Dead board?

SlimShader

Hello,

I just connected my new Duet Wifi up and it worked fine on the bench - I was able to configure it and test all the switches, heaters etc. However, I guess something has shorted as I transferred it into the printer as when I powered it up I got the following:

Board booted normally, PanelDue working. Tested IR sensor, endstops - ok.
Powered the hot end...electrical snap...PanelDue goes off.
The only light on the board now is the blue LED 5v

Have I just fried a brand new board...and potentially the PanelDue as well?

I carefully removed all wiring one at a time and tested for short on each before doing so - danged if I can find a short.

Any advice would be really appreciated please...

Colin

dc42

Is there any sign of damage to the small square chip labelled U3, close to the VIN connector?

SlimShader

Nothing visible on the U3 chip - however the 7.5a fuse has blown. The other two fuses are good. I guess I should try replacing this first?

SlimShader

OK, I just replaced the 7.5A fuse and the board is alive again. However...the hot end heater (E0) is now constantly on as soon as I power the board.

deckingman

@SlimShader said in Dead board?:

OK, I just replaced the 7.5A fuse and the board is alive again. However...the hot end heater (E0) is now constantly on as soon as I power the board.

Can you post your config.g file, in case there is something in there that is causing it.

A Former User

@SlimShader said in Dead board?:

OK, I just replaced the 7.5A fuse and the board is alive again. However...the hot end heater (E0) is now constantly on as soon as I power the board.

could be the mosfet was involved in whatever caused the fuse to burn, and the common failure mode is always on.

if the config doesn't reveal any issue then you could move to E1 (or replace the E0 fet)

dc42

@SlimShader said in Dead board?:

OK, I just replaced the 7.5A fuse and the board is alive again. However...the hot end heater (E0) is now constantly on as soon as I power the board.

My guess is that the hot end heater wiring was shorted, taking out the fuse and the mosfet. That's the only explanation I can think of for both the mosfet and the fuse blowing.

SlimShader

@dc42 said in Dead board?:

@SlimShader said in Dead board?:

OK, I just replaced the 7.5A fuse and the board is alive again. However...the hot end heater (E0) is now constantly on as soon as I power the board.

My guess is that the hot end heater wiring was shorted, taking out the fuse and the mosfet. That's the only explanation I can think of for both the mosfet and the fuse blowing.

for sure David, I completely agree - my suspicion is that a wire on the hot end heater connector at the Duet end had a stray strand of wire from the ferrule which caused a short. Those connectors aren't really beefy enough for larger gauge wires - as I'm using an 80w SuperVolcano, I extended using a (16 AWG) wire. I've since done an extension using some spare cable from an old hot end heater into an inline connector which allowed me to place the cables and tape them down to the board once I was sure it was all good. Should have done that in the first place!

After replacing the 7.5A fuse and moving to the other heater channel it seems to be working again, however I need two heater channels - can you let me know the part number for the MOSFET I need to replace, and it's placement on the board? I can see two near the heater channels - I guess it's one of those, but I don't want to pull them off to test which one it is until I have replacements to hand!

Phaedrux

https://duet3d.dozuki.com/Wiki/Connector_and_spare_part_numbers#Section_Heater_MOSFETs

SlimShader

@Phaedrux said in Dead board?:

https://duet3d.dozuki.com/Wiki/Connector_and_spare_part_numbers#Section_Heater_MOSFETs

Excellent resource, many thanks!