Munkul
Jack of some trades, Master of none
- Messages
- 7,328
- Location
- Cumbria
I have a lovely old ESAB DTM 250 Aristotig. It has a built in water cooler, does AC/DC, does 200 amps @ 100%, and has plenty adjustment to play with. I have (or had?) no intention of upgrading it to anything newer.
It's dated as 1991 (IIRC) and is an inverter driven unit.
anyways, it welds on DC just fine. Sometimes the HF seems a bit weak, but always works.
on AC i've never had a problem with it, but I don't do all that much aluminium... anyways the last few days I've been making some alloy ramps from 1/4" treadplate, and running long seams around 180-200amps.
About half an hour into welding, it starts playing up.... EITHER:
- it doesn't light up an arc, it just shoots large HF-like sparks at the workpiece
or - it extinguishes the arc mid-weld, and again just shoots HF sparks
or - the arc goes very weird - changes sound, must drop the current massively, and in general acts unstably. This only lasts a little time before it just extinguishes like above.
If I play with the frequency and/or balance knobs, I can generally get it to work again fairly easily, for a while at least. It doesn't seem related to overheating, because it used to do this sometimes if it hadn't been used for a while (I put it down to sitting in a cold garage) and also if I leave it to cool down, it doesn't make any difference.
I've had the panels off and all the boards look fine.
I've tried changing tungstens, collets, gas flow, even changed the gas bottle itself in an effort to see if it's not the machine itself...
These sparks, they are much bigger and stronger than the usual HF sparks this machine puts out.
Anyone any ideas?
It's dated as 1991 (IIRC) and is an inverter driven unit.
anyways, it welds on DC just fine. Sometimes the HF seems a bit weak, but always works.
on AC i've never had a problem with it, but I don't do all that much aluminium... anyways the last few days I've been making some alloy ramps from 1/4" treadplate, and running long seams around 180-200amps.
About half an hour into welding, it starts playing up.... EITHER:
- it doesn't light up an arc, it just shoots large HF-like sparks at the workpiece
or - it extinguishes the arc mid-weld, and again just shoots HF sparks
or - the arc goes very weird - changes sound, must drop the current massively, and in general acts unstably. This only lasts a little time before it just extinguishes like above.
If I play with the frequency and/or balance knobs, I can generally get it to work again fairly easily, for a while at least. It doesn't seem related to overheating, because it used to do this sometimes if it hadn't been used for a while (I put it down to sitting in a cold garage) and also if I leave it to cool down, it doesn't make any difference.
I've had the panels off and all the boards look fine.
I've tried changing tungstens, collets, gas flow, even changed the gas bottle itself in an effort to see if it's not the machine itself...
These sparks, they are much bigger and stronger than the usual HF sparks this machine puts out.
Anyone any ideas?