wrap starts all over again.
K-M say it's damp paper but the 7272 next to it is working fine and has never had this problem
Any ideas?

Regards
If you still have problems let me know, I'm sure i have the fix. little long winded though.

[PeterG]

4 year old thread, but I have this exact problem. Has anyone been able to come up with a definitive answer to this problem? No matter how long winded.

[Downunder]

Whats the mileage on the copier. How much gap is there between the drum pawls and the drum. Is the drum wrap happening from all trays.

DC transfer seperation should not be more than 130 max, preferably 120-125. If there is a bit of paper slippage this could mean that the pawls are coming in too early, or paper coming too late, hence the question does it happen from all A4 trays. A4R and A3 don't count in this equation.

If the drum pawls have a big gap (more than say 3mil) pack something (we use a bit of velcro (shaved) with tape on between the solonoid and the solonoid resting spot (best to look at the operation of the solonoid and this packing statement will be a bit more obvious.

Also best to try and put most settings back to factory settings if you can.

Tonermonkey was right there was a firmware upgrade -- its purpose was to have the pawls stay activated a bit longer.

The decurl roller and its bearings probably need replacing.

Hope this helps . . . l

[PeterG]

Thanks Downunder.
The copier has about 3 mil on it. The drum wrap is happening from all trays. We do a changeover fuser service and the same problem exists after a fuser change over.
I have watched the paper, maybe 40 or 50 sheets may pass ok, then one will stick.
We have had ferocious humidity down here lately, which I suspect is the root cause of the problem. Unfortunately the customer does't accept this as a reasonable excuse.

[Downunder]

Peter, you mentioned drum voltages, earth etc. Have you done an earth from the screw that holds the drum in on the drum shaft and earth. Should be 5ohm or less or should be low resistance. If it is high check the drum clamp (slide drum onto the drum shaft, then holder, then knurled bit (sorry just cant think of correct words, late in the day and bourbon has kicked in) sometimes this clamp/stay gets a bit rusty and inhibits good earth through drum bearing. If this is clean and you still have high resistance you will need to go to back of copier, remove back cover and main board, then flywheel. On the the drum shaft there is a copper leaf-spring(spelling) that rests on a round spacer which rides on the drum shaft. If this leaf spring is not firmly touching the spacer you will not get good earth. Clean the spacer, it can get a bit greasy reform leaf-spring.

Is your registration constant? sorry, harping back to paper slippage again.

Clutching at straws now, but have you changed the ADU board. Weird faults with this board.

Hope this gets you a bit further to the client's EXIT door.

Cheers

[PeterG]

Thanks again Downunder. I think you are onto it. I measured the resistance on the drum. It is 800 ohm at minimum, & goes to over 15k.
I didn't have time to rectify it yesterday, will sort it next week.
Thanks again

[SAR]

Are you absolutely sure there is no developer in the drum picker solenoid? I have seen machines where you can watch the picker fingers working during a copy run, but when you pull the solenoid apart and clean it there is just enough developer in the solenoid to make it intermittantly malfunction or the plunger pulls in too slowly and the paper gets past the picker finger.