# Help with CE-2 pedal



## Matoni (May 1, 2022)

Hello, 
I need help with my Cepheid Chorus build. I am getting a signal coming through when I plug the pedal in, but there is no chorus sound. This is probably because of the R34 47K leak resistor seen at the very top of the schematic. There is no chorus sound, however. I have probed with an oscilloscope, so I know that there is a signal going into the MN3207 chip I am using, as well as voltage going in the correct pins, however, there is no signal coming out of pin 7 or 8. Please let me know what tests I can run to try and further diagnose the problem. I am using a corresponding MN3102 clock chip, but it may not be working. I have no clue how either the BBD or Clock chip work. Please let me know what I may have done wrong. I will post pictures if they are requested. Thanks so much in advance for your help.


----------



## Robert (May 1, 2022)

Where did you get your MN3207 / MN3102 ICs?


----------



## Matoni (May 1, 2022)

Thanks for your quick reply. I got sent them by Ryan Z, another member of this forum. He had a thread somewhere saying he had extra sets of these chips that he was giving away. I assume they work because he sent them to me, meaning his pedal probably worked. Maybe they are counterfeit. Let me know if there is a more reliable source for these chips, I am happy to re-buy. Thank you so much for your help.


----------



## Robert (May 1, 2022)

Post some pics of your build, I'd hate to send you off buying more ICs if there's some other simple problem to blame.

If you do determine they are the issue you can get the CoolAudio reproductions (V3207, V3102)  from StompBoxParts or CabinTech.   Both vendors are reliable sources.

StompBoxParts:
V3207D + V3102D Combo

CabinTech:
V3207D 
V3102D


----------



## Robert (May 1, 2022)

BTW did you set the solder jumpers for the appropriate ICs?   (Page 2 of the build doc)


----------



## Matoni (May 1, 2022)

Yes I did solder the jumpers the correct way. I tested this by using my multimeter and the voltage input going into the chips is correct. I will upload pictures as soon as I can. Thanks again for your time and help.


----------



## Robert (May 1, 2022)

You might also want to adjust the BBD Bias trim pot.     

There are "proper" steps for making the adjustment but you can get there by slowly turning up the trim pot until you hear chorusing, then micro-adjust for the cleanest signal without clipping.


----------



## Matoni (May 1, 2022)

here is a picture of my board. Thanks again for all the help. I will try the thing with the trimpot and let you know if it helps.


----------



## Matoni (May 1, 2022)

Just tried adjusting the bias pot, doesn't help. If anything, it adds a little bit of gain to the signal and that's about it.


----------



## Mcknib (May 2, 2022)

Don't see anything out of place can't see R5 bands clearly not sure if the multipliers orange or brown

What's your transistor and IC voltages that might highlight something

I'm assuming your LFO functions ok if you've had it on a scope

You could obviously check the clock frequency with your scope to make sure it's working, check you get a square wave off the 3207 pins 2 and 6 etc the datasheets will give you information you may be able to use to verify whether they're working or not

This may help although I can't vouch for accuracy






						ElectroSmash - Boss CE-2 Analysis
					

Chorus Effect,Architecture,Circuit, Achematic,Layout,Components Part List,JFET Bypass Switch, Power Supply,Boss ACA vs. PSA Power Supply Adapters,Input Buffer,Input Impedance,Pre-De Emphasis Filters,Shelving Filters with Operational Amplifiers,Inverting O




					www.electrosmash.com


----------



## Matoni (May 2, 2022)

Yes, I agree that the LFO probably functions correctly. This can be backed up by the fact that I plugged in the LFO LED and it blinks depending on how far the rate knob is up. All of the transistors and op-amps are reading at the correct voltage that they are supposed to be at, so I have no clue what the problem may be. I also tried taking out the BBD chip, and I got the exact same signal that I got with the chip, making me think it was a problem with the chip. I then swapped the chip out with another one sent to me from Ryan Z (he sent me 2 sets, thanks again to him) and I got the same signal as I did without the chip and with the previous BBD chip in. Let me know if there are any other tests I can run.


----------



## Bio77 (May 2, 2022)

Use the frequency setting on you DMM or your scope to measure the frequency of the clock signal (pins 2 and 4 of the 3102).  If your clock isn't working the delay chip won't either.


