PDA

View Full Version : Miscellaneous Overall density is low, white spots on solid pattern - Pro 951


Custom Search


Takhnamishvili
03-06-2020, 04:01 PM
Hello guys!

Have a density problem on BH Pro 951. When I'm trying to print 100% density, it prints approx. 70%, also there are some strange white spots on printouts. Replacing drum, performing Max density auto adj, toner density initial adj, drum set mode did not help, replacing IDC sensor did not help, replacing TCR sensor did not help (Dev. unit has only 400K prints on counter) I'm attaching photo, any suggestions will be appreciated.

Best Wishes


45205

tsbservice
03-06-2020, 04:43 PM
On other models white spots are usually related with second transfer, I don't know this model but may give it a look.
Also you can try to Change the control of the toner density sensor to increase toner density (DipSW5-5, 6, 7).
Good luck

Takhnamishvili
03-06-2020, 06:23 PM
On other models white spots are usually related with second transfer, I don't know this model but may give it a look.
Also you can try to Change the control of the toner density sensor to increase toner density (DipSW5-5, 6, 7).
Good luck

Thanks for your advise. I've already tried changing that dipswitches but it gave nothing. I'm sure that these white spots and low density are somehow related to each other, but can not find exact solution.

Toxic
03-08-2020, 03:15 AM
Usually when i see this on my several bizhubs 950 it caused by weak developer and time to replace it.
Often it happened about 1 mil clicks in my case.

ZOOTECH
03-08-2020, 03:22 AM
I've seen this symptom on Sharp models, and the cause was poor paper quality.

blackcat4866
03-08-2020, 05:15 AM
Is there a repeating interval in the specks, on 13" X 19" paper? What direction of travel? May I assume that you are not doing the recommended maintenance as described in the manual? =^..^=

Synaux
03-08-2020, 07:55 AM
I've seen this symptom on Sharp models, and the cause was poor paper quality.

Paper causing this? What are you using 1800's parchment? (Or perhaps laid OR maybe even felt) with a built-in option for the feed-roller/blade/IU/dev issue?

Takhnamishvili
03-08-2020, 08:12 AM
Developer and Dev. Unit have only 400K on counter, no more. On other 951s I have not seen such problem even when developer counts 1.200K. Anyway I'm going to swap them tomorrow for troubleshooting purposes.

Symptom occurs on other papers too.

There is no repeating interval between these white spots, their location is random. Feed direction is from right to the left as you look at the photo. I'm doing maintenance, so printer is clean and also all spare parts are ok, they're not at the end of their life.

Synaux
03-08-2020, 08:21 AM
Developer and Dev. Unit have only 400K on counter, no more. On other 951s I have not seen such problem even when developer counts 1.200K. Anyway I'm going to swap them tomorrow for troubleshooting purposes.

Symptom occurs on other papers too.

There is no repeating interval between these white spots, their location is random. Feed direction is from right to the left as you look at the photo. I'm doing maintenance, so printer is clean and also all spare parts are ok, they're not at the end of their life.

This is out of my wheelhouse, but HV board?

allan
03-08-2020, 08:26 AM
Try switch 6 bit 7 to 1.
That will disable auto drum voltage control. Basically ignoring the DPS sensor. It would go to a preset value, option to change it would be greyed out.
If there is a massive improvement it means that the DPS the drum or the charge is wacky.
No clue whats up with your machine. Could even be environmental.

Takhnamishvili
03-08-2020, 08:42 AM
This is out of my wheelhouse, but HV board?

I did not swap it, but I think I must try. There are two HV boards, HV1 and HV2 and I think I have to try both of them. Thank you for suggestion

Takhnamishvili
03-08-2020, 08:46 AM
Try switch 6 bit 7 to 1.
That will disable auto drum voltage control. Basically ignoring the DPS sensor. It would go to a preset value, option to change it would be greyed out.
If there is a massive improvement it means that the DPS the drum or the charge is wacky.
No clue whats up with your machine. Could even be environmental.

Thanks for your suggestion, I will try this dipswitch and write here how it goes 😊

allan
03-08-2020, 11:34 AM
Thanks for your suggestion, I will try this dipswitch and write here how it goes 😊

Don't dismiss the fact that it could be developer.

Toxic
03-08-2020, 12:14 PM
I always start with basics,in this case try swap complete developing unit from another machine (if you can) and leave HV boards for the end.
But i strongly believe developer will solve this problem regardless (realively) current low part life.
I have expirience for example, developer will crash long before if machine done lot NCR paper.

blackcat4866
03-08-2020, 11:39 PM
I'm personally leaning towards primary charge. If I had wires and grid on-hand, I would do that first. If I'd gone this far without resolution and had to order, I'd probably replace the primary charger assy. =^..^=

Takhnamishvili
03-09-2020, 04:39 PM
Hello guys again! Today I borrowed Dev. unit (of course developer too) from good working machine, after installing it on problematic machine, I tried to print 100% coverage from service mode, it printed perfectly, but showed error code C2412 and it's clear why, after auto maximum density adjustment, I retried to print 100% coverage and density became lower and engine showed same error code. Definitely Developer is faulty there, but I'm little afraid, what if after replacing developer and dev. unit with new ones, making toner density sensor initial adjustment, density will become low? I'm asking because it's fact that density is very low and machine recognizes it as normal :||

