# [Solved] Cepheid Chorus - only the LEDs work



## zipfool (Aug 21, 2021)

This seems like it's going to be tricky to figure out. Bypass works fine, but the 2nd LED stays lit even in bypass. When I engage the switch, both LEDs light up, but I'm not hearing any of the Chorus effect no matter how much I crank the knobs/pots.

I opted to go with the MN3207 / MN3102 IC pairing, but I suspect that my source for these was bogus (seller on EBay). I've tried 4 out of 10 of the pairs they sold me, and I'm getting the same [lack of] effect with all 4 pairs. I could keep trying out the other pairs, but I'm suspicious that all of them will be the same.

Take a look at these photos and LMK if you see anything else suspicious.

There's a few things to this build that are new to me: not sure what the trim pot is supposed to control, and I've never had to solder an onboard jumper to signify which chip combo I bought. Did I do the right thing by putting a bead of solder to connect each of the 2 sets of pads? 

If I dial the trim pot up too high, the sound cuts out. Same if dial it too low. Right in the middle and I get clear sound/tone. What does this trim pot do?


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## Cybercow (Aug 21, 2021)

The trimpot controls the Vref value to dial in the sweet-spot for the chorus effect. Its a VERY narrow margin - usually just off center.

Also, did you use the 9.1v Zener diode for D101 withe MN32xx chipset? (If you have the higher value Zener and are using greater than 9v to supply the circuit - it might be problematic. The 9.1v Zener is to protect the MN32xx chipset. The MN30xx chipset can withstand a bit more voltage.)

I'd first ensure that no more than 9V is supplying the circuit, try a fresh set of the MN32xx chips, and try carefully adjusting the trimpot. Be sure to have the Depth pot turned up all the way and the Rate pot at the mid-point. See if adjusting the trimmer while playing an audio signal thru the circuit will dial-in. Use tiny increments.


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## zipfool (Aug 22, 2021)

Thanks, I'll give it a try. Maybe I was just adjusting the trim pot too erratically and missed the sweet spot...


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## Stickman393 (Aug 22, 2021)

Question: is your rate LED on 100% of the time, or does it cycle on and off with, blinking faster as you turn up the rate potentiometer?

If it's not cycling on and off, there's a good chance that you'll need to poke around the LFO portion of the circuit, as illustrated here:


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## zipfool (Aug 22, 2021)

The LED is on 100% of the time. I'll poke around the LFO. Thanks!


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## zipfool (Aug 22, 2021)

The plot thickens, but maybe this makes it more obvious what's going wrong ...

I see now that the LEDs only light up when I've got the ground and hot wires mixed up on the dc jack. When I have the jack wired properly, I get no LEDs or sound when the footswitch is engaged. Bypass still works fine.


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## peccary (Aug 22, 2021)

This is a shot in the dark for me, but I just wanted to ask to be sure: you replaced C20 with a polarized cap - are you sure it's aligned in the correct polarity? I took a look at the schematic, but can't tell how it needs to be aligned on the board since I can't see the traces on the PCB. Just thought I'd ask!


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## Stickman393 (Aug 22, 2021)

Oooo.

Check your LED orientation.  Anode to A and Cathode to K? During the initial build, you would want to put the long leg of the LED through the round pad.

It looks like you have C-20 oriented correctly (negative towards output)...double check the LEDs first, there may also be something else going on in the circuit.

IC voltages could help here.


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## JamieJ (Aug 22, 2021)

You could have quite a few cold joints there as well. It’s definitely worth reflowing (with the ICs removed) and then clean the board with IPA to rule that out.


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## zipfool (Aug 22, 2021)

peccary said:


> This is a shot in the dark for me, but I just wanted to ask to be sure: you replaced C20 with a polarized cap - are you sure it's aligned in the correct polarity? I took a look at the schematic, but can't tell how it needs to be aligned on the board since I can't see the traces on the PCB. Just thought I'd ask!


That's an interesting question. C20 *is* supposed to be a film capacitor. Would that cause the pedal to malfunction? I could always flip the polarity, but Stickman393 is saying I've got it right. I might just order a 1uf film capacitor if that might make all the difference...


