Mine does the exact same thing. Blows #73 fuse. Still no fix however from everthing I'm reading indicates Ign Sw bad. Less than $50 and easy to fix. I'm going to try this eventually. Will report back. Think of this. It's normal for radio to turn off every 20 min w ign SW off. With shorted Ignition SW the radio can't tell tell that the power is on. I'll let you know.