IC-R10 Distortion in audio on AM SSB and NFM

[jim44444]

Hello, recently purchased a second hand IC-R10 receiver but there seems to be a problem with the audio distorting when i turn up the volume button. It works ok in WFM mode when listening to radio stations. I've made a couple of videos of it happening.

Distortion using USB

Distortion using NFM

Tried enabling the ATT and still happens. Any help would be much appreciated.

 

[kruser]

What does NFM mode audio sound like when you are tuned to an actual fm or nfm signal like say a NOAA (162.xxx) broadcast? That's assuming you are in the US and within range of a NOAA signal of course. Or use an active public safety frequency if NOAA does not exist at your location.

For SSB modes, does the audio distort in both upper and lower SSB modes?

 

[jim44444]

Tried listening to people on 2 meters and 70cm in NFM mode still the same distortion with a buzz just before the distortion kicks in. For SSB it does it in both LSB and USB and AM. Also tried on an external speaker and same thing happens.

 

[kruser]

Tried listening to people on 2 meters and 70cm in NFM mode still the same distortion with a buzz just before the distortion kicks in. For SSB it does it in both LSB and USB and AM. Also tried on an external speaker and same thing happens.

I know the factory service manual can be found online.
I'd probably start there and go through the SM and see if you can find a common component to all the bad modes or possibly an entire circuit section that handles all the bad modes.

It may not be that hard to figure out what's responsible for the problem with a copy of the service manual.

Good luck with it!

 

[Ubbe]

As it is dependent of the volume setting it could be a leaky capacitor. When you turn up the volume you are changing a DC voltage that the capacitor should block. It must then be directly coupled to either the top or the wiper of the volume control. Could be the C958 in the main logic board. Schematics are at the mods.dk website.

/Ubbe

 

[majoco]

Have you tried listening on earbuds or headphones - I'm suspecting the speaker may be damaged.

 

[jim44444]

Yes does the same thing with headphones.

 

[jim44444]

I have found out when the rechargeable batteries are nearly empty the distortion goes away then comes back when i recharge them.

 

[kruser]

I have found out when the rechargeable batteries are nearly empty the distortion goes away then comes back when i recharge them.

Probably because the low batteries can't deliver the current and voltage needed to the audio stage that a charged set of cells can deliver.