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## JamieJ (Aug 22, 2021)

zipfool said:


> That's an interesting question. C20 *is* supposed to be a film capacitor. Would that cause the pedal to malfunction? I could always flip the polarity, but Stickman393 is saying I've got it right. I might just order a 1uf film capacitor if that might make all the difference...


If that cap is in the correct way the. Changing it to film won’t make a difference unfortunately. Where do you get your MN3207?


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## zipfool (Aug 22, 2021)

JamieJ said:


> If that cap is in the correct way the. Changing it to film won’t make a difference unfortunately. Where do you get your MN3207?


I got the MN3207 and MN32102 pairs from a supplier on eBay.


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## JamieJ (Aug 22, 2021)

That has been a problem for some people as those chips can be fakes more often than not.


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## zipfool (Aug 22, 2021)

Stickman393 said:


> Oooo.
> 
> Check your LED orientation.  Anode to A and Cathode to K? During the initial build, you would want to put the long leg of the LED through the round pad.
> 
> ...


I just checked the LEDs and they're oriented correctly. That for the suggestion though.

Here are the IC voltages:

TL022cp:
-.008
-.008
-.008
0
-.008
-.007
-.008
-.016

MN3207
0
.028
0
-.015
-.016
.025
0
0

MN3102
-.016
.029
0
.032
-.62
0
-.015
-.015

TL072CP (same readings if I use RC4558)
-.008
-.008
-.008
0
-.008
-.007
-.007
-.017


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## zipfool (Aug 22, 2021)

Bah, nevermind everyone. I'm completely missing C3 (100nf). I'm going to get my brain examined because this is some really basic shit


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## Stickman393 (Aug 22, 2021)

zipfool said:


> Bah, nevermind everyone. I'm completely missing C3 (100nf). I'm going to get my brain examined because this is some really basic shit



Ahhh, I see it.  Can really only tell from the bottom.

Yup, that'll stop your LFO cold.

Those IC voltages don't look right...how are you taking those measurements?


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## zipfool (Aug 22, 2021)

So I soldered in the missing and wrong components, but I'm still getting the same voltages on ICs (with only two exceptions). I edited/corrected the values in the list I posted above. 

Anyone know what would cause almost all of these values to be so low/negative voltages? I can't imagine that's normal for a circuit like this...


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## Robert (Aug 22, 2021)

zipfool said:


> Anyone know what would cause almost all of these values to be so low/negative voltages? I can't imagine that's normal for a circuit like this...



The most likely cause is an incorrectly wired DC jack.    What voltages do you read on each end of the 1N5817 diode at the top of the board?


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## zipfool (Aug 23, 2021)

-9v at one end and -.019v on the other end


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## Stickman393 (Aug 23, 2021)

zipfool said:


> -9v at one end and -.019v on the other end


 
You got that DC power supply backwards my friend.

Center negative, that should read (+Input voltage) on one side and (+slightly less than input voltage) on the other side.


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## zipfool (Aug 21, 2021)

This seems like it's going to be tricky to figure out. Bypass works fine, but the 2nd LED stays lit even in bypass. When I engage the switch, both LEDs light up, but I'm not hearing any of the Chorus effect no matter how much I crank the knobs/pots.

I opted to go with the MN3207 / MN3102 IC pairing, but I suspect that my source for these was bogus (seller on EBay). I've tried 4 out of 10 of the pairs they sold me, and I'm getting the same [lack of] effect with all 4 pairs. I could keep trying out the other pairs, but I'm suspicious that all of them will be the same.

Take a look at these photos and LMK if you see anything else suspicious.

There's a few things to this build that are new to me: not sure what the trim pot is supposed to control, and I've never had to solder an onboard jumper to signify which chip combo I bought. Did I do the right thing by putting a bead of solder to connect each of the 2 sets of pads? 

If I dial the trim pot up too high, the sound cuts out. Same if dial it too low. Right in the middle and I get clear sound/tone. What does this trim pot do?


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## zipfool (Aug 24, 2021)

Lol. Thanks for being patient with me. Yes, I had it backwards!

Now I'm getting a blinking LED on one side and the other LED operates as it should when engaged. The blinking LED changes speed when I'm turning the rate pot.

D100 is now getting 9.09v on one end and 8.85v on the other.

The sound is still not being affected though. I tried dialing the trim pot in small increments and nothing seems to affect the sound.


