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Posted by Gunner Asch on April 27, 2008, 5:44 pm
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I picked up a Lincoln tig 300 square wave machine a couple weeks ago.
Code 9298-ff
The guy claimed that the power couldnt be dialed down to anything less
than about 150 amps. Ive receipts for a number of boards he purchased
in '00 etc etc, with no fix.
So I powered it up today to diagnose what is really going on.
1. It will not dial down to less than about 111 amps,using either the
pedal, or the main amp control pot. The machine has digital display
for volts and amps, and with the main control all the way down, I get
an E11, and turn it a smidge, shows 111, then as the knob is turned,
goes all the way to 375 amps as one would expect
Hooking a stinger up, yes...it really is about 111 amps at low, and
all the way up blew an 80 amp breaker on my sub, so yes, that portion
is accurate.
There is no Hi/Low range switch on the machine.
No output on AC. Tiny spark, but no real welding current, using local,
or remote with a known good pedal. Pedal does kick the contactor, and
does vari welding current, but wont bring it down below that 111
volts.
No HF in any configuration. This COULD be dirty points, as its not
been used for at least 8 yrs, but thats not a big issue at the moment.
First thing Ill do is check the main amps control pot, to make sure
its in spec and both sides have the prope variable resistance.
I do have the schematics and drawings, but was looking for some input
on how things actually work..IE..when the main amp knob is turned, how
is it actually controlling the output of the transformer?
With a minimum current of 111 amps, something is not going low enough,
or high enough to vari current to lower values.
Why would it not have output on AC but does on DC? Thats a bit
odd....
Ill clean the AC/DC+/DC- selector switch of course.
It IS a square wave machine, so whatever converts the AC sine to
square wave sine may be an issue. I think thats some sort of chopper
circuit?
Anyone have any ideas or where to start looking? This is a weird one.
The FF designation at the end of the code number means "full
function"..whatever the hell that means. I assume its the timer
circuits for post and pre flow, crater, spot etc ?
Gunner
Political Correctness is a doctrine fostered by a delusional,
illogical liberal minority, and rabidly promoted by an
unscrupulous mainstream media, which holds forth the
proposition that it is entirely possible to pick up a turd by the clean end.
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Posted by RAM³ on April 27, 2008, 7:00 pm
Please log in for more thread options
> I picked up a Lincoln tig 300 square wave machine a couple weeks ago.
>
> Code 9298-ff
>
> The guy claimed that the power couldnt be dialed down to anything less
> than about 150 amps. Ive receipts for a number of boards he purchased
> in '00 etc etc, with no fix.
>
> So I powered it up today to diagnose what is really going on.
>
> 1. It will not dial down to less than about 111 amps,using either the
> pedal, or the main amp control pot. The machine has digital display
> for volts and amps, and with the main control all the way down, I get
> an E11, and turn it a smidge, shows 111, then as the knob is turned,
> goes all the way to 375 amps as one would expect
> Hooking a stinger up, yes...it really is about 111 amps at low, and
> all the way up blew an 80 amp breaker on my sub, so yes, that portion
> is accurate.
>
> There is no Hi/Low range switch on the machine.
>
> No output on AC. Tiny spark, but no real welding current, using local,
> or remote with a known good pedal. Pedal does kick the contactor, and
> does vari welding current, but wont bring it down below that 111
> volts.
>
> No HF in any configuration. This COULD be dirty points, as its not
> been used for at least 8 yrs, but thats not a big issue at the moment.
>
> First thing Ill do is check the main amps control pot, to make sure
> its in spec and both sides have the prope variable resistance.
>
> I do have the schematics and drawings, but was looking for some input
> on how things actually work..IE..when the main amp knob is turned, how
> is it actually controlling the output of the transformer?
>
> With a minimum current of 111 amps, something is not going low enough,
> or high enough to vari current to lower values.
>
> Why would it not have output on AC but does on DC? Thats a bit
> odd....
> Ill clean the AC/DC+/DC- selector switch of course.
> It IS a square wave machine, so whatever converts the AC sine to
> square wave sine may be an issue. I think thats some sort of chopper
> circuit?
>
> Anyone have any ideas or where to start looking? This is a weird one.
>
> The FF designation at the end of the code number means "full
> function"..whatever the hell that means. I assume its the timer
> circuits for post and pre flow, crater, spot etc ?
>
>
> Gunner
Dunno if it'll help but here's a URL for the Owner's Manual:
<http://content.lincolnelectric.com/pdfs/products/navigator/OBSO_IMS/im361a.pdf>
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Posted by RAM³ on April 27, 2008, 7:32 pm
Please log in for more thread options BTW, I just sent an e-mail to your de-munged addy.
If it didn't get there, send one to this one [with the ".nospam" removed]
and I'll re-send it.
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Posted by Ignoramus30765 on April 27, 2008, 8:45 pm
Please log in for more thread options I would obviously check the pot with a ohmmeter, but I think that this
welder has big problems (as in bad boards). If both a pedal and panel
pot give the same problem, the issue is in what reads the inputs, most
likely. Too many things are wrong at the same time. It should be an
interesting project, don't expect a quick answer and go slowly and
methodically.
i
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Posted by Jon Elson on April 27, 2008, 7:35 pm
Please log in for more thread options Gunner Asch wrote:
> I picked up a Lincoln tig 300 square wave machine a couple weeks ago.
