How to repair LED matrix panels.

A few years ago I had two P3 LED panels with missing LED's in the corners due to being beaten up in shipping.  Recently it happened again, this time three P5 LED panels had missing LED's from shipping abuse.  In another case I bought 18 P6 panels that were likely bad before they were shipped.  Every panel had bad LED's, some had as many as 30 LED's that were not working out of the 1024 on the panels. At first I repaired them to where 1-5 LED's were still out, but then with a better soldering iron tip I was able to get them to 100% working.

I want to show you how to repair minor problems with LED matrix panels.  Usually it is a corner LED that is loose or missing.  You can buy reels of 100 LED's for about $6.  In the P3 and P5 panels they were 2121 LED's.  The P6 panels had 3535 LED's.

First remove the almost invisible screws near the missing LED.  Then lift the panel screen and make two small cuts in the screen as can be seen in the next picture.  Remove the cut out piece. Set the screen back down.  Clean up the solder pads, leave some solder on them.

Then slide in the new LED into place with the panel powered up so you can see if it is oriented correctly by it lighting up.  Then, while holding the LED down with a small screwdriver, solder the two visible pins into place.  Next, lift the screen and prop it up.  Solder the two pins that you cannot see by "feel".  Then test the screen to make sure that it is working now.

Signs, Signs, Everywhere Signs!

I have just finished my latest book "LED Sign Projects".  I am not happy with the cover.  Besides being off center its kind of redundant.  LOL.  Also they used to add a page saying it is a proof.  But if you were happy with it you could remove that page and sell it.  Now they have "Not for Resale" on the cover!  The proof costs about the same as buying one so why do that to it!?!?

Another cover picture was "Signs, SIgns Everywhere Signs" after the song from the 70's.  But it lacked contrast.  Most cameras do not take accurate pictures of LED signs.  Would this make a better cover image??

I just completed one of my biggest signs ever.  Its 5 feet wide and 3 feet tall, the equivalent of a 70" TV screen.  There are 30 of the 32 by 64 P5 LED panels for over 30,000 pixels.  The resulting image is awesome!  Unfortunatly the pictures did not turn out well.  

This picture was taken before I put the top and bottom aluminum rails on it.  I use Steel L brackets at the corners to reinforce them and the mounting eyelet goes into that steel L Bracket as well.  So most of the weight is carried by the vertical aluminum rails.  I use external power supplies that way it is almost flush to the wall when it is hung up.

Here are some of my other LED signs from the back side.  This is similar to the one shown above.  Note that the panel joiners are all 3D printed.  I tried 3D printing the edges but they broke too easily so I use 3/4 inch L aluminum extrusions found at most hardware stores.

This is a water resistant version featureing 4x5 or the 32x32 pixel P6 LED panels.

Using LED strips to light up a Street sign instead of fluorescent bulbs

A couple of years ago I replaced the non-working five foot fluorescent bulbs in our church street sign with LED's.  However the horizontal strips were visable and became annoying.  So I came up with the idea of using edge lighting.  The LED strips would be on a metal surface so they would be less likely to overheat and burn out.  

I had some 130 per Meter or 36 per foot 2835 SMD LED strips.  They were 10 Meters or 394 inches or 32.8 Feet in length.  They are soft white and run off 12 Volts.  The total power is 90 watts per 10 meters length.  I used two of these strips for four laps around the inside of the sign.  I think if I was to buy them I would get bright white LED's instead.

This is the results as seen at night.  No more horizontal strips of lights!  It does dim a little in the center but it dure looks better.  Now to get a bigger LED sign!

We had to dig up the church well

The pump quit in the church well so we had to dig it up.  When we tried to pull it we could see somthing on the pitless adapter.  We tapped it with a long stick and discovered it was a rock and now it was further down in the well.  No amount of pounding or pulling would loosen the pitless connector.  So we had to did up the well.

After digging up the pitless and removing it, the pump came up easily.  We did not see any rocks!?!  We did see the real problem: the wires to the pump were burnt and one wire was disconnected.

