Hitachi 51S700 proj. tv - fan quit shutting off

Are you sure that it "quit" *exactly* when the set turned off (and not "shortly thereafter)?

The fan can either be wired directly to *a* power supply (likely one that goes on and off with the set's "power") or to a temperature sensor that runs the fan in demand mode (often using a power supply that is available regardless of the set's "power"). The latter can be done by a dedicated "fan controller" (e.g., a thermistor and a transistor)

*or* by a microprocessor in the set (using temperature information from or simply running the fan open-loop -- whenever the set is powered on).

Depending on the quality of the fan and your housekeeping, the fan may end up failing prematurely. This could either cause the fan to stop rotating -- which will probably result in your set failing (the component being cooled will overheat) -- or, for the fan to get quite noisy (which you will complain about).

Hard to say for sure without having schematics for the set (or another set to observe).

Absolutely sure that it always immediately shut off when the set was turned off. Thanks, I guess I will just let it run and wait for it to fail or get noisy, if it does, and hope I don't have the set that long : ) Frenchy