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Re: Lincoln Idealarc Tig 300/300 - No Joy

Hello,
My Lincoln Idealarc Tig 300 serial# 447478 stopped working last summer. It show almost no welding output around 38V at the stinger and some minor sparks trying to weld. On max I get a little more intensity but on enough to melt the rod. The AC receptacle is ok I found bad diodes on the scr board, I changed them and also sent the PC board for repair. It came back last week and they changed the 2 fuse holder and resoldered them to the board. Still no output. After having red on the forum what burnt finger had to go thru to fix his, I am now asking anyone for help. I am very attached to this machine. I used to work on the C17 at Douglas in Long beach and that was my machine for everyday use. I am now retired and lives in Brittany France where the machine is located. I have a competent electrician who is eager to help. Hope you can find the time to steer me in the right direction. Thanks.

Re: Lincoln Idealarc Tig 300/300 - No Joy

send me you email by private message. I have a file that will help you.
It is two large to post here. about 5 meg.

Re: Lincoln Idealarc Tig 300/300 - No Joy

Originally Posted by AWPMAN

I have the trouble shooting guides if needed.

Hello AWPMAN,

I'm new the forum and this is my first communication. I have a very dear-to-me Idealarc 300/300 code 7288 that I'm bringing out of storage and would be FOREVER grateful if you would be so kind as to share the troubleshooting guides since the links above do not work anymore. I acquired my welder in trade for some work on a car in the mid-80s when I had a one model/one marque auto shop. I used it quite often, then I moved to Hawaii and used it quite a bit in the 90s. Stored it for 20 years in my dining room, living room, and then my shop as I was building my house and shop. It worked fine when I used it last but now it doesn't (no surprise there). I spent a fair amount of time revamping the cooling system and it's dolly...thinking the whole time that the more work I put into it without testing it, the more likely it will need repair. I blew the fan's run cap within 5 minutes while going over components with an IR temp probe, but after it passed the initial smoke-check, I tried TIG on some aluminum and it didn't want to spark. I've done some initial checks but can't say a whole lot yet other than I believe the transformer is good (.2 ohms on AC) and I'd like to collect as much info as I can before the data becomes unavailable and I jump in with both feet. The troubleshooting guides you have (I assume the same ones from Burnt Fingers) are very likely gold for those of us that have the vintage machinery disease.

I hope this query finds you and your family well. Best Regards, tfom

Re: Lincoln Idealarc Tig 300/300 - No Joy

Hello. I have no welding power amperage and 30 V at the welding terminal of my Lincoln Idealarc Tig 300. I changed all the diodes of the SCR board put it back same thing with bad diodes again. I am sending my PC board to be checked. If anyone had this issue I would be glad to hear from you. I have a L 5271 board. This problem is the same AC or DC with the remote or panel switch position.
Thank you for your time and consideration.
Redarc

Re: Lincoln Idealarc Tig 300/300 - No Joy

I have the trouble shooting guides if needed.

Re: Lincoln Idealarc Tig 300/300 - Parts

Originally Posted by burnt_fingers

Here's a list with links below to get you started rebuilding L5269 pc board & M12654 SCR Diode stack.
the manual, troubleshooting & schematics are here: http://1drv.ms/1kPG2BY

resistors & caps - mouser.com, the quantities listed are more than you'll need, I wanted to have a few spares of each.
http://www.mouser.com/ProjectManager...sID=6d3d1ed848

you need 2 - 27 ohm 1/2w resistors for the diode/scr board i grabbed them here because I forgot to get them at mouser
http://www.ebay.com/itm/400326248247

300amp clamp meter so you can follow the procedure to adjust the trimmers.
http://www.ebay.com/itm/221383498866

10K pot- front panel curent control rheostat
http://www.ebay.com/itm/141174245766

NTE5994 diodes for the diode/scr board
http://www.ebay.com/itm/201042036856

NTE5545 SCR for the diode/scr board
http://www.ebay.com/itm/191002375053

2n525 transistor
http://www.ebay.com/itm/370525660454

2N4062 transistor
http://www.ebay.com/itm/221358189793

2n2646 transistor
http://www.ebay.com/itm/171232577633

2N3390 transistor
http://www.ebay.com/itm/370632437486

MCR107 scr

http://www.ebay.com/itm/370933275904

Kemet Axial Tantalum Capacitor 1uF 35V T310
http://www.ebay.com/itm/110831674812

for some reason I cant see the parts list you put together would it be possible to get it from you? never mind i got it sorted out ty for this my friend.