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## Stickman393 (Aug 24, 2021)

Feel like grabbing some revised IC voltages?

We're getting closer!


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## zipfool (Aug 24, 2021)

Stickman393 said:


> Feel like grabbing some revised IC voltages?
> 
> We're getting closer!


I'll write em  down tomorrow when I'm back in the shop. Thanks for all your help!


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## zipfool (Aug 24, 2021)

TL022CP:
3-5v fluctuating
4.3v
3-4.8v fluctuating
0v
.004v
4.38v
3.8-4.8v fluctuating
8.67v

MN3207:
0v
8.69v
3.58v
8.1v
8.73v
0v
.06v
.02v

MN3102:
8.73v
0v
0v
8.74v
-0.6v
0v
8.6v
8.15v

TL072CP:
4.34v
4.34v
4.34v
0v
4.34v
4.35v
4.35v
8.84v

See anything noteworthy?


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## Stickman393 (Aug 24, 2021)

Definitely Pin 5 on the TL022.  That one's supposed to be directly tied to VREF_B, roughly 1/2 of input voltage.

That should be equal to pin 2, which you have at 4.3V.  Maybe a bad solder joint...it's worth poking around in that area.


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## zipfool (Aug 24, 2021)

I'll take a look and re flow the solder leading up to that IC. Thanks!


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## zipfool (Aug 25, 2021)

Now I'm getting some different values:

TL023:
2.7-5.9 fluctuating
4.35
3.5-5.0 fluctuating
0
4.35
4.38
3.9-4.7 fluctuating
8.75

MN3207:
0
8.75
6.03
8.18
8.75
0
.002
.006

MN3102:
8.75
8.62
.002
8.75
-.835
0
8.62
8.18

TL072:
0
6.89
6.89
0
6.89
6.89
6.89
8.85

What does it all mean!?


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## music6000 (Aug 25, 2021)

zipfool said:


> I got the MN3207 and MN32102 pairs from a supplier on eBay.


They have the MATSUSHITA brand, the MN3102 looks right ????, The MN3207 has rounded corners & is missing the top Notch* ?????!*


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## Stickman393 (Aug 25, 2021)

zipfool said:


> What does it all mean!?



Basically:

Normal CE-2 LFO (TL022)
1)variable
2)Around 1/2 input
3)variable
4)0
5)Around 1/2 input
6)Around 1/2 input
7)variable
8)input voltage


Normal CE-2 pre/de emphasis filter (TL072)
1)similar to 2 & 3, around 1/2ish V
2)--
3)--
4)0
5)similar to 6 and 7, around 1/2ish V
6)--
7)--
8)Input voltage

But...I'll have to get back to you on the BBD and clock.  I'm more familiar with the MN3007 in this circuit than the MN3207.

music6000 makes a good point, it *could* be related to a counterfeit Bbd/clock.  I'm usually one to recommend a parts change as a last resort unless it's immediately obvious...you end up learning more in the process of building by doing a proper debug, and end up spending a lot less money too.

Your IC1 PIN 1 is off now.  Take a look at what's directly connected to that pin on the schematic...that value needs to be similar to pins 2 and 3.


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## zipfool (Aug 25, 2021)

music6000 said:


> They have the MATSUSHITA brand, the MN3102 looks right ????, The MN3207 has rounded corners & is missing the top Notch* ?????!*


Yeah some have a rounded notch at the top some don't. I'll try some other pairs that they sent me...


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## zipfool (Aug 25, 2021)

Stickman393 said:


> Basically:
> 
> Normal CE-2 LFO (TL022)
> 1)variable
> ...


Thanks! Are you referring to pin 1 on the TL072 when you say pin 1 is off now? Based on the list you gave, that's what it looks like...


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## zipfool (Aug 26, 2021)

I reflowed the joints for R13, R10, R9, C2, and C4. I also checked the circuit with the other MN32017/3102 pairs that I bought.

I found that only 2 pairs out of 8 pairs of MN ICs had any effect on the sound. When I have either of these 2 pair in the circuit, I get a very subtle modulation sound. It sounds more like a vibrato set to very low depth. That's the most I get even though the depth is turned all the way up and rate is set to 50%.

