# Caesar Chorus - Steady Rate LED?



## IPv6Freely (Jul 25, 2021)

Having issues with my second Caesar Chorus build. When power is applied, the rate LED does not flash at all. It just stays on solidly. 

I've gone over making sure all the parts are in the right way, the joints look good (even reflowed a couple that looked like they may have been an issue), and I'm out of ideas. Here's my board.







Now, there is one important thing to point out. The copper trace that connect Q2, R25 and D101 (the bottom right) was damaged while removing Q2 (I replaced it because I damaged it while removing it also).

This is the connection I'm talking about:






I fixed that by jumpering them together on the bottom of the board. Maybe this is related to my problem, but I don't think it should be. That trace is carrying +9V, by the way, AFAIK based on the schematic.




Oof... I really should have cleaned that flux off...

Anyway - any suggestions on where to even start on this one?


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## Stickman393 (Jul 26, 2021)

So...I had a similar symptom with my Cepheid...erm...murmaider. 

Try this...check the anode and cathode orientation on your LFO diode.  Anode to A and cathode to K?

If not, I feel ya.  I didn't study my first few pedal PCB boards that I built well enough: muscle memory.  I used the square pad for the longer LED leg...like with a polarized cap.

Can't explain why, cause I don't understand the LFO circuit well enough yet...but that caused my LFO LED to stay lit all the time.

Your repair of the 9v buss looks functional, I personally wouldn't put my money on that being the problem.


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## Feral Feline (Jul 26, 2021)

An aside:

IPv6Freely, where did you get your red electrolytics from?


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## IPv6Freely (Jul 26, 2021)

Stickman393 said:


> So...I had a similar symptom with my Cepheid...erm...murmaider.
> 
> Try this...check the anode and cathode orientation on your LFO diode.  Anode to A and cathode to K?
> 
> ...


Thanks, I'll take a look!


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## finebyfine (Jul 26, 2021)

Feral Feline said:


> An aside:
> 
> IPv6Freely, where did you get your red electrolytics from?


I have some red würth electronics electrolytics from digikey


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## IPv6Freely (Jul 26, 2021)

Feral Feline said:


> An aside:
> 
> IPv6Freely, where did you get your red electrolytics from?


They're Wurth, from Mouser.


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## Bricksnbeatles (Jul 26, 2021)

IPv6Freely said:


> They're Wurth, from Mouser.


Are they würth the money though?


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## Feral Feline (Jul 27, 2021)

IPv6Freely said:


> They're Wurth, from Mouser.


Better from Digikey?




Bricksnbeatles said:


> Are they würth the money though?



No Würth than Rubycon, but farad more red.

Okay, that's enough, I'm putting a cap on my bad puns before somebody puts a cap in my ...


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## music6000 (Jul 27, 2021)

Clean the board, a lot of excess flux especially around repair

Test for Continuity with matching coloured circles
As suggested, Led maybe 180 degrees
You can test an led on circles at R11 (Anode) & Ground (Cathode) pads to see if you can get flashing :


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## IPv6Freely (Jul 27, 2021)

Bricksnbeatles said:


> Are they würth the money though?


They look cool. So, yes.



Feral Feline said:


> Better from Digikey?


I'm sure they're exactly the same. I just like Mouser because of their shipping cost and speed. I tend to get stuff from them in only a couple days.


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## IPv6Freely (Jul 27, 2021)

music6000 said:


> Clean the board, a lot of excess flux especially around repair
> 
> Test for Continuity with matching coloured circles
> As suggested, Led maybe 180 degrees
> ...


I already have pots attached. Should I remove? Or just be super careful with my IPA?

I did verify that all four LEDs are correct orientation. Can you elaborate on the testing you want me to do? I don't quite follow what you're wanting.


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## IPv6Freely (Jul 27, 2021)

Okay, I cleaned it off as best as I can while trying to avoid the pots and switches.


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## music6000 (Jul 27, 2021)

The pad circled (R11) connects to the Rate LED, there appears to be debris around that area that might be causing an issue:


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## IPv6Freely (Jul 27, 2021)

music6000 said:


> The pad circled (R11) connects to the Rate LED, there appears to be debris around that area that might be causing an issue:



I cleaned off that section a bit more. I also tested with DMM to verify that resistor has continuity to anode of rate LED.


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## music6000 (Jul 27, 2021)

IPv6Freely said:


> I cleaned off that section a bit more. I also tested with DMM to verify that resistor has continuity to anode of rate LED.


So the pedal functions normal but the rate led glows solid the whole time you rotate the Rate knob?


