.Something Different - Power Inverter Repair

[wibble]

Friends,
Got a 1000W power inverter (12VDC in ; 240VAC out)
I's a made in Taiwan model, Nikkai brand but I believe they may be rebranded in different countries.

When I got it, it was dead, I replaced a bank of input MOSFETS and a blown resistor.

Now, the inverter has got 3 status LEDs - Normal (green) ; Over Temp (orange) ; Overload (red) when connected all 3 LEDs are lit and no output.

Does anybody have an idea the likely culprit, I noticed a couple of long ICs on the board, or any tips what other components I should be checking? Basically anyone out there get anywhere repairing inverters.

[CapLeaker]

Re: .Something Different - Power Inverter Repair

For starters, some nice high res pictures, model numbers etc. would be good.

[wibble]

Re: .Something Different - Power Inverter Repair

Picture added as attachment.

MOSFETS on left hand side replaced. Original part number was FTP18N06, [59A/60V / 18mΩ] replacement part number FDP65N06 [65 A/60 V/ 0.016 Ω]

What is the procedure for checking the functionality of these devices. I have a multimeter which I believe can operate in DC or AC mode.

So there is a driver IC which switches MOSFET pairs through part of the primary of the transformer, generating an AC waveform on the secondary side. That's about what I know. Any hints appreciated!

[CapLeaker]

Re: .Something Different - Power Inverter Repair

What is the brand and model number?
Mosfets, diodes, transistors are measured in diode mode. The unit has to be turned off off course. Google how to test diode etc. there are tons of videos about that.

I wouldn't be surprised if some or all of the IC's on top and some other little transistors are shot. I bet there is no driving signal going to the gate of the mosfets. That's not going to be easily fixed.
If the mosfets you took out were shorted to the gate, that means the gate driving circuit is toasted.

[wibble]

Re: .Something Different - Power Inverter Repair

The board no. is SP1000-1200H3

The inverter seems to run on two main ICs that I can see:
1) PIC16C72A microcontroller
2) LM324N Op. Amp

[CapLeaker]

Re: .Something Different - Power Inverter Repair

I am not able to find a schematic for it. All you can do for now is to check every component from each of the Mosfet gates back to the PWM.