Schumann PLL  [traced]

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digi2t
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Post by digi2t »

Hi everyone,

I have the great honor of being entrusted with a Schumann PLL for repair. I've also taken the time to trace it. Despite the goop, and rats nest wiring which prevented me from using my camera to trace, I present my hand drawn papers of this piece of vaporware.

Image

Image

Image

Keep in mind that the board drawings are of the trace side, so the IC pin numbers have to be mirrored.

I didn't mention on the board 1 page that the 240R, 120R, 110R, the cut 10K, 1M, 200K, and 150K are metal film. All the others are carbon comp.

I don't get the cut 10K resistor. I triple checked it, and it's as drawn. I suppose that maybe 10K here, and a jumper where the 200K is wasn't cutting it, so he filled it in with solder, and cut the resistor lead. It is what it is.

There's also an Appegiator jack, and a Drone jack, though neither is wired inside. I don't know how the Appegiator would work/connect, and maybe that's what the SIP sockets on board 2 are for. A drone signal could be easily injected though. I've been looking at the Drone Lab II project. Easy build, tunable, and would perform the tasks of the Schumann drone quite well. Not really a blip on the radar right now.

Unless someone beats me to it, I'll be transfering this to TinyCAD soon, and after breadboard verification, to vero thereafter.

This box is something else. :D
No matter how many times I cut it, it`s STILL too short!

https://www.deadendfx.com/

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jonasx26
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Post by jonasx26 »

Awesome work! Interesting. Looks like Slacker was correct about the 4017s.

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greigoroth
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Post by greigoroth »

Holy Santa Claus shit!

:applause: :applause: :applause:

tube-exorcist
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Post by tube-exorcist »

I doubt that this is a 74HC14. Running on 12V this chip will not last very long.

Probably it is a 74C14 (which is identical to a CD40106, and which can be replaced by a CD4584).
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Post by mmolteratx »

tube-exorcist wrote:I doubt that this is a 74HC14. Running on 12V this chip will not last very long.

Probably it is a 74C14 (which is identical to a CD40106, and which can be replaced by a CD4584).
I've seen at least one other Schumann PLL schem where it's a 74HC14. :hmmm: The voltages measured in that were +/-10.3, though that's still well over the 7V max operating voltages.

digi2t
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Post by digi2t »

tube-exorcist wrote:I doubt that this is a 74HC14. Running on 12V this chip will not last very long.

Probably it is a 74C14 (which is identical to a CD40106, and which can be replaced by a CD4584).
I've rechecked, with a magnifing glass as well, and it does indeed say "SN74HC14N". I do have 11.47vdc on the Vcc pin as well.

Seems to be a tough chip, to be running at almost double the recommended voltage. :scratch:
No matter how many times I cut it, it`s STILL too short!

https://www.deadendfx.com/

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Post by flood »

I earlier suspected this unit was based off the never-seen electrax synthax (PDF attached). looks different though...
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jonasx26
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Post by jonasx26 »

Schematic drawn from digi2t's diagrams. Also looked over by him. Should be reasonably accurate.
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Schumann PLL 2nd draft
Schumann PLL 2nd draft

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jonasx26
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Post by jonasx26 »

Correction: Pin 13 of IC7 needs to be grounded for the thing to work.

flood
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Post by flood »

nice work! coincidentally, i was going through this yesterday: http://hammer.ampage.org/files/Marston' ... rcuits.PDF

looks like a straightforward application, except for the fuzz on the front end and the later stages.
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Post by uncleboko »

No compression of input signal which is rather puzzling.
https://www.youtube.com/watch?v=2WdwapX59K8

It sounds dreadful in this demo!

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Post by uncleboko »

uncleboko wrote:No compression of input signal which is rather puzzling.
https://www.youtube.com/watch?v=2WdwapX59K8

It sounds dreadful in this demo!
I can't edit previous post - I forgot to say that an excellent job has been done.

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Post by AmpBastler »

Hi jonasx26,

nice work :)

I think you missed the "Lag Time Pot" at Pin 11 of cd4046 :wink:

Where did you get the pot values?

digi2t
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Post by digi2t »

I've taken the liberty of updating the schematic, but I left it at work. :roll:

I have a vero drawn up, doing the back trace tomorrow. I'll post it tomorrow as well.
No matter how many times I cut it, it`s STILL too short!

https://www.deadendfx.com/

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Post by TubeOrgasmer »

Reaaaaaally looking forward to this :popcorn:

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jonasx26
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Post by jonasx26 »

All credit goes to digi2t for the trace. I've done nothing but redrawn his diagrams.
Will post a updated schematic. Thought I'd wait for a successful build first though.
Or at least check with digi2t first.

digi2t
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Post by digi2t »

Updated schematic, and corrected vero are available here;

https://www.aronnelson.com/gallery/main. ... d272e49561

Everything is back traced to the original unit.
No matter how many times I cut it, it`s STILL too short!

https://www.deadendfx.com/

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Post by KindaFuzzy »

Well, since the cat's out of the bag I might as well share my trace that I did from a friends unit a little while ago. Was waiting to do a proper digital schematic, but the one here looks the same as mine with a few different resistor and cap values. My buddies unit had no goop, but was the biggest pain in the ass to trace ever. I made a boo boo on the first schematic, the correction is the next pic.
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correction.JPG
pll schematic.JPG

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Post by Greenmachine »

Oh-hooo lawdy. Methinks there's gonna be some PLL clones kickin' around sound. Super excited! Thanks guys! :applause:
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Post by LaceSensor »

Will anyone be working on replacing the 12AC supply for standard 9vDC and charge pump setup?

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