Hello we have this toshiba machine that has been fine until all of a sudden it started having blurry print (I haven't seen the defect, one of my colleagues did, but shortly after it came up with a service call error C970).
I'm not a printer expert but do plenty of electronic repairs and we have been taking a look ourselves.
On first inspection it showed C970 which i understand to be high voltage transformer issue. After removing toner, drums, transfer belt and cleaning and reinstalling we got a mix between CE20 and CE40. C970 would occasionally come up but mostly its been CE20 and CE40. We have been referring to service manual. We can see that the printer is printing a striped test pattern on the transfer belt in the middle and all colours are present on that but I haven't got an example to compare with to see if it's absolutely right. We checked the toothed wire and grids on each drum and they are pretty clean and nothing broken. High voltage tab/springs on each drum and inside the machine look good. There appears to be a nice even coating of toner/developer on the developer rollers of each drum unit. Everything moves freely. Waste toner box clear, transfer belt cleaner is clear. We have cleaned the image quality and alignment sensors and tested that the shutter opens and closes from the test mode.
We got to the point where we didn't know where to go next but I found in the service manual that there was a code to essentially bypass the image quality checks, and it showed that a test print could then be done in 04 mode (possibly code 127 if i remember?). To my surprise it printed off a few sheets. It contained a colour bar with CMYK but the black was awful. There was a square black blotch in the middle of the sheet and a thick dirty/smudgy horizontal black bar at the top of the page. When i then looked at all the drums, the black drum still had a thick stripe of toner adhered to it. All other toners were clean. This stripe coincides with the defect on the paper. I tried cleaning the black drum but the defect persisted and the toner still got left on the drum afterwards.
Shortly after we got the C970 error again and couldn't even do this test page in 04 mode with image check bypassed.
I then removed the black drum and 04 mode loaded without error.
Does this sound like a bad black drum? Is there anything else i should check?
Thanks,
James.
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