Need help for the repair of a Sony Bluetooth speaker (SRS-BTX300)

[VA3HDL]

Hi,

I followed the advice on the thread in this same topic for the repair of the Sony Bluetooth speaker SRS-BTX500 adding the 1 MOhm resistor. I have the BTX300 and the two models are almost identical.

It seems to help to turn on the device, however, it turn off itself after 10 seconds of running with a fully charged battery and refuses to turn back on.

To turn on again I have to disconnect the battery, wait a day, plug-in the battery again and push the power button, works for about 10 seconds and quits again.

I did a physical inspection, checked all push buttons and switches working as expected, nothing wrong at first sight.

Any advice on how to continue the troubleshooting is very welcome.

Thank you.

[m k]

A day is probably too long for cooling, but it can be needed for discharging.

[Koray]

Hi!
I have done this repair on one btx-500 and two btx-300 devices. They have been fine since then. Maybe if you post some photos of the actual circuit board there may be more help from experienced friends here.

K.

[DavidAlfa]

Try something: Turn the speaker on and disconnect the button board.
If it keeps working normally, that's the fault!

Then check the resistance between each button contacts, must be MOhms or infinite.
Moisture gets in after the years, developing a low resistance path.
I've seen buttons measuring few KOhms while not pressed down..
Try soaking them with contact cleaner and pressing them like there was no tomorrow so they clean up.

[Koray]

Try something: Turn the speaker on and disconnect the button board.
If it keeps working normally, that's the fault!

Then check the resistance between each button contacts, must be MOhms or infinite.
Moisture gets in after the years, developing a low resistance path.
I've seen buttons measuring few KOhms while not pressed down..
Try soaking them with contact cleaner and pressing them like there was no tomorrow so they clean up.

Exactly! In one of these speakers I also experienced this problem, now I remembered! Sometimes buttons develop low resistance path. Try this. :-)

K.

[VA3HDL]

Thanks everyone!

I followed the advice of cleaning the push buttons and it didn't make any change, they all had infinite resistance while open and less than 1 ohm when closed.
However, while I was cleaning and checking the buttons I removed the connector of the sensor on the side standing leg and voila the device turned on and started working perfectly.
I've attempted to clean the micro switch sensor on the leg but not matter how hard I tried every time I was plugging it back (open or closed) the device was turned off.
I've checked and I didn't find anything wrong with the circuit, the components, etc. The switch itself had very high resistance in the order of 5 MOhms when open, I presume should be infinite.
So I just removed the sensor altogether. I believe the only function was to turn off the device when the leg is closed, since the speaker is now turning on and off with the power button as it should.

Thanks again for all posts.
Pablo