old union carbide

[mr_miyagi]

Hi Guys,

I have an old union carbide UCC 305 tig set that used to work perfectly ok. It's been in storage in an old barn for the past four years and not been used, although it has been kept dry. I've just wheeled it out and taken it into the workshop to see if I can get it going again. It switches on ok but I'm having trouble getting it to start welding.

With it set to DC in about the middle of it's range I can weld a piece of 1/8" flat mild steel. However the only way I can get it to start an arc is by using it more like an arc welder where you strike up the electrode on the job. If I try this with it set to AC for aluminium the eletrode just sticks to the plate or just sparks a bit. It's almost as if it's down on power but it still does this even if I turn it right up.

I've not got a great deal of knowledge regarding how welders work, just know how to use one. Has any body got a rough guess at what might be causing the problem. Or suggest a good place to start looking at.

 

[Wozzaaah]

Sounds like the HF isn't working. Not a problem on DC as you can scratch start it but for alu you need the HF on continuously.
It should be obvious which control turns the HF on and off, check it's in the correct position. (Possible 3 positions, off, start, continuous.)
Failing that then you'll need to delve deeper.
One other possible cause is dirty or mis-adjusted spark gaps, it should be easy to find where they are as it'll have a removable cover or they will be easily accessible with the main cover off.
Have a look here for what sort of thing to look for, you can see the contacts between the alu blocks on the left, there's a small gap between the faces.
Post a pic of the front panel, it may help with more replies.

Edit: Just found a pic of the machine. HF controls are top left, there IS a 3 way switch and also an HF intensity knob.
Edit 2: Also, make sure it's in TIG mode, not stick!

 

[pedrobedro]

Have you got the cables coiled up? Lay them out flat as far as they will go then try it. Like Ghostbusters, don't cross the streams We used to have an old machine at a place I worked which did this if the leads were coiled up.

 

[mr_miyagi]

Yes the HF was set to continous and the cables were laid out on the floor. I guess I'll have to get inside it then. So what size gap do you think should be between the poles then. I suppose all the contacts inside it will need cleaning as well.

Make sure it's set to TIG. Doh. You obviously know I can be like.

 

[Wozzaaah]

I know it's stating the obvious but we've no idea how familiar you are with welding machines.
As we've now established that you do know one end of a welder from the other then you'll need to go deeper. Spark gaps are normally somewhere around 0.5mm but tbh, it could be pretty much anything and on that old machine you may struggle to find parts to repair it and it may also be cheaper to replace it.
I take it there's no difference if you turn the HF intensity control pot?

 

[shenion]

Woz, I think we already established these take a 0.008 to 0.010" gap (0.25mm). My similar machine of the same vintage uses that gap. A larger gap will burn out the caps.

Search for Union Carbide, there are several threads on them.

Most likely the HP caps have burned out, absorbed water or even leaked. Could also be dirty relays or switches.

 

[mr_miyagi]

Ok,

I got inside it today and found the HF caps. There was pretty much no gap at all. I took the poles out and cleaned up the ends then put them back and set the gap to 0.020". Whilst in there I cleaned up the contacts on all the relays I could find. It's still the same on AC, won't start up and arc. I can weld steel in DC ok so it seems to have improved a little.

It makes no difference where the HF intensity control pot is set. There's also an AC Stabilizer control pot, this makes no difference either. I've attached a couple of photos. Any more help?

 

[mr_miyagi]

Ok it's got a bit worse now.

The tig side of things doesn't work at all, AC or DC. When I press the foot pedal there are 3 old open relays that make contact, you can see 2 of them in the photo. Also the small PFTR relay for the gas makes contact and gas flows out the torch, I've taken the cover off it in the photo just to check it works. However, the other small relay marked OVR doesn't move. There is a large relay at the back of the unit for the incoming supply, as you can see in the photo. This doesn't make contact at all when the pedal is pressed.

If I switch to stick on the front panel the large relay at the back of the unit makes contact and puts power to the transformers. So I guess it would work as a stick welder but not as a Tig. The only thing I've touched inside the unit is the HF poles to clean them and set a gap. I also ran a bit of emery cloth under the open relay contacts and blew the dust away. Now I've no idea what's gone wrong. I wished I could get hold of a wiring diagram. Been searching on the net for Linde UCC 305 but not found anything yet.

Any more help?

 

[bluebobtail]

Try this site for a manual.
If you can't see it e mail him and i'm sure hell get in touch.
He helped me out with a boc adr 300 manual.

http://www.westermans.com/

 

[mr_miyagi]

Thanks for that Blue.

I rang them on monday lunchtime, they said send an email and they'd copy one and send it over in pdf form. I checked my emails later that day and there it was. I've not had time to have a proper look at it yet but at least I've got a start point, and a wiring diagram. Fingers crossed.