Need Help on Miller Circuit Board

Thread Starter

buffumjr

Joined Mar 24, 2018
52
I bought a used Miller Econotig. The stick side works great, but the TIG side doesn't let the foot pedal regulate current. Something wrong with the circuit board. OK. I pulled the board. It has the designation 164431.. SUP1 and SUP2 are blown badly. Unable to read any bands. Look like 1/2W resistor. What is the ohm rating so I can replace these? Really counting on you guys.

The repair shops stay mum, hoping to rake in the Benjamins. I can't count on reading it as the resistors' cases are ruptured, and there's carbon residue.

One fellow posted a cuircuit diagram, but it had no ohm or wattage rating, only a number, like R24. Wasn't really helpful.

ANY help appreciated.
 

Thread Starter

buffumjr

Joined Mar 24, 2018
52
Yes. I have seen that. It has no wattage or ohm rating. I need to know the ohm and watt.

I have tried many times to save a jpg to this message and failed. The board won't let me post images.

https://forum.millerwelds.com/forum/welding-discussions/30712-miller-econo-tig-100-only-welds-on-high-needs-circuit-board-repair is where to find it. The larger resistor on the lower left corner is SUP1, and the same size resistor under the left side of the heat sink is SUP2. Sorry I couldn't post the image, but with the link, you should be able to find it.
 
Last edited:

LesJones

Joined Jan 8, 2017
2,437
You first need to upload the .jpg file. When you have uploaded the file you have the choice of inserting it as a thumbnail or a full image.

Les.
 

Thread Starter

buffumjr

Joined Mar 24, 2018
52
164431.jpg

Inside the white circles. Image is too blurry to make out any bands. This was the only image I could find.
 

MaxHeadRoom

Joined Jul 18, 2013
19,685
Unless someone has reverse-engineered it already, that may be the only way to go, what is the semi part No. on the heatsink next to them.
Max., ,
 

Thread Starter

buffumjr

Joined Mar 24, 2018
52
Don't know how it would help, but the number is HS2.

Found out SUP1 may not be a resistor, but rather a "suppressor". Any idea what that may be?
 

Thread Starter

buffumjr

Joined Mar 24, 2018
52
Now we're gettin' somewhere. HS2 was on the board. The heat sink itself has no numbers.

If it's a MOV, still need the numbers to order it. Got a welder friend asking his friend who did this repair on another Econotig. May bear fruit. Will publish numbers if I get 'em first.

If they blew once, will they blow, again?
 

Thread Starter

buffumjr

Joined Mar 24, 2018
52
I guess now is the time to ask. How does that effect SUP1 and SUP2? Any idea what the identification of SUP1 and SUP2 is?
 

MaxHeadRoom

Joined Jul 18, 2013
19,685
Whatever blew the suppressor(s) could have blown the SCR, if the control is full on then a possible scenario is it is shorted.
Really need a clearer picture of the SUP's to identify the nature of.
Max.
 

Thread Starter

buffumjr

Joined Mar 24, 2018
52
Picture a 1/2W resistor, only a little shorter. Black. I'd post a picture, but you could not tell much from it.
 

Thread Starter

buffumjr

Joined Mar 24, 2018
52
I really hope I can stumble on this info. Monday, I'll phone Miller, and see what they'll tell me. If I find out, I'll publish it here. And yes, I'll dismount the SCR and test it.
 

Thread Starter

buffumjr

Joined Mar 24, 2018
52
I came to a decision. I'm chickening out. Give me the white feather. I'm sending the board to Gem Electronics. They seem to be reasonable. After Gem, I'm taking the machine to an authorized Miller repair facility. If they aren't too unreasonable, I'll have them check it out before and after installing the rebuilt board. It'll cost some bucks, but without parts information, if I find a bad part, I can't replace it. Period. I'm sure if the information was somehow exposed to the public, I would have found it, or found someone who found it by now.

In repairing technical stuff, information is everything. Ignorance generates blue smoke and fires.

Thanx to all who tried to help.
 

Thread Starter

buffumjr

Joined Mar 24, 2018
52
Great news! Disregard previous post! I called Miller Tech Support. They identified SUP1 and SUP2 as transient suppressors, part number 164412. $3 apiece. I'm going to give it a try. Still going to test the thyristor. After I'm done, I'll run the board by their test facility to make sure it works before installing.
 

Thread Starter

buffumjr

Joined Mar 24, 2018
52
Funny how the information gushes out once the dam breaks. (chuckle)

I hope the next guy who faces this has an easier job of it because of this thread.

The repair project is as much fun as a complex, close tolerance machining project.
 
Top