Quote from: Rob Strand on April 04, 2025, 08:28:13 PMIt's the circuit with the switch and C21.



It's pretty normal to go over a circuit and kick the tires a bit.   No matter how much time you spend on it, next week you will think of something else 


Clearly pins 6 and 7 are connecting, even from the voltages.  You can get weird results like that when there's a bad connection (somewhere).  If pin 5 is really different to pins 6 and 7 I'd start to be suspicious the opamp has a problem.

Well you ARE right!!! The opamp really was the problem. I changed it and bam the voltages now across pins 5,6,7 are the same 4.8v. Thank you rob. Now as I understand the voltages are all right. I wish I could figure out how to read voltages and know what they should be at any point in a schematic but idk where to start.
I will try your mod in the morning and report back as it's 3 am here.
Thank you again man.

Quote from: Lost_soul on April 04, 2025, 09:08:00 PMWell you ARE right!!! The opamp really was the problem. I changed it and bam the voltages now across pins 5,6,7 are the same 4.8v. Thank you rob. Now as I understand the voltages are all right. I wish I could figure out how to read voltages and know what they should be at any point in a schematic but idk where to start.
I will try your mod in the morning and report back as it's 3 am here.
Thank you again man.

Cool you are pretty much there now.

For a lot of circuits the input and outputs of the opamps should all sit at about Vref (Vcc/2 or whatever).  There are a few instances where the multimeter loads down the voltages and you get less than Vref but you can have an idea that's going to happen if you see a 470k or 1M resistor there.   Things like oscillators/LFO are different.

I'm confused. I'm not sure I'm looking at the right, or current, thing. here, see what I see, pins 6 and 7 shorted, and the diodes not connected as per circuit dia, and 100k resistors, perhaps instead of 10k resistors.

as I say, I'm confused now, and daylight savings ends in an hour, so it's only going to get worse.

Quote from: duck_arse on April 05, 2025, 10:01:05 AMI'm confused. I'm not sure I'm looking at the right, or current, thing. here, see what I see, pins 6 and 7 shorted, and the diodes not connected as per circuit dia, and 100k resistors, perhaps instead of 10k resistors.

as I say, I'm confused now, and daylight savings ends in an hour, so it's only going to get worse.

I am not sure what you mean. Isn't pin 6 and 7 connected together in the schematic? And there is a diode from pin 7 to a point and then another diode from pin 8 to the same point?

Quote from: Lost_soul on March 30, 2025, 01:55:18 PMand here is the schematic:

when I look on this schem, which is the only one I can see in thread, I don't see a match. am I looking in the right place?

Quote from: duck_arse on April 05, 2025, 10:16:40 AMwhen I look on this schem, which is the only one I can see in thread, I don't see a match. am I looking in the right place?

yes it's the right scheme. but could you elaborate what is the match you don't see? is it in the pin 6/7 and diode section or is it with the veroboard layout or what

we are discussing IC4 section. maybe you looked at another IC?

Quote from: duck_arse on April 05, 2025, 10:16:40 AMwhen I look on this schem, which is the only one I can see in thread, I don't see a match. am I looking in the right place?

That image is all whitespace and dim details. Here's where I see 6 and 7 connected.

excellent. yes, confused, and yes, I was looking otherwhere. pardon, carry on.

Quote from: Rob Strand on April 04, 2025, 09:32:48 PMCool you are pretty much there now.

For a lot of circuits the input and outputs of the opamps should all sit at about Vref (Vcc/2 or whatever).  There are a few instances where the multimeter loads down the voltages and you get less than Vref but you can have an idea that's going to happen if you see a 470k or 1M resistor there.   Things like oscillators/LFO are different.

Thanks rob.
I measured the voltages on my vero and here are they:





They are a little different from the breadboard. Especially when the bright switch is ON. (Btw i only have until IC4 on the breadboard)
What does this mean.

Quote from: Lost_soul on Yesterday at 05:37:12 PMThey are a little different from the breadboard. Especially when the bright switch is ON. (Btw i only have until IC4 on the breadboard)
What does this mean.

My first thought was the bright switch bypasses the filter at pin 7 IC1.2 and you are seeing the effect of more noise injected into the U4 part of the circuit.

Worst case the circuit could be oscillating, cause by the removal of the IC1 filter.

You could try putting a small valued cap across R31, say 470pF to see if it helps.

Scrounging for other causes:  there could be another small bug somewhere in the circuit or a soldering bridge.  Something related to the bright switch.  It wouldn't hurt to check the DC voltage on IC1.1 pin 1 and IC1.2 pin 7 with both bright and non-bright settings.   Then check C13 for any shorts or solder bridges.   

Quote from: Rob Strand on Yesterday at 06:17:55 PM

Quote from: Lost_soul on Yesterday at 05:37:12 PMThey are a little different from the breadboard. Especially when the bright switch is ON. (Btw i only have until IC4 on the breadboard)
What does this mean.

My first thought was the bright switch bypasses the filter at pin 7 IC1.2 and you are seeing the effect of more noise injected into the U4 part of the circuit.

Worst case the circuit could be oscillating, cause by the removal of the IC1 filter.

You could try putting a small valued cap across R31, say 470pF to see if it helps.

Scrounging for other causes:  there could be another small bug somewhere in the circuit or a soldering bridge.  Something related to the bright switch.  It wouldn't hurt to check the DC voltage on IC1.1 pin 1 and IC1.2 pin 7 with both bright and non-bright settings.   Then check C13 for any shorts or solder bridges.   

Okay i will do as you said in the morning (again ahahaha).
What bugs me is on the breadboard the voltages don't change if the switch is on or off (except for pin 14 which become 4.6 instead of 4.8
But on the vero it's way off.

Maybe i have something wrong in the layout itself? But i checked the layout i made and it was fine. Has to be something wrong with the board itself.

I will report back the voltages of IC1.1 and IC1.7 and check for that c13.

Sorry for the trouble rob. You are a great guy helping people around with thier hobbies.

Quote from: Lost_soul on Yesterday at 06:34:44 PMMaybe i have something wrong in the layout itself? But i checked the layout i made and it was fine. Has to be something wrong with the board itself.

I will report back the voltages of IC1.1 and IC1.7 and check for that c13.

Sorry for the trouble rob. You are a great guy helping people around with thier hobbies

No problem, that's how things go.

It could be a layout problem, or a wiring problem.   It's not hard for small errors to creep in.   It's also hard to check your own work.  Just check everything and you might find something.

QuoteWhat bugs me is on the breadboard the voltages don't change if the switch is on or off (except for pin 14 which become 4.6 instead of 4.8
But on the vero it's way off.

It could be very well be a simple thing throwing it off.   What about if the bright switch wiring has a swapped pin.