Author Topic: Lincoln Tig Control Board Problem?  (Read 349 times)

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drdano

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Lincoln Tig Control Board Problem?
« on: November 10, 2019, 05:47:07 PM »
I've got a Precision Tig 185 that decided to give me the first major problem since I've owned it ~15 years or so.  I got all set up to weld, unit turns on fine, fan and gas purge cycle complete.  I tap on the amptrol to verify I've got pre-gas and I've got nothing.  Pedal to the floor, nothing.  Crap.  Unplug, replug everything, same problem.  Toggle all the settings I can on the front, still no luck when set back to tig DC-.  I check the amptrol at the small microswitch inside the foot pedal, it has continuity when the switch is closed so I think that is ok.  I check also at the end of the amptrol cord where it plugs in and it also has continuity when I hit the switch.  I tried to bypass the two wires at the plug on the machine front, D and E to see if it would trip the pre-gas switch and it wouldn't do it.  Opened the top, unplugged the amptrol connector from the board and tried tripping D and E from the board and still nothing. 

Anyone familiar with diagnosing these?  Am I missing something I should try?   I'm really not wanting to have to buy a new board for this thing unless I absolutely must, they are freaking expensive!  Maybe there are some electrical shops guys use to have the boards diagnosed and repaired you can recommend?
« Last Edit: November 10, 2019, 05:48:39 PM by drdano »

Heo

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Re: Lincoln Tig Control Board Problem?
« Reply #1 on: November 10, 2019, 06:10:09 PM »
I worked as a welder for many years. Its amazing how many
problems with a welding machine, that can be solved with
taking of the cover and blow out all accumulated grinding dust
with compressed air ;)

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BattlestarGalactic

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Re: Lincoln Tig Control Board Problem?
« Reply #2 on: November 10, 2019, 08:23:00 PM »
We have typical foot switch issues with our TIG machines(blue or red machines)n at work, but they get beat on 10 hrs a day and kicked around like a football.

If it is striking an arc, then then switch should be working.  Have you checked to see if you are getting voltage to the gas solenoid?  Might get lucky and only need the solenoid?  I did a quick google and seems like there have been issues with these boards and they can't be fixed.  A new board is unreal!!  I saw $1200 new!!!  Yowza.

I've had thoughts of getting a new Miller Multimatic 220 TIG/MIG machine, but the cost to fix them is crazy and I won't get the mileage out of it.  My very vintage Millermatic MIG will keep ticking for decades with no electronics in it.

drdano

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Re: Lincoln Tig Control Board Problem?
« Reply #3 on: November 10, 2019, 09:21:11 PM »
We have typical foot switch issues with our TIG machines(blue or red machines)n at work, but they get beat on 10 hrs a day and kicked around like a football.

If it is striking an arc, then then switch should be working.  Have you checked to see if you are getting voltage to the gas solenoid?  Might get lucky and only need the solenoid?  I did a quick google and seems like there have been issues with these boards and they can't be fixed.  A new board is unreal!!  I saw $1200 new!!!  Yowza.

I've had thoughts of getting a new Miller Multimatic 220 TIG/MIG machine, but the cost to fix them is crazy and I won't get the mileage out of it.  My very vintage Millermatic MIG will keep ticking for decades with no electronics in it.

The gas solenoid is getting power, it functions normally during start up.  You flip the big switch on the front, it runs the fan and opens the gas for a few seconds then shuts both off as part of the start up cycle.  I actually dont even have any leads to try to arc with it, I should try to find a set and I could try to see if it will do that.  Yes, the circuit boards are ridiculous...I about fainted seeing how expensive they are. 

GJCAT427

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Re: Lincoln Tig Control Board Problem?
« Reply #4 on: November 11, 2019, 01:18:55 AM »
We have a small Lincoln tig at work that was starting to act up. Its 10 +/- yrs old. Investigated and found the board was shot. Like Larry said the board is stupidly expenecive. Wound up buying a new Esab unit that water cooled.

Thumperbird

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Re: Lincoln Tig Control Board Problem?
« Reply #5 on: November 12, 2019, 12:13:36 PM »
Remove board, clean, reflow all solder joints, reseat all socketed components, verify all connector sockets are "sprung" correctly and making good electrical contact with pins, retry.  Amazing how many times this will work.

