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HelloI printed out Dan W's MSB link DAC mods page a few months ago and finally got around to making some of the changes this morning. Somehow I've managed to mess up my DAC even with these very straightforward instructions and would love some advice. Sorry if some of the questions sound elementary, but my understanding of electronics is minimal.
Firstly, I swapped the op-amps.
Secondly, I cut out the small ceramic capacitors C4 and C5 and replaced them with the REL caps suggested.
Lastly, I swapped the 3 3300uf 25v caps for Nichicons of the same value.
The result...........
no sound at all until I turn the volume up to about 3/4 and even then it's very thin, distant and there's lots of hiss and interference in the background.The only thing I've tried was to swap the op-amps back. This made no difference, so that can be ruled out as the cause.
I was able to read the voltage at the 3 new caps and I think this is the problem.
C3 and C6 are dealing with 10.35v
C2 and C5 read 19.25v
C1 and C4 read 0vI can't see a problem with the joints, but is this the most likely explaination? Should I take them out and start again? Any help would be great. Thanks.
Follow Ups:
Thanks for all the advice. I think there's a problem with the 0.1uf caps that replaced the small ceramic types - either my soldering or the components. The op-amps are definitely working OK. Cheers.
You might check the orientation of the electrolytic caps you replaced also (the 3300uF ones). Hopefully you put in sockets so you can easily swap out opamps to double check them. Another thought -- because some of the circuit traces are so fine and so close together you might scan the areas where you worked and see if any of them broke or have splattered solder making an unwanted connection.
All I can suggest is to make sure you're orienting the opamps correctly. There's a notch on one end of the opamp and should be a corresponding indicator on the circuit board. Oh, and make sure all the pins fit in the socket....
Orientation of the op amps was my first thought also. The mark is a half circle at one end of the plastic op amp body. If he got them in wrong they could also be damaged by the voltage.
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