Need Help on Miller Circuit Board

Thread Starter

buffumjr

Joined Mar 24, 2018
52
I dismounted and tested the SCR. Current flows in both directions, without stimulating the sensor leg. Bad. The SCR could not be ordered from Miller, but lots of places stock it. On order by mail. The suppressors arrived from Miller. They are directional. I called Miller tech support, but they had a day off. Must wait until Monday to find out how to install them.

Another Econotig came up for sale on Craigslist. Twice the price I paid. All functional. This way is more fun. Buy broken and fix.
 

Thread Starter

buffumjr

Joined Mar 24, 2018
52
(Quote)
I thought they have ID band on them?
If single band, replace as original, if band both ends then either direction should be OK.
Max.
(End Quote)

The originals were so badly burned, there was no way to tell which way they were originally oriented. The photo posted is too blurry to tell. The replacements have no band. They have a red tape on one lead, and a white tag on the other. Only Miller knows...
 

Thread Starter

buffumjr

Joined Mar 24, 2018
52
In checking everything, I found the foot pedal was bad. Tech support said to check resistance between pins C and E. Some small resistance, 5Ω, at full up, then nothing when off full up. Tonight, I'll pull it apart and check to see if there is a replaceable rheostat.

The suppressors were not directional, according to Tech Support. All installed, and everything back together.

Once the foot pedal issue is solved, I'll be off to the official repair facility to have them check everything.
 

Thread Starter

buffumjr

Joined Mar 24, 2018
52
I opened the foot pedal. It was like a legend out of computer lore. The foot pedal was filled with mud dauber nest. After working the rheostat to shake off the mud, it came to life. Now, on to the Miller repair facility.

I wonder how many welders are scrapped for little stuff.
 

Thread Starter

buffumjr

Joined Mar 24, 2018
52
ALL WORKS!! Foot pedal control works! Dial control works!

The tests had a pleasant side effect. I found DC steel stick welding is sooooo much easier than AC. I'm selling the Lincoln tombstone. The Econotig is a keeper!

No on to exploring AC stick for aluminum, AC TIG, and more practice with 7018 in stick.

The stick weld looks a little stronger than the MIG weld, but I could be wrong. My 3,000 lb capacity trailer hasn't failed yet, and it was all MIG.
 
ALL WORKS!! Foot pedal control works! Dial control works!

The tests had a pleasant side effect. I found DC steel stick welding is sooooo much easier than AC. I'm selling the Lincoln tombstone. The Econotig is a keeper!

No on to exploring AC stick for aluminum, AC TIG, and more practice with 7018 in stick.

The stick weld looks a little stronger than the MIG weld, but I could be wrong. My 3,000 lb capacity trailer hasn't failed yet, and it was all MIG.
 
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