Idealarc tig 250 high frequency problem

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I've recently acquired an old Idealarc tig 250. It worked in all modes (very well), but yesterday, I noticed the high frequency portion is not working at all. The welder appears to operate very well in all other modes (DC, Stick in AC and DC, and normal tig), but lacks any high frequency start or run. In fact, it's nearly impossible to weld in the AC tig mode as a result. I've checked all switches in their correct setting (I even checked to make sure the spark switch was working correctly with an ohm meter), I've checked the spark gap (which is fine). Lincoln tech did not provide any useful ideas or tips, so I'm asking:Where would I start to trouble-shoot this equipment so that I get the high frequency part to work correctly (I've got some limited electrical and electronic skills and knowledge)?
Reply:Originally Posted by blueovalzI've recently acquired an old Idealarc tig 250. It worked in all modes (very well), but yesterday, I noticed the high frequency portion is not working at all. The welder appears to operate very well in all other modes (DC, Stick in AC and DC, and normal tig), but lacks any high frequency start or run. In fact, it's nearly impossible to weld in the AC tig mode as a result. I've checked all switches in their correct setting (I even checked to make sure the spark switch was working correctly with an ohm meter), I've checked the spark gap (which is fine). Lincoln tech did not provide any useful ideas or tips, so I'm asking:Where would I start to trouble-shoot this equipment so that I get the high frequency part to work correctly (I've got some limited electrical and electronic skills and knowledge)?
Reply:i have a square wave tig 175 that is doing th exact same thing.i have looked at the manual and inside the machine but i can find the problem.called one place local that wants $95 to look at it.amptroler looks like its working gas comes on and power can be controled but wont tig till i  scratch start.thanks
Reply:a fews years ago mine (idealarc 250) let me down also took to the repair shop and they found the hi freq board bad  cost  $250 with labor i did see a burnt resistor on the board but what made it go bad ??? so we just replaced the whole board  GOOD LUCK
Reply:i was looking at that board but its buried in there and i did not want to pull it apart.ill take a second lookalso are there any web sites where i could order this part if it looks like its blown?thanks for the help
Reply:the board is easy to get to if you remove front panelif i remember its behind the louvered panelmake sure to UNPLUG MACHINE
Reply:will do thanks
Reply:I had the same problem with my mid 80`s 250/250 tig  found that the hf coil that transfers HF to the weld leads (big aluminum coil with a small copper wire coil in the center) small coil windings burnt out.Couldn`t find a replacement part so I modified a blue machine part (wired it in following wiring diagram compared from both machines).works perfectly now.  PS. blue machine part is smaller in size and still available from factory,as of 2 years ago anyway.1979 LINCOLN SA-200 (FOR SALE)1954 LINCOLN SA-200MILLERMATIC 200LINCOLN 250 TIGLONGEVITY 60 IPREMIER POWER WELDER ON 4X4BRONCOVICTOR WRENCH