[Misc] Bought an old risograph RP3700. It prints very uneven.

[imax]

I have access to 3 drums with different colors. They all print uneven in different ways. So I suspect that its the drums them self and not the Riso that is the problem.

The red one has lines and big areas (always the same) with bad coverage. The other two are better but you always see the same areas where the print is bad.

The Riso was unused for a few years before I bought it. Can it be that the drums just need cleaning? And in that case, how would I do that?

Thanks!

[Shadow]

Re: Bought an old risograph RP3700. It prints very uneven.

yes you have hit the nail on the head in this one.
you do need to clean the drums thoroughly
get yourself the manuals for this machine and follow the procedure completely.
when the machine has sat for a while the ink will gel excessively and not flow well
you will need to strip down the drum completely and clean everything

[Users Tech]

Re: Bought an old risograph RP3700. It prints very uneven.

check also if the drums has dents.

[Iowatech]

Re: Bought an old risograph RP3700. It prints very uneven.

Can you see the image on the master that is on the drum? It should be visible whether the drum screen is inked or not. If the image on the master is not perfect, it is an issue with either the thermal head or the optics.
If the image on the master looks fine but the ink coverage on the master looks uneven, you might need to clean the drum. Or you might just need to run the machine for a while. Try running a ream of paper through the machine at full speed and see what happens.
As it looks like you just got a Riso, here's a tip: if you do get the machine to work, make no less that twenty prints from every master you make.

[RRodgers]

Re: Bought an old risograph RP3700. It prints very uneven.

Clean the screens. Simple Green will probably work just fine.