Hi, I have a Sony WM-DX100. Everything is working except some malfunction of control buttons on the body itself. Somehow, occasionally the walkman would fast forward or rewind if I press the play button, or play if the stop button is pressed, or in worse case it will not react at all. After running a while it functions as it should. The controls on the remote are working well without this weird malfunction. Can someone tell me what the cause is and whether the problem can be solved? Thanks.

At a guess I'd say that the flexible PCB linking the control buttons back to the main PCB is starting to fail causing short outs and misinterpreted commands.

Disassembly of the unit to establish whether it is the case or not that the flexible PCB is damaged, if so then replace with a new flexible PCB or failing that attempt to jumper wires over any splits whilst reinforcing the flexible PCB from any further damage.

Hi,

the other reason are oxidized connectors.

In early 90s SONY developed a neat system of logic control for remote controllers.
To avoid having signal line to each button (play, stop, ff, rev)
they add one signal line to a standard L+R lines,
but each button was linked through a different resistor.

This way the level of a signal going back from remote to the unit was unique for each button, so a microchip in a main unit could easily recognize which button was pressed
and start a proper action. To lower the price - they used the same rule for on-unit buttons.

but the time goes by and after 10 years or so (depending of the climat, overall using conditions, pollution etc) the button connectors started to oxidize,
at first in the remote controller (it's usually more exposed to outdoor conditions),|
later on in the on-unit buttons.
oxides have different electrical resistance than the base metal, so this way the overall resistance of a loop was changed, therefore the microchip in the main unit misunderstood
the command.
ie. if an electrical loop for a PLAY has 100kOhm resistance
and oxidized connector added another 50kOhm - it could when pressed be understood
as an FF command which loop was designed to be 150kOhm.

the more you use the buttons - the more oxides you wipe out - so afer a while everything was working fine. But not for long.

This is my idea of what is happening - I had the same thing in my old ex57
(which was hard working for a few years) and the same thing happens to some of my collection units.

You can dismantle the remote and the unit and use some contact fluids
on connectors - clean it, and it should work better.

(dd9 was old fashioned, so it works fine till this day

regards

pawel

I guess that explains one of my early 90s Sony units freaking out over the controls. Never knew that.

Thank you very much for this very useful explanation. I have several early 90's Sony walkmans and many of them behave this way. I thought it is some logic control unit problem, but I see your explanation says everything.

Marian

Good info pawel! Thnx for sharing the info! Love to see these kind of usefull explanations for problems! Have some stalled project I can pick up again with this.. Tnx for bumping it Marian...