GR 3770 Paper Feed Clutch not getting power.

**Chuck29620** · 05-31-2013

GR 3770 Paper Feed Clutch not getting power. I swapped out the clutch then tested the connection to find it's not getting power. I checked connections to the PCB and the feed limiter switch. My question is which sensors should I check or do I need to replace a PCB and if so, which one? I have 6 of these machines so I'm fairly familiar with working on them. I also have a parts machine.

**jermyth** · 05-31-2013

Check your p disk and the pf clutch sensor on it. See your manual, pg I-6 first paper feed theory.
Good luck.

**Chuck29620** · 06-01-2013

I cleaned and then replaced the PF Sensor, still no go. I also cleaned the paper feed detection sensor and assured it was secure and free of debris, I did not replace it. I run tests 25 & 41-44 with no detection. I run test 24 (Paper Feed Clutch Sensor) with detection and test 67 (Paper Feed Clutch) never gave me a response. Any other suggestions?

**Iowatech** · 06-01-2013

I think for the feed clutch test mode to work, you have to rotate the drum to a certain position, but I'm not sure (sorry, got a bug and am limited currently to thinking and moving my fingers around, and the thinker has some flaws as well).
You might make sure there are no blown fuses on the power supply board. It would be a good idea to check them with a meter for continuity, because they don't always open in the center.

**umar** · 06-01-2013

Change IC SMA in main system pcb who supplies 24 DC voltage to P.F CLUTCH,the IC is broken.
Make sure you get another same IC,if you don't i will show you how to fix that.
Good luck

**Chuck29620** · 06-03-2013

Iowatech: Thanks, I hope you're feeling better. I checked all the fuses and they are fine. Umar: The term IC SMA is a little over my head, what does that stand for and where is it located. If the main system PCB is the one with the battery on it, I swapped it out with no change. I also swapped out the Motor PCB. I also have a spare Image Processing PCB, would you recommend changing it?
Also on another topic, what components are different between the 3750 & 3770? I know basically the only difference is the resolution. The reason I ask is because I have one for a parts machine.

**jermyth** · 06-03-2013

3770 vs 3750, half of the boards are different, thermal print head is different. Check the part number on the board, or get a parts manual for each.

**Iowatech** · 06-04-2013

Thanks, I'm feeling great now. Still, I wouldn't wish that condition on anyone.
To get the paper feed clutch test mode to work, you have to rotate the drum until the cut out portion of the P disk is at the P disk sensor. The P disk sensor system determines when the feed clutch is on and off in normal operation. Good time to check if the machine is in time then, too.
I kinda agree with jermyth, you might want to get the manual for this. If you don't know what the adjustments are or why you are doing it, you could accidentally damage the machine worse, or you have more chances of hurting yourself (stupid sharp burrs on stamped metal parts and the occasional line voltage shock being examples of expected ways for experienced techs to sometimes hurt themselves).
Also, while the vast majority of people here want to help, every once in a while an aab1 will get in here here for a bit, which isn't helpful at all. So it is kind of important to have some sort of basic reference available to weed the occasional aab1 out.
If you don't have a source for the manual, you might try Paul's site:
Just Manuals, The Internet's largest selection of manuals ~ Instant Downloads
The manual is there. It isn't free, but the price is reasonable.
Hope that helps,

**umar** · 06-04-2013

Thanks to Iowatech advice,it's all true.
I had experience for that trouble machine and it was succeed.
I hope it will succes to help to another technician.
Chuck: let's make it simple way to make the machine work again.If you have another sys pcb(the one with the battery on it) with SAME MACHINE GR 3770,you can try to compare with it.How?

(Prev.sys pcb with P.F trouble)
1.Release IC ROM from it
2.Make sure you remember position the DIP SW (where it's in ON position)on that.(ussualy 5/7sw)
3.Make sure you remember position the SW (with adjustment angle)on that too.

(New sys pcb with normal condition)
1.Release IC ROM from it.
2.Put IC ROM from prev.sys pcb with P.F trouble
3.Make sure you set position the DIP SW according position from prev.sys pcb
4.Make sure you set position the SW (with adj.angle) according position from prev.sys.pcb.
Good luck

**Chuck29620** · 06-04-2013

I swapped out the main PCB as well as the Motor Control PCB and the Image processing PCB (I had a machine that wouldn't power up for two years till I swapped out the image processing PCB... Go figure). I think I'll swap out the power PCB next. Just a note, all the dip switches on all 7 of my machines are off and the angle is set to 7. Also test 24 Feed Clutch Sensor resulted in no detection with the P disc rotated to the open position.