Hello, and welcome to the Forum !
The HG2300 is apparently a SIP inverter MIG/ARC/TIG welder:
Here is a link to the manual, which does include a basic circuit diagram: http://www.sipindustrial.com/manuals/05773.pdf
Is the machine still under warranty? Even if not, due to the complexity of inverter welders, apart from a basic check for loose connecting wires and harnesses or burnt components, your best option for support would be to contact SIP.
SIP have repaired under warranty once
Was returned in April of last year
And they now say it's out of warranty. It would seem the don't even guarantee their repairs for more than a couple of hours work
About as helpful as a chocolate fireguard .....