blackcat4866
09-25-2014, 01:07 AM
KM-3051ci, 1200 total prints.
Copies off the glass and prints are normal. Scans and copies through the DP-770 are focused, clear and totally off color. In the pix the lower half is the copy off the glass or print, upper half copied through the DP. I know it's hard to believe but it is the same original.
2656126562
As you can see I used scans and my Colorpic tool to break down the RGB/CMYK color numbers of each area. I expected to find some interesting pattern, for example: 22% too much cyan across the board or 12% less yellow across the board. Wrong, it's far more interesting. Each color defined in the pixs are uniquely off color. Most have 40% or more too much yellow, but some have 24% less yellow. It's as though the color catalog was randomly re-organized.
What have I done?
First I thought that it was possible that when light source #1 reached the slit glass, it was tipping a mirror, or perhaps a loose mirror ... something like that. I checked the wire ropes, tension, mirror mounts, spring clips, focus adjustments and screws, cleaned the ribbon cable ends and re-seated the connectors.
Second I thought that perhaps the RADF was somehow out of adjustment: height, rotation, etc. So I adjusted the rotation, checked the height, and moved back the black strip ~1.3mm in case the scanner was catching sight of the edge of the strip.
Third I printed off the Maintenance Report and picked out any setting or adjustment that might have anything to do with DP image quality, and read about each one.
U063 only made a difference at it's highest setting (18), then it started to shade worse.
U068 didn't really have any quality affect between -15 and +38. Below -15 light source #1 is starting to scan the underside of the white plate, rather than the slit glass. Surprisingly, this is the best way to align the RADF with the slit glass. Set to -14 you get shading that can be made even front to back by rotating the DP. It's a ton easier than using a small ruler and flashlight, and trying to read the small marks on the ruler from 15" away, in the dark.
U074 is designed to compensate for background from light blue originals. At it's highest setting +3 it removes most of the yellow/green background, but does nothing for the totally off color representation.
U425 stores some sort of color settings. I made some pretty radical changes that had no effect on the problem.
U429 didn't seem to change anything, off the glass or through the DP. The manual is a little confusing here. In one place you think the setting ranges from -5 to +5. In another place it seems to read 1 to 10. It's the latter.
Fourth I went through the user original settings to see if I could change the issue at all.
Original Type-defaulted to Text/Photo, Book/Magazine. Both the Text settings have less yellow/green background. The Graphics/Printer setting and the Custom1 setting made it much worse, more like a heavy lime green background.
Background Density Adjustment-defaulted to Off. Set to Auto entirely removes the yellow/green background but does nothing for the off colors.
Prevent Bleed Through-default to Off. Set to On removes some of the yellow/green background.
Fifth I reloaded firmware.
Conclusions?
I've decided that the mechanical scanner and CCD are OK.
I believe that the color problem is electronic. Image processing, at the ISC (scanner PWB) or Main PWB.
I've ordered the ISC PWB, and the two Charts to calibrate the CCD.
So maybe you read to the end of all my thoughts here. I feel like I'm missing something. What did I miss? =^..^=
Copies off the glass and prints are normal. Scans and copies through the DP-770 are focused, clear and totally off color. In the pix the lower half is the copy off the glass or print, upper half copied through the DP. I know it's hard to believe but it is the same original.
2656126562
As you can see I used scans and my Colorpic tool to break down the RGB/CMYK color numbers of each area. I expected to find some interesting pattern, for example: 22% too much cyan across the board or 12% less yellow across the board. Wrong, it's far more interesting. Each color defined in the pixs are uniquely off color. Most have 40% or more too much yellow, but some have 24% less yellow. It's as though the color catalog was randomly re-organized.
What have I done?
First I thought that it was possible that when light source #1 reached the slit glass, it was tipping a mirror, or perhaps a loose mirror ... something like that. I checked the wire ropes, tension, mirror mounts, spring clips, focus adjustments and screws, cleaned the ribbon cable ends and re-seated the connectors.
Second I thought that perhaps the RADF was somehow out of adjustment: height, rotation, etc. So I adjusted the rotation, checked the height, and moved back the black strip ~1.3mm in case the scanner was catching sight of the edge of the strip.
Third I printed off the Maintenance Report and picked out any setting or adjustment that might have anything to do with DP image quality, and read about each one.
U063 only made a difference at it's highest setting (18), then it started to shade worse.
U068 didn't really have any quality affect between -15 and +38. Below -15 light source #1 is starting to scan the underside of the white plate, rather than the slit glass. Surprisingly, this is the best way to align the RADF with the slit glass. Set to -14 you get shading that can be made even front to back by rotating the DP. It's a ton easier than using a small ruler and flashlight, and trying to read the small marks on the ruler from 15" away, in the dark.
U074 is designed to compensate for background from light blue originals. At it's highest setting +3 it removes most of the yellow/green background, but does nothing for the totally off color representation.
U425 stores some sort of color settings. I made some pretty radical changes that had no effect on the problem.
U429 didn't seem to change anything, off the glass or through the DP. The manual is a little confusing here. In one place you think the setting ranges from -5 to +5. In another place it seems to read 1 to 10. It's the latter.
Fourth I went through the user original settings to see if I could change the issue at all.
Original Type-defaulted to Text/Photo, Book/Magazine. Both the Text settings have less yellow/green background. The Graphics/Printer setting and the Custom1 setting made it much worse, more like a heavy lime green background.
Background Density Adjustment-defaulted to Off. Set to Auto entirely removes the yellow/green background but does nothing for the off colors.
Prevent Bleed Through-default to Off. Set to On removes some of the yellow/green background.
Fifth I reloaded firmware.
Conclusions?
I've decided that the mechanical scanner and CCD are OK.
I believe that the color problem is electronic. Image processing, at the ISC (scanner PWB) or Main PWB.
I've ordered the ISC PWB, and the two Charts to calibrate the CCD.
So maybe you read to the end of all my thoughts here. I feel like I'm missing something. What did I miss? =^..^=