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TOPIC: Guide to troubleshoot pedalSHIELD.

Guide to troubleshoot pedalSHIELD. 4 years 7 months ago #269

  • Ray
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This is a short guide to help you out to find any bug on the hardware:

Common mistakes:
  1. Are you sure you have an Arduino DUE (not Mega, not any other)?
  2. Guitar connects to the left, amp to the right jack connector ( :guitarfende -> :pedalboss: -> :ampfender: )

  3. Electrolytic Caps place wrongly: Have a look to a good PCB high resolution image to be absolutely sure that your caps are in the right direction.
  4. Diodes placed wrongly: Do the same as in the step above.
  5. Integrated circuits place in the wrong socket: TL072 swapped with the TC1044
  6. Integrated circuits placed in the wrong direction: Do the same as in the 1st step
  7. Check any short circuit between nearby pads and check that all solder points are good.

Once all the things above are checked, the best way to troubleshoot the PCB is doing it in 3 steps:
  1. Check the power supply: The TC1044 should give ±5V (±4.75V in fact). If not check that the IC is in the right orientation and C14 and C15 are not reversed.
  2. Check the output stage: You can load the sine-wave generator program. It only uses the output stage independently that the input is wrong. If it works you can be sure that the second op-amp area is good. If not check for resistors placement, IC is the correct one? orientation?
  3. Check the input stage: Be sure that the trimmer VR1 is in a "medium" position, you can adjust it better later. Load a clean/volume pedal and check the same things as the step before.
  4. - If you have a multimeter you can verify the voltage at the pins of U1, just pedalSHIELD connected to the computer, with no guitar or amp plugged should be:
    pin1: 1.6V
    pin2: 1.6V
    pin3: 0.9V
    pin4: -5V (-4.5V is also fine)
    pin5: 1.5V
    pin6: 1.6V
    pin7: 1.6V
    pin8: +5V (+4.5V is also fine)

    - With any code loaded (it does not matter), if you activate/put down the mix switch (left one), you should listen the clean guitar (pat of the guitar signal bypass Arduino and goes to the output mixer directly).


As a tip I can to say that 99,9% of the errors are due to some connection is wrong or some component is missplaced. From previous experience building dozens of pedalSHIELDs they always work straight away from soldering correctly, but we are all humans and we all make mistakes.

If all the above fails, just carefully component by component that it is well placed and orientated, dont take anything for granted.

If can borrow another pair of eyes to have a look at it, do it. Sometimes others can be things that we are passing over.

If you have an oscilloscope or a signal generator (I use Visual Analyzer)


[UPDATE]: Some Chinese Arduino boards give problems with the ADCs and DACs, here is a small code to test that your ADCs are working fine (the DACs can be tested with the sinewave generator):
 
// the setup routine runs once when you press reset:
void setup() {
  // initialize serial communication at 9600 bits per second:
  Serial.begin(9600);
}
 
// the loop routine runs over and over again forever:
void loop() {
  // read the input on analog pin 0:
  int sensorValue1 = analogRead(0);
  int sensorValue2 = analogRead(1);
  int sensorValue3 = analogRead(8);
  int sensorValue4 = analogRead(9);
  int sensorValue5 = analogRead(10);
  // print out the value you read:
  Serial.print("ADC Audio 0: "); Serial.println(sensorValue1);
  Serial.print("ADC Audio 1: "); Serial.println(sensorValue2);
  Serial.print("ADC POT 0: ");Serial.println(sensorValue3);
  Serial.print("ADC POT 1: ");Serial.println(sensorValue4);
  Serial.print("ADC POT 2: ");Serial.println(sensorValue5);
  Serial.print("\n");
 
  delay(1000);        // delay in between reads for stability
}
 

After loading the code you can open the serial monitor (located in Tools/Serial monitor) and you should read something like:


serialmonitor1.jpg



Modifying the pots you should see clearly how the read value change, picking the strings of the guitar make also a small modification over the default 500-550 value. In the example above all the pots were maxed at 1023 value.
Last Edit: 1 year 9 months ago by Ray.
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Guide to troubleshoot pedalSHIELD. 4 years 7 months ago #277

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Hi, thank you for this, it's really very useful!

