RISO RP 3700 DIY service

**mixedfeelings** · 12-20-2012

Well, i've messed something up...

I cleaned the master making rollers and took the front and back covers on to check if the set screws on the write rollers were tight, advice i'd seen in other threads. They were. I also carefully and slowly ran a piece of cardstock through master making set up (with the tph up). But, when I put it all together and tried to run a test print nothing burned on the master. everything seems to be running through the system smoothly, but no image.

At one point there was a "TPH not connected error" but I am no longer.

I also got a T95-056 error - but was able to correct that by clearing all of the saved memory and restoring to default settings.

Any ideas as to why the TPH isn't making a master? is there a test I can run to diagnose the problem further?

**20gaugeO/U** · 12-20-2012

Test mode 50 should make a checkered pattern from memory. Make sure you have 11X17 paper in the tray. 50-55 all make different patterns.

I'd check or replace the impression roller under the drum for a skewed master. Any wrinkles on the drum shell?

**mixedfeelings** · 12-20-2012

Thanks!

I ran test modes 50 and 51, and sadly neither test image burned onto a master. At first I thought that I had somehow cleared those test patterns when I cleared the memory - so i tried to make an image from the glas top - nothing. Everything is running smoothly, the paper is feeding through the machine as expected, masters are going on and off the drum - just no master is made and there is no error. so strange!

Regarding the skew and the pressure roller. I took it out, inspected it, cleaned it up a little. It seems like its in good shape - but I ordered a new one just in case. One of my strategies has been to replace all of the commonly replaceable parts just to start from scratch with that regard (stripper pad, feed tires, etc.). I noticed there is a way to adjust the parallelism of the pressure roller could that affect skew?

**Iowatech** · 12-20-2012

If the test modes didn't make a master, that means the thermal head isn't working. Hopefully the thermal head isn't broken, it is extremely expensive. I'd take a look at the connectors on top of the thermal head, I had one that came loose after the thermal head cycled a number of times. Also check the connectors on the main board and the power supply board. Check for blown fuses on the power supply board.
As for the skewed master, clean the inside of the clamp, and maybe see if there's a way you can increase the amount of master in the clamp.
Hope that helps.

**mixedfeelings** · 12-20-2012

Thanks! I will try that stuff for the TPH tonight.

re: skewed masters - one thing I should mention is that it seems to be on every drum - so I don't think its the master clamp on the drum - is there another clamp in the master making assembly?

Thanks again!

**mixedfeelings** · 12-21-2012

Well, I double checked the connections (both on the TPH and the boards) and the fuses and everything seems fine. So it I guess it seems that I fried the TPH. It seems strange that there is no test mode to confirm if it is working or not? Also strange that I am not getting in faults or other warnings. Would the machine somehow alert me if I had messed up a PCB?

I suspect this isn't the case - but is it possible that the TPH and the 3105 and the 3700 are the same? I have access to a 3105... If not it seems like this might be my best bet?
Risograph Riso TPH Thermal Print Head for RP3700 RP3790 Used 030 98102 050 | eBay

Thanks again!

**jermyth** · 12-21-2012

The TPH are not the same between 3105 and 3700. You did test the TPH with TM 50. Either a wire/connector is off or the TPH is toast. Id recheck all connectors in the TPH unit and on the boards, reseating them all. Ive missed a connector or two in my time. Good luck.

**mixedfeelings** · 12-21-2012

sigh. that's what i figured.

I reseated all the connectors both on the TPH and on the main and power PCBs. I am still worried that I somehow messed up the PCB, but I am not getting any indication other than no image coming from the TPH.

I ordered the replacement TPH. But, Just to double check, there is the red / white wire set up to the power pcb, and the orange / red wires to the main pcb. are there any easy to over look things that I am missing in there?

Thanks again everyone!

**20gaugeO/U** · 12-21-2012

Is there any way the master roll is installed backwards?

Check the TPH resistance value in TM 288, it should match what is stamped on the TPH? If it is correctly input, then you still could input a much higher or lower resistance value make a maker to see if you get any image at all....purely for troubleshooting. If the TPH is shot you aren't going to hurt anything.

How many copies and masters are on the machine???