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SP-540V I'm Guessing A Fuse Blew During A Head Swap?

GivenToFly

New Member
So this was interesting. I decided to swap Head 2...the magenta/yellow head...because I just could not get rid of this magenta misting into non-printed areas. No amount of cleaning, no amount of wiping down with Bounce sheets would help. I had swapped dampers, cap tops, etc. and it was still misting enough to be noticeable. Anyway, I feel pretty comfortable working on these so far and decided to swap the head. I know you may not believe it, but I did discharge everything before I started. I unplugged, and then turned the main switch on and held down the sub power button for about 20 seconds. I grounded myself on everything I could before touching cables or anything like that. But even with all that, I still think it popped the F3 fuse, which controls the magenta and yellow.

After I replaced the head, the first print was just a mess. It started laying down heavy magenta before it even got to the media itself. And it completely washed out the magenta / yellow side with magenta. I've attached a pic to show what I'm talking about.

20210727_205650.jpg



I was thinking it may have been a cable issue, so I unhooked the magenta only and left the yellow connected. The yellow printed fine. With every cable move...connecting and disconnecting...I was still following the same discharging procedure to try and protect against static. Since there was so much magenta everywhere...I went through and did a cleaning procedure around the head...plus I ran some solvent down the cap tops to make sure they were flowing good since it looked like it was pooled up with magenta. Everything seemed to be flowing well.

At this point I just connected everything back up like normal, and did another test print. This time, nothing at all on the magenta and yellow side. So I double checked to make sure the head was primed and I gently pulled some ink through and it entered the syringe right away, so the dampers and head were primed and should have been good. Tried again, and nothing still on the magenta and yellow side. I then unhooked the cables from the black and cyan and connected them to the magenta and yellow. Did another test print....perfect magenta and yellow and no black and cyan. Swapped the actual cables themselves and still got the same result. So I knew at this point the cables were not the issue and more importantly, the head seemed to be ok.

20210727_231333.jpg


Looking at the main board, this one is a little different than my other SP-540 (I have two of them here in my shop). This one has a pair of wires soldered to the top of the F3 fuse, running to an external fuse. I was thinking it came like this at first until I noticed my other machine didn't have that.

20210727_230705.jpg
20210727_230545.jpg


I'm getting infinite resistance on that external fuse, so I'm guessing that would be my problem if the magenta and yellow is not printing. Does that sound right or should I be looking at anything else? I have another fuse coming and I still need to run my head adjustments if this gets working again, but I wanted to see if anyone else has had this same issue or could maybe suggest anything else I should look at. Thanks for the help!
 

Terry01

New Member
First test print looked like a cable issue. They are cheap enough so just replace them if you can. Check both F2 and F3 fuses and replace if necessary. One will be blown. Check resistance the C4131 and A1746 transistors.
Double check cables seated properly and power it up. Get the compressor going and blow all that dust off the heat sink and the transistors while you are there. External fuses are ok if you are not selling the machine..
 
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GivenToFly

New Member
Got it sorted out. I had a 1A fuse here, which will cover me until the 1.6A gets here tomorrow. I'm thinking when it was flooding the magenta ink it may have caused the short that knocked out the fuse. That's the only thing I can figure. I was extremely careful with not touching any of the cables or components without discharging first. Anyway, got everything dialed in, ran the calibrations, adjusted the head and it prints like a champ now. Really crisp. It definitely eliminated all the magenta that was misting in non-printed areas.
 
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