SP300 rear (Magenta/Yellow) Printhead not Firing.

[lodcomm]

Greetings Folks,

Could use a bit of help troubleshooting my SP300. A week or so ago out of the blue, the printer stopped printing Yellow. Relatively new printhead. I first attempted to draw some ink through the printhead with my syringe, and performed a powerful cleaning. Did not solve the problem. In my troubleshooting steps of swapping the printhead ribbons I managed to blow the f3 Fuse, and was getting no magenta or yellow at all. I removed the motherboard, replaced the F3 Fuse and tested all the transistors and found them all to be within spec. I reinstalled the motherboard, and swapped the magenta/yellow printhead with a old spare I had, replaced the 2 printhead ribbon cables with brand new ones, powered up the printer and was able to get a full Black/Cyan/Magenta/Yellow test print. rI an a few cleaning cycles and printed a few decals. This morning, I went to print some material and found that the Magenta/Yellow Printhead is not printing at all again. I checked the F3 Fuse and found it to be fine (F2 is ok too), Re-checked all 8 of the transistors and found no Issues. I swapped the Black/Cyan Printhead cables to feed the M/Y Printhead and I do get a proper test print out of the M/Y Printhead. Just for process of elimination, I tried feeding the K/C printhead with the Ribbons normally feeding to the M/Y and am getting no ink output. I swapped out the M/Y ribbons with another set of brand new ones and again, getting no output.

My Summary so far.

1) both F2 / F3 Fuses are good
2) the M/Y printhead is OK (if I swap the K/C ribbons to feed the M/Y printhead it prints fine)
3) all 8 Transistors test ohms close or equal to their respective types, and no shorts. (I tested both outer pins, left pin to center, right pin to center)
4) both Ribbon (print board to printheads) cables are all tested and good.

the Issue appears to be either in the mainboard, the long carriage ribbons, or the print/carriage control board?

Any suggestions on further troubleshooting would be greatly appreciated!

-todd

 

[Solventinkjet]

Whenever an entire head stops firing it's pretty much always the fuse, transistors, or the head itself. Since the head is known to fire with the black and cyan signal, we can rule out the head. Make sure you test the fuse outside of the machine. Sometimes when they are installed they can give false readings. Also, testing transistors can be finicky as well. My best guess is the fuse or transistors are bad in someway that your tests aren't picking up. While it could be some other electrical issue, in my experience I've never seen anything else just take out an entire head other than head itself being damaged, fuses, and transistors.

 

[lodcomm]

Solventinkjet,

Thanks for your informative reply. I swapped the motherboard with a spare that I had on a printer I was refurbishing. and all heads are firing properly. So There must be something going on with my original mainboard. I can rule out everything past the mainboard (carriage card/ribbon cables/heads/etc...) Any suggestions on getting the original mainboard repaired?

Thanks again for your help!

todd

 

[Solventinkjet]

Solventinkjet,

Thanks for your informative reply. I swapped the motherboard with a spare that I had on a printer I was refurbishing. and all heads are firing properly. So There must be something going on with my original mainboard. I can rule out everything past the mainboard (carriage card/ribbon cables/heads/etc...) Any suggestions on getting the original mainboard repaired?

Thanks again for your help!

todd

Unfortunately I don't know of anyone at the moment. They definitely exist though. I've also had minor repairs such as fixing a USB port etc. done at music equipment repair shops before. But maybe someone else on signs101 has someone they use.

 

[netsol]

we have had decent luck with inkjetperformance in georgia.
you can also go to ebay and search roland system board and find the power sellers. go to "contact seller" and ask a question

before you do this,, do some voltage checks on the transistor pairs
my sc545-ex has 41 vdc power at the fuse
check CARFULLY for voltage comparisons on all the sets of transistors

are you ABSOLUTELY SURE there is no problem with ribbon cables?
i recenly replaced a yellow printhead before i realized there was a TINY burned spot of the ribbon (i would REALLY like to think i am too smart to get fooled like that

 

[netsol]

ALWAYS better to compare dc voltages (and waveforms if possible)

 

[netsol]

wouldn't be a bad idea to check the final stage of driver transistors (resistance readings would be fine, if there was a problem, that would be drastically different resistance readings

the more i read your original post, it suggests a cold solder joint somewhere.
do you know anyone with one of those reflow /hot air rework ovens (like they used to fix all of those 1000'S AND 1000'S of laptop motherboards with nvidea chipsets.

you might want to make a new friend in the computer repair end of things

if it were mine, i would give that a try, i envision a better likelyhood of success that way ( and you would have your board back while your printheads are still functional

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there are lots of articles on google about how you can do this yourself with a heat gun. I DOUBT IT