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Yaesu VX-5R Audio Distortion Repair

AudioShockwav

Extraterrestrial
Staff member
Apr 6, 2005
7,234
4,763
343
Sierras Near Yosemite National Park
The problem:

The VX-5R is a very solid radio, but unfortunately has a nasty habit of developing a distorted audio output on the speaker. You probably know if you have the problem, but it is characterized by a very prominent buzz/hum on the speaker audio when receiving VHF/UHF transmissions and the volume is set anywhere from 50-100% level. The distortion is not present on FM broadcast transmissions (i.e. you can listen to your local classical music or NPR stations full-blast without the distortion).

The cause:

The source of this problem is from a little phenomenon called "microphonics". In brief, the speaker is in direct contact with the main control unit of the radio and the actual audio vibrations from the speaker cause the receive circuitry to resonate and introduce this distortion to the output audio at higher volume levels. The FM broadcast is not affected by this problem because of the separate circuitry used for it.

The repair:

If your radio exhibits these symptoms, you're probably yet another VX-5R user that has this problem. Fortunately for you the fix is actually very easy! I spoke with a Yaesu service tech who said that you can simply take apart the two halves of the case, sand the connection down a bit to make a more snug fit and reassemble. I've found that this works maybe 50% of the time and depends on a lot of variables. My solution involves a Philips screwdriver, a dollop of rubber craft cement, and about 30 minutes of your time.

Step-by-step:

****DISCLAIMER: You're taking apart a delicate piece of electronics and fudging around with SMD PCBs. Only crack open your radio if you are comfortable doing so and understand the risks (i.e. bricking your radio). Mods.dk and I do not take any responsibility for your radio or anything thing that could happen as a result of using these instructions. ****

The basic idea of this repair is to put a little bit of rubber cement (read: vibration dampening) on the back of the speaker so that it has a little damper where it sits directly on the main control unit. Here's the step-by-step.

Turn off the radio, remove the battery, antenna, belt clip, etc. (Also remove the barometer unit if you have it installed).

Remove the back panel of the radio by taking out the two long screws at the top and the 4 little screws in the battery bay.

Carefully pull apart the two halves of the radio. Watch for the battery retention clip and how it fits in (don't forget to put it back later!).

Release the ribbon cable from the front panel control unit by lifting the little cream-colored latch on the connector and carefully sliding the ribbon cable out.

Remove the 4 silver screws holding the main control unit to the front panel of the radio.

On the inside of the front panel, you're see the speaker nicely glued into place on the back panel. Carefully put a little blob of rubber craft cement on the center of the speaker housing (not the actual vibrating cone!!!) where it makes contact with the control unit (look at the control unit PCB for the round white silkscreen showing you where it lands).

Allow the rubber cement to dry fully.
Reassembly:

Place and secure the control unit to the front panel with the 4 silver screws

Reseat and secure the ribbon cable

Reseat the two halves of the radio shell together (watch for the rubber gasket and don't forget the battery retention clip!)

Secure the two radio halves together with the 4 little black screws and the 2 longer ones.

Screw in the antenna and pop in the battery.

Enjoy.

73
Jeff
 

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