Hi folks,
I think I may have a problem with my old Miller 330ABP behemoth. I've been trying to learn how to TIG on this 330ABP I picked up off craigslist for $400. I really only have experience with MIG welding aluminum so I'm a little unsure of what my actual problem is.
I seem to only be able to strike an arc by scratch starting the Aluminum using AC. I'm using 3/32" Pure and Zirconiated tungsten (same problem with both), my HF switch is set to continuous, HF intensity switch is set to "100" (I've also tried 80, 50, 30 with no hugely noticeable difference in arc starting or how the puddle handles). Also, I can make pretty much identical beads with the HF switch set to Start as I can when it's set to Continuous. This would lead me to believe that my HF was simply not working, but I find it impossible to start an arc with the HF switch set to Off, I just scratch it, it sparks, and no matter how I try I just burn tungsten instead of getting any kind of arc. Also! I get interference on the cable TV's in the house with small lines of static etc.
So I would say my HF is working... it's just not allowing me to start it with a gap like I've been reading about. It seems to be commonly said in books and the internet that you can start an arc within 1/4" from the base material, I can't seem to get any gap and if there is one it'd be measured in thousandths of inches.
I have assured this isn't a grounding problem by putting the grounding clamp directly on the base material I'm working on. Also, I read up in the Miller owners manual and regapped the spark gaps to .008" (factory specs). The points on it looked ok, I think there was still tungsten on it (looked like some gray point metal material before the casing material) the top two points looked like they were slightly crooked, I would say one was 1/64" high compared to the other. I do have a lengthy 25ft lead to the torch which may be part of the problem?
I'm at a loss, I can still get decent beads with the scratch start (I guess I've gotten good at it). But I think I've finally hit the skill level where the contamination caused by this problem is holding me back. Do you guys have any ideas on what it could be?
Thanks for your help!
Mike
By DaveBoyer 
Date 06-24-2007 04:35
Edited 06-24-2007 04:44
I have the same problem with My 360 A/BP. I asume the HF doesn't jump a usual gap on DC either. A few things to try: blow/wipe all the dust off all of the parts of the HF circut, and conductors leading to the TIG torch, the HF could be bleeding off to ground. Try .012" for the point gap, some of the old literature suggests trying the larger gap. Look for a waxy substance running down the circut board behind or on the HF capacitors, they are the black boxes hooked up with a copper strap. If goo is coming out of them, it aint a good sign. There are a few other capacitors in the circut, any of them could be bad in a 30-40 year old machine. These are some things to start with, I havnt gotten arround to working on Mine yet.
Replace the HF capicitors. These are the 1x2 blocks on the board behind the lift panel.
Reset the piont gap and this should fix you up.
Good Luck
brande
I have heard these are pretty expensive, do You know of a [cheaper] source other than Miller? They are 0.002 uf 10,000volt.
Well yup! Those two capacitors are certainly a problem, some black goo is running all the way down, looks like it's been there for a while. I've yet to find any alternative capacitors my owners manual specs them at .002uF 6000V.
Thanks for your help guys, and please let me know if you have any ideas on a source for replacements that are a bit more reasonable than from Miller.
Mike
Hi Mikename!
I'd get the HF capacitors from Miller instead of hunting around the planet for alternatives because you might not end up getting the same performance... As Brande is, I was once a Miller authorized equipment repairperson, and I can tell you from experience that Brande has given you sound advice on replacing the capacitors...
You have a very decent CC AC/DC HF welding power source there with the 330ABP...
You say that you paid $400.00 for the unit? Then you got real good deal for that price and if all you have to do to make it work like you want it to is to replace the leaked out/blown capacitors, then I personally would spend the extra bucks knowing that I do indeed have the correct replacement parts in the machine instead of playing russian roulette with some alternative that may not last anywhere nears as long as the OEM parts that Miller supplies you with. Something for you to consider. If you can find the MFG that supplies Miller, then if they'll sell them to ya -you'll get a better price!!! Good Luck!!
Respectfully,
Henry
Yes, after looking around I've yet to find a suitable replacement capacitor that would not require a big rearrangement of that little corner, I'll probably wind up calling around on Monday and see who has the best price on some OEM Miller ones. If anyone knows of a good parts dealer in FL, the South East, or any big online dealer, I'd be indebted. There are some larger ceramic capacitors that seem like they would work but would require some rebracketing and maybe even some cover modifications heh. Something I'm not quite prepared to do on this welder.
Thanks,
Mike
Replaced the capacitors (they cost $220 with tax etc). Still have the occasional HF start problem but 98% of the time it works, man it sure is nice :) Thanks for your help guys HF start makes life so much easier.
http://i9.tinypic.com/4v7zza1.jpg is a pic of the current project I'm working on, the end of the seam makes it look like it doesn't have enough penetration but is just a piece of a mig tack weld I have to go over. Again, thanks for the tip on the cap's.
Mike
To minimize high frequency static interference to radio/tv use a length of #12 or 10 gauge copper wire and wrap (or use a wire eye connector) one end around one of the machines sheet metal chassis screws, and attaching the other end outside to a driven earth/ground rod. Second, connect another length of the copper wire to the welding table (you might want to use a flexible #10 cable with an alligator clamp if the project is moved about) and again connect to the same driven ground rod.
Size the tungsten diameter for the actual welding amperage being used. Instead of using long tapered points on the tungsten use a smaller diameter tungsten. Have at your disposal collets, collet bodies and tungsten of the 0.040" & 1/16" instead of the 3/32" diameter for thin material/low amperage. Of course, if thicker material requires greater amperage, have 1/8 & 5/32 diameter tungstens, collets & collet bodies also.
Set the shielding gas flow rate at minimum to achieve clean welds and protect the tungsten. At low amperage welding start at 10 cfh and work up/increase the value.
Set your high frequency intensity to minimum. Increase only enough to get good starts for the amperage and tungsten diameter and type used.
