HD3070 Hypertherm plasma torch power supply Chopper board issues.

This is a nightmare problem. I can only hope that someone somewhere has seen this before. We have an AKS Machine rigged with a Hypertherm torch and power supply. The HD3070 has been obsolete for many years now. Hypertherm will no longer support any part of the machine. Unfortunately this was our fastest and biggest producing machine and I needed to find a solution a month ago and still do not have one. It was cutting fine one second and the next it started to cut poorly. After troubleshooting we determined that the chopper board was only putting out 130 of the possible 280VDC. And the red fault indicator light was lit. The chopper board test procedure in the book states • Place voltmeter across output terminals of chopper (positive lead to (+) WORK and negative lead to (-)
TORCH and press the START command.
• If the voltmeter reads +280 VDC, then replace control board 1XPCB3.
• If the voltmeter reads 0 volts, then replace chopper module.

We get from 84 to 130VDC out and the fault indicator is on and wont go out so We assume the chopper board is bad. There are none available from hypertherm so we went searching for solutions we purchased two supposedly working HD3070's from E-bay at decent prices. One of them had been chewed up and nested in by rats and after extensive rewiring I could not get it through the start up procedure. 24VAC was not going to or returning from the external interlock and that's where startup failed. Pins on the plug were jumpered out as per the book recommendations. So we took the chopper board put in in our unit and tried to cut with that. We found that chopperboard to be bad also.

We hooked up the third unit and it cut exactly the same was as the first unit did. Looking at the chopper board we had the red fault indicator lit. The sellers of this machine swear it was working when they removed it from their system. We sent this board out to have it repaired. When it came back, We installed it without hooking up the controller card or the board output. It came to up to a green status ready light and put out the required 280VDC. We then hooked J9 from the controller card to it and tested it at 100 Amp setting. We had 280 volts which dropped to 130 then returned to 280 when the torch was shut off before dropping to zero. To me that says the controller card adjusted the output as it was supposed to and everything looked ok to hook up the output of the board.
So we hooked up the output and ran a cut test. It cut poorly for about 2 seconds before it shut down the torch and blew the chopper board again.

At this point, we either have two machines from different parts of the world with the exact same problem or there is something wrong with our welding leads that is shorting out the chopper board. Just to continue troubleshooting and have some chance of fixing this we have to either find the issue and resolve it, or replace the $15000.00 welding cable leads have the controller card (just in case) and the chopper board assemblies repaired, another $5000 and hope we fixed the issue. I have no other solution for my employer, its gamle with $25k or replace the unit entirely, possibly $100K.

I've looked over all the cables from the power supply to the torch. There is no visible damage. No pinching, no scorch marks so smoke or bad smells. A lot of it is sheathed,and I cant inspect it directly. I've been unable to get the torch itself apart to remove the cables so I can unsheath them for a visual inspection or meg test the cables. Short of that I do not know how to verify the lead cables are ok. There are no shorts to ground that I can detect with a meter. Has anyone ever seen this before? and is there any other way to verify the cables are good?