Troubleshooting Mitsubishi Heavy VRV System

[Cofreth]

I have a problem with a Mitsubishi Heavy Industries VRV system. Condensing unit malfunction,control card green light blinking,inverter card green light blinking and LED3 lighted,contactor energise but nothing in the condensing unit is running.There is voltage at compressor terminal,each cable to Neutral reading 300Volt except one cable reading only 40 Volt AC current.After inspecting all other component,found power transistor top part cracked.Suspect that is the fault,replace a new set of power transistor,system and compressor run,check compressor running amp, one cable 21amps,another 16amps and last cable 7amps only,is this normal?After running this air-con unit 24 hours for 2 days,system down again, found 2 pieces of porcelain resistor burnt,advice from distributor to replace the porcelain resistor and diode too.After replace the above parts,before turn 'ON' power, found inverter PCB one of the circuit sending signal to power transistor the tiny transistor was burnt. Therfore,I went back to the distributor and purchase a new inverter card,after fix in the new inverter card and turn 'ON' the power,observe the green light from inverter card blink for few seconds,again the tiny transistor of the new board burnt again. Anyone has any clues about this problem? Thank you.

[frank]

I can't say that I've any experience trouble shooting Mitsi Heavy VRF but with any inverter PCB if the neutral is not good you will fry the board. Have you checked the neutral?

[Cofreth]

Have tightened all electrical terminals in the control.
Distributor came to troubleshoot the equipment,after a hard day of trying, they have in total burnt another 8 pieces of porcelain resistor and a power transistor, the explosion was so..loud.
The minute the power to condensing unit turns 'ON' and after waiting for few seconds,the contactor energize for 2 seconds, the contactor de-energize and the porcelain resistor became open circuit. Their solution cliams that something is shorted in the control panel and need to replace the entire control panel.
My decision now is to convert the entire system to a conventional compressor system running DOL on a 3 phase 415 volt.I have check the indoor ceiling ducted fan coil unit.Found an electric step valve (look like those use in Daikin multi split unit) with 5 wire, wonder how to make this valve fully open without the PCB,thank you.