Several owners of the TS-950SDX have reported the absence of an audio confirmation tone when using monaural headphones. The tone is present when listening with stereo headphones but only from the right hand speaker element.
Cause:
In this design the SUB AF PA circuit supplies audio when using a monaural headphone, and the MAIN AF PA supplies audio to the right speaker of a stereo headphone. The audio confirmation tone is not applied to both the SUB AP PA and the MAIN AF PA. To simplify circuit design the tone is only routed to the MAIN AF PA. Unfortunately this left monaural users without a confirmation tone and stereo headphone users with a confirmation tone only in the right side of the headphones.
Correct action:
The following modification permits the user to hear the audio confirmation tone from both sides of a stereo headphone and from a monaural headphone.
Warning: This radio uses micro-sized surface mount component, and/or multi-layer circuit boards. If you are not familiar with the techniques for service of this type of equipment do not attempt this modification yourself. You will invalidate your warranty if you attempt to modify the equipment and damage the radio. If you are at all in doubt about your qualification to perform this modification you should seek qualified assistance.
Required parts:
R138: 100 Kohm radial lead ¼ watt resistor, (RD14BB2C104J)
Procedure:
- Unplug the DSP Unit from the rear of the transceiver.
- Remove the top and bottom covers (18 screws).
- Remove one screw from each side of the front panel and tilt the front panel forward.
- Add R138 from the wiper arm of VR1 to the negative side of C39 as shown in the accompanying diagram.
- Reverse steps 1 - 3 to reassemble.
This modification may be covered under warranty.
Time required for this modification is 1 hour or less.
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