Total Recall (memory man) help!

[yuka42]

Okay so I've been working on this build slowly and meticulously for a while and finally went through the biasing process.  I think it was successful and have a nice clean modulated signal coming into pin 14 and 15 (2.2Vp-p) of the Coolaudio V571D.  The problem....nothing comes out pin 10 or 11 (24mvp-p).  My voltages seem to check out which I'll post below.  When using the sleeve input as ground (multimeter black lead), and measuring resistance, I get 0 ohms on pin 10 and 11, but only when powered on.  At first I thought this was weird but the other half of the V571D chip is also the same (0 ohms to "ground") and works fine (audio coming out of pin 7).  Maybe I should be referencing ground from elsewhere, as the power source is unusual compared to normal 9v builds I've done. 

When I inject a 0.5Vp-p sine at pin 7 of IC5 the output is fine.  Either something is wrong in-between those two chips, or maybe the V571D chip has failed...or at least half of it?  My soldering is clean, and have checked for bridges under a microscope.  I lifted pin 10 and 11 out of the socket and powered it on just out of curiosity (disconnecting the outputs from the remaining circuit in case of a short) and I still get nothing.  I don't have a spare chip to try unfortunately.  I'm totally willing to order a couple more, but wanted to ask you all for advice first.  Blend pot is cranked btw.  Capacitors have been triple checked for polarity, resistors checked.  I am using a couple resistors in series in spots where there was an odd value needed, but those have been checked and are fine.  Kinda lost at the moment.

Anyone have any ideas I can try?  I have an Analog Discovery as an oscilloscope and used it for the biasing which worked great and I learned a lot.  Here's the voltages for the V571D and IC5.

V571D

1. -13.74
2. -12.80
3. -12.80
4. -14.71
5. -12.81
6. -12.79
7. -5.70
8. -12.81
9. -12.79
10. -5.89 (low?)
11. -7.54 (low?)
12. -12.81
13. 0v
14. -12.80
15. -12.80
16. -14.16

IC5 (4558)
1. -7.41
2. -7.41
3. -7.39
4. -14.79
5. -5.86
6. -5.86
7. -5.86
8. 0v

Thanks.  Ryan.

[jimilee]

How are you testing the total out put? That thing is a bear figure out how to rock before boxing.


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