----------



## Matoni (May 3, 2022)

I just used the frequency setting on my multimeter, and bridging together pins 2 and 4, I got 60 hz. Is this what it is supposed to be? I also tried subbing in the other clock chip I was sent, and all I get is a very loud humming sound, with of course some of the signal coming in through the leak resistor. The signal may sound a little bit modulated, but it may just be gain (I can't tell over the howling sound I am getting)
Thanks again for your help. Let me know if you need any more pictures. (R5 is measuring at the correct 470Kish ohms range, so I don't think there is any problem with that.


----------



## Bio77 (May 3, 2022)

To measure the frequency you will place the black probe of the DMM to ground, then measure with the red probe at pin 2 or 4.

Also, let me know the model number of you DMM.  Some don't measure high enough frequency.  Your scope will be able to, though, if this doesn't work.


----------



## Matoni (May 3, 2022)

one of the chips measures no frequency, while the other one (the one with the howling sound) measures at about 244hz on both legs 2 and 4.


----------



## Matoni (May 3, 2022)

Not sure, but I think this means that the one reading 0hz and getting no hum is a broken chip whereas the other one is the working chip, despite. the hum? I'm really not sure here this is my first analog modulation circuit using a BBD and clock, so let me know if my assumption is correct.


----------



## Bio77 (May 3, 2022)

Matoni said:


> Not sure, but I think this means that the one reading 0hz and getting no hum is a broken chip whereas the other one is the working chip, despite. the hum? I'm really not sure here this is my first analog modulation circuit using a BBD and clock, so let me know if my assumption is correct.


No, sorry, you are only measuring pins 2 and 4 (separately) of the 3102 (the clock chip).   Also, what is the model number on your DMM?


----------



## Matoni (May 3, 2022)

Yeah thats what I meant. The frequency between ground and pin 2 is 244 hz and the frequency between ground and pin 4 is 244 hz. Hopefully I am not doing anything wrong with the measurements. I have an SDM3045X multimeter.


----------



## Matoni (May 3, 2022)

also just to clarify when I said "one chip" I meant one clock chip. I only measured the clock chip, not the BBD chip.


----------



## Bio77 (May 3, 2022)

Whoa, that looks like a legit MM.  Specification says it measures up to 500kHz, so, should be fine for most things except an A/DA flanger.

244 Hz is way too low.  It should be around 75-150kHz.  This is good news, your problem is between the depth pot and the clock.

IMO, a bad or fake chip is rarely the problem.  Some things to try first:  1. checking all the values (just with your eyes, you can't measure them once they are in circuit) of components connected between the Depth pot and the clock.   2. reflow the joints of those parts. 3. double check the voltages on the 3102.  4. use your scope to trace the LFO signal from the depth pot to pin 5 and 7 on the 3102.  If all that checks out then, yep, bad clock.


----------



## Matoni (May 1, 2022)

Hello, 
I need help with my Cepheid Chorus build. I am getting a signal coming through when I plug the pedal in, but there is no chorus sound. This is probably because of the R34 47K leak resistor seen at the very top of the schematic. There is no chorus sound, however. I have probed with an oscilloscope, so I know that there is a signal going into the MN3207 chip I am using, as well as voltage going in the correct pins, however, there is no signal coming out of pin 7 or 8. Please let me know what tests I can run to try and further diagnose the problem. I am using a corresponding MN3102 clock chip, but it may not be working. I have no clue how either the BBD or Clock chip work. Please let me know what I may have done wrong. I will post pictures if they are requested. Thanks so much in advance for your help.


----------



## Mcknib (May 4, 2022)

C11 should be 47pf yours looks like 473 or 47nf

That'll obviously affect your clock output


----------



## Matoni (May 5, 2022)

So I just reflowed all the solder for the entire board. It still doesn't work, but in the noise coming from the board I can hear a slight pulsating sound going at the same speed as the LFO LED. I like to reflow solder with the effect on to help with debugging, and something extremely strange happened when I put my soldering iron on pin 1 of Q2. I started to hear a pitch that had a modulated depth that changed as I changed the depth pot. still no chorus signal though for my guitar even with this. I will now go trace the LFO signal from the depth knob all the way to the 3102 chip. Let me know if what I found means anything, or if it is just a coincidence.


