Posted: Mon Aug 02, 2010 4:44 pm
For what it is worth, I would do the following before changing anything else:
1) Re-solder every connection on the entire board. I always use tin-lead solder for prototypes to get good flow.
2) Clean the entire board with alcohol to remove all of the flux. Make sure you get under the chip and any other big components.
3) Download a simple program, like one that reads the adc's, multiplies each by a pot, and writes them to the dac's.
4) Start with inputs grounded, and see if you get noise on the outputs. This is the configuration that I would use for any further testing.
5) Your ear is probably as good a test tool as a scope for this kind of audio circuit. Plug the outputs into an amp and leave it turned on for testing.
6) Sometimes it can be more productive to try things that you think will INCREASE the noise first. Like probing around with a bare wire in your finger, or using a noisy "wall wart" power supply. This will help isolate the issue.
Good luck,
Don
6) It is often
1) Re-solder every connection on the entire board. I always use tin-lead solder for prototypes to get good flow.
2) Clean the entire board with alcohol to remove all of the flux. Make sure you get under the chip and any other big components.
3) Download a simple program, like one that reads the adc's, multiplies each by a pot, and writes them to the dac's.
4) Start with inputs grounded, and see if you get noise on the outputs. This is the configuration that I would use for any further testing.
5) Your ear is probably as good a test tool as a scope for this kind of audio circuit. Plug the outputs into an amp and leave it turned on for testing.
6) Sometimes it can be more productive to try things that you think will INCREASE the noise first. Like probing around with a bare wire in your finger, or using a noisy "wall wart" power supply. This will help isolate the issue.
Good luck,
Don
6) It is often