problem with thermistor on miller passport

[rusty ripple]

i have a miller passport plus that is on the fritz.
i took it to the lws, tech looked at it, said thermistor went bad and it would need a new board.
new board is 1k. he said that it was possible to remove and replace just the thermistor, but they were not allowed to do that anymore.

does anyone know where i find the thermistor? i know its on a board, but i dont know which board or where, any ideas?

[duaneb55]

Aside from finding a new shop to work on your equipment, I suggest a call to Miller Customer Service to ask them for assistance in getting to the bottom of the issue.

A thermistor is simply a temperature sensitive resistor that changes value with changes in ambient temperature. Usually used in welding equipment to control cooling fans and/or interupt output when maximum operating temperatures are reached. Probably a $.50 item.

Have your unit SN ready when you call. 920-734-9821.

[MikeGyver]

It's going to be attached to a heatsink or something else that may overheat. It's a very small device. Might be covered in white thermal grease. Find one on digikey or mouser

[ccawgc]

What symptoms were you having?
A thermistor failure is indicated by flashing lights on the front panel.
Power light is on, over temp and aluminum lights are flashing.
Could be a thermistor gone bad or the whole temperature sensing circuit on the main power pcb. The power pcb is about 90% of the welder.
Miller's list price is just over $1000.00
Do call miller with your serial number and date that you bought it and see if they can help you out.

[rusty ripple]

thats exactly what it did. over temp and alum lights flashing.

havent seen anything attached to heat sink yet, but havent got the whole thing apart yet.

put in a call to the tech this am, but havent heard back yet.

im really hoping its just the thermistor...
is there a way to test the thermistor to see if its bad?

[MikeGyver]

is there a way to test the thermistor to see if its bad?

Unsolder it, clip a ohmmeter to the leads and heat it with a lighter and cool it with water, and see if the readings are within spec. They don't go bad often, I bet it's something else.

[rusty ripple]

and you were right, turned out to not the thermistor. replaced board last night and its running fine