How dirty is too dirty?

[dpmstevens]

Hi,
I took the side off my very old Murex 165 Tradesmig last night and realised it's pretty dirty in there. Thing is, I don't know if this is cosmetic or if it could harm the machine.

It works okay, but I'm suffering from intermittent arc strike. Pretty much every other weld results in a failed arc and burn back. It also seems irritatingly sensitive to minor changes in position - it goes from welding fine to utter rubbish. This could be my amateur technique but it happens so often I wonder if there's something up with it. I've changed the liner, the wire, the tip, the shroud and it's still bad.

Worth cleaning this lot out?

Cheers
Dan

 

[skotl]

That doesn’t look too bad to be honest.

If you’ve got a shop vac then giving it a bit of a going over won’t hurt. I wouldn’t go much farther though - you don’t want to loosen or unseat anything.

 

[dobbslc]

Some of the large terminals could do with checking and a clean with some emery cloth, a soft brush would shift most of the dust then a blow out with some compressed air.

 

[Barking Mat]

Nowt wrong with that, I'd stick the side back on for at least another ten years.

 

[Kram]

The dust could be the problem as some is conductive. Vacuum then spray with brake cleaner or similar.

Ankther likely item is the adjustment pots, if they have worn carbon tracks then the current setting will be all over the place - may be worth replacing.

 

[dpmstevens]

The dust could be the problem as some is conductive. Vacuum then spray with brake cleaner or similar.

Ankther likely item is the adjustment pots, if they have worn carbon tracks then the current setting will be all over the place - may be worth replacing.

I'm not much of an expert (for which read I'm not any sort of expert) on the internals of a MIG, so could do with a steer on what the adjustment pots are, where they are and how I check them...

 

[Kram]

The knobs on the front of the machine, if they use variable resistors/pots/potentiometers, the tracks can get worn.

 

[dpmstevens]

The knobs on the front of the machine, if they use variable resistors/pots/potentiometers, the tracks can get worn.

Great - thanks for this. Worth a look.

 

[Tangledfeet]

Okay chaps, I'll be That Guy. Friday night, etc., and I've had a few glasses of red...

'I wish my wife was that dirty'.

 

[Pete.]

If that's a pre-2000 machine I'd leave it well along inside just in case that white sheathing on the hot leads is asbestos. It doesn't look terribly dirty i'd leave it alone.

 

[Kram]

If that's a pre-2000 machine I'd leave it well along inside just in case that white sheathing on the hot leads is asbestos. It doesn't look terribly dirty i'd leave it alone.

Every horizontal component has a thick layer of dirt! To be safe you can go outside with a respirator, cut it off and replace with fibreglass sleeving.

It takes roughtly 40 years for asbestosis and the people getting it, many were working in a thick fog of the dust. A single exposure is unlikely to do harm. Factories are a different world now to what they were.

 

[Barking Mat]

Stick the side back on and do some welding...

 

[Smallfry]

I would at least give it a blow out with compressed air. Problem with dust, is that it can get damp, and cause semi shorts or current going where it shouldn't.

Was one of the main causes of failure with old CRT televisions. The ones with traditional BIG components.

 

[AVI_8]

The knobs on the front of the machine, if they use variable resistors/pots/potentiometers, the tracks can get worn.

I know nothing about welders but I’ve fixed amplifiers with pots which have failed due to dust getting into the tracks, strip down clean with electrical spray or isopropyl alcohol, I’d vacuum out the dust also use a paint brush to dislodge the dust.
You’ve already mentioned that it’s not working properly so you’ve nothing to lose by doing so. Just putting the cover on and keep on welding with a machine which isn’t working doesn’t make much sense.

 

[Farside]

I'd take those terminals apart, shine them up and re-assemble with a smear of vaseline or silicone grease.

 

[Kram]

I know nothing about welders but I’ve fixed amplifiers with pots which have failed due to dust getting into the tracks, strip down clean with electrical spray or isopropyl alcohol, I’d vacuum out the dust also use a paint brush to dislodge the dust.
You’ve already mentioned that it’s not working properly so you’ve nothing to lose by doing so. Just putting the cover on and keep on welding with a machine which isn’t working doesn’t make much sense.

Its difficult these days to buy decent quality potentiometer. The last new carbon track type I tried sent my lathes speed control all over the place.
I only use the wire wound type now. They are bigger but much more reliable, in my opinion, and even the cheapies are decent.

 

[waddycall]

Have you checked that the wire feed is consistent if you move the torch about at different angles?

 

[Gritineye]

Have you checked that the wire feed is consistent if you move the torch about at different angles?

Good call, mine gets a bit unpredictable if I hold it in a certain position, with the lead just off the floor. Alter the angle just a smidge and it's ok again.

 

[dobbslc]

This stuff is very good for cleaning switches and pots etc.

Kontakt Super 10 Servisol Switch Contact Cleaner Lubricant Switches Faders Dials | eBay

Contents: 200ml.

www.ebay.co.uk

 

[dpmstevens]

Have you checked that the wire feed is consistent if you move the torch about at different angles?

No, and I will. The machine isn't at home so I'll check in the week.

Great advice from everyone. I think a delicate go with a brush and a vacuum, plus some cleaning of any obviously corroded terminals is a good place to start. And a look at the pots, now I know what they are.