I have a Panasonic RQ-DP7 with a strange behavior. I originally got it with severe corrosion damage and a blown fuse and diode. I did a full service and restoration and replaced all SMDs. It then ran just fine.
Recently, I picked it up again and noticed that it did not run on AC power (totally dead). It did run on battery power, though, however: it ran twice as fast. Whenever I press any button, the device seems to go through its correct motions: it attempts to play, fast forward etc. However, no sound is heard and the motor is noticeably louder as it is apparently running about twice as fast as it should. The incorrect tape speed is visible through its window.
I assumed corrosion creep as I had not originally washed the entire PCB and reexamined it, beeping out every via and cleaning it again. No dice. It still runs much too fast.
Has anyone seen this behavior and may hazard a guess on where to start looking for a fault?
The high speed error could be the result of corrosive damage of the lower board nearby the single electolytic capacitor. It is a known fault and as a result the motor speeds up. Please read all the messages for Philips DCC 130 which should be clone of your panasonic.
To fix this error a wire patch is needed. I had this error with two of my units after replacing belt and capacitors.
Please check in forum this header for placement of the patch:
This fault as far as I remember results in analog mickey mouse playback but the player looses digital playback ability at all… wont,t be able to read at such a high speed.
If applying the patch be careful. The via must be blank and flux must be used to make connection.
Spot on advice, Michael, thanks. Fix was quickly done and worked like a charm. Another device saved from the bin.
By the way, the fact that it did not run on AC was due to a blown diode, one of those I had replaced earlier. Not sure, but this fault may have been unrelated.