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## music6000 (Jul 27, 2021)

The R11 trace that goes to the Rate LED appears to pass the Trace repair.
Check for Continuity between R11 Pad & Trace repair, There shoud not be a connection!
Check for any stray solder around both sides of the board in that area!


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## IPv6Freely (Jul 27, 2021)

music6000 said:


> So the pedal functions normal but the rate led glows solid the whole time you rotate the Rate knob?


No, there is no sound either if blend knob is turned up, even when adjusting trimpot. Blend rolled off and bypass both work fine.



music6000 said:


> The R11 trace that goes to the Rate LED appears to pass the Trace repair.
> Check for Continuity between R11 Pad & Trace repair, There shoud not be a connection!
> Check for any stray solder around both sides of the board in that area!
> View attachment 14160


I'll give that a look...


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## IPv6Freely (Jul 27, 2021)

Wait, are you sure on that @music6000 ??


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## IPv6Freely (Jul 28, 2021)

I went through and traced voltages everywhere important, and also tested continuity for the entire section of the schematic that contains the LFO, up to and including R12. I could go ahead and do the rest of it too, but that's as far as I've gotten so far.

One thing I did notice is that R11 for the LFP is 6K8, while R103 for the status LED is 4K7, resulting in significantly different levels of brightness. @PedalPCB is that by design? I'm using orange LEDs, and the LFO is really dim. None of this likely explains the lack of audio, but that's what a probe is for (I have the really nice one from TH Custom Effects on its way). One thing at a time...

View attachment PedalPCB-Caesar-01.png


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## music6000 (Jul 28, 2021)

IPv6Freely said:


> I went through and traced voltages everywhere important, and also tested continuity for the entire section of the schematic that contains the LFO, up to and including R12. I could go ahead and do the rest of it too, but that's as far as I've gotten so far.
> 
> One thing I did notice is that R11 for the LFP is 6K8, while R103 for the status LED is 4K7, resulting in significantly different levels of brightness. @PedalPCB is that by design? I'm using orange LEDs, and the LFO is really dim. None of this likely explains the lack of audio, but that's what a probe is for (I have the really nice one from TH Custom Effects on its way). One thing at a time...
> 
> View attachment 14164


Something doesn't look right, Your Vref at  1C 2.1 only has 2.94 v & elsewhere it is 4.33v which is where it should be at I believe?
Here is a resistor Calculator you can check your Values with.
Click on Bands for 5 Bands:








						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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## IPv6Freely (Jul 25, 2021)

Having issues with my second Caesar Chorus build. When power is applied, the rate LED does not flash at all. It just stays on solidly. 

I've gone over making sure all the parts are in the right way, the joints look good (even reflowed a couple that looked like they may have been an issue), and I'm out of ideas. Here's my board.







Now, there is one important thing to point out. The copper trace that connect Q2, R25 and D101 (the bottom right) was damaged while removing Q2 (I replaced it because I damaged it while removing it also).

This is the connection I'm talking about:






I fixed that by jumpering them together on the bottom of the board. Maybe this is related to my problem, but I don't think it should be. That trace is carrying +9V, by the way, AFAIK based on the schematic.




Oof... I really should have cleaned that flux off...

Anyway - any suggestions on where to even start on this one?


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## IPv6Freely (Jul 28, 2021)

music6000 said:


> Something doesn't look right, Your Vref at  1C 2.1 only has 2.94 v & elsewhere it is 4.33v which is where it should be at I believe?
> Here is a resistor Calculator you can check your Values with.
> Click on Bands for 5 Bands:
> 
> ...


2.94V for VREF. 4.33V for VREF_2

I don't fully understand why you're sending me a resistor calculator... can you explain?


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## music6000 (Jul 28, 2021)

IPv6Freely said:


> 2.94V for VREF. 4.33V for VREF_2
> 
> I don't fully understand why you're sending me a resistor calculator... can you explain?


To check that all your resistors are the correct values.
Match the bands on the resistors to the Calculator & confirm your Values are correct.


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## IPv6Freely (Jul 28, 2021)

music6000 said:


> To check that all your resistors are the correct values.
> Match the bands on the resistors to the Calculator & confirm your Values are correct.


Got it... yeah I guess I can do that. It's not that many and I'm very meticulous about making sure they're all oriented the same way.


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## IPv6Freely (Jul 28, 2021)

music6000 said:


> To check that all your resistors are the correct values.
> Match the bands on the resistors to the Calculator & confirm your Values are correct.


Aaaand I’m an idiot.




Not one resistor was wrong… FOUR are wrong.


