I need some help from a person that knows electrical problems. I have a used welder that I am refurbishing. I have made a repair to the interface board that had a blown capacitor. When I turned that welder on it seemed that everything was okay with the fix so I am testing the weld capabilities. As I don't have it set up for the tig yet, I am just testing the "arc" functions. When I selected AC and used a 7018 3/32" rod I was able to run a bead. When I selected DC (straight polarity) or DC (reverse polarity) and turned the welder on it flipped the circuit breaker. The question(s) that I have:
1) Is this a dead short in the rectifier bridge? diode? If so how can I check the fault?
2) Can can check to see if the high frequency works using the "stick" function?

Thanks for any help.

Al

With the machine OFF, use an ohmmeter across each of the diodes. It
should read high one direction, low the other direction. If you find one
that is low both ways, that's the culprit. If one reads high both ways,
it is open and will need to be replaced but it is not the cause of the
blown breaker. The actual readings in ohms is not correct since the
diode has a voltage drop.

hd_74al wrote:
I need some help from a person that knows electrical problems. I have a
used welder that I am refurbishing. I have made a repair to the
interface board that had a blown capacitor. When I turned that welder
on it seemed that everything was okay with the fix so I am testing the
weld capabilities. As I don't have it set up for the tig yet, I am just
testing the "arc" functions. When I selected AC and used a 7018 3/32"
rod I was able to run a bead. When I selected DC (straight polarity) or
DC (reverse polarity) and turned the welder on it flipped the circuit
breaker. The question(s) that I have:
1) Is this a dead short in the rectifier bridge? diode? If so how can I
check the fault?
2) Can can check to see if the high frequency works using the "stick"
function?

Thanks for any help.

Al

hd_74al wrote:

I need some help from a person that knows electrical problems. I have a
used welder that I am refurbishing. I have made a repair to the
interface board that had a blown capacitor. When I turned that welder
on it seemed that everything was okay with the fix so I am testing the
weld capabilities. As I don't have it set up for the tig yet, I am just
testing the "arc" functions. When I selected AC and used a 7018 3/32"
rod I was able to run a bead. When I selected DC (straight polarity) or
DC (reverse polarity) and turned the welder on it flipped the circuit
breaker. The question(s) that I have:
1) Is this a dead short in the rectifier bridge? diode? If so how can I
check the fault?
2) Can can check to see if the high frequency works using the "stick"
function?

Thanks for any help.

Al

--
hd_74al

That would be the logical place to start your troubleshooting. Watch
out for reverse polarity diodes if you replace any. Reverse polarity
diodes are ones that have the anode and cathode reversed in relation to
the physical configuration of the unit. Look for the diode symbol on
the side of them and match it up in direction with the new one.

John