All the mechanical functions of this cassette deck worked but there was no sound and the PPM display was blank. Recordings could bot be made either, and it was soon discovered that the 7V bias supply was absent from pin 5 of both Dolby NR processor ICs 2IC101 and 2IC201. The cause was 2C3 (220uF 10V) which was short circuit. This is a common fault with the smaller Beocord models (Beocord 4500 etc) but is is seldom encountered in the larger ones. [Beocord 8004]