Re: Lincoln Idealarc Tig 300/300 - No Joy

circuit board
Attachment 1699460

Re: Lincoln Idealarc Tig 300/300 - No Joy

circuit board
Attachment 1699459

Re: Lincoln Idealarc Tig 300/300 - No Joy

Do you know why the welder we have when running in TIG mode only with pedal after a minute or so it blows transistor Q3 2n3906 every time?
Stick weld it is always OK.
Caesar

Re: Lincoln Idealarc Tig 300/300 - No Joy

Originally Posted by burnt_fingers

Hi Charlie,
The short answer is no progress.
After all the dis-assembly,re-assembly and part replacements, still have the exact same problem, welds only on high with no control.

New parts for the control board arrived, transistors, inductors, resistors, put one of my control boards back together after isolating/checking every individual part, verifying the circuits and replacing parts I didn't believe were any good with exact replacements, cleaned up all the grounds and made sure the chassis parts are all bonded properly to each other & ground.
Got the new current control rheostat wired in on the panel and measured that circuit with the molex unplugged between pin #5 & #10 at the connector.
1-10 dial scale reads 10kΩ at 1 and lowers smoothly to 2Ω when you turn it up to 10.
Put it all back together and it's no different than before.

The machine will operate perfectly if I run a jumper from #10 at the panel remote switch to the ground side of the ac receptacle.
With the jumper on, she welds fine tig & stick, ac/dc in all the ranges with current control working both at the panel & the foot pedal.
High freq is working great as are the solenoids, soft start and switching between tig & stick - all seems to be right where it should be.

welded AC tig aluminum 120amps for a 2-3 hours continuously this week with the temporary jumper in place, nothing smoked or got warm, It did throw my 50 amp breaker during some long hot welds, but I reset it, gave it a few min break and went right back to welding and it didn't trip again.

I'm definitely open to suggestions, nothing I've done so far changed the original problem.
I'm tempted to send a board out, pay the $125 to "repair" wait a few weeks to get it and see if it makes a difference, but my gut feeling tells me it wont change.

Made a little progress on the machine in another way, bought a used procon pump and mounted it, the cart is the reservoir and will hold 40 gallons, right now I have 25 gallons of used red auto coolant in it and the pump is regulated to 50psi, I put serviceable fine mesh stainless screens on the input & output of the pump.
The few hours of welding I've done with it this week the torch is very cool to the touch and gets cold moments after you stop welding but its been cold outdoors and the coolant is probably 35-40 degrees right now, summertime temps will be a better test for that.

here's a few photos of the off topic cooler, I think its a Bernard cart?

Attachment 620291

Attachment 620241

Attachment 620251

Attachment 620311

Do you know why the welder we have when running in TIG mode only with pedal after a minute or so it blows transistor Q3 2n3906 every time?
Stick weld it is always OK.
Caesar

Re: Lincoln Idealarc Tig 300/300 - No Joy

I just picked up a idealarc 300 tig, code 8060-c. Can someone send me the troubleshooting documents and any other documents you have on the idealarc 300 tig. I contacted Lincoln and they said they only send them to authorized service facilities. I already have the owners manual and parts list off of Lincoln's site. Thank you.

Re: Lincoln Idealarc Tig 300/300 - No Joy

Originally Posted by mrartou

Hi, new to the site, looks like great info/work. Just picked up a Tig-300 for a song, it's supposedly has the same issue as described as above. Was wondering is someone could email me the schematics for the L-5271 board and rectifier/SCR assembly behind it, am going to tear into it this weekend (after testing).
This is the machine I learned to tig weld on in the mid-80's and loved it, also have a 5 pin thumb-trol for it that I still use on my lincoln high freq unit added to my ac/dc tombstone.
The machine came out of a tech school (so I was told) and is in good shape, doesn't look like anyone made any internal repairs just 43 years of dust. Powered it up and it makes good ac and dc (no load), will load/weld test it as described above.
Thanks in advance

Email Lincolns tech support for the schematics you need.
they were very helpful and prompt in sending diagrams to me when I needed them.

Re: Lincoln Idealarc Tig 300/300 - No Joy

hi BURNT!
I have a problem similar to yours, would you be so kind to uncover the complete wiring diagram, to check my machine?

