CGS113 wave multipliers, faulty or normal behaviour?(solved)

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Sparrows78
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CGS113 wave multipliers, faulty or normal behaviour?(solved)

Post by Sparrows78 » Wed Sep 11, 2019 9:19 am

Hi all!
I recently built the Serge wave multipliers using the CGS113 pcb v1.1. The lower section has very low output, significantly lower than the output straight out of my Oakley VCO. It is also very sensitive to audio input level, and cv input level. It seems to only work with very low level input signals without maxing out if that makes sense. Is this normal?
I’m using a LM13700 instead of the CA3080s and I’m also using all the stabilizing capacitors. The module is used in a system consisting mostly of Oakley modules running on +/-15v.
Last edited by Sparrows78 on Thu Sep 12, 2019 2:05 pm, edited 1 time in total.

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EATyourGUITAR
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Post by EATyourGUITAR » Wed Sep 11, 2019 8:57 pm

use CA3080. also, LM13700 vary a lot. there are new old stock, new stock, different manufacturers etc... the chineese fakes are usually pulls of something close like LM13600 repainted. you just never know unless you buy from a good seller.

there is an old thread on muffwiggler about the differences between CA3080 and LM13700. you can modify the circuit to work better with LM13700 but it is not exactly the same part.
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Post by guest » Wed Sep 11, 2019 10:00 pm

i dont think the 3080 is part of the lower folder, so might not be the issue in this case.

you should be able to check the amplitude at each stage, and see if it gets attenuated at one in particular.
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Navs
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Post by Navs » Thu Sep 12, 2019 2:00 am

The schematic I have says the bottom/rectifying folder uses LM3900 Norton amps, not CA3080s/LM13700s. Which chips do you have installed?

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Sparrows78
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Post by Sparrows78 » Thu Sep 12, 2019 9:05 am

guest wrote:i dont think the 3080 is part of the lower folder, so might not be the issue in this case.

you should be able to check the amplitude at each stage, and see if it gets attenuated at one in particular.
You are right, I see that now when looking at the schematic. In my case my problem went away today after I mounted the module in the case, using the same psu as the other modules. Before that I used a separate lab psu, seems to be the problem!

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Post by djs » Thu Sep 12, 2019 10:52 am

Sparrows78 wrote: In my case my problem went away today after I mounted the module in the case, using the same psu as the other modules. Before that I used a separate lab psu, seems to be the problem!
Could be a mechanical issue like a loose wire or solder joint that needs work...
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