We got very sick baby here, looks like it had quite a fall or tumble. Main board is cracked in few places. Lets investigate and work on it to fix it to its former glory
Specs
Type: 2-head, single compact cassette deck
Track System: 4-track, 2-channel stereo
Tape Speed: 4.75 cm/s
Heads: 1 x record/playback, 1 x erase
Motor: 1 x capstan, 1 x reel
Tape Type: type I, FeCr, CrO2, Metal
Noise Reduction: B, C
Headroom Extension: HX Pro
Videos
VIDEO
Part 1 of the repair
VIDEO
Photos
Beautiful Harman Kardon hk300xm
Harman Kardon hk300xm inside top view
Harman Kardon hk300xm inside main board view
Harman Kardon hk300xm inside powersupply board
Harman Kardon hk300xm inside powersupply and control boards
Harman Kardon hk300xm inside tape mech and control board
Harman Kardon hk300xm inside tape mech and control board motor speed adjustment
Harman Kardon hk300xm inside level adjustment
Harman Kardon HK300XM crack in the main board
Harman Kardon HK300XM crack in the main board bottom side
Harman Kardon HK300XM crack in the main board bottom side near relays
Harman Kardon HK300XM crack in the main board bottom side near relays
Harman Kardon HK300XM inside control board close up
Conclusion