This started suddenly. Every successful feeding is after a retry i.e. the machine can print 10 copies in 20 cycles. When I inspected the pickup rollers, They seem to fail to rotate in the first attempt and then rotate after a retry. This however does not print more than 10 copies before it stops with 'Paper jam in paper feed area.' Registration is normal except after jam detection, so I rule out timing. I have changed the pickup rollers but no luck. I have checked and adjusted to stack switch with no luck. Any ideas??
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Re: GR 3750 paper jam issues
The green knobs/levers in the paper feed area are in the correct position? It sounds a little bit like the green lever there is in the card stock position when the machine is trying to feed paper of normal thickness. If that's the case, the paper tray will lift farther causing too much pressure between the pickup roller and the paper stack to the point that the machine can't reliably feed paper. You might try checking the tray height adjustment, too.
Other than that, you might try giving the area where the paper goes into the machine a good blast of air to see if the sensors are covered with paper dust. If you choose to do that I recommend you take precautions, as on a machine that old there is likely to be massive amounts of paper dust nearby that cause no harm until you disturb them like that.
Finally, it could be that the paper feed clutch is beginning to wear out. Or the wiring to the clutch is going bad. Or the clutch is the older, less reliable one, if you look at the clutch and see a wrap spring, that is the case.
Hope that helps. -
Re: GR 3750 paper jam issues
Thanks for your reply.
The green lever is on normal and I even tried changing it to card but similar results.
After thorough inspection, I have noticed that the pickup solenoid is working well. The feed process stops when the paper reaches the timing roller. The paper may or may not move after a retry operation.
I have cleaned the guide roller and timing roller but same result.Comment
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Re: GR 3750 paper jam issues
If when the jams occur the paper is up to but not past the timing roller, it could be that the sector gear that drives the guide roller is stuck, but there is always a fairly loud clunk when it releases so that's probably not the case. If something isn't allowing the gap between the timing and guide roller to close properly, it could cause that to happen. You might want to check the cam follower and pressure spring. Or it still could be a worn feed clutch.
If the paper gets past the timing roller and then stops, the spring that prevents the guide roller from rotating in reverse has worn the guide roller shaft and the guide roller assembly needs to be replaced. Those haven't been available for some time from Risograph, so lets hope that isn't the case.
If you choose to check any of that, be very careful, there are some sharp edges and very strong springs in that area, and the motor won't stop if something gets stuck in the works.Comment
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