These are my results, after checking that components are correctly placed and connected:
  1. TC1044 gives -4.6v at pin 5 (Vout).
  2. The sine wave generator works, although it sounds at a very low volume, even with the right pot at maximum.
  3. The volume pedal program won't work at any position of the trimmer
  4. The values of U1 are more or less the ones you provided, except pin3 which stabilizes at 0.85v and pin5 at 1.6v

The mix switch won't do anything: guitar bypasses only with the footswitch.

I really can't guess what's wrong...
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Guide to troubleshoot pedalSHIELD. 4 years 7 months ago #281

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The power supply looks good, I remember somebody posting a similar problem with the volume at the output when using the waveform.

Try the waveform or the metronome and check if you can get nice output levels (be sure that left switch is UP (mix disabled)).

Definitely the input stage does not look good, that is a folk that posted how to make an oscilloscope with pedalSHIELD, it uses the input stage so maybe that helps you with the debugging.

I know that sounds silly but check one by one all the links to be sure that all is connected to the right place.
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Guide to troubleshoot pedalSHIELD. 4 years 6 months ago #287

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Well, this is embarrassing.

The problem was I was using input and ouput jacks reversed, taking for granted that the arrangement was similar to other pedals (left input, right output). My mistake.

Sorry for the time lost.

Maybe you want to add this as a step 0 for the troubleshooting guide :)
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Guide to troubleshoot pedalSHIELD. 4 years 6 months ago #289

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I've been putting the PedaShield together over the last few days and just can't get it to work. I'm pretty sure it's my workmanship, but here's where I am.

I've gone through the troubleshooting guide step by step and have these results:

The electrolytic caps are in the correct places and orientation.

The diodes are in the correct orientation.

The IC's are in the correct sockets and oriented correctly.

I've looked at the back of the board for shorts and didn't see anything obvious. The top of the board looks like the pictures but the back is rougher than the pictures. I had a lot of trouble with the 8-pin connectors but finally got each one soldered with no solder connecting two pins.

I've tried to check the voltages with a multimeter but wasn't sure where the probes went. I've placed the black probe on the Arduino GND pin and the red probe on what I was measuring. I wasn't sure which of the eight legs of the TC 1044 to measure but found (clockwise from the upper left): 0.69 v, 4.40 v, 4.75 v, 4.92 v, 4.11 v, 4.33 v, 4.65 v, and 0.62 v.

I'm not sure what I should hear with the sine-wave generator. I hear a very low volume up and down which might sound like a sine wave with a period of 7 sec. Or it could just be static through my amp.

The "trimmer" is a mystery. Not sure what a "medium" position is or what to adjust it to. Right now the flat portion of the "knob" is parallel to the board.

Here's where I get further lost. As I measure the voltage on the digital pins, I get:

pin1: 3.25 v
pin2: 0.49 v
pin3: cycling between 0.20 and 0.33 v
pin4: 0.54 v
pin5: cycling between 0.22 and 0.27 v
pin6: cycling between 0.20 and 0.25 v
pin7: 0.46 v
pin8: There is no pin 8 There is a hole in PS board (J1) but there is nothing connecting PS to Arduino at pin8. I thought for a while I had the board turned 180 degrees but that would mean the screw holes are out of alignment. No idea how to proceed. Note that the CLEAN sketch was running on the AD.

The final note. The LED doesn't light up UNLESS I push the button on the AD to the left of the native USB port. Both the input and output jacks must have cables in them, however.

At this turn, I'm fairly certain I've mucked up the board and components somehow with my soldering technique and don't have much hope. However, any thoughts on where I took a wrong turn would be appreciated.
Last Edit: 4 years 6 months ago by stevemiller99. Reason: Left something out.
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Guide to troubleshoot pedalSHIELD. 4 years 6 months ago #290

