hitachi 8290 fast high pitch pulsing

i have an hitachi 8290 , but its got a real fast high pitch pulsing noise, ive had it apart and ive done all the usual cleaning of switches and record play backs, all in input ports , but if i unplug the deck heads it stops, if i pug the head back in and cross left or right positive with any neg it stops but that only knocks a channel out, any ideas, thanks Geoff

Hard to tell what you mean. I think your saying it's an audioble noise and not mechanical?

The first thing I would check is your pinch roller because if it's slipping the take up spool clutch may be cutting in and out which will affect the sound.

it dose it on radio to, but not as loud, its def not the pinch roller, its a real hi pitch beep beep beep real fast to

Sounds like a noisey capacitor in the power supply. Have you trying using battery or DC supply?

I would check the connections on head and also check for pinched insulated head wire

still doing it on dc , head connection is good , even changed the head, it also recorded the high pitch beeping onto a tape , with out pressing record, could it be a bad record playback switch

Possibly a bad insulated wire to head or maybe a bad ground on deck too