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no audio beyond very quiet static #v6 #ubitxv6 #ubitxv6-help


Skip Davis
 

John measure Q90 base to emitter junction, if close to zero it has shorted. I measured about 500ohms. This will cause no output and loss of receive and it is still in circuit during receive.

Skip Davis, NC9O 

On Jan 19, 2021, at 16:18, John Scarlett <John329@...> wrote:

The wires for volume control must be ok as the volume does adjust and all the wiring connectors match the photographs I had previously taken.
That being said it does seem likely that something must have been touched or dislodged while I was working possibly one of the many coils or even heat transferred to the wrong component while de-soldering.
I will check all the connection's around the PA transistors and look for touching wires on the coils as the video suggested and let you know the results.

73
John M7CPT


John Scarlett <John329@...>
 

The wires for volume control must be ok as the volume does adjust and all the wiring connectors match the photographs I had previously taken.
That being said it does seem likely that something must have been touched or dislodged while I was working possibly one of the many coils or even heat transferred to the wrong component while de-soldering.
I will check all the connection's around the PA transistors and look for touching wires on the coils as the video suggested and let you know the results.

73
John M7CPT


Jerry Gaffke
 

Yes, get the receiver working first.

Here's an old video Farhan created to show how to take a meter of wire as an antenna to
pick up local QRN around the house, and strobe that wire to each stage of the receiver
progressing back from the audio amp until you reach a point where it no longer
makes scratchy noises in the audio.  That tells you about where the problem is.
    http://bitxhacks.blogspot.com/2016/12/troubleshooting-bitx40.html
The video is about the old Bitx40, but should work on the uBitx too.

Though first look for obvious stuff.  Maybe a wire broke off of your volume control?
Maybe a wiring harness got plugged back into the board wrong?
Are the RX stages getting 12v power? 
Note that the audio amp is powered from "12V", other receiver stages from "RX", but only when receiving.
    
If you replaced the PA transistors and now the receiver doesn't work,
sounds like you must have touched something else in the process.

Jerry, KE7ER



On Tue, Jan 19, 2021 at 11:36 AM, John Scarlett wrote:
Total loss of power output occurred 1st that Is why I replaced the PA transistors.
As it seemed likely that I'd blown my finals I replaced both with genuine RD16HHF1's.
After doing this I had no audio beyond very quiet static so also replaced audio chip and checked TX/RX relay.
Still no sound beyond very quiet static so didn't even try to TX.
Any ideas what else it could be would be appreciated?
 
73
John M7CPT


John Scarlett <John329@...>
 

Total loss of power output occurred 1st that Is why I replaced the PA transistors.
As it seemed likely that I'd blown my finals I replaced both with genuine RD16HHF1's.
After doing this I had no audio beyond very quiet static so also replaced audio chip and checked TX/RX relay.
Still no sound beyond very quiet static so didn't even try to TX.
Any ideas what else it could be would be appreciated?
 
73
John M7CPT