Timer Board?

[Donlee]

Hello all,

I am new to your forum and kinda new to tig welding. I had a AC/DC Lincoln stick welder that I converted to a Tig setup (scarch arc) a while back with a HF box. Last week I picked up a Lincoln Idealearc 300/300 (1979 model) Tig welder. I had to replace the water and gas hoses. It has a home made water cooler, but I have a friend who is getting me a real cooler for it this week. My problem is this. When I frist turned it on and started using it everything was working fine. After I used it a little while the Gas flow wold not shut off. You could hear a buzzing shound while while the gas was flowing before and the buzzing would stop when the gas flow stopped. Now the gas flow and the buzzing stays on all the time (no matter where the timer knob is placed). If the maching is off there is no gas flow so I don't think the valve is stuck open. Also if I switch the machine to stick the gas does not flow and there is no buzzing. I checked and its not the High Freq. buzz either its a louder buzz. I have a wiring diagram of the welder but it does not break down the timer switch. I was thinking that I could test the compants on the switch and replace whats bad. I can order a new timer ($155.00) retail from Lincoln but I would like to know for sure before I buy one. I would like to fine something a little cheaper (like used) or a wholesale supplier for the parts for this machine.

[gnm109]

Hello all,

I am new to your forum and kinda new to tig welding. I had a AC/DC Lincoln stick welder that I converted to a Tig setup (scarch arc) a while back with a HF box. Last week I picked up a Lincoln Idealearc 300/300 (1979 model) Tig welder. I had to replace the water and gas hoses. It has a home made water cooler, but I have a friend who is getting me a real cooler for it this week. My problem is this. When I frist turned it on and started using it everything was working fine. After I used it a little while the Gas flow wold not shut off. You could hear a buzzing shound while while the gas was flowing before and the buzzing would stop when the gas flow stopped. Now the gas flow and the buzzing stays on all the time (no matter where the timer knob is placed). If the maching is off there is no gas flow so I don't think the valve is stuck open. Also if I switch the machine to stick the gas does not flow and there is no buzzing. I checked and its not the High Freq. buzz either its a louder buzz. I have a wiring diagram of the welder but it does not break down the timer switch. I was thinking that I could test the compants on the switch and replace whats bad. I can order a new timer ($155.00) retail from Lincoln but I would like to know for sure before I buy one. I would like to fine something a little cheaper (like used) or a wholesale supplier for the parts for this machine.

The first thing I would do would be to open the macnine up and give it a thorough cleaning and blow down with an air nozzle. Next I would take a look at the potentiometer on the timer function. On my 250/250 this knob is at the lower left area of the control panel. I would try some contact cleaner, the type that evaporates like Radio Shack and see if the pot isn't simply dirty.

I would also want to look at both the gas solenoid and the water solenoid for proper operation.

Another issue might be your method of control. Are you using either the hand Amptrol or the Foot Amptrol? Those also have a 10K pot inside. I know, the print says 5K but it's wrong. I'm in the process of building a hand amptrol and I'm reverse engineering it from my foot control. That has a 10K pot with a microswitch start switch. If that pot is dirty, you could have bad results also.

If none of that works, I would contact an independent Lincoln serviceman and see about a house call to diagnose the problem. It could be very difficult to test the timer board without a test procedure and, even with a consultation fee, someone who knows the machine could save you a lot of money. Sometimes, they have salvaged parts available also. I say this because there is such a shop in my area. The fellow will come to your place for a fee and, for slightly less, he will diagnose at his place. Such a service could be a money-saver in the long run. There's probably someone in your area that knows these machines. When all else fails, I guess you could contact Lincoln for some leads..

When you get that machine fixed, it will be a winner. The 300/300 has a 60% duty cycle and lots of power.

Good luck.

[Donlee]

Thanks for the info. I will check those things and see.

[awright]

All good advice above. Donlee, the first thing to do is determine whether the problem is in the gas solenoie or in the timer board. A little work with a multimeter will answer that. Be careful if you are not used to working inside electrical equipment. It's generally best to turn off the equipment, attach your test leads, get out of the machine, and turn it on and exercise the function to be tested.

If you confirm that the problem is in the timer board you might consider installing an off the shelf "Off-delay" timing relay. These are available from Grainger (www.grainger.com) in plug-in base or quick-connect tabs, 115 VAC or 24 VAC in the $20 to $60 range.

Can't make any specific recommendation without more detailed knowledge of the control voltage and detailed control functions. In general, you might be able to bypass the built-in gas solenoid time delay circuit and install the Off-delay timer instead. Give more info if you want more detailed advice.

awright