----------



## Matoni (May 5, 2022)

Mcknib said:


> C11 should be 47pf yours looks like 473 or 47nf
> 
> That'll obviously affect your clock output


I didnt see this message until right now!! I don't have any 47pf caps, will a 51 pf cap work or should I order a 47 pf. And you were right, this was the wrong value. Im so glad you spotted that. Thank you so much!!


----------



## Matoni (May 5, 2022)

Just tried switching out the cap for a 47pF Silver mica cap I had lying around from another build and I am still getting no chorusing, but the clock is reading 1k hz now so thats at least a little bit better. Thanks for pointing that out to me.


----------



## Matoni (May 5, 2022)

and I just traced from the depth knob to the clock chip and everything looks good. I will order the new chips as soon as I can to see if it is a chip problem. Thanks again for all your help.


----------



## Mcknib (May 5, 2022)

I'd post all your IC pin and transistor voltages that might lead you to your problem area


----------



## Matoni (May 5, 2022)

so what exactly should I measure? The voltage between each pin of each chip and transistor and ground? or did you just mean the chip power voltage? I'm not completely sure what is needed here. 
if you meant what I said at first, here is the voltage between each pin of each chip and ground:
IC1: pin 1: 1.6vdc, pin 2: 4.3vdc, pin 3: 4.3vdc, pin 5: 4.3vdc, pin 6: 4.3vdc pin 7: 4.3vdc, pin 8:8.6vdc.
IC 2: all pins besides pin 8 (and obviously pin 4 because it is ground) are 2.7vdc, pin 8 is 8.9vdc
IC3: pin 1 and 2: 0vdc, pin 3: 2.1vdc, pin 4,5,6: 8.6vdc, pins 7,8: 3.7vdc
IC4: pins 8,5,1,2: 8.6vdc, all other pins 0vdc. This is still measuring at 0hz for some reason off pins 2 and 4. Maybe it is just a bad chip? new chips are on the way. 
Q1: pin 1: 2vdc, pin 2: 2.5vdc, pin 3: 8.6vdc 
Q2: pin 1: 3.4vdc, pin 2L 3.9vdc, pin 3: 8.6vdc
Q3: pin 1: 2.1vdc, pin 2: 2.9vdc, pin 3: 8.9vdc
Q4: pin 1: 0vdc, pin 2: 0.6vdc, pin 3: 20mVDC (this seems like a problem, no clue what is causing it. The cap I put in is for amps so it is way over specked, I don't think that should be a problem though.)
Q5: pin 1: 2.1vdc, pin 2: 2.5vdc, pin 3L 8.6vdc

everything but Q4 looks about right I think? let me know what you guys think may be wrong given this new information. Thank you again for all of your help.


----------



## Mcknib (May 5, 2022)

Voltages don't look right to me you'd want around 4.5 (half power) on all the VREF points

Pin 3 of the BBD is the bias pin that should have around VREF voltage too I think, you'd defo need more than 2.1v

VREF is set by the trimmer and VREF B by the voltage divider R100 and 101 that looks ok with your IC1 voltages and LFO sounding like it's working

What voltage do you get on the trimmer middle lug try adjusting that to 4.5v ish


----------



## Matoni (May 5, 2022)

I just adjusted the bias pot to 4.5 volts, still doesn't work. Would you like me to send out the new list of voltages for the BBD? I'll do anything I need to do. Thanks again for all your help.


----------



## Mcknib (May 5, 2022)

What's the voltage on pin 3 of the 3207 and IC2 pins 3 and 5


----------



## Matoni (May 5, 2022)

IC2 pins 3 and 5 are measuring at 4.5 volts DC and IC3 pin 3 is measuring at 3.8vdc. Hopefully, this helps. I have no idea why this pedal is being so difficult. Hopefully, with your guys' help, I am able to resolve this quickly!


