Hello,
I am trying to repair a Honda Eu20i Inverter Generator. The engine runs fine and the alternator seems fine as well (low resistance between windings and 300v between phases when running)
The board also seems to be working to a degree, the "Economy" function works and slows the engine when there is no load. Unplugging the board makes the generator run out of control and bounce off the rev limiter.
When plugging in the alternator to the board, voltage drops from 300v down to 1.7v. Sometime I can't get the generator started with it plugged in (bogs the engine down and wants to stall). So I'm thinking there is something wrong with the rectifier or a mosfet.
The board is completely potted. I've de-potted boards in the past with heat, but this substance is immune to heat. I've had to use Dichloromethane to slowly remove the potting. It only come off in 1mm layers and the potting is about 10mm thick...
I've uncovered some circuitry, but have come to the realization that all the the power components are under the board and somehow attached to the heatsink alloy case. I think manufacturer has screwed all the mosfets and diodes to the case, placed the board, soldered the legs and then potted the whole thing.
Is there any hope for this?