I have just serviced a Philips DCC 730. Replacement of the pinch rollers, belts and three leaky capacitors.
The device seems to work well, it reads the cassettes, you can see the time flowing, but no sound (neither on the rear terminals, nor on the headphone jack). I tried a pre-recorded dcc tape, there it doesn’t seem to read text data from the tape.
I no longer know where to look. Any suggestions are welcome.
Put it in service mode and you’ll probably see that it’s not getting signal from one or more of the tracks.
Try cleaning the head with Q-tips and isopropyl alcohol (at least 90% but preferably 97% or 99%). If that reduces the number of errors but the sound isn’t coming back, keep trying. Wipe the head with the Q-tip in vertical direction (perpendicular to the direction of the tape).
If all the tracks give all errors all the time, it’s possible that your head has failed (possibly the previous owner used a demagnetizer). You will have to replace it. If most tracks have no errors but one or two tracks give errors all the time, there’s a chance that it’s just dirty. Try it with multiple tapes, preferably known-good prerecorded tapes and tapes recorded with other recorders.
Most of the time, if the head is still good and you already replaced the pinch rollers and belts, the DCC730 can be repaired. The head, however is irreplaceable unless you get it from another recorder.