I just purchased my first TIG machine, a syncrowave 180SD (serial no. LB037766, stock no. 903600). The previous owner had this machine and another for sale stating that he was a hobbyist and both machine had given him trouble and he was done with them. This machine had the main board replaced, new HF capacitor and new arc points; however, the HF was still not working. Once home I started testing and discovered the following:

-63 volts unloaded output on DC stick and TIG
-77.5 volts unloaded output on AC stick
-73.0 volts unloaded output on AC tig
-120 volts output from main transformer via red leads (wire numbers 4 and 9)
-0 volts output from main board via lines 4 and 31 to the HF transformer
-Operation of stick without remote and tig with remote worked

I am concerned that all unloaded outputs are less than the specified 80 volts, and particularly concerned that it appears the main board is not outputting the 120 volts to the HF transformer.

I'd greatly appreciate any recommendations as to what I should test next as right now it seems to me to be the main board (hopefully Im wrong). If it is the main board I am curious if anyone has a schematic for it?