Bad Miller Matic 211 Board

[matic211]

Hello Guys, new to the forum.

I have or had a 211 that it is about 4 years old with only a few hours of usage since it is for home use and quick repairs. Used about a month ago without issues and last week went to turn it on and I had no lights or sounds from the machine. Obviously out of warranty so was told to take to repair place. Board part number is 275367 ($500 just the board).

There are no burn marks nor swollen caps on the board. It has the conformal coating so grinding dust should not be a problem. There is power going to the board pass the fuse and switch. I have tried 110V and 220V and same results, no sounds nor lights. Does anybody have schematics on the welder board or any ideas on what to check for?

Thanks.

[Auto_Tech]

My 211 is doing just fine -- around 2 hours of total usage, no problems, BUT I would say the ground clamp supplied with the machine isn't all that great (no internal copper braided cross tie for example), could contribute to issues with the main board. I changed mine out as a precautionary measure and went with an all copper ground clamp (believe it's rated 300A, don't remember).

Sorry, don't have a schematic but you might first try checking voltages out of its power supply or signals (e.g. overheat) preventing it from starting.

[G-ManBart]

First off, welcome! Sorry you're having issues with your machine...that's never fun.

Generally speaking, people with access to the technical service manuals aren't allowed to share them or risk losing access from Miller. With that said, there are folks who will likely be able to help by asking questions to troubleshoot the board. There are also companies that specialize in board repair, but you usually have to contact them with a part number to see if it's one they can fix (or try). The only downside is that it often costs at least half of what a new board does.

[jsrepair]

I have the same problem with my 211. I have power all the way to the circuit board but nothing comes on. I took the circuit board out and there is no signs of damage on either side, I also check for continuity across different point on the board and on the transformers and everything checks good. Did you find the problem metic211??????

[matic211]

Hello,

Thank you all for all the replies. I tried contacting a company that was mentioned in this forum but they basically said that anything newer than 2000 they cannot repair.

Yes I found the issue. I ended up buying a new board because I had very little hope since everything is a secret (not sure why it is, not very reliable in my eyes, but I guess they make 500 a pop and they know most of the people here do not have time to troubleshoot issues since it is their livelihood, stick to transformers for now) and I compared the values from the new board with the old board and this gave an idea where to look. My board seemed to have everything high voltage working, but no low voltage at all.

That Zettler Coil is what basically enables the welder high voltage, but you must feed it 18V on the other side in order for it to close (that is the click you hear when you first turn on the welder). On mine there was 0V, so something in the low voltage was bad.

Ended up being:
1. IC TOP257YN (This is the heart of the LV power supply) Pain to remove without proper tools especially with all the glue.
2. Transistor D6 (directional diode): US1M-13-F
3. Transistor D45 (bydirectional diode):1.5SMC150CA-E3/9AT

If you have no low voltage at all, you need to check those components above and possibly all the other diodes around the area (use the diode setting on your meter, it was very obvious that 2 and 3 were bad). With schematics, this could have been solved in 5 minutes. Somebody with a lot of knowledge probably could do it in a few hours since the board is divided into different sections and it is all standard circuits with minor modifications. Me? Took days and a brand new board. But at least I have a redundant board for when it breaks again, because it will fail again.

The green squares are the 3 failed components. With 2 day shipping from Mouser, it was around $15 for all the components and buying 3 of each because, did I mentioned that it will fail again?

Hope it helps.

[Aeronca41]

Great info! Thanks for posting.