P.S. Before installing borrowed dev. unit, I tried dipswitch 6-7=1, it gave nothing.

louis.robins
03-11-2020, 07:46 PM
I think the cause was poor paper quality. :eek::confused:
You need to do the recommended maintenance as described in the manual?:eek::rolleyes: (https://vtoptics.com/);)

WLIT
03-19-2020, 04:34 PM
I've seen this before and just replacing the developer in the developing assembly should get you back to normal as you have proven already. If you are not aware, the 951 will not shut down or stop when toner is allowed to be run out. I would reiterate this to your client as I had a client who would not pay attention to the toner level indicator in the panel. It took 2 bags of developer, only lasting around 5-600K each, before I could get my client to add a new bottle as soon as the indicator turned red. Now they are getting an easy million clicks before developer gives up. My scenario was primarily due to the Pro being a new unit and learning curve. Best of luck if you haven't fixed already.

allan
03-19-2020, 04:58 PM
Hello guys again! Today I borrowed Dev. unit (of course developer too) from good working machine, after installing it on problematic machine, I tried to print 100% coverage from service mode, it printed perfectly, but showed error code C2412 and it's clear why, after auto maximum density adjustment, I retried to print 100% coverage and density became lower and engine showed same error code. Definitely Developer is faulty there, but I'm little afraid, what if after replacing developer and dev. unit with new ones, making toner density sensor initial adjustment, density will become low? I'm asking because it's fact that density is very low and machine recognizes it as normal :||

P.S. Before installing borrowed dev. unit, I tried dipswitch 6-7=1, it gave nothing.



Keep in mind that doing those switches would take up a 1000 prints before the change would be reflected. And the change in toner concentration is very small.
Would think that you got a humidity issue there? Some moisture in the developer...
In that case the issue should return in time.

If you are a cowboy you can add a tablespoon of toner in there and run dev init again.
Don't blame me if this don't work. Been taking developer way past life with this trick but not recommended where good quality is needed.
Before you know it you could have a nice coating of toner everywhere around the imaging section.
The new concentration includes toner, paper dust, common dust, and human skin cells.

tsbservice
03-19-2020, 05:42 PM
Keep in mind that doing those switches would take up a 1000 prints before the change would be reflected. And the change in toner concentration is very small.
Would think that you got a humidity issue there? Some moisture in the developer...
In that case the issue should return in time.

If you are a cowboy you can add a tablespoon of toner in there and run dev init again.
Don't blame me if this don't work. Been taking developer way past life with this trick but not recommended where good quality is needed.
Before you know it you could have a nice coating of toner everywhere around the imaging section.
The new concentration includes toner, paper dust, common dust, and human skin cells.

Hey allan, sounds you are influenced by your neighborhood. I like your voodoo mixtures. :cool:

Regards: YouTube (https://youtu.be/YV78vobCyIo)

allan
03-19-2020, 06:53 PM
Hey allan, sounds you are influenced by your neighborhood. I like your voodoo mixtures. :cool:

Regards: YouTube (https://youtu.be/YV78vobCyIo)

Side tracking a bit here.
Back at you: YouTube (https://www.youtube.com/watch?v=o2SZWaW8m48)
If i only had an LTD like that...
I roll with the Spirit :cool:

tsbservice
03-19-2020, 07:15 PM
Side tracking a bit here.



Yes, we are going a bit or two offtopic here...but hey it's that corona vileness everywhere, so hopefully we may be excused.



Back at you: YouTube (https://www.youtube.com/watch?v=o2SZWaW8m48)

Thank You for that! Very impressive!

Takhnamishvili
03-20-2020, 10:27 PM
Keep in mind that doing those switches would take up a 1000 prints before the change would be reflected. And the change in toner concentration is very small.
Would think that you got a humidity issue there? Some moisture in the developer...
In that case the issue should return in time.

If you are a cowboy you can add a tablespoon of toner in there and run dev init again.
Don't blame me if this don't work. Been taking developer way past life with this trick but not recommended where good quality is needed.
Before you know it you could have a nice coating of toner everywhere around the imaging section.
The new concentration includes toner, paper dust, common dust, and human skin cells.

Thank you for your suggestions! I really did not know that this dipswitch gives effect after 1000 prints. I will try your ideas, as soon as coronavirus leave us alive :D

allan
03-20-2020, 10:52 PM
Let me correct myself.
To get the prints darker sould not take too long as it needs to add toner.
Reducing the density would take that long.

Did you add a small amount of toner and the ran dev init?
You can always add but if you dose in with too much toner is would fog up the machine or give you nasty background.

Takhnamishvili
06-23-2020, 09:51 PM
Hello guys, I returned to work after long time due to pandemic.

So today I turned off Drum Potential Sensor with dipswitch, tried to print a number of sheets and density started becoming higher, after 30 pages it became excellent. So as it seems DPS is dead there and I'm going to change it with new one.

Thank you all for your suggestions and attention!

Custom Search