audio preamp might be busted. the LM386 seems to be working (from the test that you performed). check the voltages around the audio preamp's base and collector.?
if the LM386 gives you noise, does the volume control give you noise too? trace the connectivity from pin 3 of the LM386 to the volume control's middle lug. if the noise ensues when you touch a wire to the middle lug of the volume control, then move to the upper lug (not the one connected to the ground), if that works, then, check at the collector of the audio preamp. essentially, you hve to get to the point beyond with the audio doesn't pick up and you have located the trouble.
On Mon, Oct 2, 2017 at 12:23 AM, Ken Macy <kmacy@...> wrote:
When I first set up the Bitx40, it did seem to receive OK.? Then there began to be various, random ¡°drop outs¡± into silence.? Cycling the power usually got it back.? Then one day it went dead and never came back.? There was noise from the speaker when touching pin3 of the LM386, or where pin3 is connected to the volume pot.? Now it doesn¡¯t even do that.? The only output is when LM386 pin3 is fed a 0 dB 1KHz audio tone; the audio amp seems to work.?
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The Raduino, DDS and display seem to be working, also the transmitter works!?
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While sitting there being quiet, it draws 170ma, which seems high.?
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I¡¯ve reviewed Farhan¡¯s troubleshooting video and I get no noise whatever at any of the points in the circuit he points out.? Measuring voltage at the points shown in the table by K7AGE all match what he lists there.
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I¡¯ve read pages and pages of postings here and I haven¡¯t read anything close to this.? Any help on where to look next is welcome.
