Hobart Problem

Arkhermit · Aug 26, 2013

I looked the diodes over, can't see any dark spots. I hooked up a 12V battery and a taillight bulb and did not get anything either way on either diode. ( the battery and bulb is good). So I hope I have located the problem. I am curious as to what caused them to quit ? I suppose it just happens. I am retired heavy equip mechanic and there are lots of things go wrong there is no explaination for. So I shall replace the diodes and try again.

CNC Dan · Aug 27, 2013

looks like the diodes are cooked. How many are there? could be two to four. You may have two different kinds of diodes also. Some will conduct stud to lead, others lead to stud. Look for a diode symbol printed on the side, or for two different part numbers.
Diodes usualy fail from overheating, or severe over current. They can fail from overvoltage, but that uaualy happens in the early design phase.

Arkhermit · Aug 28, 2013

Mine aparrently has two bolted to the plate then transformer wire and capaciter soldered to the top. Locally they are $26.00 online I found some hobart brand for $21.00 is this about right or is there some place better, Like one of the sponsers of this forum ?

CNC Dan · Aug 28, 2013

Arkhermit said:
Mine aparrently has two bolted to the plate then transformer wire and capaciter soldered to the top. Locally they are $26.00 online I found some hobart brand for $21.00 is this about right or is there some place better, Like one of the sponsers of this forum ?

Price wise that seems about right.
If you order parts from hobart, they will be the right kind and polarity.
You could look arround and find diodes that have a higher current and voltage rating, but you will need to be sure to get the right stud size, polarity, etc.

I guess that you have a center tapped secondary winding transformer, if you have two diodes.
And if they are both bolted to the same heatsink, then they are one of each polarity. Usesome heatsink compound between the diodes and the heatsink to help keep the diodes cool.

CNC Dan · Aug 28, 2013

I just looked at a manual for a 220 volt handler, and the diodes are shown in a single package.

If that is the case with your model, just get the part from hobart.