Head fuse blowing on Roland XC 540, Group A

[Splattgraphics]

Group A quit running and I found the tiny fuse blown on the main board. I pulled the head ribbons and cleaned & inspected them. Before I placed them back in their slots, I popped in a fresh fuse and booted the main power up. it blew the fuse again immediately, without the Group A heads even connected. B and C run fine. now what?

 

[Roland Certified Tech]

You most likely have a bad head. This will be a bunch of troubleshooting and testing. You can use the circuits from the group B to test the group a. It is really a bunch of troubleshooting, have a bunch of spare fuses on hand.
being my older printer is very possible that it could be the actual long ribbon cables to go from the print carriage bar back to the headboard. You also could have a bad transistor on the headboard. This is a bunch of testing with their own meter.

 

[cornholio]

If the fuse blows without the head cables connected at the carriage board, it's a bad transistor. If you disconnected the cables at the heads 1 and 2, it could also bei a bad cable.(That then killed a transistor...)

 

[damonCA21]

I replied as well to your post on the facebook group :

It is likely the ink spill has shorted out something on the head board. This would stop the head firing. As the fuse is still blowing without the heads connected it could be one or more shorted components ( transistors are likely, but it can also take out other parts of the head circuit ) . I do head board repairs worldwide if you don't have someone local. You can replace it, but repairing is a lot cheaper.
You are better off repairing the head board first as fitting a new head still won't work if the head board is damaged If it blows fuses again after the board is repaired then you know the head is causing the issue.

 

[Splattgraphics]

UPDATE!: closer inspection shows one of the big ribbons on the carriage board got ink spilled into the contacts, & shorted there. I ordered a couple new ribbons and a tested good Roland carriage board from a tech. Also, I FOUND a couple new C4131 resistors in my parts, having had this happen once long ago. Does anyone here know how I test the ones on the board with my multimeter? And where to send it out for repair if possible?

 

[damonCA21]

UPDATE!: closer inspection shows one of the big ribbons on the carriage board got ink spilled into the contacts, & shorted there. I ordered a couple new ribbons and a tested good Roland carriage board from a tech. Also, I FOUND a couple new C4131 resistors in my parts, having had this happen once long ago. Does anyone here know how I test the ones on the board with my multimeter? And where to send it out for repair if possible?

Have DMd you my guide for testing the transistors