Thumperbird

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Re: Lincoln Tig Control Board Problem?
« Reply #6 on: November 12, 2019, 12:20:13 PM »
If relays are involved, give them an ohm check in actuated state minus connections as well.

drdano

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Re: Lincoln Tig Control Board Problem?
« Reply #7 on: November 12, 2019, 03:07:18 PM »
reflow all solder joints...

Amazing how many times this will work.

How do I go about reflowing the joints?  The top side of the entire board looks to be coated in some sort of clear epoxy or something.  I can't see the bottom side, but hopefully not.  I'm game for trying anything to avoid needing to buy a $1200 control board.  I do love this welder, first trouble I've ever had with it outside of a dry rotted power lead that was leaking gas on me.

Thumperbird

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Re: Lincoln Tig Control Board Problem?
« Reply #8 on: November 12, 2019, 03:43:38 PM »
Sounds like it is conformal coated, that is a problem top side wise.
Remove it and see what the bottom is like, if exposed traces and joints just touch each joint with a solder iron until you see it go molten and release, add solder if something appears extra thin.
There are chemicals that will soften/strip coating if both sides are coated all depends on what it is, you can also usually just hit it with heat (solder iron) and maybe added pressure and melt through the coating, takes longer and stinks, use ventilation.

Maybe take two passes, double check all connections for good pressure contact between sockets and pins and remove reseat anything that will unplug, even exercising connectors several times is a good idea as it scratches off oxidation/dirt, etc..  If that does not work go after the resolder task.

c-reed

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Re: Lincoln Tig Control Board Problem?
« Reply #9 on: November 13, 2019, 08:52:30 PM »
I sent you a p.m.
« Last Edit: November 13, 2019, 08:56:34 PM by c-reed »

drdano

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Re: Lincoln Tig Control Board Problem?
« Reply #10 on: November 14, 2019, 02:11:52 PM »
A bit of an update this week.  I spoke with two tech guys at Lincoln who gave some ok advice and things to check.  On the attached schematic for the amptrol there is a microswitch that give continuity to the board telling the pedal has began to be pressed down.  This activates the gas solenoid for pre-weld purge of the weld area.  Checked the continuity on the amptrol itself at the switch, at the end of the cord where it plugs into the machine at the plug to the board, all good.  Jumping these two pins at the board (plug J5 in the photo/schematic, 6-pin unit lower center of the back) did not kick the solenoid.  The techs both suggested a board failure and had no other troubleshooting to offer.  Bummer.

A friend also put me in touch with a fellow who used to be in charge of maintaining a fleet of these machines at the hot rod school in my hometown and I was lucky enough to get a few minutes of his time on the phone.  Talking to him about the problem he stated they never would troubleshoot the board itself given most machines were always under warranty and would be credited on a new one.  His view was the board was also faulty given the scenario I described.

Looking at the board, both sides are coated in this clear epoxy looking stuff and picking at a corner it looks to be a nightmare to get off.  I can see why some industrial board repair shops online don't have this one listed.  It's also a first-gen version of the board with a -1 suffix, the new board is a -2 supposedly.  So I bit the bullet and bought a new board that will be here in a few days and carries a 1yr warranty. The old board is still valuable since it is still partially functional.  I've not yet decided what to do with it. 

drdano

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Re: Lincoln Tig Control Board Problem?
« Reply #11 on: November 14, 2019, 02:16:05 PM »
Oh, and all this was after following Thumperbirds advice above.  Cleaned all the connectors with contact cleaner, blew it all dry.  Even greased up each individual pin with dielectric grease.  Reseated everything a few times.  No change in behavior, but definitely worth a try.

BattlestarGalactic

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Re: Lincoln Tig Control Board Problem?
« Reply #12 on: November 15, 2019, 07:51:26 AM »
That coating is for protection from corrosion and vibration.

Google removing the conformal coating.  Might be beyond a home repair, but once that is cleaned off you might actually see the problem?  Or it might be internal?  Look for a dark spot on/around any component.  Though I never actually got into the electronic field, I enjoy playing with that stuff.