Panasonic NN-SD775S Error H97 (Is not Magnatron | Fuse | Door Swiches)

Although I'm not certain that there are any large capacitors (a simple consultation of the service guide says that there are) to discharge on it, yes, I practice proper high voltage and electrical safety precautions. I have done many other HV projects in the past, including the typical MOT arc welder, jacob's laddar, and the Lichtenberg Figure burner. I'm very respectful of it's power and abilities.

After analysis of the inverter board, I think it will have to be replaced. All the capacitors seem to be working (from visual inspection; no bulging tops), although I can't get a read on any of the diodes on the inverter module in either direction using the ohmmeter on max setting, which is strange. I would have expected a short on one polarity and not the other. Maybe I wasn't on the diode mode (my multimeter is a bit cheap).

@magossarah, checking components in-circuit can be misleading, as you have to take into account the rest of the circuit. For instance, if you're checking a resistor that happens to be in parallel with another resistor, you won't get the reading you're expecting.

Without knowing what's involved in the component you're checking, the only sure way is to disconnect it from the circuit, whether that's removing a fuse, unplugging something, or maybe even unsoldering one end of it in order to isolate it.

The upshot is that you can't necessarily count on getting a good reading on the diodes when they're still connected to the circuit; that may or may not be why you're not getting a read on them.