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I've tried to check the voltages with a multimeter but wasn't sure where the probes went. I've placed the black probe on the Arduino GND
Yes, black to ground (there are two test point on the pedalSHIELD labeled as "GND") and red probe to the pin you want to test.
I've tried to check the voltages with a multimeter but wasn't sure where the probes went. I've placed the black probe on the Arduino GND pin and the red probe on what I was measuring. I wasn't sure which of the eight legs of the TC 1044 to measure but found (clockwise from the upper left): 0.69 v, 4.40 v, 4.75 v, 4.92 v, 4.11 v, 4.33 v, 4.65 v, and 0.62 v.
Could you check that test points below the TC1044 labeled as +5V and -5V give you this values? (or something like +4.75 and -4.75V)
I'm not sure what I should hear with the sine-wave generator. I hear a very low volume up and down which might sound like a sine wave with a period of 7 sec. Or it could just be static through my amp.
you should hear a continuous sound like a "piiiiiiiiiiiii" and you can adjust it from low tone to high pitched.
The "trimmer" is a mystery. Not sure what a "medium" position is or what to adjust it to. Right now the flat portion of the "knob" is parallel to the board.
With the trimmer swept it from one extreme to the other and you can easily see where is the middle point approx.

Ok, so in general, first of all check that you have the correct power supply voltages +5V and -5V and this voltages reach the op-amps (pin4 is -5V and pin 8 is +5V).
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Guide to troubleshoot pedalSHIELD. 4 years 6 months ago #291

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Could you check that test points below the TC1044 labeled as +5V and -5V give you this values? (or something like +4.75 and -4.75V)

At the +5 point I get +4.9 v, but at the -5 point I get +0.81 v
you should hear a continuous sound like a "piiiiiiiiiiiii" and you can adjust it from low tone to high pitched.

I still don't hear anything of interest. Do I adjust it with one of the potentiometers or the trimmer? The through signal (the pedal pressed) is very clean with no noise whatsoever.
With the trimmer swept it from one extreme to the other and you can easily see where is the middle point approx.

The mid-point is about where I have it.
Ok, so in general, first of all check that you have the correct power supply voltages +5V and -5V and this voltages reach the op-amps (pin4 is -5V and pin 8 is +5V).

Thanks. I went back to U1 (I now know which pins are which from the data sheet.).
The voltages are:
Pin 1 2.0 v
Pin 2 2.1 v
Pin 3 1.65 v
Pin 4 +0.82 v (I noted that this is the same as the reading for the -5v test point at the power supply)
Pin 5 2.4 v
Pin 6 2.2 v
Pin 7 3.24 v
Pin 8 +4.95 v

I suspect at this point, I have a short some where causing the -5v to read positive and at 20% of what it should be. Your help is gratefully appreciated.
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Guide to troubleshoot pedalSHIELD. 4 years 6 months ago #292

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Hi,
I suspect at this point, I have a short some where causing the -5v to read positive and at 20% of what it should be. Your help is gratefully appreciated.

Yes, look that the power supply is not in working order.
The TC1044 should provide +5V and -5V to the rest of the circuit.

Try disconnecting the op-amps and check if the -5V appears.

The best idea is to focus to get -5V out of the TC1044. So with a multimeter you can check with the continuity option if there is any short circuit between pins (sometimes adjacent pins could be short circuited due to a "bad" solder job).

Then you can also check that all the pins are connected to the right part and with no short circuits, the image below of the tracks can help you to do so:

tc1044.jpg
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Guide to troubleshoot pedalSHIELD. 4 years 6 months ago #293

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Thanks for your help.

I worked on the soldering at the power supply and now have 4.95 @ the +5 and -4.56 @ -5. The sine sketch worked great and both P1 and P2 controlled the (very piercing) sound. However, once I have a guitar at the input and my amp at the output, I get nothing unless it's configured for pass through. This is very clean and clear. Once I push the button, there's nothing. I have maxed all 3 pots and have the switches in every possible configuration. Any advice?
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Guide to troubleshoot pedalSHIELD. 4 years 6 months ago #294

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- If you can get +5V and -5V (or something close)is cause the power supply is in nice working order.
- If you can generate the sinewave at nice volume and change the pitch is cause the output stage is ok too.
- Seems that the problem is the input stage, so focus in that area:
You can re-solder a little all the solder joints of the input stage to make sure that are good.
You can also check that the input op-amp gets -5V and +5V in pins 4 and 8.
Again with the continuity option of the multimeter check that there are no short circuits between adjacent pins.
With more patience you can also check looking at the schematic that all the connections and resistors are placed and connected properly.
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