SP300v one print head not firing.

[DarkSideofOZ]

So I bought this printer with 2 dried up heads, I got 2 new heads, installed them while wearing a static strap, cleaning everything along the way. Fed the ink, cycled until all 4 ink colors came out of the head caps. Went to do a test print and only the M/Y head is printing, not the Blue/Black. I swapped the ribbon cable positions from both heads (leaving the side plugged into the carriage board the way it was). Sure enough the blue/black started printing while the Yellow/Magenta did not. So this time I physically swapped both ends of the cables, just to see if it might be the cables themselves, but it is not, the cables are good and whatever is plugged into CN200 and CN202 just wont print. So now I'm at an impasse I know both heads are good and all 4 ribbon cables are fine.

I'm at the carriage board now. I don't know if the issue lies in this small carriage board which appears to merely be 1 green LED, 1 dual ground sense operational amplifier ic chip, some micro resistors, micro caps, and 3 larger caps ... or if the problem lies beyond this on the main board.

Is anyone familiar with this situation who can let me know how to find out whether this is a mainboard or carriage board issue? So I don't go wasting capital on un-needed parts.

Thanks!

 

[JTRTech]

Did you solve this?
I have exact same issue, pretty sure while aligning new K/C print head I nudged the ribbon cable (Muppet LOL)
After lots of searching think its the fuse for that printhead, have checked with voltmeter and confident one is not right, has continuity (just) but like 200M+ Ohms vs the other with virtually 0 Ohms which I believe is good sign (good that I didnt fry printhead )
Have ordered some replaceable glass tube fuses and panel holders to do a mod ive seen on this forum as looks no harder than resoldering the board fuse and if ever happens again will be easy fix.

 

[Ragnabrok]

+1 for fuse.

They are on the main board on the bottom right, labeled f2 and f3, about the size of a grain of rice. I am terrible at soldering, so i brought the main board to a local radio/electronics repair place and the guy there popped a similar specced fuse in its place, good to go after that.

 

[WalkerP]

It's the fuse mentioned in previous posts. You can meter it to measure resistance (I believe it's 7.2, but measure the good one just to make sure). Go online and just buy a cheapie axial fuse and solder it over/across the blown fuse. It will save you a TON of money and you won't have to buy a new board. I've done this dozens of times. Those fuses blow frequently.