Looking at the schematic, J14, J15, J16, and J17 (OUTPUT1 through OUTPUT4) do use the tip switch (for aux1 through aux4). Without switched jacks you’d get individual VCA outputs but no mixer output.
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thank you, i think i have some i can scavenge from another module, time to hit up the solder sucker i guess, thank you very much
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completed repairs, now its all fully functional.
thanks for the assistance everyone 
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alternatively! you can wire the switched pole and the tip together on each of the jacks. this means that the switch jacks wont work how they were designed however you can still get to use the mixer, just when you put jacks into the separate sockets it doesn’t isolate that channel if that makes sense?
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if that doesn’t make sense I need to make a vid on it anyway as I think it would be a useful mod, I did this mod on one of mine anyways cut I still wanted a mix, but also wanted separate outs, instead of the outs being isolated when plugged in
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Just found out on the Dual that I left out the 2n3904s…
Guess what! my CV LEDs on the quad don’t work because… there are no 2n3904s LOL… Nice one to fix this evening with a bit of dissasebly. They bust have been on order and got forgotten.
Rob
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Hmmm… My CV input is still non functional. On all 4 channels.
Pin 2-3 on the TLO74, Even with a MultiMeter, I can see a varying voltage from the CV input. pin 1-3 I just get near enough 12v. which is backed up by the LED being 100% solid.
I guess I need to remove the resistor between OPAMP A & B and see if I get a proper signal out of A… Althought resistance between 1&2 is 100k and between 1&6 is correct at 100k (without the OP-Amp in place )
Just tried the 74 in the Dual VCA and it worked fine… So god knows what’s going on…
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So I’m finally getting around to making this! What do people think of the taper on the pots for audio signals? I happen to have a load of log taper 100k pots after messing up an order - twice… If I’m planning on using this almost solely for audio processing/mixing (i have another 4 chan mixer better suited for control voltages) prior experience is that log pots have a better response curve on them, but I don’t know if that would be the case in this circuit.
Any advice would be grand! ta
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The pots are in the mixer stage so seems to me A100k should work just fine.
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that shit drives me crazy . when all the parts are the right ones , everything looks good but …
I guess it would be easier if my testing skills were much better !
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Yeah, everything looks bang on, I know folk may say “re-hit” all the solder joints. But I have 4 identical circuits doing the same thing on one board. not had any time to think about it more.
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My god I think I have fixed it…
Despite me thinking I had checked multiple times I went through the CV Op-Amp stage again. I sat with my dodgy multi meter at the workshop and every resistor seemed to be infinite resistance bar one or two… I took the board home and got the Fluke out…
Minutes later I had found that the resistor on the CV jack ( R1 and it’s equivilents ) was 220Ohms not 220K , With that being the only fault I could determine I replaced R1 and took it back to the workshop and I now had a flashy LED 
. Removed and replaced the other 220’s to get 4 flash lights…
Just need to do a final test later and hopefully after 9 months It’s done!
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Hek yeah! I hope that was it, it’s always something silly for me too. Although sometimes my silly ends up with smoke lol.
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all good chuffed to have it working as it should have been so simple…
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This was probably the trickiest build yet! Channels 3 and 4 aren’t working yet (though the lights are on), I think it was bad soldering of the pin headers there. The ones connected to the ground plane never got warm no matter how long I put the iron on there for, will have another poke around tomorrow. Seems to work fine otherwise though.
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that should melt that dam solder …
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i am having problems obtaining the Zener Diode BZX55C2V0 for this module, can anyone suggest a UK supplier or a suitable alternative, many thanks.
I think you can leave it out if I’m reading this right
He said he was going to update the documentation but it’s still in the schematic.
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Thank you l will have a look.
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