-
finding short on motherboards with a shorty (with display)
Posted by kripton2035 on 03 Feb, 2021 19:06 -
Hi everyone,
I would like to share a project I made recently : I adapted a shorty device and added a display.
it becomes a 0.1mΩ meter with surprising stability.
the original shorty project is here : https://hackaday.io/project/3635-shorty-short-circuit-finder
I did one showed here (http://kripton2035.free.fr/Projects/proj-shorty.html) and was pleased with its performances, but it lack a display.
here is a video showing the measuring of some small values resistors :
https://youtu.be/4F6QNSpWTos
here another video showing continuous resistance measuring along a soldier roller :
https://youtu.be/8mYyr9uKpFU
and last another video showing how to find a shorted capacitor on a 820-00165 macbook air motherboard.
fast and easy.
https://youtu.be/L4V3BWReZLY
I'm cleaning the schematic and sources, and will share it when it's ready.
just teasing
-
Excellent. I look forward to reading more of this unit
Fraser -
Super!!
I built myself a shorty (designed a board with arduino nano, THT and SMD versions, but built till now only THT version; SMD PCB is done but not populated) and did several experiments and several changes. The last version is up to 5 ohms instead of 1 ohm original. I made and tried also few sketches as I changed/experimented the approach how to translate the voltage readings in tones/sound. Actually, I am very pleased, with all versions, original and mine ones how they translated the milliohms in tones. I was thinking about adding a display, and adding voice talking. I started with voice talking implementation. Then I have seen few weeks ago, on other topic hereon the forum, your post about your shorty with display. Since then I put it in hold and I was waiting to see your realization. I hardly can wait to see your schematics and source if you would like to share. -
I love the sound frequency proportional to the resistance! And seem have quite stable reading. Really interested!
-
the good news is that inside the box everything is wired "bugstyle" on a perfboard... I will certainly make a good pcb with groundplanes...
and add one more digit to the display ! -
@kripton2035: really an interesting project. This tool can be very useful. Great! And thank you for sharing...
If there is enough interest about eevblog users, I suggest you to sell a PCB or a complete kit for building shorty. -
+1 for a Shorty kit
Fraser -
Yes, would make a great kit!
-
here are some picture of the shorty with display, external and internal.
-
I hope it is fine adding something to the subject. If it is not, I apologize.
This is my shorty. I altered the schematics and use MCP601 at voltage supply of 5v, and Arduino Nano. I setup the current level for measurements at 25.5 mA, and gain of op-amp at 27.45. I have attached a picture of PCBA (THT) with LCD (I2C) not attached to it and SMD PCB on which I plan to change supply voltage at 3.3V using 3 diodes in series.
I am impressed by this device's performance and stability at 2 milliohms resolution. It produce audible differences at changes of few milliohms and together with display and a LED I added, which is in synchronism with the buzzer, it is very nice tool to work with. I did not use 4 wires connections as I subtracted the resistance value of wires into calculations. At the end for locating a short circuit I like mostly it to be setup for a range up to 1.5 ohms. I checked this simple construction against an industrial milliohm meter in measurements and I am impressed by its performance, not speaking about visual and audio aid it brings with.
Below I included one of sketches just as an example how simple it is, in my case. It does not include LCD subroutine. I list below the code as it is short.
//by Zoli on Jan 2021
const byte sensorPin = A5; // select the input pin for sensor
int buzzer = 6;//audio output
int led = 13; //signal led
long sensorValue = 0; // variable to store the value coming from the sensor
int pnp = A3; //transistor base
float voltage;
float voltagei;
float ohm;
int j;
void setup() {
Serial.begin(9600);
analogReference(INTERNAL);//using internal 1100mV reference
pinMode(sensorPin, INPUT);
pinMode(buzzer, OUTPUT);
pinMode(pnp, OUTPUT);
pinMode(led, OUTPUT);
}
void loop() {
digitalWrite(pnp,LOW);
digitalWrite(led, HIGH);
for (int i=0; i < 20; i++) {
sensorValue = sensorValue + analogRead(sensorPin);
}
sensorValue =sensorValue/20;
voltage = ((sensorValue * 1100)/1024 );
voltagei = voltage / 27.45;
ohm = ( voltagei/25.5) - 0.05;
// print out the value you read:
Serial.println(ohm,5);
//Serial.println(voltage , 5);
//Serial.println(voltagei , 5);
//Serial.println(sensorValue);
delay (2);
if (ohm <1.5){
// change the analog out value:
digitalWrite(buzzer, HIGH);
analogWrite(6,( 4500*ohm));
digitalWrite(led, LOW);
// stop the program for <sensorValue> milliseconds:
j = 1/(.1*(ohm));
delay(j);
}
// noTone(6);
analogWrite(6, 0);
delay(10);
}
Please, let me know if you have any recommendations. I am not an expert in Arduino programming.
-
some work in progress ...
-
Very nice. I like it.
-
Quote
I have attached a picture of PCBA (THT) with LCD (I2C) not attached to it and SMD PCB
I don't see this picture ? can you post a picture with some measurment on the lcd please ? -
I did not upload the picture with LCD attached as I had not an available one and I borrowed one from other device and the setup was temporarily and I did not take the picture at the time. I ordered a LCD and in one or two days will arrive and then I will post the pictures with measurements.
-
I remade the temporary LCD setup and made this short movie.
This is the link:
https://youtu.be/kG4-mmwKYAE
I uploaded herein a picture of 1 ohm resistor' s measurement.
-
this white lcd is really nice, very bright and readable.
-
this is my work of the day.
-
I think the final design will be really really good
-
Super!! Very nice! I hardly can wait to see your project.
-
new work. implantation seems final. now the routing.
-
Looking very nice
Fraser -
I really needed one of these a few months ago, nifty idea. Might have to build one just to find the shorted part I gave up on finding.
-
Neat. More elegant than just attaching a 15A supply to a rail and waiting for the glow.
-
Neat. More elegant than just attaching a 15A supply to a rail and waiting for the glow.
absolutely, or buying a $1000 thermal camera.
this tool should not cost more than $20 -
some work in progress ...
I would be interested in a kit if you decided to make one available
Please let us know if you decided to do a kit for this project
Thanks