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Finished but no sound
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Finished but no sound

by Razvysme on Thu Oct 15, 2020 4:14 am

I finished building my x0xb0x and after a few hurdles, all seems to be alright, except that there's no sound on the output, measured at the volume knob. I have some reading based on other posts recommendations, but i can't seem to pinpoint where the signal stops. I'd really appreciate any input.

This is how the haveforms look, measured at the waveform switch middle pin:
IMG_20201013_153203.jpg
IMG_20201013_153203.jpg (724.53 KiB) Viewed 17 times

IMG_20201013_153213.jpg
IMG_20201013_153213.jpg (645.06 KiB) Viewed 17 times


When i connect r3 to r146, as indicated in the testing the VCA chapter, Vref drops from 5.33 to 4.7, and 12v rail drops to ~10
BA6110 voltages are correct.: pin 1 = 11.78, pin 8 = 5.33, not changing when pressing notes.

These are the voltages measured at pin 7 of IC11 : First number is while holding a key down, second is after release

C - 1.51, 1.48
C# - 1.57, 1.55
D - 1.66, 1.64
D# - 1.75, 1.73
E - 1.85, 1.82
F - 1.92, 1.90
F# - 2.01, 1.99,
G - 2.10, 2.07
G# - 2.20, 2.17
A - 2.25, 2.24
A# - 2.35, 2.33
B - 2.44, 2.42
C - 2.53, 2.51

Some extra readings:
q22 is c2291 7xg - could this one be fake?
C18 - 9.6
C19 - 10.11
C24 - 10.6
C26 - 11.16
Q12 has both outer pins of 5.333, but no signal on any pins

The following pictures are measured negative side of C14 and negative side of c17 (the next 2 pictures)
linked shrink.jpg
linked shrink.jpg (505.96 KiB) Viewed 17 times

Razvysme
 
Posts: 4
Joined: Fri Jul 24, 2020 8:00 am

Please be positive and constructive with your questions and comments.