Greetings, I recently purchased a used non-functional PowCon 300ST tig unit. Initial inspection has shown RV1(part # 902011-003) to be blown. All that was left of it was two legs sticking out of the pc board. I have the service manual, but it only lists the part number and no other description of the specs on the device. PowCon has been less than helpful giving me a description. They will only admit that it has a175V rating. No info on the current spec. They would rather sell me the replacement at $12 plus shipping/hassling. I suspect the part is only about $2-$3 since it's just a simple varistor. Any body have a similar unit they could get some numbers off the device? It appears the 300SS and 300SM use the same component. Thanks in advance.