Durst rcp 20 that moves backwards?

[jacnorectangle]

I bought this on ebay. The seller said he had "modified the unit with a variable speed motor so you can run the unit at any desired RPM or print/roller speed". But the rollers are moving in the wrong direction. When I stick paper in it spits it out instead of sucking it in. There's 2 black knobs on the back of the machine. I'm assuming he added these because I don't see them on photos of other machines. Turning them doesn't seem to do anything. The seller isn't responding to my messages. Anyone know how to get it to turn the right way? It came with these wheels. It looks like the white one is the original because of the marks on it and the silver one is a new one. I haven't opened it up but it sounds like something inside is scraping against the cover as it's turning.

 

[jacnorectangle]

This is the motor.

I can tell it's an adddition by the seller because the 4 screws that hold it in are not there on other people's machines. You can see in this photo of someone else's machine the movement is caused by a belt and wheel.

On mine this system has been disabled and replaced by the new motor which is dated 10-20-95. the rcp 20 came out in the 70s. the wire to the original motor has been cut.

So I could just switch the 2 wires around? Also the 2 knobs on the back are not connected to anything. I was hoping they were supposed to control the speed of the motor

 

[AgX]

It seems the original AC driven motor has been replaced by a DC driven motor, a transformer and a flexible shaft coupling, plus two unused rheostats.

But I'm missing the needed rectifiyer.

 

[jacnorectangle]

Ok switching the wires got it to run in the right direction But I'm not sure if it's going fast enough for ra4. I tried to time it but it was hard to tell when the paper was reaching the developer. It took about 60 seconds to make it through.

 

[jacnorectangle]

The seller messaged me back saying one knob is to control the speed, the other is to control the temperature. But I don't see how this is possible since they're not connected to anything. What do I need to get to connect them to the motor and use them to control speed?

 

[AgX]

Typically you would need some electronic "power" circuit that, controlled by that rheostat, keeps the Motor at the desired revolution, nonwitstanding its load.

Alternatively you might control the motor directly, but that would be less effective and would also need a rheostat capable of taking the current of that motor.