XMT 304 Problems

[meyer_frank]

Hello,
I have a xmt 304 welder that I bought in the middle of summer, unfortunately i bought it used and it only cam with a 3 month warranty. I am having intermittent problems with the machine when I turn it on. At first tt my house I got a Help 6 code maybe once out every 10 times I turned it on. Now I only works once out of every 10! I have a project truck that I am working on at a friends house and we wired up a plug there, maybe 2km from me, and I get a help7, and sometimes a help0. But again will work maybe every 10th time you turn it on. I live in the country so the power isn't as perfect as in the city but at my house I have measured 239 and received a help 6 and up the hill measured 248 and got help 7. Is the welder really that sensitive? from what I understand in should have a 15% variance before it sends out a help code... And what do you make of the help0 code? I found a manual that stated that this could mean a burnt out thermistor, but then why does this only happen sporadically.

Thanks for any help

Frank

[meyer_frank]

Nobody has any ideas?

[blue_tech]

The Help 6 and Help 7 codes tend to point toward a buss capacitor imbalance. In other words, there are large electrolitic capacitors that should store about 325VDC on them and if there is a difference in this voltage amount, it can set the "Help 7" help code. Occasionaly, it can set the "Help 6" code as well.

As for the "Help 0" code, this one is most usually caused by a failure in the Auto Link circuit. So if the contactor inside the XMT does not get energized, it usually sets that help code. The contactor coil resistance would have to be measured to determine if this is an issue with just the contactors and/or the pc1 control board as well.

[cruizer]

OK 99% of the time Hep7 is a failed drain cap resistor on the output board

99% of the time Help 6 is a control board issue.

Help 0 is a failed contactor, and its not auto linking.

[meyer_frank]

Thanks for the input,
Spoke to a tech today and he told me to measure the cap's and see if there is a difference between them, apparently they should be between 50 mf of one another. no problem i thought, but my meter only goes to 1000 mf and then maxes out not the 1200 i need.

When I purchased the welder it had a new board installed, should have tipped me off, so hopefully that isn't the problem. Not sure which ones they are but after the unit is unplugged the cap voltage does drop slowly leading me to believe that the resistors are working. Cruizer, any way you could explain which resisters are the ones i'm looking for? Are they the rc3 and 4?

Thanks for any info

[meyer_frank]

Measured the Capacitors today, 2567 and 2537. Should theses be closer to 2700 like they are rated?

[cruizer]

Caps are fine.....


Remove the 2 bolts on each of the caps and bend the board slightly back away from those caps. Take a resistance measurement reading from the 2 cap mountings,

What do you read in Kilo ohms....

[meyer_frank]

Measured through the board like you suggested, 18.68 on c3 and 18.67 on c4

Frank

[cruizer]

So there is nothing wrong with the output board. However there is glitch with the top main board. That should be removed and sent to a repair shop.

[meyer_frank]

So I had the welder in to the shop. They looked at the machine and told me that they couldn't find anything wrong. Although they agree that the voltages should be fine and that it should work for me. They also said that a new pc board isn't made for my unit any more but for the one that is a year newer it is. What they couldn't say was wether or not this board would work in my machine. Any body have any ideas? It is an hk serial number

Frank