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Post by mastertech on Jan 11, 2022 13:57:20 GMT -5
mmartell. I am really sorry but I was deleting a post and I accidentally deleted the entire thread. I am going to look into retrieving it but I do not think it is possible. But for now we can continue here. It is just a shame if all that info is gone.
The audio will only pass through if it is selected to by the ic. Can you test 2) 0 ohm safety resistors on the control lines to that ic, R8942 and R8943. They are on clock and data. If they are ok can you check for activity on those lines?
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Post by mastertech on Jan 11, 2022 14:17:25 GMT -5
Just checked with the forum host and looks like it is gone. Sorry again.
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Post by mmartell on Jan 11, 2022 15:52:18 GMT -5
No worries at all on my part. I tested those lines before I got caught up with something else. They both read 33 ohm pin to pin volume ic to MCU. I did not check yet for activity on those lines will do so when I can likely later after dinner.
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Post by mastertech on Jan 11, 2022 16:15:52 GMT -5
No worries at all on my part. I tested those lines before I got caught up with something else. They both read 33 ohm pin to pin volume ic to MCU. I did not check yet for activity on those lines will do so when I can likely later after dinner. Hmmmm, they should of been 0. Better check them. |
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Post by mmartell on Jan 11, 2022 16:28:47 GMT -5
Sorry I meant I checked the resistance of those lines from the MCU to the volume ic. Clock and data lines both measure 33 ohms like they should, so yes the zero ohm resistors are good.
Did a quick check of those lines with the scope and yes there is activity on both lines when the selector knob is turned.
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Post by mastertech on Jan 11, 2022 17:17:46 GMT -5
Ok, got it. What are you using for source audio?
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Post by mmartell on Jan 11, 2022 18:09:10 GMT -5
Tuner, internet radio and usb .mp3
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Post by mastertech on Jan 11, 2022 18:30:48 GMT -5
Is there a setting for "Direct" or "Pure Direct"?
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Post by mmartell on Jan 11, 2022 21:22:09 GMT -5
Yes, both. No sound from either.
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Post by mmartell on Jan 11, 2022 22:02:04 GMT -5
Looks like the analog to digital converter IC782 is shorted and a 3.3v regulator is dead as well.
Will keep looking for more carnage...
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Post by mmartell on Jan 12, 2022 15:33:37 GMT -5
Turns out IC782 is not shorted but there is a 39ohm short to ground on the DA3.3v line which I cannot find...
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Post by mastertech on Jan 12, 2022 16:17:35 GMT -5
What is the actual voltage on that line?
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Post by mmartell on Jan 12, 2022 16:26:52 GMT -5
That will have to wait until reassembly.
And I mispoke about IC782 it is most definitely shorted.
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Post by mastertech on Jan 12, 2022 16:33:44 GMT -5
You will have to bring me up to speed on what you have done if you need my suggestion.
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Post by mmartell on Jan 12, 2022 16:41:35 GMT -5
When I plugged everything in to test for audio there was none. I happened to be touching the board looking to feel obvious signs of a short and found IC782 to be shorted and the 3.3v regulator putting out 0v. I removed them both and bodged in another 3.3v regulator and ran the unit without IC782 but still no audio, though as far as I can tell that shouldn't apply.
If I measure that 3.3v line to ground I see 39 ohms.
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