MX-5001N - Black Image Weak

[ZOOTECH]

This machine was brought into the shop with over 1 million black count and minimal color count. The blk image is very weak, it fails TC 50-22 with a "sub black front error 11", and did have a F2-50 (blk phase detection) error.
The blk drum has no toner when TC 64-1 A=17 is ran; all the colors have a good solid fill. The blk drum, developer unit, PCU and MFP pwbs, and LSU (blk shutter was removed for test) have been tested with parts from a used machine (with no change in symptoms, which doesn't totally eliminate possible bad parts from the used machine, but I would expect a different symptom). The HV voltages are there at the PWB and were increased for testing and then returned to proper values.
I'm thinking it might be the DHPD K sensor which seems to be in the main drive assembly, although, it did change states in TC 30-1.
Am I heading in the right direction, I don't want to pull that main drive unless neccessary.
Thank you in advance...

[sharptech]

As you had a k phase error I would clean both phase sensors. Next I would clean the K and the color process control sensors. I have had dirty phase sensors give a phase sensor error and a dirty K process control sensor would cause the voltage used to create the K patches to go too low.

T.G.G.

[blackcat4866]

Is there anything else left other than the main drive? It sounds like you've covered your bases. =^..^=

[ZOOTECH]

As you had a k phase error I would clean both phase sensors. Next I would clean the K and the color process control sensors. I have had dirty phase sensors give a phase sensor error and a dirty K process control sensor would cause the voltage used to create the K patches to go too low.

T.G.G.

Thanks, sharp tech and BC; TC 44-13 was ran after cleaning sensors and results were good; TC 50-20 and 21 were adjusted close to specs, and 61-4 LSU skew was right on. From the P/M, it looks like there are 3 phase sensors in the drive unit, but these old eyes might be failing me. Short of disassembling the main drive, is there a way to clean the sensors after removing the unit from the machine? Patches on the TC1 belt are good for color, but weak for the blk. Even though voltages read good, they may not be getting to the drum, DV, or transfer belt - which opens up a whole new trouble, fun times ahead.

[DAKOTADAN]

This machine was brought into the shop with over 1 million black count and minimal color count. The blk image is very weak, it fails TC 50-22 with a "sub black front error 11", and did have a F2-50 (blk phase detection) error.
The blk drum has no toner when TC 64-1 A=17 is ran; all the colors have a good solid fill. The blk drum, developer unit, PCU and MFP pwbs, and LSU (blk shutter was removed for test) have been tested with parts from a used machine (with no change in symptoms, which doesn't totally eliminate possible bad parts from the used machine, but I would expect a different symptom). The HV voltages are there at the PWB and were increased for testing and then returned to proper values.
I'm thinking it might be the DHPD K sensor which seems to be in the main drive assembly, although, it did change states in TC 30-1.
Am I heading in the right direction, I don't want to pull that main drive unless neccessary.
Thank you in advance...

These are a couple of things I found to help with light copies, check MFP-TB-399, which was a new style MC-PWB board, if this machine is older it may have the old style board in it, and I had various issues with these old boards,
Second replace the process electrode cover and base on the blk.
PFTAP0149FCZZ=COVER PCASZ0312FCZZ=CASE
Hope this helps, Dan.

[blackcat4866]

I haven't had to do it myself, but from following threads on this topic I understand that you can remove the phase sensor without removing the whole main drive assy. You just need to know where to look to find the sensor. I recommend that you A) search the other threads on this topic. B) Take a look at the exploded view in the parts diagram to get a feel for where the sensor is at. =^..^=

[faxman28]

section 41, item 24 in parts guide, sensor is close to the black drum motor, (left side along bottom edge of drive unit.)

[ZOOTECH]

Thanks to all for your help and suggestions - the machine has been put on the 'back burner' for now, but I'll update when I can get back to it.

[ZOOTECH]

Switched the blk and yellow drum phase sensors (BC you're right the, drive unit did not have to be removed to get to the sensors) with no change in symptoms.
Next step would be the electrode cover and base, it does have the updated MC pwb, but it could be bad - thanks Dan.
But I've been told to wait, as this machine might be replaced at customer's site sooner than later.
If I get a chance, will update with a fix.

[ohightower]

I just had the same problem it had me stomped for a few days I swapped out the black developer unit and the black drum unit from a working machine and now it works fine im not sure which one was the problem i'm thinking it is the drum but I did that and it works perfectly.