Risograph RN A4 Drum on a RN B4 machine

[Lovenice]

Dear All

I'm quite new with Risograph printers.
I've got a RN 2050, that's a B4 machine. I've bought a drum from a RN a4.
This drum is perfectly the same as the others i've got and when i run the machine in test mode it makes masters and print perfectly. But when I run it in normal mode, the Riso says "wrong drum type". So i guess the problem is not the drum, but something in the electronic part of the drum that say to the machine that it is for A4 machine.
Does anyone know how to change this parameter in the drum or say to the machine that the drum is ok?
Thanks a lot,

Lorenzo

[Lovenice]

The question could also be:
How can i convert an RN A4 drum to a B4 drum?
Thanks

[ddude]

Not sure, but on many Risos there are small switches ( in two banks or rows), just under the drum cover. Try making the A4 switches match the setting that you see on the B4 drum. You may run into other cq problems by using that drum due to the drum screen size, depending upon what type or size original you run?

[Lovenice]

Thanks a lot ddude. Today i'll search for them.
But anyway i've noticed that even if the screen is the same as the b4, the area of ink is smaller. So it seems that there's also something to adjust under the screen...

[Lovenice]

There are no switch on inside, but i've tried to change the card with chips with another one of a B4 drum and the Riso accepted it. But the printer area is still A4. Do anybody knows where i can by a card for B4 and how to modify the print area?
thanks

L