On Wed, 17 Sep 2003 04:41:58 GMT, "Keith Marshall"
wrote:
OK...let me ask you this: if there was a problem with the gas feed
to the gun, would this cause voltage variations and the control
board's inability to properly regulate the output voltage?
I don't see how it could.
I checked the SCRs using a low power load, they worked fine but I
wonder if their behaviour would be different under load?
Have you ever seen control board failures?
Not personally but I've certainly heard of them and was going to point you
to a site that repairs them at a reasonable price but their site is dead so
they may have gone out of business. It was http://www.welderboards.com in
case it's just a temporary problem with their site.
I just thought of something you might try to rule out a gas problem though.
Try a spool of fluxcore wire without the gas. Be sure you switch the
polarity first, usually by swapping the ground lead and the gun lead inside
the welder. That of course is assuming that the polarity *can* be switched
on that unit. If you still have the same problem it's definitely not a
problem with the gas solenoid, regulator, flow valve or tank.
Best Regards,
Keith Marshall
"I'm not grown up enough to be so old!"
"Alex Wiecek" wrote in message
. com...
Hello everyone...
First of all, I'd like to thank each and every one of you for taking
your time and advising me as to which direction to take to tackle this
problem.
In order to alleviate any confusion, I thought I'd come up with one
reply and address all your questions.... here it goes..
Zorro writes:
You may need to answer a few of the following to get more specific
help.
Is it mild steel or aluminum, you are welding?
We tried both.
Are you using solid wire, flux core?
Mmmm... I don't know.
Are you indoors or out in the wind?
Indoors.
Keith Marshall writes:
If you haven't already checked,
make sure the gun and the ground cable have firm, clean connections.
If not
they can easily heat up and cause problems. Also, have you checked
that the
wire is feeding smoothly? If it's skipping or hanging up in the
liner it
can cause problems.
From what I could tell, the wire is feeding smoothly. He would know
better and I'm sure he'd see it first as he is a proffessional welder.
Also, if he's using gas make sure he has consistent flow.
This suggestion came up a few times. I'm trying to remember whether or
not he tried using a different tank. But I will check this next time
I'm in his shop.
Shipyard Worker writes:
Alex i had the same problem at work the voltage was fine then it
would
change five volts next time i put down the weld. It turn out to be
the
scr but how they describe it is one regulate the voltage in and one
regulate voltage out. but if the voltage going in is not right it
will
confuse the voltage going out. example: 32 volts in standered, but
actually it is 28 then the output should be 24 but in reality it is
20
volts. I dont know if this helps. im dont work on welding machines
but i
do know what happen to me.
One thing I should mention, and I forgot in my original posting, is
that I had my voltmeter sitting on the filter caps. The measured
voltage was about the same as the one on the dial. While he was
welding, the voltage held up pretty good until the weld started to
sputter and burp. I've noticed DC voltage variations and quite an AC
ripple (about 6VAC). To me this indicates an excessive current flow or
the fact that the microprocessor is firing the SCRs at the wrong time
thus not regulating the output voltage properly.
mylo writes:
Check voltage on contactor, line and load side!
The contactor is at the back of the unit? Or are you talking about the
power switch?
The contactor is just a power relay! follow the power cable in from the
back of the unit, the contactor should be located right after the
voltage selection terminal! At least all the machine i've worked on
had a contactor lincoln, linde, ltec and miller! How old is this
machine? I did'nt see it on
www.lincolnelectric.com
check wire feeder for proper wire tension! do this by removing the
ground from the work and make sure your wire pushes the gun from the
work piece!
I'm sure he would have noticed it. He is a very experienced welder.
check ground to work piece
Good idea.
IIt could also be a bad roll of wire!
We tried three different rolls.... 
if the wire is solid and not flux core it could be the gas solenoid!
This suggestion came up a few times... hmmmmm...
assume the machine is single phase, if it's a 3-phase machine you
might be losing 1 leg of the line!
Well.. apparently he used another welding machine on the same circuit
and it worked fine for him.
I have both welding and electronics background and
most of the machines i,ve worked on usually ends up to be your
consumables , tips, liners, wire, etc! And the user! The 2 major
component i've have to replace are contactors and diodes! You can
usually burnish the contacts inside the contactor!!
OK...let me ask you this: if there was a problem with the gas feed
to the gun, would this cause voltage variations and the control
board's inability to properly regulate the output voltage?
I checked the SCRs using a low power load, they worked fine but I
wonder if their behaviour would be different under load?
Have you ever seen control board failures?
Once again, thank you all very much for your help. I really appreciate
it.
Alex VE3GOP