Lincoln welder circuit board

[ItsNick]

Hi, let me start by saying I am way out of my depth here. My electrical knowledge is very basic. Purchased this machine with the hopes I could fix it, but sadly it's not looking good. Lincoln electric diagnosed a faulty "chopper board". New replacement costs more than a new machine.

Removed suspected board, found it to encased in an epoxy type resin. I removed as much of that as I could via boiling the board in water to soften the resin as I have seen done on YouTube.

Im just wondering if this board can be repaired? I realize it's hard to tell from a couple pictures, but if it's worth trying I would be happy to discuss sending it to someone for the work!

I know there is still a lot of resin on there. I got off what I could.

thanks for any help, really appreciate it!

-Nick

 

[Deleted member 242843]

Too much shadow on the pictures to tell very much, could we have some with more/better light?

Looks pretty hosed though. $2,646 (the best price I am seeing) for a part you can put in yourself is probably not going to cost a lot more than repairing this thing.

Some of these dudes are wizards, for sure........but, my component guy might hit me if i brought him this.

 

[ItsNick]

Too much shadow on the pictures to tell very much, maybe ones with more/better light?

Looks pretty hosed though. $2,646 (the best price I am seeing) for a part you can put in yourself is probably not going to cost a lot more than repairing this thing.

Some of these dudes are wizards, for sure........but, my component guy might hit me if i brought him this.

Kind of figured that'd be the case. Thank you for the information though. I'll likely end up parting out the rest of the machine.

 

[freeagent]

I would have liked to hear that part fail. I bet the guy running it never heard that sound before lol..

 

[Steevo]

Looks like int he last image the MOSFET died and took the resistor next to it out. Google the number on the MOSFET and I bet you could buy one for less than 10 bucks and probably the resistor for less than a dollar, the white part that is broken I have no idea on, a ceramic resistor maybe?

Maybe it was just the single resistor that died and the ceramic resistor? The Mosfet doesn't LOOK damaged, however a multimeter to test it and the numbers would help determine that.

 

[Solaris17]

Looks like int he last image the MOSFET died and took the resistor next to it out. Google the number on the MOSFET and I bet you could buy one for less than 10 bucks and probably the resistor for less than a dollar, the white part that is broken I have no idea on, a ceramic resistor maybe?

Maybe it was just the single resistor that died and the ceramic resistor? The Mosfet doesn't LOOK damaged, however a multimeter to test it and the numbers would help determine that.

That or an inductor but it is straight up wrecked and would need to be replaced.

 

[eidairaman1]

Kind of figured that'd be the case. Thank you for the information though. I'll likely end up parting out the rest of the machine.

Reach out to northridgefix via email, they tend to repair like 95% of stuff they receive

 

[Bill_Bright]

Back in the day, I would started by dropping all those parts in our ultrasonic cleaner using a proper ultrasonic cleaning solution. Warning - if you use this, keep an eye on your parts or you will soon discover that every spec of paint or ink used for identifying every component, connector, switch, and dial will be "washed" completely off!

Boiling in water is not something I would ever do with electronics. Not all electronics can deal with 212°F temps for one, but also I would worry about the layers of substrate in the PCBs separating and/or warping.

Also, while those resin layers can be a real pain when it comes to testing and replacing components, the resins play a vital role in protecting the components and the board itself from the environment - notably moisture and other contaminates that might damage the components and/or promote mold and corrosion that might damage the components. It is generally best to leave it intact.

But I guess that ship has sailed.

Im just wondering if this board can be repaired?

Sure, it can be repaired - if you can identify each component, test each component, then find a correct replacement for those that are bad - assuming the board itself is still good - as that is likely proprietary and Lincoln want you to replace the entire, fully populated board. But since we don't know at this point what is actually wrong with the board, there is no way of knowing if economically feasible to repair it.

It would be good if you could at least obtain from the maker a schematic of the board.

 

[qxp]

Do you have any pictures before you removed epoxy ? The first thing you would have wanted to check are electrolytic capacitors, starting with the small ones. The transistor looking part has numbers that are hard to read, but my first guess it is a linear voltage regulator for the ICs. Those are almost bulletproof.

To check the capacitors you would need a multimeter, or better yet an LCR meter like DE-5000 - have one for many years, essential unit.

 

[ItsNick]

Thank for the replies. I've decided to part out the machine as this type of repair is way above my knowledge level and time is a concern. Thank you for the information though. You all seem to know exactly what you're talking about.