I did notice a very subtle difference when dialing the trim pot. But even at a "sweet spot" it's still an almost imperceptible effect.

Any thoughts on what to try next?


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## zipfool (Aug 26, 2021)

Oh yeah, here's voltage check on ICs:

IC1 - TL022:
2.7-5.9 fluctuating
4.35
3.5-5.0 fluctuating
4.35
4.38
3.9-4.7 fluctuating
8.75

IC2 - TL072
5.65
5.65
5.65
0
5.65
5.65
5.65
8.85

IC3 - MN3207
0
4.26
4.87
8.18
8.75
4.27
5.28
5.28

IC4 - MN3102
8.75
4.27
0
4.26
.28
8.36
2.72
8.18


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## music6000 (Aug 26, 2021)

Have you cleaned the back side of the PCB board, there's a lot of flux residue & stray bits of Solder.
If not, you *need* to clean the PCB!!!


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## zipfool (Aug 27, 2021)

music6000 said:


> Have you cleaned the back side of the PCB board, there's a lot of flux residue & stray bits of Solder.
> If not, you *need* to clean the PCB!!!


Good call. I'll give it a scrub a dub with alcohol tomorrow.


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## zipfool (Aug 28, 2021)

music6000 said:


> Have you cleaned the back side of the PCB board, there's a lot of flux residue & stray bits of Solder.
> If not, you *need* to clean the PCB!!!


Scrubbed the PCB nice and clean. It still doesn't work.

I re flowed all the joints, tried a few more/other ICs and still nothing. I get a decent tone, sounds almost exactly like how it does in bypass. Just a very subtle modulation/vibe.

I'm coming to the conclusion that all of these MN chips that I bought are bogus. I bought them from a seller on eBay, so I guess that's what happens 🤷‍♂️.

Anyone know a good source for MN3207/3201 pairs? I guess V3207 or BL3207 would work as well. Let me know where you all are getting the hard to find ICs.


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## music6000 (Aug 28, 2021)

zipfool said:


> Scrubbed the PCB nice and clean. It still doesn't work.
> 
> I re flowed all the joints, tried a few more/other ICs and still nothing. I get a decent tone, sounds almost exactly like how it does in bypass. Just a very subtle modulation/vibe.
> 
> ...


Where are you on planet Earth?


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## zipfool (Aug 28, 2021)

music6000 said:


> Where are you on planet Earth?


West coast of the USA


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## music6000 (Aug 28, 2021)

zipfool said:


> Scrubbed the PCB nice and clean. It still doesn't work.
> 
> I re flowed all the joints, tried a few more/other ICs and still nothing. I get a decent tone, sounds almost exactly like how it does in bypass. Just a very subtle modulation/vibe.
> 
> ...


*MN3207 & MN3102* not MN3201!


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## zipfool (Aug 29, 2021)

I mistyped that. Yes, confirmed that they're MN3102


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## zipfool (Aug 21, 2021)

This seems like it's going to be tricky to figure out. Bypass works fine, but the 2nd LED stays lit even in bypass. When I engage the switch, both LEDs light up, but I'm not hearing any of the Chorus effect no matter how much I crank the knobs/pots.

I opted to go with the MN3207 / MN3102 IC pairing, but I suspect that my source for these was bogus (seller on EBay). I've tried 4 out of 10 of the pairs they sold me, and I'm getting the same [lack of] effect with all 4 pairs. I could keep trying out the other pairs, but I'm suspicious that all of them will be the same.

Take a look at these photos and LMK if you see anything else suspicious.

There's a few things to this build that are new to me: not sure what the trim pot is supposed to control, and I've never had to solder an onboard jumper to signify which chip combo I bought. Did I do the right thing by putting a bead of solder to connect each of the 2 sets of pads? 

If I dial the trim pot up too high, the sound cuts out. Same if dial it too low. Right in the middle and I get clear sound/tone. What does this trim pot do?


----------



## fig (Aug 29, 2021)

You have a private message @zipfool 🙂


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## zipfool (Aug 29, 2021)

fig said:


> You have a private message @zipfool 🙂


Thanks so much! This is one of the most generous forums I've visited. Generosity FTW!


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## Stickman393 (Aug 30, 2021)

zipfool said:


> Thanks so much! This is one of the most generous forums I've visited. Generosity FTW!


