Roland FJ 740 - TWO HEADS OF SAME GROUP STOPPING FIRING AT THE SAME TIME!

[boggiom72]

Two heads that were working perfectly, in the same group B, stopped firing at the same time...
I thought may have been the pump, since they share the same one, but if I do a medium cleaning I see discharge ink... So it means there is passage...
Could be an electrical problem? Is there any way to do a diagnosis?

I have a roland FJ 740 with pigment ink, bulk system with cartridges in the back.

 

[WalkerP]

Likely the fuse on the head board has blown. There are a lot of posts on here about that. Look around for them. I've posted on a few if you can search that way. There are pics and fixes.

I've blown a ton of these by doing dumb things, and simply touching the machine when dry and staticy and zapped the fuses. Check the resistance across the F fuses with a voltage meter on the head board. I suspect that corresponding fuse is bad. If so, you can solder an axial fuse of the same resistance over it and bypass the blown one for super cheap.

That's a pretty quick test to see. There are other things it could be which are fairly easy, but give that one a shot.

 

[lgroth]

Yup... Sounds like a fuse. On the head board, will be in the back by the main board, has all the ribbon cables connected to it that go to the carriage there are tiny fuses along one edge with F1/ F2/ F3/ F4 marked on the board. Unplug the machine before doing anything in there to prevent more problems! Check these fuses with an ohm meter, if one is open, that's your problem. They are soldered in, and very tiny, but if you have good basic soldering skills and a good fine point iron you can replace them. On the 740 they should be 11CT 3.15amp, Roland part# 12559102, can be purchased from several different vendors on line including some of the Merchant members on here. Always have a spare or two... Like Walker said, something as simple as static can blow them, a drop of ink on the back of a head, working on the machine without unplugging it... I blew one changing a damper once, bumped a ribbon cable and "poof" (yes, I forgot to unplug... ALWAYS unplug the machine).