I'm trying to fix a circuit from a waterboiler in my RV from 1982 (truma BO 128). It is responsible for opening the gas valve, creating sparks and monitoring the flame. The problem is that the voltage of the sparks is too low to jump the spark gap on the board.
I checked all condensators and diodes. They all seem to be fine. There are two components which I can't identify:
Both have three legs:
- Component on the left: the diagonal legs are shorted. The other ones have 160 Ω resistance.
- Component on the right: only the two left legs are connected on the board. They are shorted. On the top is the high voltage connection to the spark gap inside the burner. The legs on the bottom have 134 Ω resistance to the spark connection.
I'm also unsure what creates the high voltage. I would expect a transformer, but can't see anything like this.
Best Answer
The gray part should contain transformer and possibly a multiplier.
It's encased in plastic and epoxy to avoid arching to PCB and between components.
You should be able to identify exact type, by measuring resistance between output and both input terminals in both polarities. Either way, listen for arching noises inside it when the spark should jump but doesn't. That's a clear sign it's failed.
As for the black component i can't answer.