One of us, one of us...


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## zipfool (Sep 4, 2021)

Update: I'm getting a bit more of a chorus effect now that Fig sent me some verified MN3207/MN3102 ICs. I only notice the effect when I have both rate and depth turned all the way up. Even then, it's very subtle. 

I have tried dialing the trim pot a bit and there's definitely a sweet spot but it's still barely noticeable.

Here are the voltages I'm getting:

TL022
3.9-4.5 fluctuating
4.35
4.0-4.5 fluctuating
0
4.35
4.35
4.2-4.5 fluctuating
8.73

MN3207
0
4.24
5.21
8.14
8.73
4.21
6.5
6.5

MN3102
8.75
4.21
0
4.23
0.28
8.38
2.87
8.14

TL072
6.01
6.0
5.9
0
6.01
6.002
6.01
8.86

Any thoughts on what I could try next?


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## carlinb17 (Sep 4, 2021)

Have you tried using a 4558 chip in place of the tl072? I believe it has a lower voltage draw and it’s what’s in the parts list for this build. I can grab the voltages from mine in the am for reference if you want them.


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## zipfool (Sep 4, 2021)

Thanks! Yeah, I tried a 4558 today and got the same measurements.


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## Stickman393 (Sep 5, 2021)

I'll have to double check against my own IC voltages, but truthfully the CE-2 isn't the craziest chorus in the world.  It doesn't quite go where the Julia does.

It's a more subtle beast...you won't get super whacked out sounds from that pedal.

I'd say try this: adjust the trimpot until pins 7/8 on the MN3207 are at roughly 1/2 input voltage as a starting point, and adjust by ear from there with rate at min and depth at max.  Each BBD will be different, and you might have it dialed in right now...or maybe something else is going on.  Hard to say without hearing/putting a scope on it.


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## music6000 (Sep 5, 2021)

zipfool said:


> Update: I'm getting a bit more of a chorus effect now that Fig sent me some verified MN3207/MN3102 ICs. I only notice the effect when I have both rate and depth turned all the way up. Even then, it's very subtle.
> 
> I have tried dialing the trim pot a bit and there's definitely a sweet spot but it's still barely noticeable.
> 
> ...


Are all the voltages listed are as pictured:




1.
2.
3.
4.
5.
6.
7.
8.


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## music6000 (Sep 5, 2021)

If Voltages are matching pinout above, Check matching circles for continuity.
What Voltage do you get @ R22 - 150K Yellow circle?
What voltage do you get @ R22 - 150K Blue circle?
*UPDATE: Can you confirm R26 = 33K - Orange, Orange, Black, Red , Brown*


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## carlinb17 (Sep 5, 2021)

ok here are my voltages for reference if it helps

4558
4.8
4.8
4.9
0
4.8
4.8
4.8
9.1

22

Fluctuates 3-6
Fluctuates3-6
Fluctuates3-6
0
4.5
4.5
Fluctuates 3-6
8.99


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## music6000 (Sep 5, 2021)

music6000 said:


> If Voltages are matching pinout above, Check matching circles for continuity.
> What Voltage do you get @ R22 - 150K Yellow circle?
> What voltage do you get @ R22 - 150K Blue circle?
> *UPDATE: Can you confirm R26 = 33K - Orange, Orange, Black, Red , Brown*
> ...


The Op Amp Diagram was to confirm the order of your previous Voltage readings are correct!!!
Your MN3102 has some low voltage going on, Can you test the PCB as marked above for Continuity & Voltage in Yellow & Dark Blue, both sides of R22 - 150K?


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## music6000 (Sep 5, 2021)

Stickman393 said:


> I'll have to double check against my own IC voltages, but truthfully the CE-2 isn't the craziest chorus in the world.  It doesn't quite go where the Julia does.
> 
> It's a more subtle beast...you won't get super whacked out sounds from that pedal.
> 
> I'd say try this: adjust the trimpot until pins 7/8 on the MN3207 are at roughly 1/2 input voltage as a starting point, and adjust by ear from there with rate at min and depth at max.  Each BBD will be different, and you might have it dialed in right now...or maybe something else is going on.  Hard to say without hearing/putting a scope on it.


Have you built the PedalPCB version?


