Epson Stylus SX515W Mainboard Fuse replacement

Markus1988

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Hi Everyone



I’m new to the forums so I hope I’ve posted in the correct sub forum. This is my first post and I was hoping someone might be able to help me with my problem if possible please.

It’s simple in theory, but I have had immense difficulty in finding an answer. The value of a mainboard SMD fuse “F1” (the only SMD fuse).

I own an Epson Stylus SX515W (old, I know, but it’s a workhorse) and I recently blew the PCB fuse on the mainboard after a failed printhead cleaning attempt, embarrassing. Everything else seems fine, firmware boots etc. But printhead and CSIC model are not powered. I’m trying to determine the value of the fuse that was on the board. All I can assume from the fuse itself is it’s a fast blow as it’s marked “F”, other than that I have no information. Epson have been unhelpful and advised me to get a new printer rather than help me maintain this……. brutal. The mainboard is a CA48 (photos attached) but I can find no information on board components (like the F190010 Printhead). I’ve tried other electrical forums but so far no one seems to have this information so a friend suggested this forum to me.

Is there anyone who knows the value of this fuse? I have fitted a 20x5mm fuse holder in lieu of the SMD fuse but I am reluctant to just randomly pick a value to start trial and error from.

Any and all help would be appreciated.

Thank you all in advance

😊


Investigation so far.

  • 42V power supply is fed directly to only one pin each in the printhead and CSIC model through the fuse in parallel with an NPN-PNP in source-sink configuration for many other pins. So, I assume the fuse supplies Vcc for the board components and the parallel transistors conduct the majority of the current in operation (How and why, I don’t know).
  • The fuse dimensions seem to give me an upper limit on the SMD package of 6A but most are less that 4A. The FFC is rated for 2A, further lowering the estimate.
  • Power consumption in copying mode is 12W, so at 42V that would be 286mA DC side with ideal 100% efficiency. This seems low but I know nothing about printhead circuitry.
  • An obscure Russian website that directed me to the fuse issue with the symptoms displayed mentions a “100 Ohm planar fuse”. If that’s a fusible resistor it would limit current at approximately 420mA. However, my model is never mentioned. Link
 

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The Hat

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Is there anyone who knows the value of this fuse? I have fitted a 20x5mm fuse holder in lieu of the SMD fuse but I am reluctant to just randomly pick a value to start trial and error from.

Any and all help would be appreciated.
My advice would be to go ahead and fit a small (F) fuse to test whether or not something else may have blown and damaged this original fuse, and until you can establish the integrity of the PCB board then all further progress is futile..
 

Markus1988

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I was the printhead. I have a new one. SoC is all fine as far as I can tell. Boots up :) Being fast blow fuses they will blow at their rating so I assume this is a value that exceeds its operating current by a good margin.
 

Markus1988

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My advice would be to go ahead and fit a small (F) fuse to test whether or not something else may have blown and damaged this original fuse, and until you can establish the integrity of the PCB board then all further progress is futile..

After having a think and getting concerned, I'm going to follow your advice as I do not truely know the topology of the circuitry, and I'm no pro lol. Something else may indeed by damaged I don't know exists. The lowest I have is a 630mA. do you think this is low enough?
 

The Hat

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The lowest I have is a 630mA. do you think this is low enough?
That size fuse should be ok, but have determined what amp power the original was ?, if it was me I'd go higher like a 1 amp fast fuse just to be sure..
 

Markus1988

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Yeah it was definately the head, I botched the cleaning of it and it buzzed when powered up. After that it just kept telling me the cartridges were incompatible. Presumably because the printhead had no power. I have a new/reconditioned one but given its source and I really don't want to overestimate the value of the fuse if this "new" one is faulty too. I'm concerned that would blow the BJTs aswell, or any other unknown components powered through this fuse.
 

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Some once said that a 100 $ component will protect a 10 cent fuse by burning out first, On a Canon Pixma iP4000 mainboard there are some driver transistors for some lines to the print head. In series with these lines and transistors are SMD fuses.

I read about this many years ago in this post, I think, and as I had an iP4000 with a dead MB and print head, I found and checked these fuses and they were not blown.
 
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Markus1988

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What other choice have you got… At least you’d know.. ! :hit
Hehe this is true. So, I'm going to go for the start up attempt with a 1A fuse (quick blow) . Quick question though, I'm installing a new printhead, do I install it without cartridges and insert them as usual when it's running, one at a time?
 
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