hifi engine

Realistic STA-90

This is my first post, please be nice...
I have in for repair a Realistic STA-90 receiver, I'm losing FM radio after about 5-10 mins, all the other inputs work OK.
Have found dry joints on TR801 & TR802, have resolder these, the fault is now more intermittent.
The FM does come back after 2-3 mins of going off.
Has anyone had this fault before.

Re: Realistic STA-90

I would first check/replace all the capacitors around TR801. If the problem was still there I would monitor the 12 volts out from TR801 (I think it's a negative voltage with respect to ground). If this voltage drops then the zener diode may be failing.