Electrical probs on 90' 240SX

[240SX New2Me]

Hi, Im new to this board. I recently bought a 90 240SX, automatic trans (though I dont know why anyone would make this car automatic!) I love this car, it really hauls a$$, but I have been having a few problems with my dash display.

When I start the car from a cold start, the entire dash is shut off, and since the speedometer is a digital display, if the dash has no power, I cant see how fast Im going (no speed needle). After driving for between 10-20 miles, it will usually turn on, and doesnt seem to have anything to do with hitting a bump on the road, or tapping on the dash or anything normal, its just a strange intermittent electrical problem that no one seems to be able to fix. Ive had all the wire connections checked, and no one has any replacement dashs for the automatic 240, which has a heads up display of the speed on the windshield.

Does anyone have any ideas, suggestions, comments, or any other information that might possibly be able to help.

I think I like driving this car too much, and Im driving with a bit of a heavy foot, so not seeing how fast Im going and occasionally breaking the sound barrier doesnt seem to be the safest way to travel on the planet.

Thanks.
-NewNissanGuy