----------



## Mcknib (May 5, 2022)

Check your Q3 voltages the emitter should be round about the same as pin 3

Try reflowing Q3, the joints look ball like and may be partially dry inside and causing some resistance to voltage

Obviously only reflow for around 4 seconds per pin till you see a nice solder flow you don't want too much heat frying your transistor 

It's just a process of elimination you've now got your VREF set correctly, so all the VREF points you can see on the schematic should have the same voltage as the trimmer middle lug if they're not you'd just trace it back using the schematic to see where it stops or changes

Pin 3 voltage is almost there so again you'd trace back to Q3


----------



## Matoni (May 6, 2022)

The voltage on the middle lug of Q3 is not 4.5 volts. Is this a problem? I reflowed the solder. I will send a picture of the bottom of the board shortly and you guys can tell me if theres anything that looks sketchy going on under there.


----------



## Matoni (May 6, 2022)

wait never mind I was measuring the wrong transistor. The middle pin of Q3 is 4.5 volts. THis is what I would expect it to be. PLease let me know what the next step is.


----------



## Matoni (May 6, 2022)

As promised, here is a picture of the bottom of my board. Hope this helps us in figuring out what is wrong with this thing.


----------



## Mcknib (May 6, 2022)

You've a few dull looking joints on the BBD and clock

Remove the ICs from their sockets and reflow the socket joints

Clean the pcb with isopropyl alchohol or something similar

All the steps taken so far are basically trying to confirm whether your clock and or BBD are faulty ie make sure the surrounding circuitry is doing what it's supposed to there's nothing worse than replacing an IC and it's the same, so you're best trying to diagnose it properly although it's time consuming it's also a learning opportunity

From your description you do get clean signal and the LFO works with varying voltage on the IC output pins so gotta be something on the wet side again you've improved things with a higher bias voltage on pin 3 albeit I don't know if 3.8v is high enough or it needs to be 4.5v minimum

If someone has working voltages they can post that'd be good

You've fixed a few things so can't be that far away


----------



## Matoni (May 6, 2022)

Ill order a new clock and BBD, as well as reflow the solder on these ic sockets. I doubt that this will fix the problem, but its not a bad idea to try and make sure that everything else is OK.


----------



## Bio77 (May 6, 2022)

CE-2 is a weird circuit the bias sets the VREF.


Matoni said:


> Ill order a new clock and BBD, as well as reflow the solder on these ic sockets. I doubt that this will fix the problem, but its not a bad idea to try and make sure that everything else is OK.


When you reflow the IC sockets, it'd be a good idea to add some solder.  Just a touch on each joint.


----------



## Matoni (May 6, 2022)

As expected, it didn't fix anything. Let me know what I should try next.


----------



## fig (May 6, 2022)

Out on a limb here…check that pin one of IC2 is not folded under. It appears that a partially dry signal might still make it to output.

Then again, I have no idea if that makes any sense. 🤷‍♂️


----------



## Matoni (May 1, 2022)

Hello, 
I need help with my Cepheid Chorus build. I am getting a signal coming through when I plug the pedal in, but there is no chorus sound. This is probably because of the R34 47K leak resistor seen at the very top of the schematic. There is no chorus sound, however. I have probed with an oscilloscope, so I know that there is a signal going into the MN3207 chip I am using, as well as voltage going in the correct pins, however, there is no signal coming out of pin 7 or 8. Please let me know what tests I can run to try and further diagnose the problem. I am using a corresponding MN3102 clock chip, but it may not be working. I have no clue how either the BBD or Clock chip work. Please let me know what I may have done wrong. I will post pictures if they are requested. Thanks so much in advance for your help.


----------



## Matoni (May 6, 2022)

just clipped that leg, doesn't fix it. I didn't think it would but thank you for making me clip that, it definitely was too close for comfort.


----------



## Matoni (May 6, 2022)

new BBD and clock are ordered and on their way. I got the ones Robert recommended. Hopefully, this is the issue. Tell me in the mean time if there is anything else that looks bad on the board.


