hello fello sparkers!

[sifi]

Its nice to know there is help out there!
I run a small classic vw resoration workshop and use a cheapo clarke 151turbo mig which has done very well, until the other day when i tried to tack on a pannel and it blew a 13amp fuse in the plug. I then replaced the fuse and tried again, same thing happened when i pulled the trigger, it struggled to turn the wheel for about a second (and didn`t sound pleased!) then blew the fuse again this time with a small fizzing noise coming from inside the poor bugger!
Being a bit of a geek, i like taking things apart and trying to work out whats wrong, but to no avail on this occasion. it was very dusty and ive blown it out, but unless there was somthing (fried) glaring at me i dont have a clue what the problem could be.
Can anyone shed any blue light on this? I would like to fix it myself, as its a lot cheaper! Thankyou for reading and happy new year.

 

[shenion]

Most likely a shorted rectifier.

PM weldequip, he should stock them.

 

[malcolm]

Worth checking those two aluminium plates with all the big diodes on them - I suspect shenion is right with the rectifier. One of the diodes gone pop as the photo.

According to the guys you should really replace the diodes as a set. Though it you can find a part number it would be interesting to see what happens if you replace the one (I've no idea about this sort of stuff). Or get a new rectifier - easier.

 

[malcolm]

Just had a thought - you know it's winter - surge when filling the transformers is more prone to blowing fuses in cold weather.

Check for fried things inside first definately especially if it's fizzling. Otherwise what sort of supply do you have for the welder? 13a is marginal (but normally OK).

Welcome to the forum by the way.

 

[steve53]

Hi,
Sad to say that it sound like the rectifier has died, blowing fuses like no tomorrow is the usual sign. You can get spares and it isn't a difficult fix.

Regards Steve

 

[steve53]

From picture one of the diodes has blown, definitely the rectifier.

 

[malcolm]

From picture one of the diodes has blown, definitely the rectifier.

That's a pic of another broken welder - just an example of what to look for.

 

[steve53]

Hi Malc,
Realised that after I posted!! Look before you leapthey say!! I still feel that its the rectifier although if the connections to the rectifier are loose, oxidised or have been overheated, this will give high resistance at that connection and cause the fuse to blow as well!!
Sorry for the confusion.

 

[sifi]

thanks!

Wow this forum is brilliant, i didnt expect so many replies so quickly, as soon as daylight comes around ill have a more detailed look (now i kindly have some clues). I only have 13amps at the workshop and yes, it does get v cold in there.
As welding being the main part of my restorations i have (incase all else fails) been looking for a replacement and have stumbled across a clarke 160 (blue mig) thats fairly cheap, but needs a 15amp plug. Would i get away with it? its a bit crude i know!
Thank you all very much for your time and advise

 

[shenion]

It has been covered here before. It can run on a 13A plug.

If you run it full power, it might trip a 13A fuse. But many here said they have run bigger units on 13. For bodywork, you would be running much lower anyway.

 

[sifi]

Good stuff. I have just discovered rule no. 1, discover the rest of the information on web site before posting stupid questions!!
Ill let you know my findings, thanks again.

 

[Wozzaaah]

Hehe, rule number 2 is that there are no stupid questions. It doesn't matter how many times the same question gets asked on here, you'll either get politely directed to a thread (as Shenion has done) where the question has been answered already or you'll get the question answered again. Having said that, the search option works very well in most cases but I think posters just tend to find it easier to ask rather than search.
Anyway, a 13A plug will be fine, I ran my 220A Butters on one and only occasionally popped the fuse.

 

[sifi]

initial inspection

well ive had a quick look at the diodes on the aluminium plates (of which there are 2 on each of the 4 plates) and there are no apparent cracks (as in the photo) and that part looks clean free from corrosion.
Is the rectifier the complete unit, i.e the four plates and all the diodes? it has a 13mm bolt running through it mounting it to the body.

 

[weldequip]

There aren't always visible signs of failure, you can test them with a Multimeter on resistance... they should only give a reading one way. If any of them read both ways they've gone open circuit. I've got the replacement Rectifiers off the shelf if you need one
weldequip

 

[sifi]

Thanks for the info, can i check them using a continuity test? Also, how much would a new rectifier cost?

 

[weldequip]

Continuity is what I meant yes. Remove the Rectifier & test each diode by putting one probe on the diode & one on the aluminium plate, reversing the probes on each diode. If any read both ways they are faulty.
PM me for a price if required
weldequip

 

[sifi]

Ok, ill let you know how i get on, it may be a few days as i dont have a computer at workshop and i stay there in the week. THANYOU ALL FOR THE KIND ADVISE!

 

[sifi]

Well ive done a continuity test and some are reading both ways and (as you say) must be open circuit. There is also one which does not read anything at all
If i could check the price and availability a new rectifier (clarke 151 turbo) that would be great.
As i needed a mig so much this week i had to bite on a stick (which is now in two halves!) and buy a new one, a clarke 135 turbo. It feels a little different to my old girl (may be the 0.6mm wire) but has its advantages on thinner steel as i can produce smaller welds, its not the strongest or best quality machine but i do recomend it as a great little hobby mig, that (depening what you put it through) should last a good two years.
Enjoy the weekend folks!

 

[weldequip]

It's goosed then Got them off the shelf but no idea on price, I'll check at work on Monday for you & drop you a PM
weldequip

 

[sifi]

yea, looks that way! is it the whole unit with all the diodes? should imagine so. Thanks for the reply mate.