Lincoln Idealarc Tig 300 # 4474 78 faint sparks at the stinger. same on AC

[Redarc]

Hello to all members of this Lincoln forum. I need help in troubleshooting my welder. I tried to contact several members who succeeded in repairing their thru persistence but have not got an answer. My machine has 35 volts at the output terminals, enough to give faint sparks when trying to stick weld.The AC tool receptacle works. I changes the diodes on the SCR card some were bad. Since I have very little knowledge in electricity, I need someone who could identify for me the different composants which need testing. I can send you a picture since the covers are off and you can highlight for me which is which by name and location. I have the diagnosing procedure sent by Lincoln so I can start testing. Thank you for your help, support and understanding. Sincerely,
Redarc

[ccawgc]

Double check the line voltage setting next to the big contactor on the right side on the welder. If you are trying to run it on 230 volts, make sure the welder is not set for 460 volts. Welder will not operate if all voltages are 1/2 of what they should be.

[Redarc]

thanks for your reply. I moved the input power to 220 5 years ago and had used it without any problem. I got a 17 pages trouble shooting guide from Lincoln for that machine but i am unable to identify the components that I am supposed to test. I would need someone to walk me thru the whole testing procedure in order to get somewhere. I have the basic volt amp continuity tester. I replaced the SCR bridge with the diodes. I am still looking for someone to test and repair the PC board. I had it check by some clowns who told me after I got it back that they did not have the proper equipment to do a complete check but found out the fuse holders were bad and changed them. I am getting full 120v at the tool receptacle and 35 v on my output power (stinger) I really want to save the old lady. All I am getting are faint sparks even on high in stick mode and a little more sparks after disconnecting the PC board. Last summer I used it it worked ok while doing TIG and then no more arc. Never worked again. The electrician who changed the diodes told me 2 or 3 were bad. Thank you for you help.

[ccawgc]

The 35 volts bothers me. you should have 65 to 75 volts AC or DC. at the weld terminals. contactor on HF turned off. These units use a reactor that goes to minimum if control current is removed. More control current = more weld current.
If no current is being draw from welder voltage should be 65 to 75 volts.
Try finding the transformer leads. one end is on the range switch swing arm. the other can be tested by putting the welder in AC and measuring at the electrode terminal. with 120volts at the service receptacle. the primary is ok. but with only 35 volts OCV at weld terminals is a problem. you need to get as close to the weld transformer lead connections as you can. if you still have 35 volts. then the transformer is bad.