Originally Posted by OTAhead
KFDMs signal just went kaput a couple of minutes ago... Nothing from the transmitter.
Back on @ around 7. I wonder what happened???
In accordance with Ohm's law, when a resistors' value changes from a few hundred Ohms to several million Ohms, current flow decreases. This results in less current (and therefore less power) being produced by the IOT. Since it takes more than zero watts to make pictures fly through the air, none of the local OTA receivers could make a picture from the digital stream on channel 25 (which, of course, was not there anyway). Next question?
OK, the BS session is over (but it was fun).
Actually, the transmitter notices the lack of current flow (any one of the 8 high voltages drops close to zero), and shuts the IOT off.
I have no idea what caused the transmitter to have a momentary overload. But this shut the transmitter down. At least one of the 8 ceramic resistors in the IOT's high voltage section cooled down just enough to lose connection with its mounting clip.
Since the transmitter will not let you open the cabinet while the 480 volt primary power is "on", it takes five minutes or more just to get to these resistors. (You have to trip the main circuit breaker in order to get the "green key" you need to open the power cabinet.)
Now you can rotate the 8 resistors (verrrrry carefully) to clean the contact surface (you have to rotate all 8 since you really don't know which one lost connection).Then you have to reverse the "green key" procedure to turn the transmitter back on.
And that, in a nutshell, is what happened.