GR3750 printing short images

[Puck]

Hello,

I'm a newbie so forgive my inexperience!

I'm having issues with my GR3750 which has started printing off centre by quite a margin and is even truncating the image by about a centimetre or two from the original. It has only started doing this recently and I have printed some fairly tight registrations before without trouble. Any ideas what could be causing this? I have seen a few things pop up relating to timing issues or the P-disks. Am I on the right track? Here is an example.

IMG_7093.JPG

Any guidance would be great!

Cheers

Dave

[Iowatech]

Re: GR3750 printing short images

You might try resetting the machine by holding down the "Reset" key and then turning the machine on. You'll have to hold the "Reset" key down until the initializing motor sounds get quieter and then release it. If there's been any disturbances to the voltage being supplied by the outlet the machine is plugged into that's a good thing to try first.

[Puck]

Re: GR3750 printing short images

Thanks for your help! I have attempted the reset a few times and even done it through the test mode (90). It doesn't seem to have made any difference unfortunately. I made a new master and it was the same issue. Any further thoughts?

Cheers

Dave

[DAG COPIERS & COMPUTERS]

Re: GR3750 printing short images

What happens if you try to adjust the image position using the vertical print position shift key? find this on the control panel.....you refer to the user manual. Try also to compare the image positions of the copy with that of the original and that of the master on the drum. If the image formed on the master is of the correct vertical height with the original but the printed image is inconsistent with the original, then you could be having a timing issue. The 'timing' procedure can be a little intimidating to a novice on the machine, but if you have the service manual and take sometime to study it and digest its contents, you can give the 'machine timing' a trial. Else, seek professional help from the experts.

[Puck]

Re: GR3750 printing short images

Hi, the vertical position adjustment doesn't make any difference to the squashed nature of the print. I pulled out the used master and it looks to match the print so that suggests that it isn't a timing issue I suppose. I don't have the interface option so produce the masters from the scanning table.

I don't have the service manual, I googled it thoroughly but just got sent on a spam filled goose chase!

[Iowatech]

Re: GR3750 printing short images

Thanks for your help! I have attempted the reset a few times and even done it through the test mode (90). It doesn't seem to have made any difference unfortunately. I made a new master and it was the same issue. Any further thoughts?

Cheers

Dave

I'd try turning the rubber roller in the master making area by hand both ways. If you don't feel the drag from the roller's drive, even for a little bit, it could be that the drive pulley for the roller has come loose. That happened on a few machines of the GR line back in the day, and it caused the printed image to shrink in the paper transport direction.
You can also check the length of the master on the drum to see if it is shorter than previous masters, because if the drive pulley is loose the master on the drum will be somewhat shorter than before. But that's kind of hard to do if you are not expecting it.

[Puck]

Re: GR3750 printing short images

I have attempted to turn the rubber roller in the master making area and it seems to have pretty solid drag. It's quite hard to turn. I'll have a look and see if the drive pulley is loose but i'll have to poke about with it. It doesn't look like the master is shorter than before but then it is hard to tell.

Thanks for your help so far!

[Iowatech]

Re: GR3750 printing short images

I have attempted to turn the rubber roller in the master making area and it seems to have pretty solid drag. It's quite hard to turn. I'll have a look and see if the drive pulley is loose but i'll have to poke about with it. It doesn't look like the master is shorter than before but then it is hard to tell.

Thanks for your help so far!

Just be careful when you check the pulley, as it is above the main power supply. Especially where you are at, line voltage is only 120 VAC here, and I find that quite uncomfortable when I come in contact with it.

[DAG COPIERS & COMPUTERS]

Re: GR3750 printing short images

Hi, the vertical position adjustment doesn't make any difference to the squashed nature of the print. I pulled out the used master and it looks to match the print so that suggests that it isn't a timing issue I suppose. I don't have the interface option so produce the masters from the scanning table.

I don't have the service manual, I googled it thoroughly but just got sent on a spam filled goose chase!

It could still be related to 'timing' issue. Try this website for a free manual: www.copytechnet.net, you'll have to learn how to navigate the site.

[Iowatech]

Re: GR3750 printing short images

Apparently you can get the manual from the link provided by CTN user filmplane in this thread, too:

http://www.copytechnet.com/forums/digital-duplicators/95532-looking-gr3770-service-manual.html

I'm not sharing the link for actually downloading the manual because this is filmplane's contribution, if you find it useful give them the credit.

[hibbles]

Re: GR3750 printing short images

Puck, thanks for creating this thread. within the past couple of weeks one of my GR3750's started exhibiting the exact same issue and I hadn't been able to find anyone else that was trying to solve the problem. If it would be in any way useful to have extra documentation of this problem from my end, I'd be happy to contribute!