Heaters stuck on

rmriggin · 21 Nov 2018, 00:41

My duet wifi v1.04 running 2.02RC4 heaters started acting up. As soon as the printer is powered on the bed and hotend heaters turn on at seemingly max power output and temps keep climbing until thermal protection kicks in. I also noticed that my paneldue screen no longer displays... while typing this I just checked the paneldue control board and the 5v input mosfet is blown... could it have taken out the 5v output on the duet and if so how could that cause the heaters to be stuck on?

dc42 · 21 Nov 2018, 10:48

It sounds to me that you had an over-voltage on the 5V rail, which has damaged both the heater mosfet driver chip (U11, 74HCT02) and the 3.3V regulator on the PanelDue. It may also have damaged the 3.3v regulator on the Duet. Are you able to communicate with the Duet? What devices were you powering from the 5V rail?

rmriggin · 21 Nov 2018, 12:45

@dc42 I just noticed that I had been running the fans on 5v rather than system voltage. Changing the jumper to the system voltage and fans are working again so I guess what was powered by the 5v would have been the hotend fan, part cooling fan, and paneldue. I can still communicate with the printer and connect to the web control although I have not tried directly connecting to the priner via the micro USB port. The heaters still all turn on full blast when the board is powered on so at the moment I have disconnected the hotend and bed heater.

dc42 · 21 Nov 2018, 13:39

My guess is that you had a short between the fan wiring when the fans were on 5V and the heater wiring, putting 12V or 24V on the 5V rail. It sounds like you were lucky and the 3.3V regulator didn't fail; so it may be that replacing U11 will fix the Duet.

rmriggin · 21 Nov 2018, 16:28

@dc42 would either of these work?

https://www.digikey.com/product-detail/en/texas-instruments/SN74HCT02DR/296-14861-1-ND/562563

https://www.digikey.com/product-detail/en/texas-instruments/SN74HCT02PWR/296-31831-1-ND/3506070

dc42 · 21 Nov 2018, 18:45

Yes, it's the -PWR one. You may find the the existing U11 chip is getting hot.

rmriggin · 30 Nov 2018, 05:12

@dc42 did my first ever hot air chip removal and install and I am pleased to report that it is working perfect again! Thank you!

dc42 · 30 Nov 2018, 08:05

@rmriggin, congratulations!

idaho creator · 17 Sept 2019, 03:52

Same thing just happened me but I think I also lost U2 (the chip not the band) what is the part number for that. I have looked around but can seem to find it and there is a small burnt hole in my chip.

dc42 · 17 Sept 2019, 09:36

U2 on Duet WiFi revision 1.04 is AP7361C-33E-13. It's different (and not compatible) on some earlier revisions.