Thank you for your advice, which I am reading only AFTER the fact, because I had already moved my butt towards the bench to fiddle with this thing... but I more or less did what you suggested....
First I popped the cover, disconnected the battery terminals (couldn't remove the battery itself though, it's stuck in there
) and measured voltage. 1.0V, not a lot !
So was probably dead. I tried recharging it with the lab supply you never know, but it failed to take any current no matter what voltage I applied... went up to 30Volts the max the supply will do, still not a single electron willing to flow into that battery.
So the battery is dead, open circuit.
So instead I powered the inverter from the lab supply rather than from the battery, limiting the current and increasing voltage slowly.... but nothing happens.
Pressing the button on the front panel doesn't help, no LED activity, and the board just doesn't draw any current at all, it's dead as a dodo.
Of course I checked on the output mains socket, zero volts coming out either.
So.... dead battery and dead inverter board, not a good start !
So did some disassembling, pulling wires connectors and unscrewing lugs... so I could flip the board to have a close look at the component side.
Tried to take a half decent pic of the board for your immense pleasure. I know squat about inverters and of course there won't be any schematic.
I looked around... can't see any obvious sign of component failure or over heating...
All I can see if that the buzzer is damaged/missing : its cover/top part came off and inside was... nothing. The piezo bit is not in there anymore... I don't know, guy who hacked that thing probably damaged it in the process
I can't see any CPU on the board. It looks 100% discrete through-hole design with a bunch of jelly bean DIP ICs as you can see. 9 of them.
- 4001 (NOR gates)
- 4011 (NAND gates)
- 4013 (x2) dual flip-flop
- 4066 (quad analog switches)
- LM339 (x2) comparators
- Good old LM317 !
- UC3524AN (PWM controller)
As for transistors, we have 5 of them, all 50N05.... 50 Amps 0.022 ohm N-MOSFETs ! Boy at the least I can salvage those !!!
4 come in TO220 packages, organized as two pairs, each pair being mounted on its separate heat sink.
Then the fifth comes in a very large plastic package and is a lone wolf, mounted on a different heat sink, same heat sink as the LM317.
- A 40A Fuse, in an automotive style package ?!
- x3 relays
- a small transformer, I guess to power the board and recharge the battery.
- a big ass transformer mounted to the chassis which obviously is driven by the inverter and powers the output mains sockets.
So it doesn't look like rocket science ? Maybe I could spend a couple hours probing around, maybe I can fix it... and even if I can't it's still fun trying to anyway...
Since it's a " No Power " issue at first glance, with some luck it's fairly simple...