The power in my car (1990 Accord) randomly turns off for a split second, turning off my radio, and my spedometer, ect... Usually happens when i apply the brakes, or hit the turn signal..Some days it happens 5 or 6 times in a row.. other times i can go all day without an incident, its driving me nuts i cant find it. It's like its an overload of power or something. I have no problem starting the car though and I checked all connections to the battery. Is this an alternator issue ? if so.. why is startup so easy? Thanks !

 

I doubt the problem is the ALT. or BATT.
I'd think there is a wire touching ground "somewhere". LOL
Maybe watch the wire harness down by the brake pedal arm, to see if moving it can cause the problem, or wiggle the turn signal/light harness where it exits the steering column shroud.
any other recent work been done to the car/ other electrical problems?

 

Make sure your battery cables are clean and tight at the battery terminals. Follow the ground cable down to where it's bolted to the engine/trans. Look for major corrosion at the end of the cable. You may have only a few good strands left.