----------



## Mcknib (May 6, 2022)

Maybe time for a wee recap

I can't remember everything I've asked

You've got clean signal going all the way to the mixer stage IC2.2

Your LFO output pin IC1 voltage  fluctuates

Post IC3 and 4 and Q3 base voltage  as they are now check Q4 base voltages with the depth pot fully up and fully down

Try cranking the bias voltage up to 5v


----------



## Matoni (May 6, 2022)

Everything you said is correct. The LFO does appear to be working, as indicated by the LFO LED. The voltages on Q4 are a little bit strange. the base (middle pin) doesn't change when I turn the depth pot fully up and down. Is this a problem? the voltages here are also extremely low, and I' dont think they are supposed to be. The voltages off Q4 are as follows: pin 1: 0vdc, pin 2: 0.6vdc, pin 3L (this is very strange as this should be directly connected to voltage): 20mvdc. Maybe something is wrong with R25, the 2.7k resistor bringing voltage to the transistor. Or maybe this is caused by it being directly attached to the chip. Either way, i think I might try and change out this resistor to see if it changes anything. Let me know if I should try that and what other measurements I should try. My hope is that it is just a simple chip problem and the new chips I ordered should take care of it. Hopefully... not sure though. Thanks again for all the time and effort all you guys are putting in to helping me fix this pedal. I am only 15 and so I am a relatively new builder, so all of these debugging techniques will help me in the future. Thanks so much.


----------



## Mcknib (May 6, 2022)

Check the voltage both sides of R25 first

You're correct you will learn a lot debugging even though it's frustrating I always try to look at it as learning new stuff


----------



## Matoni (May 6, 2022)

One side is 8,6vdc and the other side is 20mvdc. I changed out the resistor anyways, and it didn't fix anything. so I still have no clue what the problem is. if you look at the picture of the bottom of the board I sent, right by R25 there is a small bit of exposed copper from the board that must have been burned off by the soldering iron or something like that. Maybe this is part of what is causing the problem? maybe something is shorting? I have no clue. Let me know if you think that is a problem.


----------



## Mcknib (May 6, 2022)

Lift the low voltage side of the resistor  out and try soldering that resistor leg directly to D4 cathode

In fact D4 cathode solder joint looks dry try reflowing that first


----------



## Matoni (May 6, 2022)

I used solder to bridge the two legs together. It doesn't create any difference in the sound I am getting out of the unit. Is the low voltage correct or should it be higher? Im not completely sure what it should be at. Thanks again for all of your time and effort on this project I really appreciate it.


----------



## Bio77 (May 6, 2022)

Don't use a solder bridge. Try the D4 reflow with more solder, if nothing, pull the legs out and connect. If you have bare copper, the solder bridge is going to connect the components to ground. 

Did you bend the leads down and cut them with clippers before soldering?  That's usually fine, in fact, its the way I do all of my builds.   I'm asking because, I did this once with some very sharp snips and I ended up removing the solder mask (when I snipped) and I grounded a bunch of components.  Your comment on the bare copper made me think of that.


----------



## Matoni (May 6, 2022)

no, i bridged it on top not on the bottom with the bare copper. And yeah I think that's what happened.


----------



## Mcknib (May 7, 2022)

Yes I'd think with a 2K7 you wouldn't drop that much voltage but I'm no expert with this circuit according to the electrosmash article it's set up as an astable 

Continuity check that part of the circuit put your probes on the component legs/pins rather than solder joints make sure it's all connected as it should be

Hopefully you'll be lucky with your new ICs

For further learning you could check resistance using the schematic if you look at resistance between +9v and Q4 collector (pin 1) you can see you should get 2K7

With no power to the circuit check your resistance from any +9v to Q4 collector

You can use this method for finding bridges, shorts, open circuit etc basically look at a particular trace and use a reference point in this case +9v to check resistances along that trace / path if it's not as expected e.g. infinite you know you've got an open circuit or bad connection and so on

Obviously in some cases you'd need to take into account paralell resistance etc

Now I'm not always sure if other resistances would be added if you take for example resistance between IC2.1 pins 1 and 2 I'd say 47K (R14) but I don't know if R9 and 10 would affect resistance

Try it and let me know!

I just do the easy stuff VREF to pin 3 = 10K if it ain't 10K there's a problem between VREF and pin 3


----------



## Matoni (May 7, 2022)

just measured all the spots you recommended to measure with my DMM. R25 does measure at 2.7K, so I have no idea why the voltage drop-off is so huge. FYI, the other resistor values don't affect the value of R14, and R14 measures at the correct 47K.


