Moen - Jimi Nova

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

Moen Jimi Nova vibe, excellent sounding easyvibe.
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modman
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Post by modman »

split from the I'd like to see the gut shot thread
Please, support freestompboxes.org on Patreon for just 1 pcb per year! Or donate directly through PayPal

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CheapPedalCollector
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Post by CheapPedalCollector »

Can you tell me what value C2 and C4 are, C2 in mine is .047uf which is wrong and it should be .0047uf, and C4 is missing (470pf?)

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Post by cctsim »

C2 is 0.047uF (code 473) and C4 is 0.22uF.

C2 is the input cap connected with a 2.2M (code 2204) resistor to the ground. In easyvibe it is 1nF/10M.

Cut-off frequencies for the highpass filters are ~1.5 Hz (Jimi Nova) versus ~16 Hz (easyvibe). I guess this combination lets more low frequencies in at this input, but they are both too low for guitar anyway.

C4 seems to be correct as in the easyvibe (0.22uF).

C5 (SMD, 470pF) and C6 (Code 472, 4.7nF) seem to follow the easyvibe design too.

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Post by CheapPedalCollector »

Actually I mean C6, on the right side, it's missing from my unit. So that should be the 4n7, thanks.

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Post by cctsim »

Missing ? Talking about quality control!

I put black heat shrink tube over the LDR/LEDs in my unit and it seems to improve the range of the Hue control.

However, my pedal has a nasty "pop" when you switch it on and it sounds terrible if you have a reverb or delay pedal after the vibe.

I am looking at fix right now. It seems the output cap is leaking a small DC (~10mV) on the output when the pedal is off.

Does your pedal have this problem ?

This is how it looks after the mod.
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Post by CheapPedalCollector »

I did the heatshrink mod too, yes it sounds deeper now.

I found that the caps in leak in almost all the Chinese pedals and I replace them with WIMA or Panasonic caps. I replaced them in this pedal with Wima polyprops. It also made it sound better slightly.

I bought the pedal from a Canadian Ebay seller, I've gotten like 2 bum pedals from them, but nothing I couldn't fix, prefer the low prices.

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Post by cctsim »

I found a fix for the 'pop' caused when you switch the pedal on.

It seems when the pedal is off the oscillator is also switched off. This causes then a 'jump' at the signal level when switched on. I am not sure why the designers felt the need to do this as it seems the LEDs are still on. So no battery life is preserved.

Maybe they wanted to avoid LFO ticking in bypass mode? Who knows.

The fix is very easy. You only need to cut a pcb trace near the switch with a sharp blade and the 'pop' sound is gone.

I have also added a 470 Ohm resistor in parallel to the existing 470 resistor that connects to the Hue potentiometer so that you get a 220 Ohm resistor and drive the LEDs 'hotter' as in the original easyvibe.

I am very pleased with the results now. I full agree with a 'low prices' argument. I found the pedal is a very high quality build and the small issues are easy to fix.
Last edited by cctsim on 02 Mar 2021, 23:49, edited 2 times in total.

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Post by cctsim »

The potentiometers are

B10k for the Depth and Rate and B5k for the Hue controls.
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Post by cctsim »

Here is also the mod for the 'pop' issue.

If you zoom near the left bottom of the switch, you can see where the PCB trace has been cut. This trace connects the positive side of the 100uF/10V cap to ground when in bypass, which in turn switches the LFO off.
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Post by CheapPedalCollector »

Hrm, I'm gonna change the rate control to audio taper then, it's far too sensitive in the lower end. Wonder if there's space for an expression pedal jack.

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Post by matimoksa »

Is it possible to add additional switch to switch between vibe and chorus mode more easily? I find that the vibe setting is very good before od/dist and fuzz but its too extreme to put it after fuzz and I like chorus setting if I put the pedal after fuzz.
Thanks

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