Re: Where did the modulation go . . .


Thanks to Stuart for pointing out that the AIC3204 is likely not completely dead as alsamixer appears to be working correctly. 

OK, now with a tone input I can check the pins on the AIC3204. Running the modified tone generator script with this command (no need to use sudo):

./ 1000 100

I see:

On pin 1 *NOTHING* the schematic shows a 25 MHz Master clock on here but I see no signal. Is this the issue?

On pin 2 I see an approx 3 MHz 3.4v rectangular waveform

On pin 3 I see a 48 kHz 3.4v rectangular waveform

On pin 4 I see a rectangular waveform that is 3.4v but with variable pulse width. This is the tone input? 

On pins 22 and 23 I see a small DC level, about 1v, but no output waveform. 

Any other pins I should check? 

Freq and amplitude measurements are from my Rigol 100 MHz scope. 

Is the issue the missing Master Clock on pin 1 or is the schematic in error and we have something else? 

I dunno if this is germane or not but when I told the RPi to switch to the wireless internet, and killed the modulation, the UDRC was transmitting an ID. Is there something in one of the scripts that would go crazy if we switched internet while key is down?

73 de dave


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