Re: Lincoln Idealarc Tig 300/300 - No Joy

Hi, new to the site, looks like great info/work. Just picked up a Tig-300 for a song, it's supposedly has the same issue as described as above. Was wondering is someone could email me the schematics for the L-5271 board and rectifier/SCR assembly behind it, am going to tear into it this weekend (after testing).
This is the machine I learned to tig weld on in the mid-80's and loved it, also have a 5 pin thumb-trol for it that I still use on my lincoln high freq unit added to my ac/dc tombstone.
The machine came out of a tech school (so I was told) and is in good shape, doesn't look like anyone made any internal repairs just 43 years of dust. Powered it up and it makes good ac and dc (no load), will load/weld test it as described above.
Thanks in advance

Re: Lincoln Idealarc Tig 300/300 - Welding excellent!!

Yeah would it be possible to get the part number and everything for check in the diode board because I sent my resistors off the tile board and and they were lost in shipping

Re: Lincoln Idealarc Tig 300/300 - No Joy

Doug,
I found the part number for the diodes- all of the black diodes on my board (4 places on my board and 3 places on yours) are zener diodes 1N4747.
I will assume that the white ones on my board (9 places) are the 1N4004.
The colors in the picture you posted above suggest you used 15, 47 ohm resistors.
Tim

Re: Lincoln Idealarc Tig 300/300 - No Joy

I got the sense Lincoln revised this board 3-4 times, your board also has an extra diode below the 2N4062 transistor at the center left side.
They changed the resistor values for the KAG of the 2 scr MCR107-3 - on the earlier scheme they used 10-10-27 on the newer boards it was 10-15-47.

I ended up rebuilding the older 5269 board instead of the newer 5271 board, I'll have to check some photos I have on my shop computer to know exactly which resistor values I used.
There are 2 different diodes used from what I could tell, the majority are 1N4004 general purpose rectifiers - mouser part
the other few diodes, I couldn't get a good number off, so ended up not changing them.
the varistor isn't on either of the 2 schematics, they must have decided to add that in at some point, I could check my photos and show you exactly where to drill into the traces to add it.
good luck with the rebuild, now that its warming up, Im getting ready to finish the paint on mine.

Re: Lincoln Idealarc Tig 300/300 - No Joy

Doug,
First of all thanks a bunch!

Did you use the Vishay diodes (Mouser description- Rectifiers Vr/400V Io/1A Glass Passivated) for all 13 of the diodes on the board?

My board has slightly different resistors, where you have 15ohm resitors, mine are 27 ohm and where you have 47ohm, I have 10 ohm. Also my board has no varistor.

I'm ordering some parts now and will keep you posted.

Thanks again,
Tim

Attachment 699501

Re: Lincoln Idealarc Tig 300/300 - No Joy

Originally Posted by tprothma

I think it's why he's had problems with a first and second board on his machine.

I wouldn't mess with the pedal at all until you get the machine stick welding in all ranges and verify the rheostat on the panel is responding with a broad range of fine current control in each of the ranges first.

grab the pdf troubleshooting files at the link I posted above, there's a flow style chart that outlines how & what to test and what the results should be.

Check the pc board plug at the harness side,
looking for 0-10k across #5 & #10.
6.3vac across #63 & #64
115vac across #1 & #4

Good luck!
Doug

Re: Lincoln Idealarc Tig 300/300 - Parts

Here's a list with links below to get you started rebuilding L5269 pc board & M12654 SCR Diode stack.
the manual, troubleshooting & schematics are here: http://1drv.ms/1kPG2BY

resistors & caps - mouser.com, the quantities listed are more than you'll need, I wanted to have a few spares of each.
http://www.mouser.com/ProjectManager...sID=6d3d1ed848

you need 2 - 27 ohm 1/2w resistors for the diode/scr board i grabbed them here because I forgot to get them at mouser
http://www.ebay.com/itm/400326248247

300amp clamp meter so you can follow the procedure to adjust the trimmers.
http://www.ebay.com/itm/221383498866

10K pot- front panel curent control rheostat
http://www.ebay.com/itm/141174245766

