Thermistor problem…
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The fuse is behind the ESP8266 WiFi adapter in a little rectangle on the silk screen labelled F1. It doesn't have metal end caps, so the easiest way to check it is to use a multimeter to measure the resistance between one of the endstop ground pins and the VSSA pin on one of the thermistor connectors. It should be about 2 ohms on production boards and about 8 ohms on pre-production boards.
To replace the fuse you would need a hot air soldering station. That is why some users bypass it with an external fuse instead.
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hi thanks found it it has popped and i solidered onto the (E0 vssa) pin and the paneldue ground pin
i left a long wire soldered onto a slow blow 0.25a fuse which ill replace with a fuse holder and small glass fuse 0.25a next week which is why i left a long wire on for now
before i plug this in and connect is this correct also will this over load the negative trace if i plug a paneldue in ? -
here the responsible party for blowing the fuse
not usre if its too clear but the heater wires have become exposed and must of made contact with main body of the extruder at some point
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Just a rant but I really hate how these Chinese thermistors come with their leads sleeved in paper-thin PTFE. One reason…tighten that screw more than a little and you've just pinched right though. I imagine in some scenarios this could even lead to a potential fire.
Another reason is PTFE isn't safe to use at temperatures as high as some hot-ends are capable of operating. I've seen several "all metal" hot ends come equipped this way. And look for type-K thermocouples on Amazon, they're all sleeved in PTFE. It's like making a kitchen pan out of plastic.....why even bother?
@Cap: If I were you I'd get some high-temperature fiberglass sleeving and use that to insulate the thermistor leads. Also, looking at that fuse fix makes me cringe. There's a strong potential for those long fuse leads to pick up noise and interfere with your temperature readings. I also doubt that big glass fuse is even remotely capable acting fast enough to protect the processor in the event of another short. If you're in the US, I stock replacement VSSA fuses and could properly repair your board for a reasonable cost and turn it around the next day.
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im in the uk and i now have fiberglass sleeving and new thermistors heading to me from e3d
as for the wires they go straight down throw the case printed in abs and dont run along the board it self so hopefull they should be fine but yes tomorrow ill go to me local hardware store and change the fuse to as small glass 0.25a fuse inside a fuse holder
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rant warning
but i am vexed about a blown fuse i could not software reset are pull out and change where was the logic in having a fuse you need specialized equipment to change and selling the board to hobbyists…....grr vents steam
do not get me wrong i have and will still recommend this board to others over other boards i have tried and tested Menzies rumba and ramps
but if it needs a fuse please make an easy reset fuse are easy changeable fuse are whats the point
i choose this board over beagle bone boards and smoothie boards but if this board dies because of a fuse i counld not easily replace then ill try a different board completely -
Use a 100 to 250mA quick-blow fuse. A slow-blow fuse might not protect the PCB traces and vias,
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thanks i do have to say costumer support on a Sunday iyour just spoiling us you guys are on top of your costumer support game
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While I don't disagree a socketed fuse would be nice, you're actually fortunate that VSSA fuse is there at all. Had this been a wired Duet, Smoothieboard, any Makerbase board, and probably a few others that don't have analog ground protection you likely would have permanently damaged the board beyond reasonable repair.
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yes i do agree i am fortunate that a fuse was there
but all early boards came with reset fuse are old car fuse to protect some parts of the circuity
kind of shocked that we are now stepping backwards and not using them -
p.s ive now done a quick test power and thermistors plugged in only and it works again few think i may change over to the pt100 stop this from happening again
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As W3DRK says, the VSSA fuse is something that you won't find on any other board AFAIK. The reason for it is that there have been sporadic reports of the microcontroller on wired Duets getting fried. Other details of the failure suggested that a likely cause was a short from a heater output to a thermistor input. That's why I added the VSSA fuse. I thought that it might save perhaps 1 user in 1000 writing off their Duet WiFi. I am very surprised that it seems to be more like 1 user in 100.
I have already suggested that when we next revise the Duet WiFi PCB, we use a different fuse. If we do then it will still be SMD because of space and cost constraints, but it will be larger and have metal end caps, making it easier to replace.
The fuses that you get on some other control boards may not protect the PCB and the microcontroller from this type of short. The fuse I chose has a low current rating so that it blows quickly, and a resistance high enough to limit the current before it blows, so that the vias on the PCB can handle the surge and the ground voltage disturbance is kept at a safe value.
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To add to that, the only boards with blade fuses I have seen are there to limit the total current to high power elements of the board (heaters) while that may be useful, it would not have helped this sort of fault.
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understood and again thanks for the reply ok so adding a big chunky fuse is not viable and /or cost effective in the case of future development what about pin out hole so people can add there own fuse easily if the need arises
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Connecting an external 250 mA fuse between E1 thermistor VSSA pin and E0 stop GND pin as a substitute for F1 fuse solved my problem
Temperature readings now ok. Thanks again, AndreS and dc42!So just to clarify (so I don't do something stupid), you do the above with the hotend thermistor plugged in to E0. Correct?
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See https://duet3d.com/wiki/Connector_and_spare_part_numbers#VSSA_fuse for ways to get your Duet working after a VSSA fuse failure. How you wire the thermistor to the Duet is not affected by any of these methods.
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See https://duet3d.com/wiki/Connector_and_spare_part_numbers#VSSA_fuse for ways to get your Duet working after a VSSA fuse failure. How you wire the thermistor to the Duet is not affected by any of these methods.
Thanks!
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Got the fuse and wired it in. All is well.
