Miller Diversion 165 TIG no arc

[CapLeaker]

maybe trace back the solenoid drive - that is probably simple.
maybe a buffer is bad
did you post pictures of the cpu area?

I wish it would be that simple. I've uploaded a few things.
Tonight, I went the other route: I know the trigger signal makes it to the ATMEGA fine. So there should be something commanding something else on like the gas valve. Went around the ATMEGA and these op-amps to see if I can see a commanding signal going out, but had zero luck with that. I think the gas valve has 24V on it all the time and they switch the ground in an out to complete the circuit. I have to trace the gate drive of the mosfet back and see where that ends up, maybe I do the same with the blue LED.

[CapLeaker]

stj I am up early and everyone else in da house are still cutting logs. So I went after the gate drive circuits for the fan and for the gas valve.

[CapLeaker]

Did even more yesterday… but no matter what I do to the input, the Atmega just sits there and does nothing. The caps are within 10% of original value, the thermistors have like 15k to 30k ohm resistance… it’s like something of the inputs is held low or high on one of the inputs disabling the output. Hmmm what about helping the Atmega and force the logic inputs to go to the opposite from what it is now? If it is logic’s high, pull it low with a 1k ohm resistor to GND? Maybe worth a try.

[sam_sam_sam]

Did even more yesterday… but no matter what I do to the input, the Atmega just sits there and does nothing. The caps are within 10% of original value, the thermistors have like 15k to 30k ohm resistance… it’s like something of the inputs is held low or high on one of the inputs disabling the output. Hmmm what about helping the Atmega and force the logic inputs to go to the opposite from what it is now? If it is logic’s high, pull it low with a 1k ohm resistor to GND? Maybe worth a try.

Did any of this help make it change state or is there something that is in the input signal that it’s condition not being met

[stj]

i presume because you read it that the atmel crystal is resonating

[m1ch43lzm]

i presume because you read it that the atmel crystal is resonating

I think the programmer also supplies the clock on the ISP header
Worth measuring the xtal with a x100 (or X10) oscilloscope probe, sometimes xtals fail to start, or sometimes probing the xtal will cause it to start...

[CapLeaker]

sam_sam_sam , stj
I see the crystal for the ATMEL works fine. I also see some data coming from the ATMEL to the PGM port and another data signal I have no clue where that goes.. Then I can see the input trigger going into the ATMEL o.k, but the rest of the programmable pins on the ATMEL I see nothing. Sweet diddly squat. Zero. Zilch. So I am not sure what all of these programmable pins go to what circuit, but some of them I had traced. It's like I have to reverse engineer the damn thing, before I do any more testing. That's why I think changing the state of the pins may yield something. Because if the thing starts to do something, I can just back trace that circuit and see if I can find a fault like a resistor that went high etc. I didn't screw around yet pulling pins high or low, but sooner or later I have no other choice. Have to admit, it's not looking good.

However I did find out that this Miller Diversion 160 is identical to a Hobart EZ-TIG 165! It shows the exact same not much good wiring schematic. They probably have the identical boards too.

[CapLeaker]

I think the programmer also supplies the clock on the ISP header
Worth measuring the xtal with a x100 (or X10) oscilloscope probe, sometimes xtals fail to start, or sometimes probing the xtal will cause it to start...

Nah... that clock works perfect.

[CapLeaker]

Unfortunately this is as far as I got. I returned the unit and the owner got a new board.