MX-5500N Yellow issues

[graybeard]

Got an odd one on an MX-5500N. All individual colors look fine except yellow. We're getting a fade-out toward the front frame side of the machine. The transfer belt is new, the developer...then the developer unit... was replaced, the drum unit is new, and went so far as to try a controller board. The problem occurs on prints and copies. A tech is installing a laser unit today. The calibration has been done the long way, strictly by the book. The firmware is up to date........can you say 'baffled'?

[ZOOTECH]

Check the yellow LSU shutter, we have seen them warped a bit causing the problem you described. You may want to check all the shutters at the same time.

[Lawrence]

I have never seen inside a color dragon but ive had something similar on the 2300. The shutters for the color drums did not totally open all the way and parts of the image were missed by a color. On the 2300 there is a big white plastic peice that slides back and forth and opens the shutters when the solinoide activates, the machine was in a dusty enviroment and dirt built up under the plastic and it did not slide smoothly any more and the shutters would some times not open all the way. After removing the shutters and the slider, i cleaned the metal and sprayed it with silicone oil to make it slippery. Never had that problem again on that machine.

[OMD-227]

Zootech & Lawrence are correct as always.
I'd check the LSU shutters. Also clean the LSU with the cleaning wand.

Problem is more than likely the Shutter solenoid, as I've never seen an issue with the C-Dragon actual shutters..... and we have heaps of these machines.
Check the 24v supply from PCU drops from 24v to approx 0v when operating. If the voltage drops to approx 8.5v, you have a faulty solenoid. If the solenoid is faulty, it hasn't got the power to pull all shutters open. With yellow being on the end, it would open up the least, causing yellow fade out, either through the centre or along an edge (like you are getting).

[MHeon71]

I am not sure if this is your problem, because my yellow was almost non existant from front to back. I had to replace the 2 transport clutches. They are in sec. 59 item 4. I got to this conclusion because the cam on the pri. transfer belt was not in the correct position when all transfer rollers were suppose to be down. Sharp says when the clutches for applying pressure to transfer belt goes, yellow seems to suffer and maybe a little of magenta. I think there is a bulletin on the 3501 but not the MX5500.

[Lawrence]

Wazza to the rescue!!

FYI locking the shutters open at least on the 2300 is a bad idea. It would be a good test to see if your yellow shows up properly but don't leave it! You get a line front frame to rear frame of each color when the machine runs multiples, you get more colors the longer the paper. I guess the laser does a quick scan when the shutters are supposed to be shut.

@MHeon7
I remember seeing that bulletin to, it was a e-clip damaging the shaft and as a result when the clutch would activate to turn the cam to push the transfer rollers down it would hang up or something but it was supposed to be isolated to the 3501/4501 only.

[graybeard]

We stopped a solid yellow so we could see it on the drum......the fade is there. Swapped shutters between yellow and magenta with no change to the image. The solenoid seems to be yanking the shutter open completely (had the side off and could see....good thing it's the yellow). The laser unit itself had no effect. I pulled the drive unit and, please forgive me copier gods, adjusted the receptacle for the post on the developer unit.....yes, I touched red screws. The image improved drastically, but was not perfect. We've emergency ordered a drive unit, and already have a high voltage board on hand just in case. I appreciate the input to this point....I hate hitting a wall with no more ideas.

[Copy10871087]

Any success? We have the exact problem on a 6201 and looking for the answer to this. We also locked the shutters open without success.

[graybeard]

I ended up going back step by step what the last technician had done prior to this issue. Under the rear frame end of the fuser is a block that houses the contacts for the secondary transfer belt. There is only one screw holding that block solid to the frame, and it had been removed. The block was wobbling noticeably. When secured the problem disappeared, but no one....even in my own shop.....believes that was the cause. I just know it's still working.

[OMD-227]

Wow... I'm stunned.
Why was that screw even removed in the first place? Never had to touch it myself in years.
I'm with you.... cant see how that would fix the image anyway. The image is put on the primary belt, well before transfer onto paper at the secondary belt unit. The problem image cause should be around the yellow drum/dev/shutters/transfer roller etc etc. Will keep an eye out for that one in future anyway.