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buzzbox blues
I picked up an old AC/DC buzzbox the other day. It's branded Airco and has a red
case, but it's a Miller Thunderbolt AC/DC. It's probably from 1980 or so. I started testing it and it was welding fine but suddenly the box started buzzing much louder than before and it won't weld worth beans any more. I haven't taken it apart yet. I figure something could be shorted to ground (although the 30A mains fuse didn't blow) or whatever holds the transformer laminations together might have cracked. Anyone got any bright ideas what to look for? I'd like to salvage this one. Grant Erwin Kirkland, Washington |
Is it pooched in both a/c and d/c?
JR Dweller in the cellar Grant Erwin wrote: I picked up an old AC/DC buzzbox the other day. It's branded Airco and has a red case, but it's a Miller Thunderbolt AC/DC. It's probably from 1980 or so. I started testing it and it was welding fine but suddenly the box started buzzing much louder than before and it won't weld worth beans any more. I haven't taken it apart yet. I figure something could be shorted to ground (although the 30A mains fuse didn't blow) or whatever holds the transformer laminations together might have cracked. Anyone got any bright ideas what to look for? I'd like to salvage this one. Grant Erwin Kirkland, Washington -- -------------------------------------------------------------- Home Page: http://www.seanet.com/~jasonrnorth If you're not the lead dog, the view never changes Doubt yourself, and the real world will eat you alive The world doesn't revolve around you, it revolves around me No skeletons in the closet; just decomposing corpses -------------------------------------------------------------- Dependence is Vulnerability: -------------------------------------------------------------- "Open the Pod Bay Doors please, Hal" "I'm sorry, Dave, I'm afraid I can't do that.." |
Look for a loose connection. I've fixed lots of welders that needed nothing
more than a new lug or a connection tightened. You did not mention smoke escaping or internal arcing so look at your connections. Pete "Grant Erwin" wrote in message ... I picked up an old AC/DC buzzbox the other day. It's branded Airco and has a red case, but it's a Miller Thunderbolt AC/DC. It's probably from 1980 or so. I started testing it and it was welding fine but suddenly the box started buzzing much louder than before and it won't weld worth beans any more. I haven't taken it apart yet. I figure something could be shorted to ground (although the 30A mains fuse didn't blow) or whatever holds the transformer laminations together might have cracked. Anyone got any bright ideas what to look for? I'd like to salvage this one. Grant Erwin Kirkland, Washington |
JR North wrote:
Is it pooched in both a/c and d/c? It buzzes loudly regardless of whether any leads are plugged in at all. If it had any capacitors I'd guess they shorted. But it doesn't. I'll pull the cover as soon as I can. GWE |
Grant Erwin wrote:
I picked up an old AC/DC buzzbox the other day. It's branded Airco and has a red case, but it's a Miller Thunderbolt AC/DC. It's probably from 1980 or so. I started testing it and it was welding fine but suddenly the box started buzzing much louder than before and it won't weld worth beans any more. I haven't taken it apart yet. I figure something could be shorted to ground (although the 30A mains fuse didn't blow) or whatever holds the transformer laminations together might have cracked. Anyone got any bright ideas what to look for? I'd like to salvage this one. Grant Erwin Kirkland, Washington My guess would be a shorted diode, assuming the diodes are always in the circuit. Second guess would be a shorted secondary winding in the transformer or a short to ground, either in the transformer or a lead shorted to the cabinet. John |
Sounds like it burned through some insulation and made some shorted
turns. Those boxes are only good for a 40% duty cycle and overheating ruins the winding insulation. Probably need to chuck it or try DIY rewinding. Bugs |
On Fri, 12 Aug 2005 20:16:53 -0700, Grant Erwin
wrote: I picked up an old AC/DC buzzbox the other day. It's branded Airco and has a red case, but it's a Miller Thunderbolt AC/DC. It's probably from 1980 or so. I started testing it and it was welding fine but suddenly the box started buzzing much louder than before and it won't weld worth beans any more. I haven't taken it apart yet. I figure something could be shorted to ground (although the 30A mains fuse didn't blow) or whatever holds the transformer laminations together might have cracked. Anyone got any bright ideas what to look for? I'd like to salvage this one. Grant Erwin Kirkland, Washington Pop the case and look on the right side for a main bus ribbon that has melted in half. Gunner |
If it has the many turn crank on the front, check to see if the magnetic
shunt has broken away from the crank. If it does, the shunt will pull all the way into the core, sets the welder for the lowest possible amperage, and buzzes like the devil. Grant Erwin wrote: I picked up an old AC/DC buzzbox the other day. It's branded Airco and has a red case, but it's a Miller Thunderbolt AC/DC. It's probably from 1980 or so. I started testing it and it was welding fine but suddenly the box started buzzing much louder than before and it won't weld worth beans any more. I haven't taken it apart yet. I figure something could be shorted to ground (although the 30A mains fuse didn't blow) or whatever holds the transformer laminations together might have cracked. Anyone got any bright ideas what to look for? I'd like to salvage this one. Grant Erwin Kirkland, Washington |
On Sat, 13 Aug 2005 14:42:33 GMT, RoyJ wrote:
