Not scanning lighter colours

[systemnova]

I've got a C458 that's dropping light colours when scanning, but prints perfectly well.
The issue seems to effect both the front and back scan, which is what makes me think it must be an adjustment I'm missing.
I've tried gradation & stabilization. Also moved the CCD to a few different locations, with no improvement.
Thoroughly cleaned back & front reading units. Any ideas?
The way it's impacting both sides makes me worry it's the main board.

[Max]

Looks fine e to me. Scan as text not as a photo. Optics cleaned?

[copyman]

How does it look if you place original on glass? This would be only time optics are used. When scanning with ADF it only uses the CCD units. Also did you try the different user scan settings, "fine, text/photo, etc" ?
I've never had to "move" CCD units or had a bad board that caused ADF quality issues.

[blackcat4866]

What scan settings are you using? (DPI, compression, background, etc)

Have you tried making changes to those settings? =^..^=

[Synthohol]

bgrd.jpg
those images look perfectly normal to me, you will lose 3-5% of saturation.
you can play with these settings as well as original type but ive had good results combining these two.

den.jpg

[systemnova]

How does it look if you place original on glass? This would be only time optics are used. When scanning with ADF it only uses the CCD units. Also did you try the different user scan settings, "fine, text/photo, etc" ?
I've never had to "move" CCD units or had a bad board that caused ADF quality issues.

This occurs both for the original on glass & when scanning via the ADF.
It's better when turning off compression at maximum resolution using photo settings on the TWAIN driver, but these options are not all available on the device. It's odd because there is much more control of the scan settings from the copier page on device, than the scan page. eg. image hue adjustment etc.

Looks fine e to me. Scan as text not as a photo. Optics cleaned?

Yes, optics so clean I'd eat dinner off them.

What scan settings are you using? (DPI, compression, background, etc)
Have you tried making changes to those settings? =^..^=

See below for the settings i'm using that seem to have the best result:
optimized_image.png

Those images look perfectly normal to me, you will lose 3-5% of saturation.
you can play with these settings as well as original type but ive had good results combining these two.

Those settings definately change the result for the better, but i was already at the maximum density. Only with density set to max. It's strange because even if i calibrate density from the admin or service menu's, the result always seems to need the maximum darkness density set on the scan settings prior to the scan.

I've also noticed that the preview button never seems to do anything and when i run Service Menu > State Confirmation > Memory Check >JPEG Check
In the JPEG2 i get a NG result. Yet the service manual doesnt even mention JPEG2 check anywhere in the manual.

The main reason I'm concerned about the saturation loss is that it seems to result in grey's that the compact PDF conversion can't handle, resulting in centres of words going missing, bit of a cross post but see below:
image.png

[Synthohol]

not for nothing, scan to a usb stick instead of twain and look at it on the PC.

TWAIN scanning is still a thing?

[systemnova]

Same thing when scanning to usb, except a little worse because not all the same options are there.

To make matters worse, i've done gone goofed the software switches trying to find a way to fix the outline grey shading in compact pdf... Seems to now be in a debug mode with pink squares around each icon button and it thinks it's an accurioprint.
The counter button has dissapeared & I cant seem to call up the service menu anymore. I've tried reflashing the firmware, but It doesn't seem to help. I think i need to clear the software switches, but not sure how without the counter button visible.

Does anyone have a service manual for the accurioprint C759? Maybe the buttons are different to access the service menu?
Or know how to exit this debug/kiosk like mode?
Or know how to reset the switches from the firmware update without access to the service menu?

I've got admin access via the Data Administrator & Pagescope, but the harddrive now isnt installed, so the options there are limited.

[Synthohol]

OMG!
run a data initialize if you can get to service mode maybe the trouble reset way if needed.
its switch 10 should be hex 02 if it is a konica.
these should be the default switches from the manual.
bits.pdf

[Synthohol]

also i sent you the manuals so you don't do silly stuff anymore or at least be able to un-silly it

[systemnova]

Thanks Synthohol!
I've managed to unsilly-fy it somewhat and she's functional again.
I've noticed that the C759 has a CCD-ID table configurable from the service menu, where as the C458/C658 does not mention it in the manual. I think that's the only method of configuring the raw CCD parameters for colour. The C759 specifically mentions "after gradation adjustment, if the gray balance of black (four colors) becomes worse, use this function to adjust the density"... which i think is the core of my problem. I've ordered a new CCD unit anyway, but think I might end up with the same problem because the C458 manual says to switch off the default calibration if the CCD is replaced, which I think auto-activates the use of the CCD-ID table... but it seems the C458 has no means of adjusting that table?
Do you know if there is a method of exposing this table or something similar on the C458?

I've also found that JPEG2 is returning NG, and non-image area erase check is returning NG (even when there is no light in the room at all).
But the auto self-diagnostics are all clean.

Not sure how i restore JPEG2 or fix the non-image issue, as I can't find any documentation anywhere on either issue.
I've managed to get the debug tool working I think, hoping that might reveal more.