[CQ] TaskAlfa 620 Problems Copy / Print too light

[c.olivieri]

Hi ! I have a problem with taskalfa 620.
Total Print/copy 1.062.000
The problem occurred by the customer, suddenly became very clear copies.
I have replaced the 2 maintenance kit that includes: corona primary, web transfer, developing unit, fixing unit, ecc. ecc.
I also replaced the High voltage PVB MC and the motor toner unit .
The toner is original and the copier is clean.
But the problem is this as in the image published, it seems that no toner but the developing unit is full.
Please help us....
Thanks in advance
Carlo from Sardinia (ITALY)
GrayScale (2).jpg

[Kyo fan]

Re: TaskAlfa 620 Problems Copy / Print too light

I think your problem is worn out fuser drive assembly. Follow this bulletin and you should be ok: TA620.pdf Also make sure firmware is latest.

[Geo]

Re: TaskAlfa 620 Problems Copy / Print too light

Hi.

Did you clean,re-string and or replace the Pre Charge Corona assy? It is located under the drum unit.

Cheers

[blackcat4866]

Re: TaskAlfa 620 Problems Copy / Print too light

Have you looked at any of the traditional high voltage problems?

1) worn/arcing developer bias contact (do not lubricate)
2) worn/arcing/rusting transfer roller contact (use conductive grease)
3) Fuser inlet ramp (mylar coating can wear through).

=^..^=

[Geo]

Re: TaskAlfa 620 Problems Copy / Print too light

Have you looked at any of the traditional high voltage problems?

1) worn/arcing developer bias contact (do not lubricate)
2) worn/arcing/rusting transfer roller contact (use conductive grease)
3) Fuser inlet ramp (mylar coating can wear through).

=^..^=

Hi Blackcat.....

Since you are talking about conductive grease , if you don't mind, I need to pick your brain. For field and shop use we can't come to a general consensus as to where and when to use conductive grease. We use a good quality carbon infused conductive grease, very conductive and stable. So, what is your general rule of thumb as to the proper use and application of conductive grease.

THANKS!

Have a happy healthy and prosperous New year.

[c.olivieri]

Re: TaskAlfa 620 Problems Copy / Print too light

I think your problem is worn out fuser drive assembly. Follow this bulletin and you should be ok: [ATTACH]27525[/ATTACH] Also make sure firmware is latest.

Yes the firmware is lastest

[c.olivieri]

Re: TaskAlfa 620 Problems Copy / Print too light

Hi.

Did you clean,re-string and or replace the Pre Charge Corona assy? It is located under the drum unit.

Cheers

The pre-charge corona has been replaced.

[c.olivieri]

Re: TaskAlfa 620 Problems Copy / Print too light

Have you looked at any of the traditional high voltage problems?

1) worn/arcing developer bias contact (do not lubricate)
2) worn/arcing/rusting transfer roller contact (use conductive grease)
3) Fuser inlet ramp (mylar coating can wear through).

=^..^=

I checked all the contacts of high voltage but I never put the conductive grease, I will do as you say blackcat4866. I will let you know. Thank you all for now and good year.

[blackcat4866]

Re: TaskAlfa 620 Problems Copy / Print too light

Hi Blackcat.....

Since you are talking about conductive grease , if you don't mind, I need to pick your brain. For field and shop use we can't come to a general consensus as to where and when to use conductive grease. We use a good quality carbon infused conductive grease, very conductive and stable. So, what is your general rule of thumb as to the proper use and application of conductive grease.

THANKS!

Have a happy healthy and prosperous New year.

That's a great question ... and I wish I had a nice crisp standard criterion. But more often than not, it's the screw-ups that define my methods. Here's a few examples:

1) Having replaced quite a few developer bias contacts (around 1M), I thought I might be able to get better mileage out of them by applying some of that magical conductive grease. Two days later I was back for intermittent light copies and void bands crossfeed, Since that was my only departure from the standard procedure and the last call was a complete 500K PM, I wiped away the conductive grease, and I got the fill back immediately.
2) At the 500K PM, when you're changing out the transfer belt it's impossible to miss the piles of rust from the transfer contact. By the same reasoning, I figured I might get better mileage from the contacts with conductive grease. This time it worked. The contact will make 1M. By then the aluminum idler shafts are wobbling badly, and it's time for idler shafts and bearings ... and a new contact with grease.
3) Back to my Canon days, I remember that most Canons of the 90's have ground contacts to the registration roller or other feed rollers, especially in the DF. Some techs would get that nasty black grease all over their fingers, and would wipe off as much of it as they could get. Shortly after that the squealing and static buildup would start. Those contacts had to have conductive grease.

Here's a theory:
Conductive grease seems to work fine on primary, transfer, drum ground, and registration grounds, but not on developer bias or fuser bias. My guess is that developer and fuser bias current is lower, suffering noticeable resistance (and consequently voltage loss) through the grease.

That's about as close as I can get to a general rule. What do you think? =^..^=

[c.olivieri]

Re: TaskAlfa 620 Problems Copy / Print too light

That's a great question ... and I wish I had a nice crisp standard criterion. But more often than not, it's the screw-ups that define my methods. Here's a few examples:

1) Having replaced quite a few developer bias contacts (around 1M), I thought I might be able to get better mileage out of them by applying some of that magical conductive grease. Two days later I was back for intermittent light copies and void bands crossfeed, Since that was my only departure from the standard procedure and the last call was a complete 500K PM, I wiped away the conductive grease, and I got the fill back immediately.
2) At the 500K PM, when you're changing out the transfer belt it's impossible to miss the piles of rust from the transfer contact. By the same reasoning, I figured I might get better mileage from the contacts with conductive grease. This time it worked. The contact will make 1M. By then the aluminum idler shafts are wobbling badly, and it's time for idler shafts and bearings ... and a new contact with grease.
3) Back to my Canon days, I remember that most Canons of the 90's have ground contacts to the registration roller or other feed rollers, especially in the DF. Some techs would get that nasty black grease all over their fingers, and would wipe off as much of it as they could get. Shortly after that the squealing and static buildup would start. Those contacts had to have conductive grease.

Here's a theory:
Conductive grease seems to work fine on primary, transfer, drum ground, and registration grounds, but not on developer bias or fuser bias. My guess is that developer and fuser bias current is lower, suffering noticeable resistance (and consequently voltage loss) through the grease.

That's about as close as I can get to a general rule. What do you think? =^..^=

Thanks for pointing this out as soon as I can I send you the photo of the contact of the developing unit. We feel tomorrow.