GR375 Black copies

[copycart]

I have a 3750 that was producing black copies. Changed the lamp driver board and the exposure lamps stayed on. Put the old board back on and lamp still stays on. Started with making completely black copies, now lamp stays on continuously. Check fuse on power supply board. Also need a source for Riso parts if I upgrade to a newer model.

[Iowatech]

Have you tried printing any of the test patterns in test mode? You might want to do that to be sure it really is a problem with the scanner. Test modes 117 through 120 should work, if the machine prints all black for any of those the scanner is not the problem.
This might be silly, but is there a master on the drum? And is it the correct size? A few times I've seen people disregard the "Change Master Roll" message, which under the best of conditions will put a master that is too short on the drum, which can cause something like this. So I had to ask.
You might try resetting the machine. There are plenty of posts in the "Digital Duplicators" thread here on how to do that, it is the same for all machines in the GR product line.

[copycart]

Master is on the drum but is not being burned, still making black copies. Master on the drum is completely black. Inked up but no print on the master.

[Exok]

If your master is on the drum and you are getting an all black print, then your master is indeed being burned. A master that has not been burned will produce a blank page. To produce a full black page that means the whole printable area on the master is being burned. You need to made a master using test prints to determine if your problem is scanning or a problem with your thermal head. If you make a test print and that is all black too, you can rule out your scanning. If the test print looks fine then you can rule out your thermal head. I've worked on many Risos over the years but I've never come across one printing all black. Good luck!

[jermyth]

I have seen a broken scanner flat ribbon cable make partial black prints.

[ddude]

I have seen a broken scanner flat ribbon cable make partial black prints.

I just happen to have a GR3750 that I am parting out- Maybe you would like to purchase this cable from me?

(Jeeze, I feel like PAUL right now- I'm gonna go take a shower......)