Brooken diodes - Cem Tri Mig 190

[bacanc]

Thanks for all response!

To sum up my understanding:
Even though it's a three phase machine, each phase from transformer will be exposed to the 190 Amp. A diode can be paired as long as it is same model. Still a bit confused on if I need to change the other diods on the other phases.

 

[cocker]

I know nothing about the electrical stuff but our petrol welders all end up not working because them wires have broken .
Our service bloke always tells the boss they're beyond economical repair so they're scrapped . And he sells us a new £1200 one .
After reading this thread I found on the internet , brand new bridge rectifiers for our machines for £100 . With loads of them diode things inside .
Just saying you might be able to get the whole thing for less than just the bits you want .

 

[skotl]

T...Still a bit confused on if I need to change the other diods on the other phases.

I don't think you need to replace the diodes on the other phases. Have you tested them with a multimeter?

...brand new bridge rectifiers for our machines for £100..

Is that a single phase rectifier?

 

[the snooper]

the problem with those diodes is they are a press fit so unless you are able to press new ones in you would have to buy bolt in

 

[bacanc]

I don't think you need to replace the diodes on the other phases. Have you tested them with a multimeter?

Sounds great!
The welder is able to melt some material on only two phases so I guess they are working. As written before, I have measured the other phases with multimeter and the diods looks like they are working.
Diods seems not soldered, rather welded to connector so I would like to avoid cutting the connection in order to test individuals.

the problem with those diodes is they are a press fit so unless you are able to press new ones in you would have to buy bolt in

I guess I could attach both types, as long as they are price worthy and functional in the setting.

 

[mike 109444]

You might try a car/lorry alternator repair place as they use very similar diodes

 

[gaz1]

wont match yours but gives you a good idea

http://www.ebay.co.uk/itm/400-AMP-3...048904?hash=item1a0db3fbc8:g:-p4AAOxyzi9SdtbO

http://www.ebay.co.uk/sch/i.html?_o...ifier.TRS0&_nkw=mig+bridge+rectifier&_sacat=0

 

[bacanc]

You might try a car/lorry alternator repair place as they use very similar diodes

I will try to find a local repair place to check what they have!

wont match yours but gives you a good

It is possible that I could fit another bridge, but I'm not shure it is worth that amount of money since the welder machine is old and soon needs investment/upgrades on torch also.

 

[bacanc]

Anyway, complete encapsulated 3ph 200A bridge on eBay for under 20quid... Mounted on a decent heatsink, I see no reason it wouldn't work.

This seems like a really good alternative worth consideration if you mean the Chines ones. I guess one would have to make some additional cooling fins.

 

[bacanc]

Some months later I finally had some time to put the new rectifier into the welder. As suggested, I bought it for like 20 quid from china and got some aluminium from a trashed motor controller board.


I have done some testing and it seems to work. There are some more work on the welder (changing torch, fixing wire motor) to do before one can assure it is really working.

 

[the snooper]

Some months later I finally had some time to put the new rectifier into the welder. As suggested, I bought it for like 20 quid from china and got some aluminium from a trashed motor controller board.


I have done some testing and it seems to work. There are some more work on the welder (changing torch, fixing wire motor) to do before one can assure it is really working.

Great, can't beat fixing stuff and saving a load of cash