We could also see the pitless was bigger than normal and after hitting it many times with different hammers it finally came apart.  there was no O ring!  It had likely leaked and the leaked water formed a rust/calcium bond glueing it in place.

Waveshare Zero to Pi3 Review

I recently purchased a Waveshare Zero to Pi3 adapter.  I had a couple of Pi zero's laying around not being used because I had to look up the HDMI and USB adapters in order to use them.  One Zero was even so old that it did not have any built in network ability.  I had to use USB memory sticks to add programs to it.  

This next picture shows the Zero adapter in use.

I could not get it to fit my 3D printed case as it is a very tiny bit wider and the memory card jack is in the wrong place.  I might design a modified case with the new memory card position.  It did mount fine on a piece of plastic with the standard raspberry Pi hole spacing.

When I went to test it, the video worked but the USB jacks did not work.  Then I squeezed it a little more and the USB jacks moved a tiny bit and started working.  Even the network jack worked but, to be honest, the Zero is a model 1.3 and it is to slow for browsing online web sites.

The adapter is also missing the audio jack, but most of the time I have to disable audio to run my projects so that is not an issue for me.  Alltogether I love this little adapter as it brought back usefulness to my Zero's.  

I own a raspberry Pi model 1, 2, 3 and 4.  I was surprised whrn I discovered that I needed a HDMI adapter for the model 4!  Now if I can just keep from loosing it!

Mackie Thump TH-15A Powered speaker Repair

 I was asked to repair a Mackie Thump TH-15A Powered speaker by a friend.  It powered on and everything looked good but there was no sound coming out.  I checked the speakers and the power supplies but everything was just fine.  However, the computer board was getting really hot.  It had 3.3 volts coming into a voltage regulator but only .5 volts coming out.  I tried easter egging the capicitors and it turned out to be the tiny little .1 uF capacitor that was shorting out the power supply.  The correct output is 1.2 volts.

This is what the guts look like, we are going to zero in on the logic board.

This is the logic board once the metal cover is removed.

These are the filter caps on the 1.2 volt power supply circled in red.

This is what the powered speaker looks like once it was back together.

ESP32 HUB75 DMA Hue Value Spectrum demo

The Hue Value Spectrum demo is beautiful, cameras do not do it justice.

This is found at https://github.com/mrcodetastic/ESP32-HUB75-MatrixPanel-DMA

This software connects to just the input port of the LED array.

The issue with this software is that it it too fast.  The speed results in noise from the 3 volt logic driving the 5 volt panel.  You have to play with the ground wires and keep the ribbon cable as short as possible to prevent noise and even then there are faint blinking LED's from th noise issue.

Another issue is the software does not support "Strange" LED panels like most 8S outdoor panels.

Aurora Demo on ESP32 with a 16S 32x32 LED panel

This is the Aurora Demo working on 32x32 RGB LED matrix panel with an ESP32 Processor.  I bought a circuit bard to do this but could not get it to work, so I went with jumper wires and it worked almost perfectly from the start!

This wiring arrangement uses two sets of jumper wires going to both the input and output of the LED panel.  This makes it almost impossible to transfer it to another panel to test different ones to see if they are supported inthe software.

The wiring looks like this:

This wiring makes it difficult to add more panels or to try using another panel.

New Big LED sign powered by Raspberry Pi

I have made another big LED sign, but this time it is powered by a Raspberry Pi.  At first I used the Adafruit Hat ,but I have upgraded to the three HUB75 Hat from ElectroDragon! This enalbes three chains of LED arrays. So far I have 5 32x32 panels in each chain but I will likely expand that.

This is a view of the back of the assembled panel. I am using metal brackets to hold the panels together as they have on inch spacing. 24mm is ideal as the one inch spacing leaves about a two mm space between the panels. I have a 3D printed version of the brackets on thingiverse and have used them in other designs.

Here is a couple of pictures of the panel being lit up. The text demo is limited to one line of panels.

There are several demo programs to check out the proper operation of the Raspbery Pi adapter.