NTE5994 diodes for the diode/scr board
http://www.ebay.com/itm/201042036856

NTE5545 SCR for the diode/scr board
http://www.ebay.com/itm/191002375053

2n525 transistor
http://www.ebay.com/itm/370525660454

2N4062 transistor
http://www.ebay.com/itm/221358189793

2n2646 transistor
http://www.ebay.com/itm/171232577633

2N3390 transistor
http://www.ebay.com/itm/370632437486

MCR107 scr
http://www.ebay.com/itm/370933275904

Kemet Axial Tantalum Capacitor 1uF 35V T310
http://www.ebay.com/itm/110831674812

Re: Lincoln Idealarc Tig 300/300 - No Joy

Tim,
sorry for the delay, I don't rx emails when there's a new post here for some reason.
Later this afternoon, I'll put some info together on the parts, I have it all on my laptop at the shop, I flipped Trevor all the procedures on pdf via email, perhaps he overlooked them.

K772 is the right pedal according to the manual, that pedal and the panel rheostat as well as my original hand amptrol are all 0-10K and the pots can be wired wrong making the current raise/lower opposite.
What I think happened with my machine, and this is pure speculation is the hand amptrol (which is all they used, no pedal) twisted up, shorting all to ground, that damaged the diode/scr board and the pc board. neither of the previous 2 owners that I know of got it working and it may have been the reason the original owner got rid of it.

I couldn't find the right pot to repair my hand amptrol yet, its tiny so a normal pot wont fit the space.

Here's the pedal I found and it works great, 0-10k, nice smooth microswitch, and fine control throughout the range, the panel rheostat setting determines the max the pedal can dish out when set to remote.

Attachment 663601

Attachment 663611


Doug

Re: Lincoln Idealarc Tig 300/300 - No Joy

Burnt Fingers (aka Doug),
Trevor (the guy who helped you earlier with the board part numbers and post-it notes) and I would definitely appreciate you posting the parts list and the tuning procedure.

Also please confirm that this machine needs a K772 foot pedal which is a 10k ohm pot. I think he's using a low resistance rheostat/slider style foot pedal based on what he described to me verbally- when he and I talked the pedal/machine was not nearby so I could verify. I think it's why he's had problems with a first and second board on his machine. I'm trying to rebuild one board and he's trying to rebuild the second.

Is it possible that someone did the same thing on your machine and tried to hook up the wrong pedal?

Thanks,
Tim

Re: Lincoln Idealarc Tig 300/300 - No Joy

Good tip for sure Wayne and thanks again for all your help, will definitely seal it up when I get the sheet metal done later this spring.
Lincoln also recommends humiseal on the big diodes and SCR
AWPMAN, the info you sent me on your transistors & photos of the board in your machine were very helpful to compare, thanks for taking the time to help me out.

Originally Posted by tprothma

Excellent work! You deserve an award for persistence.
Do you have a complete parts list. Is it safe to assume that at some point your board was working ok after replacing the failed components and it just needed the trimmer adjustments?
Thanks.

I'm a glutton for punishment but have to admit, I put the covers back on and rolled it back out of sight more than once after I'd got nowhere with it.
Irish & ccawgc pulled me back on the right track, without their input I'd still be trying to figure it out.

I never found a bad part, everything tested good, but obviously something wasn't right so my testing method was flawed & couldn't duplicate the failure, I removed every single part to isolate and finally decided after no success identifying anything bad, considering how old the parts are to just go ahead and replace everything and see if the shotgun approach will work and that did it.

will put together a full parts list when I can, all the resistors, caps, diodes I ordered from Mouser, the big diodes, transistors and scr I found on ebay.

as far as the trimmer adjustment goes, I'd say its absolutely necessary if you've changed control board parts to be sure you're getting the proper output (enough output) and then not too much as to avoid overdriving the SCR's.
The trim pot settings are worth doing even if your machine seems to be working fine, individual components change value over time, 40 years is a long time so its an easy procedure to make sure the output is still up to snuff.

Many thanks fellas! Doug

Re: Lincoln Idealarc Tig 300/300 - No Joy

Excellent work! You deserve an award for persistence.
Do you have a complete parts list. Is it safe to assume that at some point your board was working ok after replacing the failed components and it just needed the trimmer adjustments?
Thanks.

Re: Lincoln Idealarc Tig 300/300 - No Joy

Burnt fingers,
Thats great !! I have found this fourm to be very helpful on these projects. I have a Miller MM250 mig and was able to build the optional board to run my spoolmatic 30a saved 300 dollars and had some fun making it. The wiring diagrams were clear and a fellow member gave me a few tips.
The AWPman