EarMic phono connectors - no gnd?

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jesperp
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Joined: Fri Jun 10, 2022 11:41 am
Location: Denmark

EarMic phono connectors - no gnd?

Post by jesperp »

Hi there

Yesterday i tried to save a small basic program, from my 8300 via MIC connecter/phono-jack cable to a PC soundcard. When SAVE, only noise came into the PC’s recording program.
I discovered that no schield (GND) was connected from mainboard to the phono socket - only signal wire (center pin) was connected from board to socket.

How can it be possible transferring sound, without a reference (GND) connection?
Best regards
Jesper Petersen
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1024MAK
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Re: EarMic phono connectors - no gnd?

Post by 1024MAK »

Do you mean that the PCB mounted socket has no 0V/GND connection? Or do you mean something different?

Mark
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jesperp
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Re: EarMic phono connectors - no gnd?

Post by jesperp »

1024MAK wrote: Sat Jun 25, 2022 10:41 pm Do you mean that the PCB mounted socket has no 0V/GND connection? Or do you mean something different?

Mark
“Do you mean that the PCB mounted socket has no 0V/GND connection?”

Excactly, same thing with socket “EAR”.
I will take a picture one of the upcoming days, of both Lambda 8300 and Your Computer.
Best regards
Jesper Petersen
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jesperp
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Re: EarMic phono connectors - no gnd?

Post by jesperp »

Hi All

Disregard this question/issue.
The computer sockets are NOT Phono, but JACK SOCKETS!
I am on the right track again and will return when further testing is done.
Best regards
Jesper Petersen
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XavSnap
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Re: EarMic phono connectors - no gnd?

Post by XavSnap »

Hi jesperp,

You should try a MONO JACK socket instead of a STEREO one...
Xavier ...on the Facebook groupe : "Zx81 France"(fr)
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jesperp
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Re: EarMic phono connectors - no gnd?

Post by jesperp »

Hi XavSnap

I am using mono jack plugs into the Lambda 8300, and stereo jack into PC soundcard.
Best regards
Jesper Petersen
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XavSnap
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Re: EarMic phono connectors - no gnd?

Post by XavSnap »

Hi jesperp,

As 1024MAK said :"Never use both STEREO channels to like a ZX81 !"
... Or another sound MONO input...

I usually use a "Y" link to couple the both Left/Right channels, but i can't now !
:oops:

I ever experimented a shortcut on the GND and a sound wire, and the sound was very low.
Just check connector's wiring quality and test the ground/live sound channel resistor. Just in case.

Edit: Tread link to :viewtopic.php?p=47291#p47291
Xavier ...on the Facebook groupe : "Zx81 France"(fr)
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