Scratchy noise on RX


Joe KE0FF
 

This morning, my IC7000 started producing a very loud "scratchy" noise when in RX.  It is not RF since it will produce the noise with the antenna disconnected, band and mode don't affect the noise.  The radio is normal at power-on, but the noise will start anywhere from a few seconds to a few minutes after power-on and comes from either the internal speaker or headphones.  Reducing the AF to 0 silences the noise, and its level tracks the AF somewhat (the noise is VERY loud, so it is easy to hear even at the lowest AF setting above 0).  I tried a different power supply and it took about 30 minutes after it had been off for several minutes.  "Fiddling" with the power cable doesn't affect the issue either way.

Sounds like a thermal-runaway somewhere in the radio, but wanted to see if anyone else had seen this issue before I put the radio on the bench.

Cheers,

Joe


Joe KE0FF
 

After much hair-pulling, I have determined that the likely cause was a thru-hole via failure somewhere in the speaker amplifier circuit.  This seems to be a common problem with ICOM radios (more common than I'd like, anyway).

Since the PCB has tented vias, I chose to run jumpers-wires to bypass most of the vias (this also saves me from having to remove several parts that cover one or both sides of the vias in question).

The bad news is that it is likely only a matter of time before another via fails in some other part of the PCB.

Thatisall.