----------



## Mcknib (May 7, 2022)

Use your scope to see if you get a triangular waveform at lug 2 of the depth pot some info here









						The chorus effect: origin, and working of the Boss CE-2 | Anasounds
					

Addict to te sound of analog chorus? We talk about it right here! Back to the origins and the working principle of the chorus effect.




					anasounds.com
				




I'm not sure on the workings of Q4 but reading the brief description on the electrosmash analysis it's described as an RC astable oscillator so could vary transistor voltage depending on it's state

Edit I should add this is just for info and learning + checking all the circuitry around the clock and BBD, as you read the articles you'll see it's all interconnected and if one bit doesn't work it'll have a knock on effect


----------



## Matoni (May 7, 2022)

yes I do have triangular wave forms after the depth pot. This is the first time i've scoped for these waves, and it certainly is cool to see.


----------



## Mcknib (May 8, 2022)

Matoni said:


> yes I do have triangular wave forms after the depth pot. This is the first time i've scoped for these waves, and it certainly is cool to see.


Yeah it's interesting reading about the circuit and seeing it for yourself

Another useful exercise is to remove the clock in this case from it's socket and see what the voltages are on the empty socket and compare them to voltages taken with the IC in socket 

This will sometimes indicate the IC is indeed kaput you can see from the schematic where you'd get signal regardless of whether the ICs in or not 

Looking at the clock you'd expect signal on pins 5 and 7 with the 9v connection to Q4 try that and see if there's any difference to the voltages on those pins 

For your own learning and amusement  you should look at the waveform from the rate pot middle lug and turn the pot up and down to see how it changes it 

You can also check with your scope if the signal to the base (pin 2) of Q2 changes as you turn the depth pot from one extreme to the other


----------



## zgrav (May 9, 2022)

Mcknib said:


> Yeah it's interesting reading about the circuit and seeing it for yourself
> 
> Another useful exercise is to remove the clock in this case from it's socket and see what the voltages are on the empty socket and compare them to voltages taken with the IC in socket
> 
> ...


Lots of good suggestions in those posts for learning and getting more understanding for troubleshooting.


----------



## zgrav (May 9, 2022)

also -- after you improved your voltage reading, did you try the trim pot for the BBD again?  probably a good idea to keep checking that after any changes you are making that might be restoring the wet signal path, since the setting on that trim pot can affect whether you hear any changes at all.


----------



## Matoni (May 9, 2022)

jut got my new chips from cabintech, the place Robert recomended. It doesnt fix the problem. now I do hear though a chip every time the LFO light blinks. Bummer the new chips dont work. I was really hoping they would fix the problem.


----------



## Matoni (May 9, 2022)

OK I GOT IT!! Im so excited. using McKnib's methodology, I probed pin 7 to make sure it was connected to the diode... and it wasn't. I figured out that the trace between the 47pF capacitor and that diode got cut, probably when I took out my 47nF capacitor. Thanks for all your help guys. I really appreciate all the time and effort that went into helping me figure out what was wrong with this pedal. Next up is going to be the XC phase board, which hopefully I wont have any problems with. Ill let you great people know if I have any issues with that. Thank you again for all of your help and support.


----------



## giovanni (May 9, 2022)

Awesome! Mark it solved!


----------



## Matoni (May 1, 2022)

Hello, 
I need help with my Cepheid Chorus build. I am getting a signal coming through when I plug the pedal in, but there is no chorus sound. This is probably because of the R34 47K leak resistor seen at the very top of the schematic. There is no chorus sound, however. I have probed with an oscilloscope, so I know that there is a signal going into the MN3207 chip I am using, as well as voltage going in the correct pins, however, there is no signal coming out of pin 7 or 8. Please let me know what tests I can run to try and further diagnose the problem. I am using a corresponding MN3102 clock chip, but it may not be working. I have no clue how either the BBD or Clock chip work. Please let me know what I may have done wrong. I will post pictures if they are requested. Thanks so much in advance for your help.


----------



## zgrav (May 9, 2022)

Glad you got it working, and that you were able to get some great troubleshooting guidance and practice getting there.  That is the time investment that pays off for your upcoming projects.


----------

