HELP!! VP540 Advancing while printing like crazy!

[damonCA21]

If G-ENC is always 0 in all tests, even after replacing the encoder disk and sensor and confirming the wiring is good, then it’s about 90% likely not the feed motor or the sensor. It usually points to a problem on the Feed Motor Board or Servo Board where the G-ENC signal is read.

If G-ENC never changes, it means the grit encoder signal is simply not being seen by the system.

The encoder uses an IR LED, which is naturally very dim to the eye. Ambient light doesn’t matter.dark or bright makes no difference.

Broken wires or bad connectors have already been ruled out, which pushes the problem back to the board.

On a normal VP-540, the feed motor aging test should run forward, stop, reverse, and repeat.

If it only runs forward every 5 seconds and never reverses, the controller knows it’s missing a key feedback signal and falls back to basic one-direction drive instead of closed-loop control.

That points to a failed G-ENC input circuit on the Feed Motor Board (optocoupler / counter / input stage).

The practical fix is replacing the Feed Motor Board.

The posters printer is an RS not a VP

 

[Jim Hancock]

Oops! However, the feed motor circuitry on the feed motor board show the same straight pass-through for the feed motor circuitry on both printers.

 

[garyroy]

Totally understand your thought process on this. I'm retiring after 35 years of this and equipment is not worth anything for resale, and would still like a working printer for personal use (we have pictures all over the house and other peoples houses). Still have 2 vinyl cutters, seal 600c laminator, seal EP42 thermal laminator, CNC machine... All things I still use that don't have enough resale value to sell. If I could pick up a used Roland 54" machine for 3k-4k that didn't need new print heads I would and sell my RS-640 for parts.

Yeah at that age the heads are pretty well spent.

 

[HCG]

I've already replaced 2 of the heads in the last 5 years and they are firing fine. The VP-540 uses many of the same parts as my RS-640. I don't think the feed motor is the issue either, more likely the feed motor board or servo board, just don't know which to try next.

 

[damonCA21]

I would take out the motor board and check for continuity through it. As the signals just pass straight through you should get it from one connector to the other. If that all tests OK then the servo board is the most likely culprit

 

[HCG]

Brilliant suggestion, I can do that and maybe cancel that out or find it's the problem. The ribbon cable from it to the servo board never moves so should be fine but I can also check those 3 wires too.

 

[HCG]

I can check continuity from the grit encoder disk sensor connector to the end of the ribbon cable at the servo board first to rule out everything before the servo board. If no continuity work backwards. That way I can leave the board in place.

 

[damonCA21]

I can check continuity from the grit encoder disk sensor connector to the end of the ribbon cable at the servo board first to rule out everything before the servo board. If no continuity work backwards. That way I can leave the board in place.

It's a good idea to work through the signal paths methodically like this yo rule out any bad connections

 

[HCG]

Feed motor board is not getting signal from green wire from grit encoder board (#5 wire on connector - Grit encoder phase B) to pin 13 on ribbon cable connector on feed motor board, Blue wire (#3 wire on connector - Grit encoder phase A) to pin 15 has continuity so feed motor board trace is broken somewhere for phase A. Need new feed motor board, does that sound right?

 

[HCG]

Anyone know of a good place to get one? Amazon? ( https://www.amazon.com/ROLAND-RS-64...roland+rs-640+feed+motor+board,aps,239&sr=8-1 )

 

[Jim Hancock]

A technically correct repair in this situation would be to simply solder a jumper wire from the pin 5 on CN413 to pin 13 on CN412, in effect, bridging the trace break. A good electronics repair shop should do it for an inexpensive fee.

 

[Ewan yu]

What you want is this, it has been discontinued for a long time, and I only find dismantling in China. It is almost impossible to find the original. So you need to pay attention when buying

 

[Ewan yu]

What you want is this, it has been discontinued for a long time, and I only find dismantling in China. It is almost impossible to find the original. So you need to pay attention when buying.
Part number: W700981230

 

[damonCA21]

Anyone know of a good place to get one? Amazon? ( https://www.amazon.com/ROLAND-RS-640-VP-300-VP-540-Printer/dp/B079L6Z6M8/ref=sr_1_1?crid=H1TWKL824EFH&dib=eyJ2IjoiMSJ9.n7e3G8pNTWYnfeaJ3acv7P9VPrsphXer59ws6gokbnPFTEhMmiCD1gKMHaeh-bwZj118xrlOX6l62eOIfI57RK8SoXcgn3j83m-MfZkyW50IOVWQpBDpAUD_v2S0iflY.iAW4SJv9C-8cJRFFfifUDyI3OFc7O099LglCCTdENEg&dib_tag=se&keywords=Roland+rs-640+feed+motor+board&qid=1767843123&sprefix=roland+rs-640+feed+motor+board,aps,239&sr=8-1 )

I should have the oem.ones in stock, I will check in a bit. Or i can do the repair for you if you dont have someone local who can do it. As Jim says that would be a cheaper way of doing it

 

[damonCA21]

Feed motor board is not getting signal from green wire from grit encoder board (#5 wire on connector - Grit encoder phase B) to pin 13 on ribbon cable connector on feed motor board, Blue wire (#3 wire on connector - Grit encoder phase A) to pin 15 has continuity so feed motor board trace is broken somewhere for phase A. Need new feed motor board, does that sound right?

And well done for finding the problem. At least we are getting closer now!

 

[damonCA21]

Just checked and I have the oem boards. They are used ones but tested and fully working. Will send you a message now

 

[HCG]

I told my wife I could verify by soldering a wire between the 2 points but found a used one in the states I'm going try first since I can get it quick and cheap. I'll keep all informed on the progress and thanks for all input.

 

[HCG]

Thanks, I'd found that was the part number.

 

[Ewan yu]

You got this!

 

[HCG]

There is no part number on the board that I can see, I have to rely on any seller and buy 1 that exact matches.