Need Schematics for Diagnostics Testing on Arduino Uno

Other Hardware General Electronics
1

When using an Arduino Uno, I put through 15V (I now know 5V should be the maximum). I'm unsure where the problem is, and have even replaced the microcontroller unit, to no avail. When the board is connected to a USB power supply, an LED lights when in pins 0, 4, 13, and in no others. Those pins were not OUTPUTs or INPUTs in the code, shown below.

const int led = 2;
const int led2 = 9;
int voltage = 0;
int brightness = 0;

void setup() 
{
  pinMode(led, INPUT);
  pinMode(led2, OUTPUT);
}

void loop() 
{
    voltage = analogRead(2);
    
    if(voltage > 0 && voltage <= 1029)
    {
      for(brightness >=0 && brightness <255; brightness +=5;)
      {
        delay(10);
      }
      
      for(brightness <= 255 && brightness > 0; brightness +=5;)
      {
        delay(50);
      }
    }
}

There was a breadboard/outside power supply that, if the code would work (the board popped and fizzled before I could see if it works) would trigger an LED to fade in quickly and fade out more slowly.

So, again, I'm looking for a schematic or diagram to direct me in using a voltmeter to diagnose which components need to be replaced on my Arduino Uno.

2

(deleted)

3

Can you explain, or post directions which explain, how and where to use a voltmeter to check to see which specific component(s?) are burnt out?

4

(deleted)

5

You probably zapped the 328P, the 16U2, the comparator, the FET that controls auto-voltage selection and the 5V and 3.3V regulators, and maybe the reverse polarity diode.
Start with the 328P out, with power from USB.
Got power on both sides of the resettable fuse?
Got 5V and 3.3V? No, fix those. Check the LM386 and the FET, see if 5V from USB is getting passed thru ok.
Go to the power header next.
Got 5V & 3.3V? Check the Power LED, that might have been zapped aslo.
Try the loopback test. Fails? Replace the 16U2, check the Rx & Tx LEDs, should flash as data is transmitted back & forth. They might have been zapped also.
Or remove the 16U2 without damaging other stuff and use an offboard USB/Serial module (FTDI Basic or equivalent with a DTR output).
Got all that working? Plug a good 328P in, bootload if needed, if already bootoaded try a simple sketch download.

6

Thanks spycatcher and crossroads! I'll get working on that tomorrow when I have time and will post any further inquiries I may have.

7

CrossRoads:
You probably zapped the 328P, the 16U2, the comparator, the FET that controls auto-voltage selection and the 5V and 3.3V regulators, and maybe the reverse polarity diode.

Fifteen Volts you say?

I think it might be much easier to start with the shop where you purchase a new Arduino.

The 16U2 for a start is SMD, expensive to buy as a replacement and difficult to solder. I would not be too confident about the LMV358IDGKR either.

8

Is this a successful loopback test?

9

In the meantime, here are the results of testing our arduino.

With USB in:

  • Resettable fuse: Continuity checks out, but no voltage passes through (well: 0.09V).
  • I don't know where or what the LM386 is. Googling makes me think it has to do with sound.
  • I think the FET is next to the USB and resettable fuse. 4.95V passes from the side near the fuse to the opposite side farthest from the USB. No voltage passes from the near-fuse side to the opposite side nearest to the USB.
  • Pins: I tested the pins originally thinking it was the power header :roll_eyes: From ground to each pin, 2 through 12 had no voltage, pin 0 had 4.95V, pin 1 had 4.9V, and pin 13 had 0.53V.
  • Power Header: IOREF, RESET, and the 5V all had 4.95V. The VIN had 4.45V, and the 3.3V had..... 3.3V.
  • Power LED is on. (When I connectected the USB directly to the resettable fuse while trying to test the fuse, the power LED turned off. I assumed that this was the fuse doing its job)
  • See previous reply regarding the loopback test.

Also, I'm unsure of what voltage to use as my input (to trigger an LED)
This is from aduino's webpage for the Uno

1680×1050 208 KB

10

If you don't have an oscilloscope, I would chuck-it and get a new one. It will cost you more to repair it, then to replace it.

Unless you just up to the challenge to repair it.

11

steinie44:
If you don't have an oscilloscope, I would chuck-it and get a new one. It will cost you more to repair it, then to replace it.

Unless you just up to the challenge to repair it.

We literally just got back from purchasing a new one. However, I think the task of fixing it might be enjoyable.

I do have an oscilloscope. Directions for proceeding with the repair procedure?

With love and the utmost regard,
plausiblephysicist

12

I wrote LM386, I intended LM358. 1/2 checks for Vin/2 > 3.3V and controls the FET.
The other 1/2 buffers D13 output to drive the L LED.

Loop back looks good if "Does this ..." is what you typed in.

Can you download a sketch with a new '328P chip?
I just use the onboard LED as a real simple test:

void setup(){
pinMode(13, OUTPUT);
}
void loop(){
digitalWrite (13, HIGH);
delay (250);
digitalWrite (13, LOW);
delay(250);
}

The Rx & Tx LEDs should blink as the bootloader does its thing talking to the PC and writing the sketch into memory, and then the L LED should start blinking.

13

CrossRoads:
. . .
Can you download a sketch with a new '328P chip?
. . .

Unfortunately we cannot upload any programs to our Arduino, even with a new '328 chip.

This is the error message:

avrdude: stk500_recv(): programmer is not responding
processing.app.debug.RunnerException
	at cc.arduino.packages.uploaders.SerialUploader.uploadUsingPreferences(SerialUploader.java:125)
	at processing.app.Sketch.upload(Sketch.java:1719)
	at processing.app.Sketch.exportApplet(Sketch.java:1625)
	at processing.app.Sketch.exportApplet(Sketch.java:1597)
	at processing.app.Editor$DefaultExportHandler.run(Editor.java:2397)
	at java.lang.Thread.run(Thread.java:745)
Caused by: processing.app.debug.RunnerException: Problem uploading to board.  See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.
	at cc.arduino.packages.Uploader.executeUploadCommand(Uploader.java:111)
	at cc.arduino.packages.uploaders.SerialUploader.uploadUsingPreferences(SerialUploader.java:123)
	... 5 more