Philips DCC130/Panasonic DP7: Strange PLAY button malfunction

Recorders, Players, etc.
1

I am hunting a strange malfunction of the PLAY buttons on two of my 1st gen-portables: a Philips DCC130 and a Panasonic DP7. Both exhibit a similar, but not fully identical problem.

On both machines, the PLAY button does not work reliably. On the DP7, pressing PLAY in OFF mode will cause a “shuffling” sound to be heard as if the machine is trying to start but doesn’t succeed. If it’s already ON, the PLAY button will either not work at all or induce the SKIP back one song function. Here’s a video of what’s going on (turn up to volume to hear the “shuffle”):

Link to video

Strangely, on both machines, the PLAY button on the remote works just fine. Also, all other buttons on the machine work fine.

On the 130, the PLAY button does the same shuffle in OFF mode, but usually works well when it’s finally on.

I was about to consider simply a worn-out button, but the “shuffling” seems to indicate that the button actually does click electrically. There’s possibly something else going wrong here.

Any idea what might be going on here?

2

Hi,
I have seen dirty switches, causing strange behavior, but it could also be that while pressing play, another/multiple buttons are pressed at the same time.

It is fairly easy to take the cover off, by removing 4 screws and check underneath.
2 screws on the left and 2 on the right hold the cover to all switches.

3

Thanks, Ralf. Since PLAY engaged through the remote and the on-device buttons goes through two entirely different electrical routes, and since the on-device buttons make use of a resistor ladder to signal IC500 which button was pressed, my first guess is that there’s something wonky with the resistor ladder. I’ll check its values first and also the two transistors connected to it. Maybe I can dig something up here.