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907tec
04-25-2012, 12:53 AM
I've got a low-miles (15,000 clicks) Bizhub C452 that is kicking my ass. Machine is throwing constant C8104 codes because the glass assembly is unable to reach home position. A previous tech had tried swapping the motor from another working machine and it worked...for 100 copies.

Today I removed all the covers, the platen, the glass movement assembly, both belts, the motor, gears, shaft, and collar. Also inspected the wires for any breaks, per the KM bulletin, and reseated all connections to PWB-ID. Before reassembly, I cleaned each and every part, reapplied grease, and checked movement for any friction or blockage. Nothing. I partially reassembled the Original Glass Assembly, loosely installed the scraper and top cover/ramp, basically just enough to run paper through the ADF. For some odd reason, it worked after assembling it this far. I was able to run ~250 pages (mostly 1 and 2 page jobs, some longer runs as well) without issue. I even cranked the Split Line Detect up to the maximum sensitivity to force the Glass Movement to be more active. It passed all of my stress-testing, so I began to install the covers. After installing all the covers and reattaching the finisher, I restarted the machine....C8104 after warmup.

"Alright", I say: "it's obviously the covers impeding movement of the glass assembly". Remove all of the covers in the area, including the scraper, to alleviate any added friction...still C8104. After resetting the code each time, the Glass Assembly attempts to briefly unblock, then reblock the home position sensor. At present, the motor is only making a tiny "pulse" in the direction of unblocking: not nearly enough to even move the glass a millimeter. The strange thing is that the motor feels "locked" when it is attempting to move out of home: it is very difficult to rotate the motor shaft by hand, even when the motor has been removed from the drive assembly.

I am at a loss. Everything looks perfectly pristine. Rather than aggravate myself any further, I have ordered the PWB-ID, another M202, as well as a complete Original Glass Movement Assembly. With that being said, it still annoys me that I can't figure out why this is happening. The customer is (understandably) angry that their new machine is having issues, so I'm still hoping to get it fixed before the parts arrive.

Any ideas?

blackcat4866
04-25-2012, 01:16 AM
I've seen cases where a strategic index plate screw was stalling the scanner. From your detailed post I think you've covered that.

It sounds to me like excessive drag on the scanner drive, or motor driver circuitry problems.

When I first started working on Sharp I noticed that the scanner cables were typically looser than I expected. Based on my experience with Canon I went around to many of my machines and increased scanner cable tension. Along with tighter cables I also got scanner drive errors. The lesson is that a Sharp scanner does not necessarily get adjusted like a Canon scanner.

=^..^=

Mr Spock
04-25-2012, 03:58 AM
Check the length of the screws. I think a couple are shorter and have to put in the correct place. Also make sure the covers are down flat or that will cause it.

SmellsHot
04-25-2012, 08:23 PM
This wont help you, but just shut off the cleaning mechanism :)

907tec
04-25-2012, 08:46 PM
Oh, how I wish it were so easy...

Even with the Split Line Detect at "Not Set" and sensitivity levels at minimum, the Movement Assembly still does it's home position check. I was scrutinizing that lil assembly for hours trying to figure out a way to cheat it or make the machine believe it was still operational after disabling. Nothing popped out at me. It acts a lot like some of the KM finisher tray limit sensors, where they descend until the paper stack isn't blocking the sensor, then raise up just far enough to block the sensor again. Every time the C452 wakes from sleep/low power/restart, and even after lowering the ADF, the Glass Movement assembly checks it's home position.

Anyone have a list of DipSw settings / Software Switches? There are only a handful of DipSw's listed in the manual, not an actual list like older machines. Am I just not finding it in the manual? It's times like these that I wish KM still included Load Check modes...

SmellsHot
04-25-2012, 09:02 PM
TAKE THE BELT OF THE MOTOR :p

907tec
04-25-2012, 09:05 PM
It sounds stupid, but I actually did try that. I tried removing the belt on one side, hoping it would reduce drag and allow the other end to move enough to unblock the sensor. No dice.

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