Miller Diodes

admin

Hi,  New to the forum and hope someone will be able to help me with my problem. My welder stoped working and I think it's a diode. Does anyone know where diodes can be purchased to replace the one's in a Miller Thunderbolt 225 VP?  How can they be checked to see which are bad?  I searched the Miller site for a service dealer and was given 3 places the closest being about an hour and a half away. I'd like to order online if possible. Does anyone have a part number for the diode?  When I bring up the manual on miller's site only an AC part list is shown.Thanks
Reply:Where are you located??? Sims Welding has a good service department, and there are quite a few of them, especially in SoCal.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:They can be checked, by testing with a meter.  *most* multimeters have a diode check function, a diode will pass current in one direction, and block it in the other.What is your welder doing?  or not doing?I'd give you the part number off my 'spare' diode, but they come in two flavors - straight polarity or reverse.  In my case, it failed shorted.
Reply:I'm a little SW of Pittsburgh, Pa.  The welder in DC does nothing and in AC give a light spark.  It had been working fine for the past 20 years, but I was working on a set of forks to go on my crawler and think I over did the duty cycle.  Anyway she stoped welding totally.
Reply:whats the open circuit voltage reading?  it should be stated in the literature that came with it or on the site.. it shouldn't deviate any more than maybe +/-10% or so.. southwest of the burgh.. like towards washington or carnegie? theres tons of places there.. i'm from there.. you should be able to find a reputable shop closer than an hour and a half, unless you're really in BF.. lol.. worst case, i'd say test, confirm the part, then if you can't get a shop nearby, hit up a local electronics supply place or industrial supply place (liek one that carries motor contols..) good luck man!! http://kawispeed.com/ -moderator and tech deluxewww.myspace.com/trickortrack -cuz i have no life
Reply:Sounds like a shorted diode...  Without the serial number, the only manual listed shows an a/c output machine.Disconnect the output BEFORE the rectifier circuit, and try for an arc.  (standard working on electrical parts DISCLAIMER applies, though you're not working on a live circuit. )If the machine creates an arc ( at the end of the electrode, mind you ), it's a simple process of elimination to find the shorted diode.Then armed with the model and serial of the machine, just about any Miller dealer can get you the parts.  Or a pm to weldersales.  ( im sure there are others on the list, but his name sticks in my mind )
Reply:I have the part number. I found my manual and parts breakdown. The number for the diode is 087998
Reply:Diodes should be purchased and installed in matched sets.  Subtle differences in values can cause an imbalance in the load handled by one versus another, causing a never ending cycle of replacing one diode at a time.
Reply:Thanks for all the info and reccomendations.