Yahoo Groups archive

Cgs synth

Index last updated: 2026-04-28 23:16 UTC

Message

CGS88 - one channel not working

2018-08-10 by richs19

I'm troubleshooting 2 CGS88s I've built that both seem to be doing the same thing. I've built them up as Triple Bi-Directional Routers. I've added the 3 position switches and I'm taking +15 off the positive Bead.


The channels connected to U3 and U4 work fine. They flip the inputs based on switch position and CV input. The channel connected to U5 will not flip inputs by either switch or CV.


When not connected to jacks and switches, with the +15 being sent directly to pads E I & A I get whacky readings on U5 at pins 3, 8, 10, and 13.


Here's what I measured;



U2

U3

U4

U5

1

-6.53

2.65

2.39

2.33

2

-6.46

2.49

2.34

2.36

3

-6.97

6.21

6.23

-6.87

4

6.24

2.45

2.24

2.24

5

-6.88

2.40

2.38

2.46

6

-6.45

6.21

6.23

-6.87

7

-7.01

-7.01

-7.01

-7.01

8

-7.01

-7.01

-7.01

6.22

9

6.23

2.30

2.42

2.41

10

6.23

-7.01

-7.01

6.23

11

-6.98

2.41

2.42

2.31

12

-6.47

2.37

2.35

2.30

13

-7.01

-7.01

-7.01

6.23

14

7.06

6.23

6.23

6.23


I should also note that for U3, U4 and U5 the readings I got continuously cycled between zero and the values indicated on pins # 1, 2, 4, 5, 11 and 12.

I can't seem to see an obvious mistake although I've made one somewhere.... twice. Does anyone have any suggestions as to where to look to resolve this?

Thanks,

Rich



Attachments

Move to quarantaine

This moves the raw source file on disk only. The archive index is not changed automatically, so you still need to run a manual refresh afterward.