Error: Temperature reading fault on heater 0
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@felixlvh said in Heater Fault:
Hi @dc42, i have the same issue as mentioned above. can you eleborate how can i use a multimeter to verify if i have vssa fuse blown? i am pretty sure all wiring are ok and now i am getting open circuit error message. thanks a ton!
FIRMWARE_NAME: RepRapFirmware for Duet 2 WiFi/Ethernet FIRMWARE_VERSION: 2.05.1 ELECTRONICS: Duet WiFi 1.0 or 1.01 FIRMWARE_DATE: 2020-02-09b1
@dc42 said in Heater Fault:
Yes, if your Duet is a revision 1.0 or 1.01 then with power off, use a multimeter to measure the resistance between VSSA on a thermistor pin and GND on an endstop pin. It should read no more than a few ohms. If instead it's very high, the VSSA fuse has blown, which will make all thermistors read 2000C.
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@bearer said in Error: Temperature reading fault on heater 0:
Hi @bearer thanks for your reply.
I look closer to my board and found something is blown as screenshot. I am not sure if this is VSSA, can you point me to the right fuse?
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Which revision board is it?
First picture is a fan output, looks damaged. (TR1 designates transistor, as in mosfet)
Fuse should have been a fairly large 1206 smd part (3.6x1.6mm) in the second picture, fuses are designated Fn.
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Hi @bearer
It should be 1.02. i searched around and found the vssa. assumed i am on the right fuse, the multimeter doesn't give me any reading. do i need to connect to power? thanks again!
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@felixlvh said in Error: Temperature reading fault on heater 0:
do i need to connect to power
no, it should measure as close to 0 ohm when its ok, but it can be tricky to pierce oxide layer on old solder joints. You could repeat the measurement between Vin- and both pins on the thermistor input (one of them should be close to 0 ohm if the fuse ok)
Looks to be the right part, but smaller on rev 1.2.
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@bearer said in Error: Temperature reading fault on heater 0:
no, it should measure as close to 0 ohm when its ok, but it can be tricky to pierce oxide layer on old solder joints. You could repeat the measurement between Vin- and both pins on the thermistor input (one of them should be close to 0 ohm if the fuse ok)
Looks to be the right part, but smaller on rev 1.2.
Thanks @bearer , in this case i don't think my vssa fuse is blown.
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@dc42 @bearer
i have tried to disconnect all wires to isolate the issue. i am plugging in the extruder heaters e1, extruder thermistors, bed thermistor, heated bed still showing the same error. do you think is should get a new board?
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if you measure the resistance across the two pins of the thermistor plug, when its not connected to the board wht do you get?
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@bearer said in Error: Temperature reading fault on heater 0:
not connected to the board wht do you get?
@bearer , i got reading 80.3K
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@felixlvh said in Error: Temperature reading fault on heater 0:
80.3K
config says its a 100k thermistor so it should be about right
maybe you should connect vssa directly to ground on a unused thermistor input now that you have nothing else connected; power from usb and see if that makes a difference
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@bearer Thanks, i am still uncertain about the vssa fuse. if you see the image here, https://ibb.co/TYb2MNS i got reading 90.9K. i can now confirm board is v1.01.
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you should get pretty much 0. (or at least single digit ohms)
if you have a wire handy, run it as shown here, connect the thermistor to e0 or bed and power from usb.
(it'll bypass the fuse, which should be safe when only the thermistor and usb is connected)
edit: seems the 1.02 board do not have a resettable fuse
https://duet3d.dozuki.com/Wiki/Connector_and_spare_part_numbers#Section_VSSA_fuse -
@bearer said in Error: Temperature reading fault on heater 0:
vssa directly to ground
@bearer If i did it correctly, It still shows the same error 2000'C
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you've got the thermistor connected to e1 and configured for e0? move it to e0?
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so you need a new fuse, ref the wiki link above.
edit; and you probably have to remap or repair fan2 as well.
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@bearer am i right to say usign external fuse like this? can i still print by bypassing it temporarily? thanks a ton!
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if the pins read vssa and gnd, then yes. (also very low value fuse, less is better, wiki says "between 125 and 250mA and a resistance of between 2 and 4 ohms.")
you can print with a bypass either a wire instead of the fuse, or like you tested - BUT there is likely a reason the fuse blew and the fan blew - your fan and thermistor have likely shorted on the hotend; and if it happens again with no fuse the CPU will likely be damaged.