>
> Code 9298-ff
>
> The guy claimed that the power couldnt be dialed down to anything less
> than about 150 amps. Ive receipts for a number of boards he purchased
> in '00 etc etc, with no fix.
>
> So I powered it up today to diagnose what is really going on.
>
> 1. It will not dial down to less than about 111 amps,using either the
> pedal, or the main amp control pot. The machine has digital display
> for volts and amps, and with the main control all the way down, I get
> an E11, and turn it a smidge, shows 111, then as the knob is turned,
> goes all the way to 375 amps as one would expect
> Hooking a stinger up, yes...it really is about 111 amps at low, and
> all the way up blew an 80 amp breaker on my sub, so yes, that portion
> is accurate.
>
I have one of these, and the Lincoln machine schematic, which is
all they will give out to the general public. The current
controls are potentiometers. I wonder if a wire has got a bad
connection, leaving one end of the pot disconnected. Maybe you
could read the voltage across the current set pot and I can
compare it to my machine.
> There is no Hi/Low range switch on the machine.
>
> No output on AC. Tiny spark, but no real welding current, using local,
> or remote with a known good pedal. Pedal does kick the contactor, and
> does vari welding current, but wont bring it down below that 111
> volts.
>
> No HF in any configuration. This COULD be dirty points, as its not
> been used for at least 8 yrs, but thats not a big issue at the moment.
>
Hmm,
> First thing Ill do is check the main amps control pot, to make sure
> its in spec and both sides have the prope variable resistance.
>
> I do have the schematics and drawings, but was looking for some input
> on how things actually work..IE..when the main amp knob is turned, how
> is it actually controlling the output of the transformer?
>
First, when the pedal is up, the display is just reading the
setting off the knob. So, the knob provides an adjustable
voltage, and the Amps dial reads that voltage with pedal up, and
the current coltroller tries to match that voltage with output
current when the pedal is down.
The actual welding output is controlled by the phase angle of
firing of an SCR bridge. But, if the dial reading is wrong with
pedal up, then this problem sounds much less serious.
> With a minimum current of 111 amps, something is not going low enough,
> or high enough to vari current to lower values.
>
> Why would it not have output on AC but does on DC? Thats a bit
> odd....
That is a puzzle, and may indicate more trouble.
> Ill clean the AC/DC+/DC- selector switch of course.
> It IS a square wave machine, so whatever converts the AC sine to
> square wave sine may be an issue. I think thats some sort of chopper
> circuit?
>
No, it just fiddles with the SCR timing to control the current.
> Anyone have any ideas or where to start looking? This is a weird one.
>
> The FF designation at the end of the code number means "full
> function"..whatever the hell that means. I assume its the timer
> circuits for post and pre flow, crater, spot etc ?
Yes. There are machines without many of those functions and no
gauges.
Anyway, I had to replace a Tantalum capacitor in the post-flow
timer. Otherwise, I haven't had any problem with the machine.
Jon
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>
> Code 9298-ff
>
> The guy claimed that the power couldnt be dialed down to anything less
> than about 150 amps. Ive receipts for a number of boards he purchased
> in '00 etc etc, with no fix.
>
> So I powered it up today to diagnose what is really going on.
>
> 1. It will not dial down to less than about 111 amps,using either the
> pedal, or the main amp control pot. The machine has digital display
> for volts and amps, and with the main control all the way down, I get
> an E11, and turn it a smidge, shows 111, then as the knob is turned,
> goes all the way to 375 amps as one would expect
> Hooking a stinger up, yes...it really is about 111 amps at low, and
> all the way up blew an 80 amp breaker on my sub, so yes, that portion
> is accurate.
>
> There is no Hi/Low range switch on the machine.
>
> No output on AC. Tiny spark, but no real welding current, using local,
> or remote with a known good pedal. Pedal does kick the contactor, and
> does vari welding current, but wont bring it down below that 111
> volts.
>
> No HF in any configuration. This COULD be dirty points, as its not
> been used for at least 8 yrs, but thats not a big issue at the moment.
>
> First thing Ill do is check the main amps control pot, to make sure
> its in spec and both sides have the prope variable resistance.
>
> I do have the schematics and drawings, but was looking for some input
> on how things actually work..IE..when the main amp knob is turned, how
> is it actually controlling the output of the transformer?
>
> With a minimum current of 111 amps, something is not going low enough,
> or high enough to vari current to lower values.
>
> Why would it not have output on AC but does on DC? Thats a bit
> odd....
> Ill clean the AC/DC+/DC- selector switch of course.
> It IS a square wave machine, so whatever converts the AC sine to
> square wave sine may be an issue. I think thats some sort of chopper
> circuit?
>
> Anyone have any ideas or where to start looking? This is a weird one.
>
> The FF designation at the end of the code number means "full
> function"..whatever the hell that means. I assume its the timer
> circuits for post and pre flow, crater, spot etc ?
>
>
> Gunner