Here is a link to the video of the demos;

https://youtu.be/44ykJb_ZB7A?si=ylKY5zBix4FU4i2X

Testing LED panels for bad LED's

I have written two programs to test LED panels after someone sold me a pile of them with many bad LED's.  Some panels had over 30 LED's that were not working.  He also shipped them with no padding between the LED's!  This resulted in smashed LED's and some of the alignment nubs were broken off.  Fortunatly with some soldering I was able to reduce the number of bad LED's to 3 or 4 per panel.  Now I can use them for testing out programs and configurations.  Some LED's had broken runs but most of them just needed to be resoldered.

The first program tests the colors and leaves the panel white for quickly testing if the LED's just soldered are working.  This does not work on 16S panels for some reason.

// RGBcolors test for Adafruit RGBmatrixPanel library.

// For testeing LED arrays for bad bits.

#include <RGBmatrixPanel.h>

#define CLK  8   // USE THIS ON ARDUINO UNO, ADAFRUIT METRO M0, etc.

#define OE   9

#define LAT 10

#define A   A0

#define B   A1

#define C   A2

#define D   A3

// Does not work with 16S panels if you add "D" nothing happens!

RGBmatrixPanel matrix(A, B, C, CLK, LAT, OE, false);

void setup() {

  matrix.begin();

   // fill the screen with colors

  matrix.fillRect(0, 0, 32, 32, matrix.Color333(0, 7, 0));

  delay(1000);

  matrix.fillRect(0, 0, 32, 32, matrix.Color333(7, 0, 0));

  delay(1000);

  matrix.fillRect(0, 0, 32, 32, matrix.Color333(0, 0, 7));

  delay(1000);

  matrix.fillRect(0, 0, 32, 32, matrix.Color333(7, 7, 7));

  delay(1000);

}

void loop() {

}

The next program is for sorting LED panels by how they are internally wired.  There are 16S, 8S (There are many varieties of 8S) and 4S panels.  It scans all LED's one at a time.

I could not get this to work with the normal drivers so I wrote my own using "bit banging".  Its slow but works great!  Note:This program was improved in March of 2021, it runs much better now!

// RGB bitbang test bits by scanning

#define CLK  8  

#define OE   9

#define LAT 10

#define A   A0

#define B   A1

#define C   A2

#define D   A3

#define R1  2

#define G1  3

#define BL1  4

#define R2  5

#define G2  6

#define B2  7

int tbit;

int row;

int col;

void setup() {

  pinMode(A, OUTPUT);

  pinMode(B, OUTPUT);

  pinMode(C, OUTPUT);

  pinMode(D, OUTPUT);

  pinMode(CLK, OUTPUT);

  pinMode(OE, OUTPUT);

  pinMode(LAT, OUTPUT);

  pinMode(R1, OUTPUT);

  pinMode(G1, OUTPUT);

  pinMode(BL1, OUTPUT);

  pinMode(R2, OUTPUT);

  pinMode(G2, OUTPUT);

  pinMode(B2, OUTPUT);

  }

void loop() {

  // Set sequential bits

  for (row=0; row<16; row++){

    for (col=0; col<64; col++){

      for (tbit=0; tbit<64; tbit++){

        digitalWrite(R1, LOW);  

        digitalWrite(G1, LOW);  

        digitalWrite(BL1, LOW);  

        if (tbit <= col){

          digitalWrite(R1, HIGH); 

//          digitalWrite(G1, HIGH); 

//          digitalWrite(BL1, HIGH); 

        }

      digitalWrite(CLK, HIGH);  

      digitalWrite(CLK, LOW);  //Clock data in

      } 

    // latch and display results

    digitalWrite(OE, HIGH);  // disable output while latching data.

    digitalWrite(LAT, HIGH);  

    // select next column if it has changed

    digitalWrite(A, LOW);

    digitalWrite(B, LOW);

    digitalWrite(C, LOW);

    digitalWrite(D, LOW);

    // update row selection

    if ((row & 0x0001)>0)digitalWrite(A, HIGH);  

    if ((row & 0x0002)>0)digitalWrite(B, HIGH);  

    if ((row & 0x0004)>0)digitalWrite(C, HIGH);  

    if ((row & 0x0008)>0)digitalWrite(D, HIGH);  

 //   delay(5); // dim display

    digitalWrite(LAT, LOW);  

    digitalWrite(OE, LOW);  

    delay(50);

    }

  }

}

Explaining the different types of LED Arrays

Not all LED arrays are the same, there are many varieties within a set size and set amount of LED's.  There are the P numbers.  P10 means 10mm LED spacing.  P6 is 6mm spacing.  P3 is 3mm spacing.

