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Up Topic Welding Industry / Technical Discussions / HF start problem on Linde 250HF
- - By yalisan (*) Date 06-10-2003 00:44
I have an old Linde 250 HF welder that seems to work fine except that when trying to start the arc during tig welding I have to touch the base metal to start. I know that the machine is setup properly because I have the manual for it, I have adjusted the spark gap to proper specs, any advice on what to check will be appreciated.

Thanks
Parent - - By aircraft (**) Date 06-10-2003 07:56
Look at your points gaps and push your pedal down, you should see the HF kick in and arcing across the points. If not more than likely the caps are bad.
Most OEM caps are not that good to begin with. replacement caps are much better (like from Grainger). If you can get 10 years out of the OEM caps you have done very well.
Parent - - By yalisan (*) Date 06-10-2003 21:26
When you say caps, do you mean the "points"? If yes, I took them out to check them and they do look to be in real good shape, but any way I will do the check that you suggested. Thanks,

O. Sanchez
Parent - - By 357max (***) Date 06-10-2003 22:33
Aircraft is probably referring to capacitor bank. They look like a six-pack of beverage cans.
What gas, amperage, tungsten type and diameter are you using. Argon starts easier than helium or argon/helium or helium/argon gases. Tungsten is a poor conductor of electricity and it needs to be "hot" to be a good starter. Use the smallest tungsten for the amperage you are welding. In other words, don't use a 1/8" tungsten to weld 1/16" material thickness at say 50-75 amps. Don't use thorium alloyed tungsten for ac. Use pure, zirconium or cerium.
Hope this helps.
Parent - - By yalisan (*) Date 06-11-2003 00:10
I did what Aircraft said to do and got some nice sparks across. Now I'm not yet familiar with my machine but I am using 3/32 tung 2% to weld (learn) .032 aluminum with pure argon. I don't know how to adjust for a specific amperage yet. The options are 5A min, 35A min, 70A min and the fine tune knob. What are the ranges within each setting?? Once again thanks,

O. Sanchez
Parent - By 357max (***) Date 06-11-2003 02:13
0.032 Aluminum would need 20 - 60 amperes alternating current. Set your coarse range as low as possible to provide this amperage. And then adjust the fine current adjustment to the amperage needed for penetration and travel speed. To weld at this low amperage requires an 0.040 or 0.0625 (1/16) inch diameter pure (green color code) tungsten. The 2% Thoriated Tungsten is difficult to start at low amperages on ac.
Hope this helps.
Up Topic Welding Industry / Technical Discussions / HF start problem on Linde 250HF

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