B.
Hi-Fi REC.
It is impossible to record and playback
Hi-Fi Audio signal.
YES
Check Vcc of IC801. (Pins 34,40)
YES
Check IC801 Pin 42(Data),Pin 43(CLOCK).
YES
Do Audio signals appear at IC801
Pins 16, 17?
YES
Do FM Audio signals appear at IC801
Pin 36?
YES
Check the Contact Points of Drum
Connector if good then Replace the Drum.
NO
NO
NO
Check Audio input signal of IC801
Pins 2, 3(TU.A.), 6, 7(Scart 1)
NO
3-20
Check Power.
Check ports of µ-COM.
Replace IC801.