BC346XT: Repetitive noise, powered off or on

[Paradox9]

THE NOISE:
It's a repetitive pulsing. It does not have a tone, almost more of a clicking. The volume and rate increases if connected to external power to a 20+Hz rate, or is at a mild 6Hz when on batteries only.

THE SITUATION:
From the moment the device has a power source connected (batteries or AC adapter) the noise starts. If the speaker is "active" in any way then the noise stops. For instance if I'm receiving a broadcast, or set the squelch to zero, or press a button and button beep occurs the strange noise is not present. The moment the speaker isn't active the noise reappears and this includes if the unit is powered off. The only way to make it stop is to disconnect the power or batteries, or power it on and receive a broadcast.

THE BACKSTORY:
I purchased this radio a few years ago, used on eBay. I powered it up and programmed 2 local frequencies and it worked correctly with no issues. I removed the rechargeable batteries, and boxed everything back up and it has sat on my closet shelf ever since.


Suggestions? I contacted Uniden support and they say it should be repairable for their flat fee if I think $69.

 

[JamesO]

Sounds like the Muting feature of the audio driver chip is not working properly.

Does the sound stop if you stop the radio from scanning even if there is not signal present?

Sounds like it will need to be sent in for repair if you cannot DIY component level repair on equipment.

 

[Paradox9]

Sounds like the Muting feature of the audio driver chip is not working properly.

Does the sound stop if you stop the radio from scanning even if there is not signal present?

Sounds like it will need to be sent in for repair if you cannot DIY component level repair on equipment.

No, the sound does not stop if I stop scanning and monitor a single channel. The sound only stops when the speaker is being actively used.

 

[Paradox9]

Sounds like the Muting feature of the audio driver chip is not working properly.

Does the sound stop if you stop the radio from scanning even if there is not signal present?

Sounds like it will need to be sent in for repair if you cannot DIY component level repair on equipment.

The noise does not stop unless the speaker is active, regardless of the mode. So no, the noise does not stop.

 

[slicerwizard]

First step is to disassemble all boards and connectors, then reassemble. If that doesn't fix it, you've probably got a failing electrolytic capacitor somewhere in the power circuitry.