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CGS88 Bi directional switch issue

CGS88 Bi directional switch issue

2014-01-29 by anthony_dematteo

Hi guys, I'm having some issues with this circuit and i'm out of troubleshooting ideas.
I've wired this up as a triple bi directional switch.

I'm getting 12.5v into the lm3900 and +/-6v out.I've checked all the wiring,traces,values and have also tried swapping all of the chips and transistors out.

If i try to send 2 separate inputs(a1,a2) out to 1 source(d) i basically just get a weird mix of the 2 waveforms with no cv/gate trying to toggle between the 2 outputs.When i put a cv/gate into the pulse input that signal than gets mixed with the other 2 and still no toggle occurs.Also, i've noticed if i only use a1 input i get what sounds like a inverse of the waveform on a2.
All 3 sections exhibit the same behavior and if i plug a signal into a1 say in the top (b,c) section i get that signal coming out of every other i/o jack in the other 2 sections.

I don't have a scope so i've been using my meter and ears to try to see whats
happening.I tried to trace the pulse input (a) i used i 50/50 gate.Directly after the first 1m5 resistor i get -6v, when i measure the output of the lm3900 going to pin 3 of 4007 switch i am measuring almost +6v but none of these values ever changes with the gate
cycle.

Any ideas ? As always suggestions and help are so VERY much appreciated!
-Tony

Re: CGS88 Bi directional switch issue

2014-01-29 by cg_synth

When things get unexpectedly mixed, check your power rails. Follow them
right through to the pins of the chips, particularly the 4007s.
Ken
Show quoted textHide quoted text
>Hi guys, I'm having some issues with this circuit and i'm out of
troubleshooting ideas.
>I've wired this up as a triple bi directional switch.
>
>I'm getting 12.5v into the lm3900 and +/-6v out.I've checked all the
wiring,traces,values and have also tried swapping all of the chips and
transistors out.
>
>If i try to send 2 separate inputs(a1,a2) out to 1 source(d) i basically
just get a weird mix of the 2 waveforms with no cv/gate trying to toggle
between the 2 outputs.When i put a cv/gate into the pulse input that signal
than gets mixed with the other 2 and still no toggle occurs.Also, i've
noticed if i only use a1 input i get what sounds like a inverse of the
waveform on a2.
>All 3 sections exhibit the same behavior and if i plug a signal into a1 say
in the top (b,c) section i get that signal coming out of every other i/o
jack in the other 2 sections.
>
>I don't have a scope so i've been using my meter and ears to try to see whats
>happening.I tried to trace the pulse input (a) i used i 50/50 gate.Directly
after the first 1m5 resistor i get -6v, when i measure the output of the
lm3900 going to pin 3 of 4007 switch i am measuring almost +6v but none of
these values ever changes with the gate
> cycle.
>
>Any ideas ? As always suggestions and help are so VERY much appreciated!
>-To
>
>
>
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>
>
>Hi guys, I'm having some issues with this circuit and i'm out of
troubleshooting ideas.<br>I've wired this up as a triple bi directional
switch.<br><br>I'm getting 12.5v into the lm3900 and +/-6v out.I've
checked all the wiring,traces,values and have also tried swapping all of the
chips and transistors out.<br><br>If i try to send 2 separate inputs(a1,a2)
out to 1 source(d) i basically just get a weird mix of the 2 waveforms with
no cv/gate trying to toggle between the 2 outputs.When i put a cv/gate into
the pulse input that signal than gets mixed with the other 2 and still no
toggle occurs.Also, i've noticed if i only use a1 input i get what
sounds like a inverse of the waveform on a2.<br>All 3 sections exhibit the
same behavior and if i plug a signal into a1 say in the top (b,c) section i
get that signal coming out of every other i/o jack in the other 2
sections.<br><br>I don't have a scope so i've been using my meter
and ears to try to see whats <br
>>happening.I tried to trace the pulse input (a) i used i 50/50
gate.Directly after the first 1m5 resistor i get -6v, when i measure the
output of the lm3900 going to pin 3 of 4007 switch i am measuring almost +6v
but none of these values ever changes with the
gate<br> cycle.<br><br>Any ideas ? As always suggestions and help are
so VERY much appreciated!<br>-Tony
>
>
>
><!-- |**|begin egp html banner|**| -->
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><br>
>
>
><br>
>
><!-- |**|end egp html banner|**| -->
>
>
><div width="1" style="color: white; clear: both;"/></div>
></body>
>
></html>
>
_______________________________________________________________________
Ken Stone sasami@... otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>

Re: CGS88 Bi directional switch issue

2014-01-30 by anthony_dematteo

Seem to be getting correct voltge on all ic's +6 to pin 14 / -5.6 to pin 7 but i do notice the positive rail is swinging up and down about 1v.This is only with 2 voltage sources plugged into a1,a2 no gate.
When i plug a gate in the first section i notice pin 3 and 6 of u3 go from -6v to +5.5v but just sit there at +5v.

Thanks for you help Ken, this seems like such a simple circuit but is killing me.

