Does anyone out there have any servicing information for a 80's
vintage Idealarc 300/300? I've put the unit on a load resistor and can
only get it to deliver about 50A worth of current regardless of the
heat selector. Doesn't matter if I use the front panel control or the
Amptrol, AC or DC. I suspect the problem may lie in the output control
pc board. The manual I have for it doesn't show the schematic for the
board. I found a similar schematic for a TIG 250/250 on the Lincoln
site, but it's not identical to the board that's in my welder.
With that being said, are there any common failures for this machine
that I should be looking for? I got a great deal on it($200), so I'm
not afraid to stick a bit more $$ into it. It welds like crap right
now. Thanks for any help/advice.
I have some information, and I'll be happy to check my files. What is the
code number for your machine?
You could also contact Lincoln Customer Service at 800-833-9353. Those guys
can be very helpful, even on some very old machines.
replying to Bob, bernie wrote:
hello, I have a Lincoln Idealarc 300 serial447478 no output on pos terminal only
30v in stick mode on medium range same thing on Tig . I need someone to guide me
thru the troubleshooting thanks if you can help firstname.lastname@example.org
Here's the info from the nameplate:
Model: TIG 300/300
Thanks for any info and thanks to the rest of you for your help. I'll
try Lincoln and Arco and see what happens.
The machine you have is special, that's what the "SPL" stands for in the
code number. It's not a machine that would have been offered for sale to
the general public. It was ordered by a specific customer with some feature
they wanted. What makes it special could be as minor as a different paint
color, or as major as a transformer designed to operate at an unusual
I have contacted one of my friends at Lincoln, he should be getting back to
me to let me know what's special about it. I'll post here as soon as I know
Jim...have you plugged in the foot pedal and mashed down on it to see
if the amps increase? There is a possiblity that your machine was
used in a welding cell or with other outboard controls, based on the
gentlemans comment about it being a Special.
I have a big assed Hobart Cybertig 2 that will not put out dick
without a dummy plug in the foot pedal socket, or the foot pedal
itself, no matter if its set for tig or stick.
And I need the dummy plug...sigh
"That which does not kill you,
has made a huge tactical error"
Yeah, mashing the pedal produces a change in welding current, just
like the front panel control, but I can never get beyond 50A,
regardless of pedal/knob position. Even setting the current control to
it's highest setting(300A, which should probably trip my breaker),
results in 50A at the output leads.
The welder was originally purchased by the Govt. so the SPL may
relate to some additional badging that's attached to the welder. It's
painted the same battleship grey as others of that vintage. The
drawing number for the schematic glued to the inside matches the
drawing number in my manual, so I would assume there were no circuit
changes. Same with the part numbers on the control board and timer
I found an outfit that sells refurbished control boards for about $125,
exchange and I wouldn't mind spending that to fix it. However, if
that's not what's wrong, it's money wasted and the frustration level
I was told that the machine is the same as a code 8888. It was shipped in
nonstandard packaging, and was prime painted only. You might want to write
down that code number, it may come in handy if you ever need parts or
I used to work in the transformer welder department at Lincoln back in the
mid 80s. They would move people around as demands changed, but I spent most
of my time assembling on the TIG line. I may have had a hand in building
your machine. : ) I also built lots and lots of AC-225 (tombstone)
machines. If I recall correctly, machines that were "prime painted only"
looked just like the standard gray that was used on the standard production
I checked my files and found that I had several packets of troubleshooting
information from past Lincoln service school classes, but none for this
machine. One of my packets is for codes up to 8887. (Go figure!) I'll
forword everything I have received so far about your machine, but you may
have to call and speak to one of the TIG troubleshooters at Lincoln.
I would definately try my best to pinpoint the problem before sinking any
serious money into the machine. I'm not an expert in repairing these
particular machines, but the problem you described could possibly be a
shorted saturable reactor coil. If this is the case, it may not be worth
repairing. If the machine always acts like it's in the lowest range, no
matter where the range switch is set, that would seem to me to be the most
likely cause, but check with someone who really knows these machines before
you take any action.
I wonder if the current control pot took a dump? Measure it with an
ohm meter and see if you get a large change in resistance from one end
of the movement to the other. If it goes to a certain point in the
first part of its travel, and never goes higher as you increase the
setting...its toast. I saw that with a foot pedal I was fixing for a
"At the core of liberalism is the spoiled child -
miserable, as all spoiled children are, unsatisfied,
demanding, ill-disciplined, despotic and useless.
Liberalism is a philosphy of sniveling brats." -- P.J. O'Rourke
Any luck with the old TIG? I just had a thought. I have heard of machines
that are setup in a particular application where the engineers want to limit
the changes that can be made by the operator. One guy told me that several
switches, in a machine he was working on, were disabled in an effort to
prevent anyone from changing the settings too drastically. I know such a
thing would be a long-shot, but you never know. It's probably worth taking
a good look at your machine to see if there are any signs of internal
Good note Bob
Another idea - in the pedal - is one end of the pot - there are three leads -
one off ?
Maybe the cable has a bad wire for one ?
A three terminal would be used for voltage - like a volume. A high voltage on
the other end is the low end (maybe gnd) and the center (wiper) sweeps from one
to the other.
If the GND is broken somewhere, then a series resistance of some value is
from the high level to the wiper. It would depend on the input (drawing)
current as to
If the High side was broken - then it would be a resistor to the low setting.
Might be this one!
You might be just setting above the low side due to a voltage drop in the lead.
I bet you have a broken POT, Broken wire, or like Bob - an internal terminal
prevent putting 300 amps on a little tiny thing.....
Good luck Gunner,
@ home at Lion's Lair with our computer lionslair at consolidated dot net
No progress yet. I've had a bunch of projects dropped on me at work,
so I've been unable to talk with Lincoln or Arco as of yet. I like
Bob's idea of an internal modification and being as it was a Gov't
spec'd unit, it's very possible although I've yet to discover any
changes in the wiring.
The foot pedal is good. I've checked the resistance readings from
one end to the other, no issues. And even if it was bad, the front
panel control should still be operational. I get the same results no
matter which pot controls the heat.
A colleague of mine has a friend that's closing down his shop and
what's one of the things he's selling? Another Idealarc TIG
300/300..... I need to find out what he wants for it. This one is
I'll keep ya posted. Thanks again for all your assistance.
replying to Bob, bernie wrote:
hello, I have a Lincoln Idealarc 300 serial447478 no output on pos terminal
only 30v in stick mode on medium range same thing on Tig . I need someone to
guide me thru the troubleshooting thanks if you can help email@example.com
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