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UBitx no audio! Could use some advise

Brett Deschene All Messages By This Member #43060 Hi everyone. I recently received the ubitx and have wired it up but am not getting any audio signal. When I initially wired it up I accidentally had the PTT shorted to ground causing it to go into TX immediately. I disconnected the power, rewired the jack and continued. Powers up fine All functions appear to work (except audio) Rotary encoder tunes up and down the bands and goes through the menus a like a hot knife through butter. Screen says that it Goes into TX when PTT is engaged or when Keying begins. During receive everything appears fine but no audio Speaker and headphones are tested and work. Audio Jack is correctly wired and works. Potentiometer is wired correctly, tested and works. Antenna works and brings in a signal just fine on other radios. Antenna jack is wired correctly and connected to the board. I am tuned to a frequency where I know my antenna is receiving signals heard on other radios. Audio is completely nonexistent. No sidetone heard from CW, no static, hissing, popping, nothing. I am pretty sure the issue is something simple and located on the board somehow but even with the schematic of the received audio path I just do not know how to diagnose and am not sure where on the board to take readings. Any help would be much appreciated. -Brett Deschene
Jerry Gaffke All Messages By This Member #43086 Remove PA-PWR from the rig so the IRF510's won't be working, then try sending CW. Does the sidetone come through the speaker?? If not, you have a very simple? path from CW-TONE to the speaker to debug.? Perhaps wire a speaker between? the junction of R250,R251 and ground, should hear the sidetone there if it's coming? out of the Nano properly.? ? If not, triple check connections at the volume pot and out to the speaker. Many here have reported a blown TDA2822M, apparently due to shorting the speaker line to ground. Probably best to add a series resistance of 4 to 8 ohms at the output of the TDA2822M and/or reducing the supply voltage to the TDA2822M:? ? ??/g/BITX20/message/42723 If you suspect a blown TDA2822M, you could of course swap that chip out. Hard to get as NXP has discontinued manufacture, perhaps now cloned in China? An alternative is to google for "lm386 kit", and wire that into the volume control pot. Perhaps permanently. If you hear the sidetone when transmitting CW but no receiver audio, try soldering a wire across nodes M1,M2 in case the relay at K2 is not working properly.? Does that fix receiver audio? Can you hear a pop when stroking C50 with a screwdriver? Beyond that, perhaps try the tricks shown in this video on receiver debug. The wire he uses is just 3 or 4 feet of hookup wire, nothing on the other end, it is acting as an antenna to pickup up random noise. ?? Be sure to restore the hacks I suggested (PA-PWR removed and M1,M2 short) before trying to operate the rig. Jerry, KE7ER toggle quoted message Show quoted text On Wed, Feb 28, 2018 at 04:20 am, Brett Deschene wrote: Audio is completely nonexistent. No sidetone heard from CW, no static, hissing, popping, nothing. I am pretty sure the issue is something simple and located on the board somehow but even with the schematic of the received audio path I just do not know how to diagnose and am not sure where on the board to take readings. Any help would be much appreciated.
Brett Deschene All Messages By This Member #43137 开云体育 Ok! So I tried what was suggested and here is what I found.? R253 was bad and ?I was able to replace but that did not fix.? I suspect a blown TDA2822M. I have one on order, so now I wait until it arrives and I swap it out. ?If there are still issues I will continue to work the problem and post if I get stuck again. Thanks Jerry! -Brett Deschene KN4AQC? toggle quoted message Show quoted text On Feb 28, 2018, at 10:59 AM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote: Remove PA-PWR from the rig so the IRF510's won't be working, then try sending CW. Does the sidetone come through the speaker?? If not, you have a very simple? path from CW-TONE to the speaker to debug.? Perhaps wire a speaker between? the junction of R250,R251 and ground, should hear the sidetone there if it's coming? out of the Nano properly.? ? If not, triple check connections at the volume pot and out to the speaker. Many here have reported a blown TDA2822M, apparently due to shorting the speaker line to ground. Probably best to add a series resistance of 4 to 8 ohms at the output of the TDA2822M and/or reducing the supply voltage to the TDA2822M:? ? ??/g/BITX20/message/42723 If you suspect a blown TDA2822M, you could of course swap that chip out. Hard to get as NXP has discontinued manufacture, perhaps now cloned in China? An alternative is to google for "lm386 kit", and wire that into the volume control pot. Perhaps permanently. If you hear the sidetone when transmitting CW but no receiver audio, try soldering a wire across nodes M1,M2 in case the relay at K2 is not working properly.? Does that fix receiver audio? Can you hear a pop when stroking C50 with a screwdriver? Beyond that, perhaps try the tricks shown in this video on receiver debug. The wire he uses is just 3 or 4 feet of hookup wire, nothing on the other end, it is acting as an antenna to pickup up random noise. ?? Be sure to restore the hacks I suggested (PA-PWR removed and M1,M2 short) before trying to operate the rig. Jerry, KE7ER On Wed, Feb 28, 2018 at 04:20 am, Brett Deschene wrote: Audio is completely nonexistent. No sidetone heard from CW, no static, hissing, popping, nothing. I am pretty sure the issue is something simple and located on the board somehow but even with the schematic of the received audio path I just do not know how to diagnose and am not sure where on the board to take readings. Any help would be much appreciated.
Dennis Yancey #52206 How did you determine that resistor was bad?
Richard E Neese All Messages By This Member #52487 the TDA2822M is removed in the version 4 of the ubitx. and the audio on speaker sucks.

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