SOLVED Caesar Chorus (help!)

[NateLC]

Hello Everyone!

Relatively new pedal builder. I have a few under my belt and now tackling the Caesar Chorus.

Currently I have soldered all the main parts and doing the first testing, so haven't soldered the cables from the power jack, nor the white LEDs.

Here's the issue: When I plug it in and turn (stomp) it on, neither LED lights up but the pedal somehow works weirdly: Depending on the switch's position, the Lag and the Blend only act to reduce the actual clean signal. If i fiddle with the other pots I sometimes get some weird fuzzy sounds but that's it.

I have double checked and all components seem to be in order, or have I missed something?

Attaching some pics. If you want to see any part in detail let me know

Appreciate any input, thanks!

 

[EGRENIER]

Hello Everyone!

Relatively new pedal builder. I have a few under my belt and now tackling the Caesar Chorus.

Currently I have soldered all the main parts and doing the first testing, so haven't soldered the cables from the power jack, nor the white LEDs.

Here's the issue: When I plug it in and turn (stomp) it on, neither LED lights up but the pedal somehow works weirdly: Depending on the switch's position, the Lag and the Blend only act to reduce the actual clean signal. If i fiddle with the other pots I sometimes get some weird fuzzy sounds but that's it.

I have double checked and all components seem to be in order, or have I missed something?

Attaching some pics. If you want to see any part in detail let me know

Appreciate any input, thanks!

At first look I couldn’t find anything obvious, however here’s a few observations:

- I notice you have socketed your transistor but then soldered them in the socket. That’s not necessary, the great thing about sockets is that it allows you to swap your transistors if the pedal doesn’t work. Now you can’t do this.
- On the top 2 left transistors you seem to have been generous on the solder (pic 1 and 4), you may have bridge some legs, I would clean this up to be sure.
- some solder points seem “blobby”, reflow those that are not a nice cone/shinny shape.
- Clean the board with 99% iso alcool and a toothbrush. Sometimes flux leaks creates some weird issues.
- I would solder the white led, I don’t think they are necessary, but being sure if they light or not would help.
- Also check your voltage for VCC, 9V, VREF B and VREF. I had a quick look at the schematic and you should be able to mesure that at C101, 102, 103 and 104.

 

[NateLC]

Thanks Egrenier!

I did solder them out of a bit of panic. The pedal behavior was the same before I soldered them. They felt pretty lose on the sockets so I thought that could be the issue but it was the same after soldering them.

I''ll give it a thorough check considering your advice and hopefully that does the trick!

Cheers,

Nate

 

[jimilee]

Thanks Egrenier!

I did solder them out of a bit of panic. The pedal behavior was the same before I soldered them. They felt pretty lose on the sockets so I thought that could be the issue but it was the same after soldering them.

I''ll give it a thorough check considering your advice and hopefully that did the trick!

Cheers,

Nate

After swapping them in and out, they start to get loose and fall out. I do the same thing.

 

[warteck]

hello
can you double check diodes on the bottom right of the board
You must have D3 and D4 1N914 and D101 a zener 9.1volt diode.
D101 is very important it will makes all IC's power supply. if you put something else, it never works.
Then other question is about the two chips V3207 and V3102 :
where did you buy them ?
Some are fake, some are bad (I ordered 25 pair of them on ebay only 5 works)
this pcb is easy to understand => you have power supply, transparent amplificator
And in the middle of them a clock (v3102) and a delay (v3207)
clock make delay works fast to build echo/chorus effect.
if theses chips are not good, it never works
The simple test you can do is :
-remove V3102 and V3207 form the board
-disconnect the wire going to the ouput jack

take a peice of wire connect output jack on one side of the wire.
Connect the other side of the wire to PIN 2 of the 3207 => guitar sound going out
Disconnect wire check on PIN 6 of IC2 => guitar sound out
Disconnect wire check on PIN 7 of IC2 => guitar sound out
Test middle pin of blend pot=> guitar sound

if this works => probably a bad V3207

Normaly the led LFO works with the LFO rythm, speed change with the rate pot.
If this works you can put back the V3102
if you have a multimeter with frequency function, you can test PIN2 on 3102

 

[EGRENIER]

After swapping them in and out, they start to get loose and fall out. I do the same thing.

But I bet you do so after testing the pedal

I sometime tack mine on the middle leg just to secure them. having only one leg soldered make them easy to swap if you ever want to. Having all 3 legs soldered makes it nearly impossible to remove without cutting the legs off. Well with my skills anyway…

 

[Bio77]

Your LEDs don't appear to be soldered in. Double check the orientation of the LEDs. Robert uses a the a more correct AK orientation for LEDs, which is the opposite of all the other PCB vendors. It is sometimes confusing.

Am I understanding correctly: as you turn the blend knob, you hear all clean signal at one extreme and then nothing (or very little) at the other extreme? If this is the case this would indicate you are not getting your delay signal through. I would check your bias setting. Set the blend knob to the extreme where you are not getting signal, then play guitar and adjust the bias knob until you hear signal. If the LFO is working, it should be vibrato.

 

[jimilee]

But I bet you do so after testing the pedal

I sometime tack mine on the middle leg just to secure them. having only one leg soldered make them easy to swap if you ever want to. Having all 3 legs soldered makes it nearly impossible to remove without cutting the legs off. Well with my skills anyway…

Oh huh

 

[Guilherme Collateral]

Hello Everyone!

Relatively new pedal builder. I have a few under my belt and now tackling the Caesar Chorus.

Currently I have soldered all the main parts and doing the first testing, so haven't soldered the cables from the power jack, nor the white LEDs.

Here's the issue: When I plug it in and turn (stomp) it on, neither LED lights up but the pedal somehow works weirdly: Depending on the switch's position, the Lag and the Blend only act to reduce the actual clean signal. If i fiddle with the other pots I sometimes get some weird fuzzy sounds but that's it.

