[radiotechnician]

The output of right channel rec amp board (pin 2) goes to a 5.6 mH coil L401

which is in parallel with a 470 pFd capacitor. These are on the track selector

board. This circuit passes the audio from the rec amp to the head, but blocks

the bias from flowing back to the rec amp. If the 470 pFd was shorted, or L401

was open, bias would be shunted to ground with the trap inoperative.

Insets from pages 117, 120 and 123 Akai Schematic Register Sect 0.