electricdruid chip instead of an ssm2056 on a polysix

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fg
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electricdruid chip instead of an ssm2056 on a polysix

Post by fg » Sun Jun 06, 2021 2:12 pm

hello, i am currently working on adapting the electricdruid circuit to replace a ssm2056 chip which is dead in my polysix.

the original circuit looks like this:
Image

the idea would be to replace it with this (in red are the connections to be made on socket 14 of the ssm2056):
Image
the ideal (because simpler) would be to use the passive output circuit, but do you think that this would work on a polysix ?

thank you for your answers and other ideas

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Re: electricdruid chip instead of an ssm2056 on a polysix

Post by Don T » Sun Jun 06, 2021 6:08 pm

If the Electric Druid chip accepts 0-5V directly on the ADSR pins, this won't work directly, the ADSR input voltages on the 2056 are MUCH smaller. You would have to find the point in the circuit where the control voltages DO range from 0-5V. I don't have the schematic in front of me, but there is probably a voltage divider on each input pin to drop the max voltage down from 5 to just a few millivolts. In other words, if the Electric Druid chip does indeed accept 0-5V directly, then the voltages presented directly to the input pins by the PolySix will be too low to have much effect.
Just got off work, can look later.
Of course, I'm tired, and I could be totally wrong on this.
The easier solution is to find a spare 2056 someplace (Just happen to have a few here)

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Re: electricdruid chip instead of an ssm2056 on a polysix

Post by fg » Mon Jun 07, 2021 3:57 am

the diagram of this part of the circuit (ADSR input voltages) is completely unreadable on the service manual, unfortunately :-(

buy 1x chip ok, but x6, it's starting to get a bit expensive

thanks for your answer

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Re: electricdruid chip instead of an ssm2056 on a polysix

Post by fg » Mon Jun 07, 2021 5:17 am

You are right !

the input will be too small except for the sustain.

SSM2056 voltage
release pin1 ___ 0/295mv
decay pin3 ___ 0/295mv
attack pin4 ___ 0/290mv
sustain pin12___-80mv/4v90
gate pin6 ___ 4v62
out pin10___0/4v8

i must boost A D R input x 16 (+/-)

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Re: electricdruid chip instead of an ssm2056 on a polysix

Post by fg » Mon Jun 07, 2021 8:59 am

it would probably work like this for a chip

Image

but to replace the 6, it may be easier to connect directly to the potentiometers of the polysix

Image

it's just theoretical but it should work, right ?

thanks for your help

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Re: electricdruid chip instead of an ssm2056 on a polysix

Post by fg » Mon Jun 07, 2021 12:50 pm

something like that ?

Image

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Re: electricdruid chip instead of an ssm2056 on a polysix

Post by amonti » Mon Jun 07, 2021 4:05 pm

A viable replacement for the 2056 would be great - I purchased two to replace dead ones in my PolySix, but they run ~45USD each these days, so not cheap.
I recall someone else on the PolySix board coming up with a replacement circuit; unfortunately, once Yahoo! groups closed down, the 3D PCB view of the circuit appears to be lost. Here's what the person wrote:

"I've already got an equivalent circuit together for the SSM2056 that fits on 22.5mm x 26.8mm.
It is using an LM13700 and a few more SMDs. Attached is a 3D view of that PCB.
That can be either plugged into the DIL socket, or I directly replace the SSM in the PCB design by those easy to get ICs."

Edit: Found the pic, but I doubt if it helps!
859788063-SSM2056-Equivalent-Circuit-RC-Slope-SMD.jpg
859788063-SSM2056-Equivalent-Circuit-RC-Slope-SMD.jpg (29.21 KiB) Viewed 396 times

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Re: electricdruid chip instead of an ssm2056 on a polysix

Post by fg » Tue Jun 08, 2021 11:11 am

COOL, The first step seems to work well,
-5 / +5 input, 0 / + 5v output, without this interfering with the original circuit.
It remains to connect the pic16F (s) to the SSM2056 socket.

Image

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Re: electricdruid chip instead of an ssm2056 on a polysix

Post by fg » Wed Jun 09, 2021 12:28 pm

it works ! the passive output is ok but still requires an buffered output,

the lm321 looks perfect but I haven't tested it yet ??
I tried with a transistor but the signal dropped too much, maybe someone would have a solution to this problem?
LML358 is ok
Thanks for your help
Last edited by fg on Thu Jun 10, 2021 2:16 am, edited 1 time in total.