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## Stickman393 (Sep 5, 2021)

music6000 said:


> Have you built the PedalPCB version?


Yup...got a build report on the forum.  Actually got one of the first batch, before the revision that enlarged SW1&2 and fixed the issue where r27 bypassed SW2 and connected directly to ground.  It would have worked fine with a *3207, but I built it with the NTE1641, a mn3007 work alike.  Spent a good couple of hours tracking that one down...

Zip, you're best off taking music6000's advice here.


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## zipfool (Sep 11, 2021)

music6000 said:


> If Voltages are matching pinout above, Check matching circles for continuity.
> What Voltage do you get @ R22 - 150K Yellow circle?
> What voltage do you get @ R22 - 150K Blue circle?
> *UPDATE: Can you confirm R26 = 33K - Orange, Orange, Black, Red , Brown*
> ...


Sorry for the delay. Yes, my voltage readings follow the order/numbering in your diagram.

As for continuity, yes both the Teal and the Red sets in your image have continuity (respectively).

R22:
Yellow: 8.7v
Blue: 2.9v

R26: 33k confirmed by both the stripes and double checked with a multimeter.


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## zipfool (Sep 11, 2021)

Stickman393 said:


> I'll have to double check against my own IC voltages, but truthfully the CE-2 isn't the craziest chorus in the world.  It doesn't quite go where the Julia does.
> 
> It's a more subtle beast...you won't get super whacked out sounds from that pedal.
> 
> I'd say try this: adjust the trimpot until pins 7/8 on the MN3207 are at roughly 1/2 input voltage as a starting point, and adjust by ear from there with rate at min and depth at max.  Each BBD will be different, and you might have it dialed in right now...or maybe something else is going on.  Hard to say without hearing/putting a scope on it.


Thanks for the suggestion of adjusting trim until legs 7/8 are roughly half voltage. I'm getting more reasonable numbers now for all the ICs:

TL022:
2-5 (fluctuating)
4.3
3.5-5 (fluctuating)
0
4.3
4.3
3.6-5 (fluctuating)
8.7

MN3207:
0
4.2
3.59
8.12
8.7
4.2
4.2
4.2

MN3102:
8.7
4.2
0
4.2
0.27
8.35
2.8
8.12

TL072:
4.3
4.3
4.3
0
4.3
4.3
4.3
8.85

I recorded a short video to give a sample of the tone I'm getting through the pedal:








						New video by Colin Day
					






					photos.app.goo.gl
				




It's almost imperceptible in the video. I can just barely hear a difference between bypass/enabled with my ears. And maybe I'm just fooling myself with that observation. Truly, this pedal shouldn't be that subtle, right!?


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## music6000 (Sep 11, 2021)

zipfool said:


> Thanks for the suggestion of adjusting trim until legs 7/8 are roughly half voltage. I'm getting more reasonable numbers now for all the ICs:
> 
> TL022:
> 2-5 (fluctuating)
> ...


No, it's not right, I have an Original Boss CE-2!
I have gone over your PCB with a fine tooth comb, *Magnified* it as big as the screen.
Can you tell me the Voltages at the Pads on both sides of R22 -150K marked in Yellow & Dark Blue in the Picture above.
C*an you re check all your Resistor values with this Calculator*
Click on Bands for 5 COLOURS:








						Resistor Calculator
					

Resistor Calculator is an App developed by CherryJourney to help the user find the value of a resistor.




					resistor.cherryjourney.pt


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## zipfool (Sep 11, 2021)

For 


music6000 said:


> No, it's not right, I have an Original Boss CE-2!
> I have gone over your PCB with a fine tooth comb, *Magnified* it as big as the screen.
> Can you tell me the Voltages at the Pads on both sides of R22 -150K marked in Yellow & Dark Blue in the Picture above.
> C*an you re check all your Resistor values with this Calculator*
> ...


For voltages at R22,  (8.7/2.9) look at my post from earlier this morning... I'll double check that all resistors are right. Thanks for the band reader tool.


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## zipfool (Sep 11, 2021)

music6000 said:


> No, it's not right, I have an Original Boss CE-2!
> I have gone over your PCB with a fine tooth comb, *Magnified* it as big as the screen.
> Can you tell me the Voltages at the Pads on both sides of R22 -150K marked in Yellow & Dark Blue in the Picture above.
> C*an you re check all your Resistor values with this Calculator*
> ...


