Moen Shaky Jimi Vibe  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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cspar
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Post by cspar »

The schematic for the EasyVibe is on the top of John's page.

http://www.hollis.co.uk/john/circuits.html


MODERATOR: Added it to the first post, too.
"Just because the forgoing circuits have produced results there is no reason experimenting won't lead to added results." L. E. Darling, in his article containing the earliest published vacuum tube synthesizer circuit, Popular Science Jan 1920

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Post by stevestrat »

Thanks mate
do you know how to add the Hue control to the version that hasnt got it

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Post by cspar »

Look at the 1st post in the topic and the schematic.

It's just a potentiometer swap and adjusting a resistor to taste.

The hardest part is drilling a new hole in the enclosure if your pedal doesn't already have 3 knobs.

I've taped a bag inside an enclosure to keep metal shavings from getting into the circuit/inner enclosure before but most of the time I've had to remove everything from the enclosure to drill a new hole.
"Just because the forgoing circuits have produced results there is no reason experimenting won't lead to added results." L. E. Darling, in his article containing the earliest published vacuum tube synthesizer circuit, Popular Science Jan 1920

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Post by stevestrat »

Ok mate thanks for advice
I just cant really work it out ,it says replace the preset,mine hasnt got one

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Post by cspar »

stevestrat wrote: 17 Nov 2021, 21:37 I just cant really work it out ,it says replace the preset,mine hasnt got one
A picture of the guts would help.
"Just because the forgoing circuits have produced results there is no reason experimenting won't lead to added results." L. E. Darling, in his article containing the earliest published vacuum tube synthesizer circuit, Popular Science Jan 1920

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Post by cspar »

Ok, no trimpot in your version and the Drive/Hue is a fixed resistor.

This fixed resistor is connected somewhere between the 4 leds that are bent over the ldrs and one side of an op amp.

Unfortunately the trace is not visible in the pictures and it's hard to read the values. But lucky for you there aren't many different values in the schematic.

What you need to do is locate the fixed resistor and identify it's value. Which shouldn't be to hard with the process of elimination. It's going to be less then 10k. Probably less then 5k.
Maybe 1k like the Easy Vibe trimpot, but it's definitely not the 1k resistor that's attached to the depth pot.

The fixed resistor is either going to need to be lifted on the op amp side or removed altogether depending on it's value.

This is the place you need to solder the wires that will go to and from your new potentiometer and a resistor in series too if you end up needing to remove the "fixed" resistor.

Op amp > potentiometer > resistor in series > 4 led

I hope this helps.
"Just because the forgoing circuits have produced results there is no reason experimenting won't lead to added results." L. E. Darling, in his article containing the earliest published vacuum tube synthesizer circuit, Popular Science Jan 1920

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Post by stevestrat »

Ok mate thanks for help appreciated
Tricky bit is the tracks are probably on both sides,so i might have to take whole assembly out to check this
so if i find the resistor ,all i do is replace it with say a 5k pot ?
I could mount it on the side next to jack socket

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Post by cspar »

It's definitely double sided and taking it apart to follow the trace and drill the hole will help build your skills and confidence. Good stuff.

You need more than just a 5k pot.

You want to have some resistance in between the pot and the leds.

That's the "to taste" resistor that sets the minimum amount of drive/hue.

The original Easy Vibe value is 220R, it seems that in the Shaky Jimi version with a Hue pot the stock value is 2K2.

If the "fixed resistor" is around 1k you might be fine with using it as your "to taste" resistor that sets the minimum of the drive/hue.

It's your pedal, your ears, you modding it, etc.

I'd personally do it like Floris's original suggestion and use a 220R or something close.
"Just because the forgoing circuits have produced results there is no reason experimenting won't lead to added results." L. E. Darling, in his article containing the earliest published vacuum tube synthesizer circuit, Popular Science Jan 1920

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Post by Ben N »

Bugg, Kevin, you guys up to an EasyVibe project?

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frankenxtein
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Post by frankenxtein »

Anyone here added an expression pedal jack to the Shaky Jimi ?
I found a mod for the Moen Jimi Nova UniVibe on Reddit
I was looking for a schematic to confirm the Rate pot value and found it here. Expression pedals vary so I wanted to make sure to get the right value. So, I'd imagine the On-Stage KEP100 will work.

The link for the expression pedal mod:



http://expressionpedals.com/list-of-expression-pedals

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Post by frankenxtein »

I had to switch the wires in the KEP100 that go to the pot. I just changed them in the little connector.
The pedal was in reverse.
https://www.dropbox.com/sh/51w4r8nhmp8n ... j9OLa?dl=0

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