bizhub pro 1050 ,toner background,sc29-11

[allan]

I would then get all the PM stuff and that sensor board ready.
And then do a PM.
Could be a simple as a shot drum.

Is the machine on contract or a cash customer?

[itan84]

I service the machine on which I work

[allan]

So a new drum not just another drum?

The one time you switched it on an got good print was the one time the drum voltage was in range to produce a good print.
So its like a slot machine you got lucky.

Remove all previous tweaks! Make sure all soft switches are set to default.

Switch 6 bit 7 from 0 to 1 will disable drum potential auto adjust.
Switch 6 bit 6 from 0 to 1
Switch 6 bit 5 default stays on 1 These two is to set stabilization control from 20K to 50K.

Then you need to do something the manual warns you against doing. You can fry the drum or the HV unit by over driving the voltage.
Service Mode -> Process Adjustment -> Drum Peculiarity Manual Adjust.
Go find a machine running ok and go look what the defualt value should be if you can.
If you can set it in the middle of the range and work up and down from there.

Switch 7 bit 3 from 0 to 1
Switch 7 bit 2 from 0 to 1 Use these two only if print are still dark after adjustment.

If this does not change things then the answer is simple your not getting charge onto the drum and need to take a close look at the charge unit and HV supply and even the control board.

If that works then go find another DPSB.
And undo all the switches again.

[itan84]

I changed all the defaults and it turned out that setting the auto drum potential Switch 6 bit 7 from 0 to 1 settled the matter, it's a pity that I forgot about this bit. It seems that this setting will do the replacement of the drum sensor.