C350 Error P-5 Hell

[Zorb]

I have a customer with a Konica Minolta Bizhub C350 with a recurring P-5 error.

Here's what I know:
- Printer has about 130000 pages on it
- IUs rechipped about 1000 pages ago, with normal other services to accompany (clean everything, clean LEDs, clean LPH, test all) *
- Belt counter approximately 190000
- Replaced Paper Dust Remover and Odor Filter at same time as drums serviced
- Waste toner bottle replaced

* Problem existed before drum service


Here's what it's doing:
- Problem occurs when printer hasn't been used for a while.
- Machine refuses to print from copier or computer.
- Machine resets itself with one page partially loaded, almost to the belt and transfer roller under the right cover, about 6" below the fuser entrance.
- Printer displays error icon, code P-5 is shown when icon touched. P-5 corresponds to front AIDC sensor.
- P-5 returns after removing loaded page.
- Error is not cleared by running image stabilizer+reset.
- Error is cleared by opening and then closing left printer cover (access door for belt) and then running the stabilizer, as per service manual troubleshooting.
- Will run hundreds of copies at a time without errors after error is cleared.
- Error only returns if machine is not used for more than a couple of days.
- Print quality nearly perfect.

Here's what's been done to diagnose/correct:
- Cleaned LPH (again)
- Cleaned AIDC sensors
- Checked movement of AIDC sensor cover plate and lever mechanism
- Cleaned transfer belt surface
- Transposed AIDC sensors (to see if error moved with sensor, it is unchanged)

Any ideas about this one? It is quite strange to me. The service manual indicated what could be done to make the error go away, but did not explain what it meant if the error did go away due to this test (open + close left cover then run stabilize). Please enlighten?

I am not a Minolta expert, and customer not amiable to an overly expensive fix, as the machine was bought off lease for $1500. Customer would likely prefer to replace the machine if the repair cost will exceed $1000

[Zorb]

I have new information... I have a faint show-through of the image from the previous copy on subsequent pages. It's only apparent with bright white paper which is has a slightly rougher than usual service (cardstock), and doesn't happen with the smoother copy paper. It shows up the most with horizontal lines, printing lengthwise along the machine's long axis (parallel with belt).

[laserman06]

Have you replaced the transfer belt?

[Zorb]

Have not changed the transfer belt. It seems perfect though, so I really don't think it needs to be replaced. It's not coming out of the machine with toner sticking to it, there are no marks in it, and there is only very very faint banding lengthwise. It appears to be in much better order than many I have seen.

What exactly happens when you open and close the left door? Why does this clear the error? It is mentioned in one of the troubleshooting supplements to the manual to do it as a diagnostic step, but does not indicate what this actually does to the machine. It does not indicate which specific cause of the P5 error would be indicated if this works to get rid of it. Does it force it to ignore a sensor? Skip a step somewhere? I can't find the item at the moment, so I can't quote it.

Refer to page 4-15 in service manual where it lists to open and close the left door, then run an image stabilization sequence, then check voltage levels from AIDC sensors. This check always passes. The check result is the same if you do not open and close the door however. As far as the AIDC voltage, mine is fairly high, about 4.1 volts, and they are consistent between the two sensors. What is the cause of it being out of the expected range? 4.3 is as high as it expected, 1.0 is as low is expected. Does higher voltage correspond to higher reflectivity of the surface and lower voltage correspond to lower reflectivity, as I am thinking?