transmig 140 down on power

[gaz_moose]

I bought an old transmig 140 a week or so ago. i fired it up today with some .8 wire and a bottle of argon (as i have no co2 argon mix) and a bit of scrap 1" box section set the power and wire speed to 4 and had a play.
it had no penetration and was just a line on lumpy blobs stood proud, i grabbed my hammer and managed to knock them clean off. after fiddling with the controls i can get it to work fairly decent with the wire speed on 4 and the power on 8 but both settings only go up to 10 and it seems unusual for there to be such a massive variation in power setting and wire speed.

i know its a fair old beast so i took the side panels off when i got it and had a quick look around inside to make sure it was all good before i fired it into life.

what would cause it to lack in power output? surely it either works or doesn't work at all.

 

[NotANormalCoder]

Assuming you have made sure that the wire feed is good, most common problem with these, was failure of the capacitors or the connections to them. Look for 4 (I think) large round cans stood vertically near the front of the machine on the baseplate. These are all connected together with reasonably heavy wires and 1/4" spade connectors with one wire connected to the welding earth terminal. The connectors work loose and arc out. Check them all, one at a time, because keeping the correct polarity is vital!!! Replace any faulty connectors. If this doesn't solve the problem, check that none of the cans have distorted or pushed their tops off as this indicates failure. Replace if required.
Finally, if this doesn't work, then check the main diodes on the aluminium plates. Also, note that you will get a poor weld with pure argon, so test with argon/co2 mix if possible.

 

[gaz_moose]

the wire feed is the best part of it.it has pulse and spot weld and another dial ive not worked out yet!!. i will have a look at the capacitors and the connectors.

 

[mike 109444]

If the caps on yours are like the one in mine (same connection) then check as per attached pic. This loose connection was causing intermittent poor weld and penertration

 

[gaz_moose]

i will have a look at it after work tomorrow. cheers guys.

 

[NotANormalCoder]

The 'other dial' is Burnback. Depending on the setting of this knob, the weld current is killed at the same time as you let go of the trigger, or delayed by a second or two, allowing the wire to 'burn back' a little towards the tip so it doesn't get stuck in the weld pool. So, assuming you don't move the gun away from the weld at the same time as releasing the trigger (not what most people do), at minimum (anticlockwise) the wire should stick to the job. At max (fully clockwise) it will pull back slightly away from the weld.
Not fitted to too many small migs nowadays!
Dave

 

[gaz_moose]

the two spade connectors on the live side were really loose and had been arcing both of the ends of the wires were quite toasted. the one that goes to earth was fairly toasted as well. going to get some new spades this week and see how it goes.

 

[gaz_moose]

seems i have long weeks.
i have replaced the dodgy bit of wire and the connectors but its still lacking in power.

this is the top of the cap that i had to change the wire on. as you can see the hexagonal thing that the spade connector pushes onto looks higher on the right side one.

whilst mooching around i noticed the yellow thing on the left was a bit cracked.

it can be found in the centre of this pic

dont make em like this any more eh?

 

[mike 109444]

A week my as* Any hoo the one that "looks higher" is ok it's the other one that's the concern. It has got very hot (due to arcing?) and the plastic has softened and the terminal has sunk! Yes the plastic will be high melting point so goes to show how hot it got. You might be lucky in that the cap/s are ok (don't rush out to buy replacements there not cheep) the "yellow thing" will prob be a milar type capacitors that are there for suppression (look in you electric flymo, will have similar device, stops the crackel on your tv) The m/c looks to have a fair bit of corrosion inc most of the connections. I would one at a time pull the spade connectors off the caps, get a small file and clean up to bright metal. Then undo the large nuts that connect the very thick connector and diodes taking note of any insulating spacers and the order they go together and clean with file these connections. Same with the connections to the case through to outside. How good are you with a multimeter?

 

[gaz_moose]

i could be mistaken but i dont think that one has sunk as it looks exactly the same as the ones on the other caps.

ive had a wiggle of the majority of the wires and nothing seemed loosed or damaged.

nothing inside is really rusty, just has the usual dust and dirt that one would expect.

 

[Windy Miller]

Have you tried using it on the proper gas yet? That should help!

 

[Piero]

Hi Guys

I have one off these welders, changed up to it from a Sip.
These are a cracking mig,
I would like to say, it looks to me that it has been kept in a damp inviroment.
I dont know if thats the problem, but as sugested, do take the terminals of everything you can be bothered to, one at a time of course.

I am going to check mine for these lose terminals on the capasitors, just as a precaustion.
I will take a photo of mine and show you the differance,

Ps, any one got a manuel or a link to the manuel.

many thanks

 

[xf87]

Transmig not working

Hi... just bought a Transmig 140 (made in NZ by industrial gases) 2nd hand for $75.... could well be a lemon! Power light and fan work, wire feed motor is a non-runner. Have checked/tested the wiring to the wire feed motor and no go. What else can I check..... the beast was made in 1976! Any comments are much appreciated.
Cheers Chris

 

[NotANormalCoder]

You don't say whether the contactor comes in when you pull the trigger. If it does, then refer to the previously posted picture that shows the pcb and check that the small relay (top centre) is moving. If not, gently prise off the cover and remove all dirt/dust from inside. This is a common problem that stops this relay from operating and applying power to the motor. Otherwise, check the trips/fuse on the rear panel. Also, well worth removing the pcb and resoldering all the joints on the line of pin connections, relay and any other larger components. This machine was notorious for poor soldering.
If the contactor doesn't operate, try shorting the thermostat, as if this fails, it stops the trigger working.
More info would help.
Dave

 

[the snooper]

note the terminal on the capacitor has lifted when capacitors expand they have failed and this could well be a sign of it being no good, get them tested