WorldwideDX Amateur Radio Forums

I bought a nice looking Cobra 25 at a garage sale.

It powers up nicely, when I connect the mic I get a rapid and loud thud thud thud thud coming over the speaker. I thought it was the mic so I tried 4 other Cobra mics and same thing, as soon as a mic is connected the noise starts. Hooked it up to 2 other power sources and still the same thing.

Anyone ever encounter this?

Any thoughts where to start?

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That's how I roll!!

Anyone?

__________________
That's how I roll!!

Could be a shorted audio chip.Have you did a p.a. test??Is the signal meter
detecting signal??I know you will not be able to hear the receive audio
without the mic connected.But you can put the radio on say channel 19
and see if the signal meter is detecting signal..Also as i say do a p.a. test..
Put the radio in p.a. mode.Plug an external speaker into the p.a. jack
Then connect your mic.Then plug your mic in,and see if you are getting
audio through the p.a. stage.This test will tell you if the audio chip
is functioning properly.If when you plug the mic in.In the p.a. mode,You
get the same loud thudding sound through speaker.Then you probably
have a shorted audio chip..Or it could be one of the large elect. caps
beside the audio chip..The audio chip will be the 10 legged i.c. bolted
to the right side of the chassis rail.Radio facing you,component side up.
The audio i.c. part number is TA-7222AP

what 259 said, tell us more. I'd like to hear that rapid thud thud thud , Good luck Hamer

I HAD THE SAME THING HAPPEN WITH A DAK9 IF THE RADIO IS QUIET WHEN YOU UNPLUG THE MIC IT PROBALY NEEDS TO BE WIRED FOR MIC,OR MIC NEEDS WIRED.