Riso GR3750- 11x17 black drum makes partial masters-very annoying

**avidgamr** · 10-14-2016

Ok, let me start from the beginning.
We were having feed issues and my previous manager (retired now so it's my problem) took the Riso apart (what all he did I'm not sure as I wasn't there) and fixed the feed issue (wouldn't feed above speed of 3 I think it was- it was several years ago and my memory isn't so great anymore LOL).
Anyways, after he fixed that problem I noticed when I tried to make a master, most of the image appeared on the master but upper 2 11/16" of an 11" original doesn't reproduce on the master- chopped off.
I have confirmed:
1. It is *not* being printed on the master (pulled out the drum and rotated it- partial image on master made). (11" master is there, just a partial image)
2. Did test modes 117, 118, 119 & 120- same result so that leaves out the scanner section as the problem.
3. Tried doing the memory reset (button and test mode)- doesn't help.
4. Cleaned the print head with alcohol- it's *not* dirty...

It worked fine before he took it apart- something he did as a result... Does anybody have any ideas? Perhaps a loose cable somewhere?
P.S. No error messages.

**avidgamr** · 10-17-2016

Attached are examples of it. I noticed they are also just barely printing on the paper for whatever reason as well...
test118 isn't really that bad- had a hard time scanning the page and had to keep darkening it to pull the lines...

**Woxner** · 10-18-2016

its off because all the timeing is off. all the gears have home pos hole and they must all line up.

**20gaugeO/U** · 10-18-2016

Agree with Woxner. It's belt driven and may have had a multifeed jam and the belt jumped a couple teeth. Check the cam on the right and read up on it's home position and how to bring it back. I'm sure it's here many times

**avidgamr** · 10-19-2016

Just want to verify that this problem I see is caused by timing? I can understand the image running off the edge due to timing but why is it chopped on the side? Revised pic to show how they went through the machine is attached.test120.jpg

**avidgamr** · 10-22-2016

Forgot to mention, please note the blank space at the top of the sample in which I wrote and made notes in; that area did not print on...
Does something have to be timed sideways too?

**20gaugeO/U** · 10-24-2016

Sorry I change my vote. If the arrow you drew was the feed direction path then I would say an entire block of the TPH segments have failed. Reseat the connectors that go to the TPH. I have seen this a couple times over the years and a couple times reseating connectors have repaired the issue. The other times a new TPH was needed. You can do the connectors on the main board also, that wouldn't hurt anything either. Could be a broken/pinched wire...

Good luck

**Iowatech** · 10-25-2016

Originally Posted by 20gaugeO/U

Sorry I change my vote. If the arrow you drew was the feed direction path then I would say an entire block of the TPH segments have failed. Reseat the connectors that go to the TPH. I have seen this a couple times over the years and a couple times reseating connectors have repaired the issue. The other times a new TPH was needed. You can do the connectors on the main board also, that wouldn't hurt anything either. Could be a broken/pinched wire...

Good luck

Good catch, I was first looking at the inked parts of the leading edge of the picture as the shadow from the leading edge of an original for some reason and almost posted about a scan unit registration issue. I checked again and that wasn't even close. Thanks!

**avidgamr** · 10-27-2016

Originally Posted by 20gaugeO/U

Sorry I change my vote. If the arrow you drew was the feed direction path then I would say an entire block of the TPH segments have failed. Reseat the connectors that go to the TPH. I have seen this a couple times over the years and a couple times reseating connectors have repaired the issue. The other times a new TPH was needed. You can do the connectors on the main board also, that wouldn't hurt anything either. Could be a broken/pinched wire...

Good luck

Correct, the direction of the arrow is the direction the sheet was feeding through. Thanks! I was thinking along the lines of a bad connection at the thermal print head but wasn't sure (just an "educated guess"

)... Considering it *was* working fine before he worked on it, I'm leaning towards a connection rather than a failed printhead...? Oh, and to confirm as I said before, the master looks the same as the printout- it never prints the upper section of the page there either.

But I do agree with you guys that it does seem to be a little out of time as well as the trailing edge of the paper is "cut off" a wee bit a have some blank lead edge.
Thanks for the luck! I'll need it. LOL My second time working on a Riso.

**avidgamr** · 10-27-2016

Great news! That was the problem. I reseated the connectors on the main board and that did it! (I reseated the connectors on the printhead first but that didn't help so I moved on)
Thanks to all who helped!