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## music6000 (Jul 28, 2021)

There was a revision recently, The values on the PCB should be the correct values, sometimes the ones in the BOM are incorrect ?????


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## IPv6Freely (Jul 28, 2021)

music6000 said:


> There was a revision recently, The values on the PCB should be the correct values, sometimes the ones in the BOM are incorrect ?????


Nah, it’s all me. To be fair, they are all various 33 values that were sorted into the wrong bins. 3.3K instead of 330K. 330K instead of 33K


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## IPv6Freely (Jul 28, 2021)




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## IPv6Freely (Jul 28, 2021)

Well that problem is solved... now to figure out why there's no sound. lol


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## Stickman393 (Jul 28, 2021)

MOAR OP AMP VOLTAGES!!


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## music6000 (Jul 28, 2021)

IPv6Freely said:


> Nah, it’s all me. To be fair, they are all various 33 values that were sorted into the wrong bins. 3.3K instead of 330K. 330K instead of 33K


33ohm, 330ohm, 3K3, 330K, 1 Band to ruin it all !
That is why I measure *every *Resistor, Capacitor, Transistor, Diode, LED  I put in a PCB & I Bend the legs first in case it damages the component!!!

Can you post the voltages you have on each OP Amp now?
1.......8
2.......7
3.......6
4.......5


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## IPv6Freely (Jul 28, 2021)

Stickman393 said:


> MOAR OP AMP VOLTAGES!!





music6000 said:


> 33ohm, 330ohm, 3K3, 330K, 1 Band to ruin it all !
> That is why I measure *every *Resistor, Capacitor, Transistor, Diode, LED  I put in a PCB & I Bend the legs first in case it damages the component!!!
> 
> Can you post the voltages you have on each OP Amp now?
> ...


Here's the list with before and after values.

IC1: TL022
1 - 4.319 - cycling 3.5-4.5
2 - 4.339 - 4.27
3 - 4.339 - 3.9-4.5
4 - 0.000 - 0.000
5 - 4.337 - 4.27
6 - 4.357 - 4.29
7 - 4.339 - 3.9-4.5
8 - 8.690 - 8.570

IC2: RC4558
1 - 2.942 - 8.67
2 - 2.954 - 8.63
3 - 2.944 - 8.68
4 - 0.000 - 0.000
5 - 2.946 - 8.69
6 - 2.948 - 8.68
7 - 2.948 - 8.63
8 - 8.76 - 8.69

IC3: V3207D (using MN3207)
1 - 0.000 - 0.000
2 - 8.68 - 4.16
3 - 2.292 - 7.8
4 - 8.12 - 8.0
5 - 8.68 - 8.55
6 - 0.2 - 4.14
7 - 1.1 - 8.08
8 - 1.0 - 8.08

IC4: V3102D
1 - 8.68 - 8.55
2 - 0.1 - 4.138
3 - 0.000 - 0.000
4 - 8.68 - 4.158
5 - 25.0 - 272mV
6 - 8.60 - 8.22
7 - 2.871 - 2.82
8 - 8.11 - 7.99

Q1: 2N5088
C - 2.112 - 7.16
B - 2.593 - 7.47
E - 8.74 - 8.66

Q2: 2N5088
C - 3.65 - 8.51
B - 1.1 - 4.0-4.2
E - 8.66 - 8.51

Q3: 2N5088
C - 2.283 - 7.77
B - 2.831 - 8.29
E - 8.74 - 8.66

Q4: 2N5088
C - 0.000 - 0.000
B - 27.0 - 356mV
E - 8.26 - 7.40

Q5: 2N5088
C - 2.33 - 7.31
B - 2.904 - 7.69
E - 8.72 - 8.66





Of course, I assume some of these values are gonna change depending on the pots and the trimpot settings, but at least we have the real baseline now that we know the components are actually correct... lol.


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## music6000 (Jul 28, 2021)

Can you confirm that R26 - 33K is correct - Orange, Orange, Black, Red, Brown !

What's going on with IC2: RC4558 double Voltage readings, something screwy there!


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## IPv6Freely (Jul 28, 2021)

music6000 said:


> Can you confirm that R26 - 33K is correct - Orange, Orange, Black, Red, Brown !
> 
> What's going on with IC2: RC4558 double Voltage readings, something screwy there!


R26 is indeed 33K. It's one of the ones I replaced.

IC2 seems right. VREF is changeable by the trimmer pot. So, turned all the way up its 9V, turned all the way down its 0V. I now have it at 4.5V and will keep it there for troubleshooting because that's about where it needs to be in the end anyway. Therefore, at the moment IC2 is all 4.5V except for pin 4 and pin 8


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