No heaters working on Duet 2 + Duex 5

Dakkon426

I shorted something while checking a fan voltage on my duet wifi v1.01 and blew out my bed and extruder heater channels. The LEDs for the bed and E0 and E1 do not turn on and I am getting no current on any of them all of my fans and stepper drivers still seem functional. I have a DUEX 5 v0.8 attached that is having the opposite problem, the heaters are all stuck on steppers and fan control seems to be functional. Any chance this is fixable?

SIam

@dakkon426 did you check the fuses?

Dakkon426

@siam the only fuse I know of on this revision of the board is the VSSA fuse which is intact. If there is another fuse I can check please let me know where it is.

SIam

@dakkon426 It seems that on your board revision is the vssa fuse I have overlooked that your board is relative old sorry What you can check is which led's are lit https://duet3d.dozuki.com/Wiki/Hardware_Overview#Section_LED_indications

Dakkon426

@siam yes like I said before My Bed, E0 and E1 LEDs are not lighting and the Duex all heater channels and associated LEDs are on and I cannot get them to turn off. All other lights come on and I am able to control all components not on a heater channels.

SIam

@dakkon426 ok, your board is a bit old and i don't know this Version, maybe @dc42 can say more about it.

T3P3Tony

@dakkon426 if everything else on the Duet is working, except for all the heaters then its likely that U11 (a74HCT02 IC) is damaged by the short. if you have hot air rework skills or have access to someone who does then replacing it may fix the problem. With faults like that its not possible to know 100% in advance that there is not other damage as well.

For the Duex5 it could be the same ICs (u9 and U10), failed in the opposite way, i.e. failed short instead of failing open, or it could be another issue. With the ribbon cable disconnected between the Duet and the Duex5 (do this with the power off), then with power on to the Duex5 do all the heaters come on?

Dakkon426

@t3p3tony The heater channels on the Duex the heater LEDs all turn off when the Duex is disconnected. I'm going to see if I can source that IC, and will try to replace U11.

Dakkon426

@t3p3tony I ended up sourcing a new controller board everything on this new board is working, but all of the heater channels on my duex are still active even with the replacement Duet board. Are there any likely components causing this on the Duex? Also I am awaiting the replacement for U11 and will be attempting to replace the chip.

dc42

@dakkon426 on the DueX, U9 and U10 drive the heater mosfets. They will likely fail if the 5V rail is shorted to a higher voltage. They are both 74HC02 chips in TSSOP package, the same as U11 on the Duet.

Dakkon426

@dc42 @t3p3tony I have replace the IC on the Duet and things appear to be functioning normally now, thank you both for all your help. I am going to proceed to swap out the chips on the Duex now.

Dakkon426

Update: Duex is now working after replacing U9 and U10.

T3P3Tony

@dakkon426 good news!