question about diode of an old welding machine

[Wolf1977]

hi in an old welding machine i have the power diodes you can see from the fotos
these diodes the most of them are damaged
do anybody know if there is possibiliti to change them ;
the one side is easu to dissasemply and connected the pins the other side is connected in a material on metalic plate likes as seal
does anybody has change diode like in mine case ;

[petehall347]

Re: question about diode of an old welding machine

stud diodes by the looks of it .they press in . replace all with matching diodes .

[Wolf1977]

Re: question about diode of an old welding machine

so sir to understand better
The foot of the diode that seems to go to the metal plate in a point like insulation you can see in the picture i have tsese points in circle is not glued with a rod I mean but it is like nailed inside so if I pull the passage up its foot will come out from the inside and the new one corresponding to the old diode I will press it inwards at that point where there will be a hole left to nail correctly I understood ?

[redwire]

Re: question about diode of an old welding machine

What make and model is the welder? Voltage and current rating. It is 3-phase?
Looks like https://www.mig-welding.co.uk/forum/...t-diodes.51350

The rectifier diodes are a "press-fit" into the heatsink. Using hydraulic press, they push in/out of the heatsink plate. But do not crush the other side- so a special tool or die is needed.

Can you can read the part numbers, writing on the side of the diode?
They look like Motorola/On-Semi parts like MR254?. My guess 25A each one.

There would be two different diodes used - common anode, and common cathode.

[Wolf1977]

Re: question about diode of an old welding machine

its one phase sir
is there for replace do you think ;
if i know the amperes of cource

[redwire]

Re: question about diode of an old welding machine

Bosch BD2504 25A 400V is 13mm check size (DO-21 0.5"/13mm).
Many others here and cheap ones at Aliexpress but most are low voltage ones for car alternator, so watch out for that.

These (press-fit) diodes are hard to work with. If there is room, stud-mount would be easier. This has a cooling fan?

[Wolf1977]

Re: question about diode of an old welding machine

ok sir my rectifier writes pms 8/02/140

[redwire]

Re: question about diode of an old welding machine

What make model is the welder? It seems to be a Sealey SuperMIG140?
This is relevant: https://www.instructables.com/Mig-We...-in-bridge-rec
They used qty. 2 of 70HFR160 70A 1600V VISHAY and qty. 2 of 70HF160 70A 1600V VISHAY stud-mount.

[Wolf1977]

Re: question about diode of an old welding machine

thanks a lot sir but because it seems a little bit dificult procees is there case on your opinion to find a new rectifier with the information of the previoudlu informstion ;
thanks on advance

[petehall347]

Re: question about diode of an old welding machine

do a search for welder rectifier single phase . see if you can match it

[Wolf1977]

Re: question about diode of an old welding machine

i dit it already
i cannot found anything match

[petehall347]

Re: question about diode of an old welding machine

try electrotech solutions

[redwire]

Re: question about diode of an old welding machine

I found some but after asking twice for the welder make and model, I don't think the bulb is bright enough

[Wolf1977]

Re: question about diode of an old welding machine

sorry sir
the model is electro mic 210

[Wolf1977]

Re: question about diode of an old welding machine

in this photo i think seems better the rectifier

[redwire]

Re: question about diode of an old welding machine

Did you mean "elettro MIG 210" ? It is discontinued but you could ask them for a replacement rectifier.
Rectifier assy. is PMS 8/02/140 (140A) which is made by Scomes Italy.
Faet also sells a PMS 160 version. But you need 6 diodes, so need to add 2 more.

Either you hunt and try find a new one, or go to an electronics repair shop and get them to fix it.

P.S. - No picture of the front panel? Are you trying to make this stupid hard? Why does Post #3 scratch out the label and part number. I'm out now.

[petehall347]

Re: question about diode of an old welding machine

being as its made in italy and that's where good welders are made .. had my mig 30 years cebora 155 and its still working only thing that's ever gone wrong was a low voltage transformer .
am wondering why those diodes didn't last long .maybe crap was used and needs upgrading . or some other fault like a broken fan .

[Wolf1977]

Re: question about diode of an old welding machine

hi again in your opinion is single or fuel rectifier;