My first thought is that perhaps the generator isn't powering the 12 volt system at all - perhaps that's still running off the battery. You can check by using the panel that shows the status of the battery (in mine, it's above the sink) - if the generator is actually charging the battery, the battery status should be all the way at the top. Another way to tell would be to disconnect the battery while the generator is running and see what happens - if the generator shuts off then it's not powering the 12 volt system.The problem they are having is they cannot get their generator to power anything over 12volts. When they plug in to electricity at a campsite everything is fine. but when they unplug and turn on the generator it will not power any of the electrical outlets, ac, microwave, or any of the things they need. Can you tell me is their a switch the need to hit to turn this function on or off? or does it sound like they have a problem with their B190 and need to take it somewhere to have it looked at?
If the generator isn't powering the 12 volt system either, then my first thought is the transfer switch under the couch. It's an automatic transfer switch that selects between shore power and the generator, and you should hear it click over when the generator starts. It's possible someone replaced it with a manual switch, too. If you look under the couch, you should see an electrical box behind the drawer - that's the transfer switch.
Another possibility that occurs to me is that perhaps the generator isn't producing 120 volts, and it's enough to power the 12 volt converter but not enough to run the outlets or something. But the problem with this theory is that the transfer switch shouldn't flip over until it sees 120 volts, so the converter shouldn't work either.