Roland Vp540 Printing issues - Fuse?

[creativevinyl]

Hi, I have a Roland VP540 that was working fine, I had to move the printer due to relocation and lost half of the blue print, after checking this was a manifold break so ordered those parts and replaced. When replacing i noticed that one of the head ribbon cables was not right the little blue hard plastic part came away, I had a spare but was too short, so tried to make a temp repair, it all looked good, the green light on the print head board didnt come on, removed the cable and it came back on.
I ordered the cables and replaced all 8 (They did look a bit rough).
After putting all the cables back and putting it all back together ran a test print and the Black / Cyan heads are not printing. Had this issue before with my previous printer and ended up being a fuse. So i checked the fuses and sure enough one was blown. Luckily i had some of these, they are non soldered and fit into a little block soldered to the board, Replaced and tested, its the same, tested the fuse and was blown again. Changed again and tested again, no B/C still, checked the fuse and is OK, there are 2 head fuses and another next to them all 3 are good but no ink from B/C.
Changed the cables over and the B/C heads fire from the M/Y cables so the heads are OK..
Any ideas, could it be the Transistors?? There are two types A1746 & C4131..
This is where my limited knowledge ends, i dont know how to test them
Could there be anything else??
Thank you for taking the time to read this, and I hope someone will know how i can proceed.
Mark.

 

[damonCA21]

It could well be the transistors if you still aren't getting any output. Where are you based as I do board repairs and test and replace transistors. I'm in the UK
If you aren't near you can take the board to an electronics repair shop and they would be able to test and replace for you

 

[damonCA21]

Hi, I have a Roland VP540 that was working fine, I had to move the printer due to relocation and lost half of the blue print, after checking this was a manifold break so ordered those parts and replaced. When replacing i noticed that one of the head ribbon cables was not right the little blue hard plastic part came away, I had a spare but was too short, so tried to make a temp repair, it all looked good, the green light on the print head board didnt come on, removed the cable and it came back on.
I ordered the cables and replaced all 8 (They did look a bit rough).
After putting all the cables back and putting it all back together ran a test print and the Black / Cyan heads are not printing. Had this issue before with my previous printer and ended up being a fuse. So i checked the fuses and sure enough one was blown. Luckily i had some of these, they are non soldered and fit into a little block soldered to the board, Replaced and tested, its the same, tested the fuse and was blown again. Changed again and tested again, no B/C still, checked the fuse and is OK, there are 2 head fuses and another next to them all 3 are good but no ink from B/C.
Changed the cables over and the B/C heads fire from the M/Y cables so the heads are OK..
Any ideas, could it be the Transistors?? There are two types A1746 & C4131..
This is where my limited knowledge ends, i dont know how to test them
Could there be anything else??
Thank you for taking the time to read this, and I hope someone will know how i can proceed.
Mark.

Oh just saw you are in suffolk Feel free to DM me if you want me to check and repair for you

 

[Solventinkjet]

I would try doing a data swap to pinpoint where the issue is. It could be the transistors but it could also be damage to the heads themselves. Basically you just swap the position of the cables from a head that is working with one that isn't. You only move the end of the cable that connects to the head so that the black head, for example, is getting the data from the magenta head and vice versa. Then power up and run a nozzle check. The color positions will be messed up but you will be able to see if the black head can fire connected to a different channel. That will tell you if it's the head or a board component.

 

[mark lord]

I would try doing a data swap to pinpoint where the issue is. It could be the transistors but it could also be damage to the heads themselves. Basically you just swap the position of the cables from a head that is working with one that isn't. You only move the end of the cable that connects to the head so that the black head, for example, is getting the data from the magenta head and vice versa. Then power up and run a nozzle check. The color positions will be messed up but you will be able to see if the black head can fire connected to a different channel. That will tell you if it's the head or a board component.

I did do this and B/C are both firing as they should.
Thank You

 

[damonCA21]

Hi Mark, have replied to your message

 

[creativevinyl]

If anyone in the future is reading this with the same problem.......

It was infact the transistor, it was just one of them, the C4131 version.
I Tested them still soldered to the board to see if i could find and fluctuations.
I put the multimeter on the lowest OHM setting 20 i think it was and tested the outer legs. 7 of them tested at approx 43.8 and one at 0.08. I assumed this was at fault. I installed a new one, i had some left over from when i had an SP540 a while back and got them for the guy who was coming to fix it.
Popped it in, reinstalled the board and off it went, all working again.

Thought this was going to cost me a mint.

Thanks all that participated Mark.