I checked all the resistor colors/bands and all of them besides two matched perfectly with the image you posted above...

...but it looks like either that's an old/inaccurate image and PedalPCB updated their build docs, or the image you posted is correct and thats where I got resistor values wrong.

In your image, R34 and R35 are 12k. But in my build docs (and the PCB screenprint), those two resistors are supposed to be 47k. This is the only discrepancy I can see between your image and the current build docs, so it makes me curious what I should be using in those two spots.

I could try 12k in those two spots, but I run the risk of wearing out the pads soldering and resoldering.


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## zipfool (Sep 11, 2021)

music6000 said:


> No, it's not right, I have an Original Boss CE-2!
> I have gone over your PCB with a fine tooth comb, *Magnified* it as big as the screen.
> Can you tell me the Voltages at the Pads on both sides of R22 -150K marked in Yellow & Dark Blue in the Picture above.
> C*an you re check all your Resistor values with this Calculator*
> ...


I checked all the resistor colors/bands and all of them besides two matched perfectly with the image you posted above...

...but it looks like either that's an old/inaccurate image and PedalPCB updated their build docs, or the image you posted is correct and thats where I got resistor values wrong.

In your image, R34 and R35 are 12k. But in my build docs (and the PCB screenprint), those two resistors are supposed to be 47k. This is the only discrepancy I can see between your image and the current build docs, so it makes me curious what I should be using in those two spots.

I could try 12k in those two spots, but I run the risk of wearing out the pads soldering and resoldering.


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## zipfool (Sep 11, 2021)

I poked around a bit more and discovered what was going wrong. It works now!

I noticed that C16 was the wrong capacitor. Swapped it out for the right one and it works great now.









						New video by Colin Day
					






					photos.app.goo.gl
				




Huge thanks to everyone who pitched in to help:

Music6000 and Stickman393 for patient wisdom taking me back to the fundamentals.

Fig for sending me a pair of MN3207/3102.

Everyone else I missed, thanks for all the help!


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## zipfool (Aug 21, 2021)

This seems like it's going to be tricky to figure out. Bypass works fine, but the 2nd LED stays lit even in bypass. When I engage the switch, both LEDs light up, but I'm not hearing any of the Chorus effect no matter how much I crank the knobs/pots.

I opted to go with the MN3207 / MN3102 IC pairing, but I suspect that my source for these was bogus (seller on EBay). I've tried 4 out of 10 of the pairs they sold me, and I'm getting the same [lack of] effect with all 4 pairs. I could keep trying out the other pairs, but I'm suspicious that all of them will be the same.

Take a look at these photos and LMK if you see anything else suspicious.

There's a few things to this build that are new to me: not sure what the trim pot is supposed to control, and I've never had to solder an onboard jumper to signify which chip combo I bought. Did I do the right thing by putting a bead of solder to connect each of the 2 sets of pads? 

If I dial the trim pot up too high, the sound cuts out. Same if dial it too low. Right in the middle and I get clear sound/tone. What does this trim pot do?


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## music6000 (Sep 12, 2021)

zipfool said:


> I could try 12k in those two spots, but I run the risk of wearing out the pads soldering and resoldering.


47k is correct for those 2 Resistors, That was the first thing I noticed way back when you first posted,
It was changed from 12K as the pedal was Louder than Unity when On!


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## zipfool (Sep 12, 2021)

music6000 said:


> 47k is correct for those 2 Resistors, That was the first thing I noticed way back when you first posted,
> It was changed from 12K as the pedal was Louder than Unity when On!


Thanks for all the help. I was starting to think I'd never have the sound of the 80's/90's coming through my amp ever again 🤓.

I'll post an enclosures and gut shot once I have everything finished up.


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## zipfool (Sep 12, 2021)

Here's a look at the final build:
Chorus of Disapproval

More stuff on Instagram @stompgarage .


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## Stickman393 (Sep 12, 2021)

One flew over the cuckoo's nest?

Cause...bird...flip...nevermind.


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## zipfool (Sep 12, 2021)

Stickman393 said:


> One flew over the cuckoo's nest?
> 
> Cause...bird...flip...nevermind.


😂


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