Sony Car Stereo Front Face Plate Buttons Not Working

[GT250]

Even'n all,
My car has a Sony (3 years old), super dooper car stereo pre amps outs etc, fitted.

The front control buttons are not doing what they should be doing....

From eons ago, the car was fitted with a Sony front head unit and a 10CD stacker, sub woofer and 6 speakers etc..

When the first head unit gave up the ghost, i went to purchase another unit -only to find out that a different head unit would need re wiring etc.
However, a new Sony unit would plug straight in! So i got another Sony.

On the last legs of the second head unit (some buttons not responding), i then heard (urban rumour maybe), that the Sony head units always fail, crap quality etc.

The third Sony head unit was stolen after approx 1 year of usage!

Anyway, i bought another Sony head unit 3 years ago, a CDX-F7710.

We live near the coast and i have noticed that over time (with the buttons i rarely use), they started to get a crisp depression feel to them.

As the 10cd stacker carrys most of the music i listen to, i don't often press the buttons on the face plate.
I only have 4 radio statins that i listen to.

However, what has been happening lately is that when i press the OFF button, it changes to CD. Only repeatedly pressing the buttons (and hearing a bleep bleeps as the face unit acknowledges the press), does it turn off.

Other issues are pressing track forward will change the Cd. Pressing track back will work one time, but other times will change Cd or turn off the DSO.

Pressing Cd up will change tracks and then pressing Cd down will make the Cd change up or visa versa...!!!

Sometimes pressing a radio station will not change the station at all, unless repeatedly pressing 5-10 times...

I took the face plate off a few months ago and undid the back of it.
All the buttons press goto mico switches on the PCB.

I have sprayed with IPA Cleaning Solvent into and around the switches and it has made no difference.
I have cleaned all the Head unit to Base unit contacts with ISO Propol etc...

From my understanding the mico switch has only to make contact. So if it makes the contact, where is the problem?

Thanks.

[mickstv]

Hi GT250, Did you meter all the switches because they may have started going resistive basically the nice clean contacts tarnish. So get the old meter out and maybe move some of the working switches into the non working spots just to make sure it is the switches.

Normally spraying contact cleaner wont have any effect because it doesn't get into the contacts.




Mickstv

[GT250]

Hi GT250, Did you meter all the switches because they may have started going resistive basically the nice clean contacts tarnish. So get the old meter out and maybe move some of the working switches into the non working spots just to make sure it is the switches.

Normally spraying contact cleaner wont have any effect because it doesn't get into the contacts.




Mickstv

Yeah Mick you're right about the contact cleaner not working...

I haven't metered any switches actually. Can i measure the suspect switches whilst on the PCB?

Didn't want to (the worry of messing it all up), start soldering off switches..
Surely i might as well buy some new switches if i'm going to unsolder them eh?

When i do press a button (after not using it for say weeks), it does have a hardness and resistance and then that 'click' to it. And if i keep pressing it repeatedly it does perfom the function it was meant to do...

So what you're saying is that even though the switch has made contact, the resistive value is being looked at by the main IC?

I have some (damn expensive), Wurth Contact OL - Oxidation remover. But i didn't want to risk it on face plate as it has warnings about possible damage to certain plastics etc.

BTW Mick: If you haven't tried this Wurth Contact OL stuff, it's amazing. Any green copper oxide on copper contacts - spray and watch it all become shiny again! Brilliant stuff!

I'll have another look at the switches tonight...

[mickstv]

Hi GT250, Yeah the switches generally have to be zero resistance when pressed and you can measure them in circuit. If they are a non-standard size you should be able to buy them via "Speedy Spares" but maybe check them against what is listed in the WesComponents catalogue.


Your right Wurth products are expensive but the do have a really good range of product and the quality is good.