If it has the many turn crank on the front, check to see if the magnetic shunt has broken away from the crank. If it does, the shunt will pull all the way into the core, sets the welder for the lowest possible amperage, and buzzes like the devil. oooo..yah...that could be it! Gunner Grant Erwin wrote: I picked up an old AC/DC buzzbox the other day. It's branded Airco and has a red case, but it's a Miller Thunderbolt AC/DC. It's probably from 1980 or so. I started testing it and it was welding fine but suddenly the box started buzzing much louder than before and it won't weld worth beans any more. I haven't taken it apart yet. I figure something could be shorted to ground (although the 30A mains fuse didn't blow) or whatever holds the transformer laminations together might have cracked. Anyone got any bright ideas what to look for? I'd like to salvage this one. Grant Erwin Kirkland, Washington |
I had the pleasure of trying to keep such a machine going in a school many
years ago. I ordered new guides and parts for the crank screw assembly to firm up the movable core. It improbved it a bit but the machine had run so much rod at rates well over the duty cycle that I was very happy to see it replaced with a 300 amp dialarc. Randy "RoyJ" wrote in message nk.net... If it has the many turn crank on the front, check to see if the magnetic shunt has broken away from the crank. If it does, the shunt will pull all the way into the core, sets the welder for the lowest possible amperage, and buzzes like the devil. Grant Erwin wrote: I picked up an old AC/DC buzzbox the other day. It's branded Airco and has a red case, but it's a Miller Thunderbolt AC/DC. It's probably from 1980 or so. I started testing it and it was welding fine but suddenly the box started buzzing much louder than before and it won't weld worth beans any more. I haven't taken it apart yet. I figure something could be shorted to ground (although the 30A mains fuse didn't blow) or whatever holds the transformer laminations together might have cracked. Anyone got any bright ideas what to look for? I'd like to salvage this one. Grant Erwin Kirkland, Washington |
Mine was $5 a yard sale. :) had to fix the ball joint that attaches the
screw to the shunt assembly. :( Works fine, albeit a bit noisy. Randy Zimmerman wrote: I had the pleasure of trying to keep such a machine going in a school many years ago. I ordered new guides and parts for the crank screw assembly to firm up the movable core. It improbved it a bit but the machine had run so much rod at rates well over the duty cycle that I was very happy to see it replaced with a 300 amp dialarc. Randy "RoyJ" wrote in message nk.net... If it has the many turn crank on the front, check to see if the magnetic shunt has broken away from the crank. If it does, the shunt will pull all the way into the core, sets the welder for the lowest possible amperage, and buzzes like the devil. Grant Erwin wrote: I picked up an old AC/DC buzzbox the other day. It's branded Airco and has a red case, but it's a Miller Thunderbolt AC/DC. It's probably from 1980 or so. I started testing it and it was welding fine but suddenly the box started buzzing much louder than before and it won't weld worth beans any more. I haven't taken it apart yet. I figure something could be shorted to ground (although the 30A mains fuse didn't blow) or whatever holds the transformer laminations together might have cracked. Anyone got any bright ideas what to look for? I'd like to salvage this one. Grant Erwin Kirkland, Washington |
Grant Erwin wrote:
I picked up an old AC/DC buzzbox the other day. It's branded Airco and has a red case, but it's a Miller Thunderbolt AC/DC. It's probably from 1980 or so. I started testing it and it was welding fine but suddenly the box started buzzing much louder than before and it won't weld worth beans any more. I haven't taken it apart yet. I figure something could be shorted to ground (although the 30A mains fuse didn't blow) or whatever holds the transformer laminations together might have cracked. Anyone got any bright ideas what to look for? I'd like to salvage this one. Grant Erwin Kirkland, Washington Is it a arc point to point that wore down and once jumped it makes plasma and dumps. Might be a matter of adjusting for the wear of he points so it does it normally. Just a thought - might be it. Can't think of the 'real name' it is a gross form of a regulator. Martin -- Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
I tore it down today. First I ran the shunt all the way down and back up again,
then I wiggled every heavy wire. All looked good. So I plugged it in and no more bad buzz. Didn't try running a bead yet, but the main symptom has gone. Rules out a shorted diode. If it starts again when I'm actually running a bead, I'll figure it's a thermal related issue with a transformer winding. Thanks for all the tips, excellent help! GWE Randy Zimmerman wrote: I had the pleasure of trying to keep such a machine going in a school many years ago. I ordered new guides and parts for the crank screw assembly to firm up the movable core. It improbved it a bit but the machine had run so much rod at rates well over the duty cycle that I was very happy to see it replaced with a 300 amp dialarc. Randy "RoyJ" wrote in message nk.net... If it has the many turn crank on the front, check to see if the magnetic shunt has broken away from the crank. If it does, the shunt will pull all the way into the core, sets the welder for the lowest possible amperage, and buzzes like the devil. Grant Erwin wrote: I picked up an old AC/DC buzzbox the other day. It's branded Airco and has a red case, but it's a Miller Thunderbolt AC/DC. It's probably from 1980 or so. I started testing it and it was welding fine but suddenly the box started buzzing much louder than before and it won't weld worth beans any more. I haven't taken it apart yet. I figure something could be shorted to ground (although the 30A mains fuse didn't blow) or whatever holds the transformer laminations together might have cracked. Anyone got any bright ideas what to look for? I'd like to salvage this one. Grant Erwin Kirkland, Washington |
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