Idealarc 250 problem

admin

Just picked up a non working Idealarc 250 ac/dc. Has been sitting unused for a few years, supposedly worked last time it was used. When its powered on it sounds like its under a load- loud groan- just like while welding. The amp control slowly turns on its own. Anyone have any ideas?ThanksBen
Reply:Check the diodes on the heat sinks on the back. sounds like one or more has shorted out.There were two types of diodes used. The older machines used groups of diodes soldered to copper strips and bolted to the heat sinks. This type has a bad habit of failing. All it takes is one of the diodes to short out. The newer units use just four diodes. These diodes are still for sale. With a little work the old style diodes can be replaced with the new style diode.Unplug the welder, remove the covers. check the polarity switch for damage then test the diodes. You can use a multimeter with diode test.Post a picture and the code number.. Send me a PM if you need help modifying for a new diode.
Reply:Its code # 6933-c. It has the soldered diodes, I'll check them this weekend.
Reply:bad diodes it is
Reply:Problem solved. Welds beautifully. Attached Images
Reply:Good Repair - new diodes and away you go!Big advantage of the transformer arc welders - they are simple enough to trouble shoot and DYI repair.Can I ask you, where you got the diodes and what did they cost?Rick V 1 Airco Heliwelder 3A/DDR3 CTC 70/90 amp Stick/Tig Inverters in Parallel1 Lincoln MIG PAK 151 Oxy-Acet
Reply:Ebay. They are 150a 600v rated, $17 each. Lincoln wants around $90 each and I wasn't going to spend that much to find out i had another problem.
Reply:Well done, sir!Lincoln Idealarc 250 (circa 1962)Lincoln Weldpak 155 w/Mig KitLincoln Squarewave TIG 175
Reply:Stroked 550, I just picked up a couple idealarcs neither of which will weld dc. I'd like to do a full restoration on them and change the diodes in the process. Can you point me in the right direction with a part number maybe?Thank you,Marc Leonard