I have double checked and all components seem to be in order, or have I missed something?

Attaching some pics. If you want to see any part in detail let me know

Appreciate any input, thanks!

As stated above, the LEDs don't appear to be soldered, and you said that if you fiddle with the knobs you can get some fuzzy sounds, and your trimpot seems to be centered. Have you tried adjusting it? You have to do it with the pedal on and it's mandatory to get chorus out of it hehe

 

[Locrian99]

After swapping them in and out, they start to get loose and fall out. I do the same thing.

I can’t stand them for this reason I only use them in situations where I’m making a sub or I want to try different transistors. Sometimes I’ll remove the socket after I decide it’s good. Never burned a transistor yet.

 

[NateLC]

But I bet you do so after testing the pedal

I sometime tack mine on the middle leg just to secure them. having only one leg soldered make them easy to swap if you ever want to. Having all 3 legs soldered makes it nearly impossible to remove without cutting the legs off. Well with my skills anyway…

Don't disagree with you there....as I said it was a desperate move so lessons learned!

 

[NateLC]

hello
can you double check diodes on the bottom right of the board
You must have D3 and D4 1N914 and D101 a zener 9.1volt diode.
D101 is very important it will makes all IC's power supply. if you put something else, it never works.
Then other question is about the two chips V3207 and V3102 :
where did you buy them ?
Some are fake, some are bad (I ordered 25 pair of them on ebay only 5 works)
this pcb is easy to understand => you have power supply, transparent amplificator
And in the middle of them a clock (v3102) and a delay (v3207)
clock make delay works fast to build echo/chorus effect.
if theses chips are not good, it never works
The simple test you can do is :
-remove V3102 and V3207 form the board
-disconnect the wire going to the ouput jack

take a peice of wire connect output jack on one side of the wire.
Connect the other side of the wire to PIN 2 of the 3207 => guitar sound going out
Disconnect wire check on PIN 6 of IC2 => guitar sound out
Disconnect wire check on PIN 7 of IC2 => guitar sound out
Test middle pin of blend pot=> guitar sound

if this works => probably a bad V3207

Normaly the led LFO works with the LFO rythm, speed change with the rate pot.
If this works you can put back the V3102
if you have a multimeter with frequency function, you can test PIN2 on 3102

Thanks for the thorough reply!

All the kit came from Musikding.com (in colab with pedal pcb), so I will assume all the components are legit.
I have checked all the diodes and they are correctly placed.....I suspect the chips may not be working.
I will do the checks you suggest and see if thats the issue!

 

[NateLC]

Your LEDs don't appear to be soldered in. Double check the orientation of the LEDs. Robert uses a the a more correct AK orientation for LEDs, which is the opposite of all the other PCB vendors. It is sometimes confusing.

Am I understanding correctly: as you turn the blend knob, you hear all clean signal at one extreme and then nothing (or very little) at the other extreme? If this is the case this would indicate you are not getting your delay signal through. I would check your bias setting. Set the blend knob to the extreme where you are not getting signal, then play guitar and adjust the bias knob until you hear signal. If the LFO is working, it should be vibrato.

They were not intentionally soldered for quick disassembly to paint the case, but for sure they were making contact. At the suggestion of another commend I have soldered them anyway and the problem persists.

Yes, that is correct, at one extreme its completely zero. I will play with the bias setting and see if that makes a difference. Thanks!

 

[NateLC]

Update:


After adjusting the bias trimpot I get all the sounds now. Not sure if I am getting the full pedal functionality but does sounds like it as all the pots and switch seem to do their job. However, the pedal LEDs still do not light up, I checked the position of all LEDs (A for neg and K for pos) and they all seem correct.

 

[mybud]

Update:


After adjusting the bias trimpot I get all the sounds now. Not sure if I am getting the full pedal functionality but does sounds like it as all the pots and switch seem to do their job. However, the pedal LEDs still do not light up, I checked the position of all LEDs (A for neg and K for pos) and they all seem correct.

You might want to double-check your LED orientation. A is positive (Anode) and K negative (Kathode = Cathode).

 

[NateLC]

You might want to double-check your LED orientation. A is positive (Anode) and K negative (Kathode = Cathode).

Now I get the comment about the confusion vs other PCB's. I used more the square pad as the guide on where to place the positive side.

Thanks!

 

[mybud]

Now I get the comment about the confusion vs other PCB's. I used more the square pad as the guide on where to place the positive side.

Thanks!

You’re most welcome. I usually deal with LEDs last in a build and only solder them in when I’m convinced they’re working properly. To each his own, naturally. They can be useful to verify that the circuit is getting power but don’t have to be soldered in until the boxing stage is imminent.

 

[NateLC]

Update:

After my confusion with the LED polarity (I also realized that D1 and D2 were wrong) all the front LEDs light up!

Final question: are D1 and D2 supposed to light up when being used? De-soldering them was a bit challenging and one of the ring pads from the PCB detached so had to push it back in.

Thanks for all of your help!

Nathaniel

 

[Bio77]

Update:

After my confusion with the LED polarity (I also realized that D1 and D2 were wrong) all the front LEDs light up!

Final question: are D1 and D2 supposed to light up when being used? De-soldering them was a bit challenging and one of the ring pads from the PCB detached so had to push it back in.

Thanks for all of your help!

Nathaniel

Those diodes shape the LFO. Supposed to smooth out the sharp edges. I seem to remember a comment from PPCB, that they weren't that important. I'm not sure there is enough current from the LFO to light them up. If you have lifted pads, I would leave it alone.

 

[NateLC]

Well, seems everything is in order so now its time to pain the case. Thanks everyone! Really happy with this pedal!