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Re: electricdruid chip instead of an ssm2056 on a polysix

Post by fg » Wed Jun 09, 2021 3:01 pm


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Re: electricdruid chip instead of an ssm2056 on a polysix

Post by amonti » Wed Jun 09, 2021 5:17 pm

Well, that was fast! Can you explain the boards a bit more? 1x pot board to connect to ADSR, 1 boost board to boost signals, and 6x socket boards? I would imagine that you only have to create socket boards for any "bad" ssm2056s and the rest can remain as-is?

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Re: electricdruid chip instead of an ssm2056 on a polysix

Post by fg » Wed Jun 09, 2021 5:39 pm

oh yes sorry,

there are 2 choices:

-the first is to connect directly to connector 5, through the converter +/- 5 to 0 / 5v, which is connected to the pcb socket

the diagrams are above ^


-the second is to use the boost circuit (not yet tested) which is also connected to the pcb socket
for this version there is only one -15v wire to connect. /!\ the pcb is a double face
schema :
Image
boards points:
Image
silk:
Image

the pcb socket are common to both versions
schema:
Image
silk:
Image

I used lm358 but I only use it halfway :(
hoping it is clearer as well?

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Re: electricdruid chip instead of an ssm2056 on a polysix

Post by fg » Wed Jun 09, 2021 5:54 pm

it is possible to replace only 1 or 2 ssm but you need either the converter card - / + or the booster card in all cases

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Re: electricdruid chip instead of an ssm2056 on a polysix

Post by amonti » Wed Jun 09, 2021 6:26 pm

fg wrote:
Wed Jun 09, 2021 5:54 pm
it is possible to replace only 1 or 2 ssm but you need either the converter card - / + or the booster card in all cases
Great - thanks for the clarification; I've saved your designs - always happy to have alternatives in case rare chips go south!

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Re: electricdruid chip instead of an ssm2056 on a polysix

Post by fg » Thu Jun 10, 2021 1:43 am

+ coolaudio v2044a for the filter 5€ /pc

Image

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Re: electricdruid chip instead of an ssm2056 on a polysix

Post by emmaker » Thu Jun 10, 2021 1:28 pm

Did you do a test to see if you put X volts on the ADSR pins that the electricdruid chip and the ssm2056 have the same timing?

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Re: electricdruid chip instead of an ssm2056 on a polysix

Post by fg » Thu Jun 10, 2021 4:04 pm

Currently, it's hard to say because my cpu board is still totally buggy (I'm waiting for parts to completely repair it)
I think to put 6x druid chip in it in order to avoid any problem of this kind, but maybe the envelope will be a little different, it is possible.

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Re: electricdruid chip instead of an ssm2056 on a polysix

Post by emmaker » Thu Jun 10, 2021 4:56 pm

fg wrote:
Thu Jun 10, 2021 4:04 pm
I think to put 6x druid chip in it in order to avoid any problem of this kind, but maybe the envelope will be a little different, it is possible.
There's going to be a lot more electronics then and uCs usually take more power than analog chips.

Are you going to exceed the power supply max current if you do this?

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Re: electricdruid chip instead of an ssm2056 on a polysix

Post by fg » Fri Jun 11, 2021 12:40 am

I don't know, but I think it's really quiet.
I ask myself the questions when I am confronted with the problem rarely before.
:hmm:

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Re: electricdruid chip instead of an ssm2056 on a polysix

Post by fg » Fri Jun 11, 2021 6:17 am

the seconde option (boost) seems to work too

Image

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Re: electricdruid chip instead of an ssm2056 on a polysix

Post by fg » Fri Jun 11, 2021 8:39 am

new pcb socket !
now trimmers are free.
Image

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Re: electricdruid chip instead of an ssm2056 on a polysix

Post by amonti » Fri Jun 11, 2021 11:04 am

Always a plus to have trimmers accessible...just (re)downloaded your latest set of files. Looks like you're using a photosensitive mask and etching (and drilling) your own boards - that's my preferred method as well (just have some issues with vias on double-sided boards).

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Re: electricdruid chip instead of an ssm2056 on a polysix

Post by fg » Fri Jun 11, 2021 4:39 pm

For my pcb i use a laser printer on glossy paper and an iron, as it goes really fast.
I don't really like double faces because it is a very complicated exercise mentally, and source of more potential errors.
To conclude this project , I am thinking of using the first version (the one directly connected to the cn05) with 6 pcbs socket v2 (free trimmers).
et voilà

http://pjmnc.free.fr/archives/2056%20druid%20adsr.zip

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