Linde 225 MIG welder in bad shape

[Eugen]

Sometimes things unplanned get done in a hurry. Was looking yesterday for something in one of the tents and came across this welder. Wasn't planning to restore this any time soon, but the planets were strangely aligned yesterday so it got pulled out of the tent and went on a date with the pressure washer.

It is customary in the electronics world to start restoring vintage devices with a trip in the dishwasher, but one this wouldn't fit and two I'd probably sleep in the tent if I did that.


It'll take some time to get all dry. The plan is to take all electrical contacts one at a time and make sure they are clean and dry. They will also get some contact cleaner and lube spray.

However, first thing to address now is the capacitor bank. A few leaked already, but I will replace them all.

This is the capacitor type it has at the moment.

Looking for high ripple capacitors now, at least 9800uF, between 50 and 60 working volts, 2" diameter and at most 6" tall.

[Spike188]

@Eugen this link might help.https://weldingweb.com/vbb/threads/4431 ... Capacitors

I often find that a local welder rebuilder will stock caps at a reasonable price. But here is a fleabay link to a possible replacement https://www.ebay.com/itm/272501381335

[Eugen]

@Eugen this link might help.https://weldingweb.com/vbb/threads/4431 ... Capacitors

I often find that a local welder rebuilder will stock caps at a reasonable price. But here is a fleabay link to a possible replacement https://www.ebay.com/itm/272501381335

Thank you @Spike188 , these are very good leads! Looks like the capacitors alone will cost more than the whole welder cost me oh well, it'll be a good welder once it works, I think.

[Spike188]

https://www.digikey.ca/en/products/filt ... ABhABdAL5A

These might be stock in Toronto. I have an account.

[Spike188]

https://www.digikey.ca/en/products/deta ... 2B/2538257

This is definitely stock in Toronto.

[Eugen]

I have a digikey account, I used to buy electronics parts from them when I was doing audio stuff. Looks like I have options, will just have to decide which one to go for.

[MattA]

I'm not sure you can get 105C rated caps in that size but in theory they should last longer. For every 10C you lower the capacitor operating temp, the lifetime in hours doubles.
Just put a good fan in the welder and call it done?

[Jancoe]

Why not install 10,000uf 50v caps? They will be just fine. More than likely a hair smaller in size than those 9800uf thats harder to find? I do believe they just need to be weld output capacitors

Sent from my SM-S906U using Tapatalk

[Eugen]

Ok, there's an electronics surplus store in Toronto which I used to visit often when I was into audio stuff. The job needed me in Toronto today so I went by the store and found some big cans. These are not the same physical size as the original capacitors but if I could make them fit they'll do just fine. The three big ones at the back are 16000uF and cost me $12 a piece. New old stock. The other ones are 10000uF except for the tall skinny one which is 25000uF. They were $5 and $8, for the used ones.

I just reformed them. This is a procedure one should do after a capacitor has sat for a while. The reforming is quite easy if you have a variable power supply and a power resistor. Basically the capacitor gets charged through the resistor (in my case 1200 ohms) up to their normal working voltage, which in this case was 50 volts. The rule of thumb is to charge the capacitor for an initial 5 minutes, plus an additional minute for each month it has sat on a shelf. If after a few minutes you observe a significant voltage across the resistor that indicates more than normal leakage current. These capacitors got to less than 1 volt after a few minutes. One volt divided by 1200 ohms gives 0.833 milliamps. That is just fine.

[Eugen]

Mock up fitting. It's fine and more capacitance than the original.