R10 IC-R10 squelch / muted audio

[rk17]

Hello All,

I bought a IC-R10, the seller sold it with "no audio" defect.

Hopefully any of you can help me to find the problem.

I try to describe the issue:

When I turn it on and I put my ear to the speaker I hear that the receiver is receiving stations, all bands working, display and all buttons functioning normal. That means that the audio is working but volume is really low (muted), same as when I connect headphones.
The squelch is closed and the turn knob is not responding on the squelch, when I use the MONI button the squelch opens but volume remains still very low.

I have been looked on the schematic and first impressing was that the IC361 was faulty, but there is audio, but muted. That means this IC should be fine.
Then I looked into the IC950 (mute switch) but can't really understand if this IC will keep the volume low as this would be not working correct.
What happens when you press the MONI button, it opens the squelch, but should this also open de mute function from IC950.... ?

I'm stuck.... hope that anyone of you can lead me in the correct direction...

Thank you.

 

[Ubbe]

I hear that the receiver is receiving stations

The squelch is closed and the turn knob is not responding on the squelch, when I use the MONI button the squelch opens but volume remains still very low.

So the squelch knob are not opening and closing the audio, the muted one, but squelch opens as it should when it receives a transmission and the squelch also open with the monitor button. If the squelch works to stop scan on active transmissions then it's functioning as it should and I would concentrate on the VSC logic, who also mute if it doesn't sense any audio.

/Ubbe

 

[rk17]

Ubbe, thank you for your response. The VSC I have switched on and off and this is functioning as I should be. (not stopping at noise)
The squelch knob is not responding, it looks like the squelch is stuck in the closed position. And open with MONI works.
But sound stays really low..

I appreciate your help.. I hope to find the issue.

 

[Ubbe]

Ubbe, thank you for your response. The VSC I have switched on and off and this is functioning as I should be. (not stopping at noise)

It has a dual function, like most sound squelches, that it needs audio that are shifting between none and full audio like a talking voice. If there's a constant carrier without any modulation or a constant full signal like a datasignal it continuous to scan. Check with a speech modulated signal that it stays on the frequency, or otherwise it probably doesn't have enough audio to trigger as speech instead of a dead silent carrier.

The squelch knob is not responding, it looks like the squelch is stuck in the closed position. And open with MONI works.

If the audio from the discriminator could be low, creating a low audio, by some component fault it would be like it was detecting a signal and squelch should stay open and not be able to be closed. But now it seems like that part are working, if it only stops scan on an active transmission.

The IC 471 filters the audio to only get the high frequency part, where the noise are, and sends to the CPU to be detected, and the SQ knob sets that audio to different levels, and the CPU also gets the VSC signal and decide when to mute and unmute and also when to stop and start scan.

If scan stop and start and VSC works as it should then those circuits works fine and the CPU gets that info. It then must be the mute signal that either doesn't come out of the CPU or some component from CPU to the audio amp have a problem, if the keypad beep are heard at a normal volume or the amplifier in itself are damaged, or speaker or earphone jack.

/Ubbe

 

[rk17]

I removed the main unit, which is connected to the RF unit via a connector, and tested the squelch potentiometer with a multimeter. The potentiometer was functioning correctly.

After reassembling the main unit, the radio started working normally—with proper volume and squelch operation.

It appears that the issue was related to the connection between the main and RF units, specifically the connector on the boards.

I hope this information helps anyone encountering or troubleshooting the same problem.

Thanks to Ubbe for this assistance, much appreciated.

 

[pb_lonny]

Great to hear you fixed this