Re: CGS88 Bi directional switch issue

2014-01-30 by cg_synth

Swap the 3900. If you still get fluctuations, swap out each 4007 (or pull
them, and put them back in one at a time).
Show quoted textHide quoted text
>Seem to be getting correct voltge on all ic's +6 to pin 14 / -5.6 to pin 7
but i do notice the positive rail is swinging up and down about 1v.This is
only with 2 voltage sources plugged into a1,a2 no gate.
>When i plug a gate in the first section i notice pin 3 and 6 of u3 go from
-6v to +5.5v but just sit there at +5v.
>
>Thanks for you help Ken, this seems like such a simple circuit but is killing m
>
>
>
><head>
>
><style type="text/css">
><!--
>
>/* start of attachment style */
> .ygrp-photo-title{
> clear: both;
> font-size: smaller;
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></head>
><body>
>
>
>
><!-- |**|begin egp html banner|**| -->
>
><br><br>
>
><!-- |**|end egp html banner|**| -->
>
>
>Seem to be getting correct voltge on all ic's +6 to pin 14 / -5.6 to
pin 7 but i do notice the positive rail is swinging up and down about
1v.This is only with 2 voltage sources plugged into a1,a2 no gate.<br>When i
plug a gate in the first section i notice pin 3 and 6 of u3 go from -6v to
+5.5v but just sit there at +5v.<br><br>Thanks for you help Ken, this seems
like such a simple circuit but is killing me.
>
>
>
><!-- |**|begin egp html banner|**| -->
>
><br>
>
>
><br>
>
><!-- |**|end egp html banner|**| -->
>
>
><div width="1" style="color: white; clear: both;"/></div>
></body>
>
></html>
>
_______________________________________________________________________
Ken Stone sasami@... otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>

Re: CGS88 Bi directional switch issue

2014-01-30 by anthony_dematteo

Well swapping the 3900 did stop the fluctuations but still no dice and i've swapped out about 10 different 4007's from 2 different batches.

The thing that's throwing me for a loop is i'm not getting any change in voltage off pin 10 of the 3900.I'm assuming i should be seeing the voltage i'm feeding that pulse input and able to see pin 10 go high and low?

Re: CGS88 Bi directional switch issue

2014-01-30 by cg_synth

>The thing that's throwing me for a loop is i'm not getting any change in
voltage off pin 10 of the 3900.I'm assuming i should be seeing the voltage
i'm feeding that pulse input and able to see pin 10 go high and lo

Yes, you should be able to see that. They are just being used as comparators.
Find out what voltage is at the junction of the 8k2 and 10k voltage divider
resistors.

Ken

_______________________________________________________________________
Ken Stone sasami@... otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>

Re: CGS88 Bi directional switch issue

2014-01-30 by cg_synth

>I'm getting 5.4

Too high. Should be around 1-2 V. The pull down isn't correct, or isn't in
circuit.


>
>
>
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> .ygrp-photo-title{
> clear: both;
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><head>
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><!--
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> border: 1px solid #d8d8d8;
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><body>
>
>
>
><!-- |**|begin egp html banner|**| -->
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><br><br>
>
><!-- |**|end egp html banner|**| -->
>
>
>I'm getting 5.4v.
>
>
>
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><br>
>
>
><br>
>
><!-- |**|end egp html banner|**| -->
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>
><div width="1" style="color: white; clear: both;"/></div>
></body>
>
></html>
>
_______________________________________________________________________
Ken Stone sasami@... otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>

Re: CGS88 Bi directional switch issue

2014-01-30 by anthony_dematteo

Ok so things have changed.I noticed the pnp case was melted a little so swapped it out and am now getting -.061 at the junction.
Another exciting development is now when i probe pin 10 i can get it to function correctly.I tried with a small screw driver to see if it was a bad connection.That also worked but gave me a unsteady and weaker output than when using the multimeter probe.

I'm not exactly sure were to go from here, do you suggest i alter the 22k resistor ?

Re: CGS88 Bi directional switch issue

2014-01-30 by cg_synth

>Ok so things have changed.I noticed the pnp case was melted a little so
swapped it out and am now getting -.061 at the junction.
>Another exciting development is now when i probe pin 10 i can get it to
function correctly.I tried with a small screw driver to see if it was a bad
connection.That also worked but gave me a unsteady and weaker output than
when using the multimeter probe.
>
>I'm not exactly sure were to go from here, do you suggest i alter the 22k
resistor

No.

If assembled correctly, it will work. Changing parts values will only make
things worse.

Ken
_______________________________________________________________________
Ken Stone sasami@... otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>

Re: CGS88 Bi directional switch issue

2014-01-30 by anthony_dematteo

Ok makes sense.Gotta call it a night but want to thank you so much for all the help! I'm feeling much closer to getting this working.

Re: CGS88 Bi directional switch issue

2014-01-31 by anthony_dematteo

Ok so i got the junction at the regulator section giving me 1.4v now, i replaced the 10k i had subbed back w/ the 8.2k that is supposed to be there originally,but still functioning the same.

Begging for any other ideas/suggestions

Re: CGS88 Bi directional switch issue

2014-01-31 by anthony_dematteo

Got it going.I noticed the same voltage fluctuations happening again and switched out the 3900 and presto all is good.

Thanks again Ken for all your help. YOU ARE AWESOME!

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