Question about audio input for CPC 464 to load programs

[pacomix]

Definitely the input signal is lost when going through the first inverter (I'm checking it by using a small speaker) using the 74LS14.
I've tried using the amplifier shown here http://www.kernelcrash.com/blog/frankenstrad/2017/01/18/

but even I get output the cpc doesn't react.

I'm starting to think that this CPC is defective.


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[Bryce]

Are you trying to do all this without an Oscilloscope? That could be difficult.

Bryce.

[pacomix]

Yep. Unfortunately I don't own an oscilloscope since I barely have to mount this kind of circuitry. Having read BatJoss 🦇 post I assumed it was working perfectly.
Maybe if I start again studying electronics then will acquire one of those...

I think this circuit is interesting enough to be built professionally in a small batch.

I will try today to find another of my cassette faulty cpc's in order to try the circuit again. It is also strange I don't get sound from the sound output cable of the CP001 connector although I get it from the speaker connector.


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[Bryce]

The CPC speaker has an amplifier stage right before it. There will be sound at the CP001 connector if it's coming out the CPC speaker, but it probably isn't enough to drive a bare speaker at that point.

Bryce.

[pacomix]

Thanks for the tip! I'll connect it to an amp small circuit I've built in the same protoboard next to mcleod_ideafix circuit and check it then.


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