Inside a vintage Cebora Pocket Mig 880

[a111r]

After discovering a Stone age hobby MIG,
https://www.mig-welding.co.uk/forum/threads/vintage-migmate-reunited.101179/
I think I've now found the definitive Paleolithic version:


Dissection was revealing. Here we have a huge drive motor with a single wire groove on the spindle, no roller; you are to use 0.6 wire. Centre tapped transformer and a half wave bridge rectifier (removed)


There's no wire feed PCB, the astute may have spotted. That'll be a 'live' torch, then...


It's got a rectifier or transformer problem but I'll try and fix it.

 

[frank horton]

nice to see a wiper motor wire feed.....
not some modern piece of plastic irreplaceb carp

 

[eddie49]

I love the wirespeed motor "rheostat".

 

[a111r]

Fault finding now completed.
It came to me with a blown 13 amp fuse in the plug. When replaced, it blew in about 2 seconds and hummed. Classic signs of a dead rectifier.
With another fuse installed, I connected my meter for some 'speed OCV' reading in the 2 second envelope. It was around 6 Vdc. Two of the diodes were shorted.

The min / max switch rocker was quite tarnished, so mindful of my past Clarke experiences, I removed the switch and cleaned the tabs and spades.

This set has not seen much use; no-one's practiced on the clean earth clamp, the torch is undamaged as is the clear plastic side cover.

 

[a111r]

Repaired with some paralleled 50 Amp silicon bridge rectifiers.

If you really like soldering, a 250 Amp rectifier can be made up very cheaply (£5) using the old one as the heat sink.
https://www.ebay.co.uk/itm/5PCS-50A-1000V-Metal-Case-Bridge-Rectifier-KBPC5010-sU-ZT/363042640252?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649