Samlex SSW-2000 Pure Sine Power Inverter Repair: Part 2

The entire DC input section is shorted. 6 out of 10 fuses were blown. These are a pain in the balls to remove being they are not socketed but directly soldered to the board.
***The gamble is for the cost of parts and my hourly labor to get the input section rebuilt. There is no way to tell if the drive circuitry for both the input/output stages was damaged. I can fix the drive circuitry boards however if I have to do that, the cost is over half of what this inverter costs new. The owner of this unit may/may not want to go ahead and repair it.

[@Speedracer415]

Hey, the guy that is 9 Years behind. Where did the 2 grounds screw in ... Please and thank you

[@Bassguitarist1985]

I dont recall. Maybe to the heat sink? Apologies.

[@ixamraxi]

Just a note, fuses *should* look like dead-shorts, so if your inputs indicate a short, that suggests, instead, that at least some of the fuses were still good (and that some *other* components in the circuit are shorted), It doesn't indicate that some of the fuses are bad. If your inputs had been open/infinite resistance, *then* it would have suggested the fuses were all blown.

[@Bassguitarist1985]

Amra True fuses show a dead short, but not wanting Murphys Law to hit me because i didn't check all the fuses I removed and inspected each one. Without the daughter board installed it did not hold the FETS to ground keeping their gates closed. Applying DC voltage to the input without the daughter board I realized only later was causing an avalanche effect and caused the resistance to lower and cause the FETS to overheat because they were not shutting off like they should in the push/pull config in the boost stage.

[@ixamraxi]

***** Yeah, removing them all, given their location, was probably the best course of action, and doing so would also indicate which areas of the board to inspect first (i.e. the areas protected by the blown fuses are more likely to have faulty components).
Watched the whole series, nice to see you were able to get it going, got lucky on that daughterboard working in the old ones place!

[@cruzincondo3395]

So, I take it that an ANL 200A fuse on the positive cable would've avoided such catastrophic failure?

[@Bassguitarist1985]

not necessarily.

[@cruzincondo3395]

OK, watched all 5 vids....overload heat/power surge blew the weakest link with domino effect. Samlex aren't cheap.....Exeltech are well made; brass posts, coated boards, direct connectors, yet hard to find......GREAT show! Thanks.

[@user-se8st1og4c]

sr what is the transistor code in input section and output section

[@gearup603]

one like. what it the part number for the mosfet power output side? irfpXXX

[@Bassguitarist1985]

IRFP4332PBF for the output transistors, and IRF3205PBF for the input transistors

[@willtomkinson8083]

Looks like reverse DC polarity damage.

[@Bassguitarist1985]

looks like it yeah.

[@user-se8st1og4c]

sr can you give me the numbers of the transistors ....

[@Bassguitarist1985]

I show the transistor numbers in another video in this series thank you for watching!