Internal wiring mod?

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DaleMokroye
Learning to Wiggle
Posts: 4
Joined: Mon May 28, 2018 11:43 am
Location: Netherlands

Internal wiring mod?

Post by DaleMokroye » Wed Feb 05, 2020 9:58 am

Hi all,

Was wondering if it would be possible to save some space by soldering two modules together internally.

Would this work or would I completely screw up the modules by doing this?
I'm trying to save an input on the linear mixers and clutter from patch cables on the front end.

jorg
Wiggling with Experience
Posts: 436
Joined: Fri Apr 03, 2015 9:38 am
Location: East Coast USA

Re: Internal wiring mod?

Post by jorg » Wed Feb 05, 2020 11:51 am

I've done it.

For example, the Doepfer A110-1 VCO has a hidden linear FM input. I wired it behind the panel to a passive attenuator. I wired it so that if the attenuator output is connected to something else, the FM connection gets disconnected. Works great for me.

Insert usual disclaimer here about voiding your warrantee, making connections without reading schematics, or just being a clumsy solderer.

DaleMokroye
Learning to Wiggle
Posts: 4
Joined: Mon May 28, 2018 11:43 am
Location: Netherlands

Re: Internal wiring mod?

Post by DaleMokroye » Fri Feb 07, 2020 9:00 am

Hey, thanks. I'll do some research then try it

Ayab
Wiggling with Experience
Posts: 306
Joined: Wed Dec 18, 2013 7:19 am
Location: London, UK

Re: Internal wiring mod?

Post by Ayab » Fri Feb 07, 2020 12:20 pm

If you are planning to solder connections to the 138S sockets and then also plug input signals into those sockets, it is not advisable. Read the following thread about "stacking" inputs:

viewtopic.php?p=1718024
From the thread:- Outputs are low impedance and must only be connected to high impedance inputs -- never, never tie two outputs directly together -- never. If you do, then each output tries to drive the very low impedance of the other, forcing both outputs into current-limit and possible damage. As a minimum, severe signal loss results.

What you can do is see if you can find some suitable switching jacks that will fit the footprint of the Doepfer's existing jacks. (n.b. WARNING BELOW) Then you could connect your "hidden" wires to the switch connections and then you can still patch into the sockets (but plugging into the sockets will disconnect the "hidden" wires on the switch connections). I don't have any experience with sockets on Doepfer modules, maybe someone else on here can advise.

WARNING: If you do find some switched sockets that fit be very careful desoldering the existing sockets (remove all solder carefully with desoldering braid so the sockets will come out without being forced).

jorg
Wiggling with Experience
Posts: 436
Joined: Fri Apr 03, 2015 9:38 am
Location: East Coast USA

Re: Internal wiring mod?

Post by jorg » Fri Feb 07, 2020 4:31 pm

As far as I know, all Doepfer sockets are switched. Any hidden connections should definitely use the switched feature to prevent shorting outputs together. It would also be advisable to add a series resistor to limit current during the instant while the jack is being inserted. There is an instant where the tip makes contact, but has not yet pushed the switch open.

Ayab
Wiggling with Experience
Posts: 306
Joined: Wed Dec 18, 2013 7:19 am
Location: London, UK

Re: Internal wiring mod?

Post by Ayab » Sat Feb 08, 2020 11:10 am

Hey Jorg, sounds like useful advice generally - What size resistor would be best to use? 1K is usual, no?

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