Then there are the S or scan or row select numbers.  Typical S numbers are S4, S8, and S16.  But they even vary within these numbers!  Lets start with a 16S arrangement.  In a 32 by 32 LED array there are two 32 bit shift registers one for the top half and one for the bottom (As well as one for each color).  Then there are 16 row selectors that select what two rows are currently lit up.

Next there is an 8S LED array.  Withing a 32x32 array there are four 32 bit shift registers.  The top two and the bottom two are sequential. (This is for each of the three colors) Then there are 8 row selectons.  These select what four rows are currently lit up.

Now things get tricky.  Some arrays do not follow the normal pattern.  For instance the modified 8S panel depicted below.  These are not compatable with some controllers.  There are two 16 bit shift registers and a 32 bit shift register for the top half and the same for the bottom.  (This is for each of the three colors)  The shift register sequence is the top 16, then the middle 32, then the other top 16 bits.

So not only are you dealing with color differences between different batches you are dealing with scanning differences.  You cannot mix an 8S and a modified 8S in the same chain of LED arrays.

Big LED sign with 6x4 of 32x32 P6 LED panels

My latest LED sign is by far my biggest LED sign yet!  I purchased a pile of P6 32x32 LED panels on eBay for about $10 each.  The seller even included the cables needed to get it to work!

Here is a picture of it with a TF-QS3N Controller.  It uses PowerLED to set it up from a computer over a newwork.

This is the back side of the sign as I was assembling it.  The sign is now over twice the size shown in this picture.

Here is a newer picture at 4 by 7 panels.  It is now 5 by 7 panels in size and growing!  I hope to get to 5 by 8 panels but the model numbers of the next panels do not match and the color balance might be too far off to intermix them.

One option to connect the panels together is these metal brackets available at most hardware stores at four for $5.00.  Thes have a hole spacing of one inch (24.5mm) and the panel mounting holes are 24 mm so there is a 1.5 mm gap between the panels if you uses these brackets. 

I have 3D printed my own brackets for connecting the panels.  They were designed on TinkerCad.  The STL files are available on thingiverse. 

Here is a video of when I first got them working.

Expanding my sign with 16x16 addressable LED arrays.

 I am expanding my sign with 16x16 WS2812B Addressable LED arrays.  Currently I am at 3x5 of these arrays but am working on adding three more for a 3x6 or 48 by 96 sign.

This is the built in demo with a T8000 controller.  I had more luck with the SP801E controller.

Here I am starting to add the grids to make the pixels square.  The grids are on thingiverse.  I drilled too many holes in the luan because I confused the orientation.  They need to connet from top to bottom.

This is another picture of assembling the arrays.  I am using E-6000 glue to hold them in place.  I glue two or three at a time just in the corners then put something on them to hold them in place till the glue dries.

Here is the first video with the T8000 controller

https://www.youtube.com/watch?v=STn5s0Ipr-M

This is a demo with an SP801E controller

https://www.youtube.com/shorts/VzCqLekaI-U

Here it is with WLED on an ESP32 processor

https://youtu.be/ZxGXOkgYxrg

Here are some pictures from the WLED demo.

Sunrise Systems LED Sign revisited

 I was asked to convert another Sunrise Systems LED sign to Arduino control and wireless updates via bluetooth.  This time I wanted to make the conversion simpler by reusing the driver IC's and Transistors.  To do that I cut the board in half just to the right of the processor.  Then I tapped into signals on the 74HC04 and 74HC138.  The following picture shows the location for the cut and where to tap into the signals:

Here is a picture of the prototypeing of this new setup.  Everything worked but some of the signals were inverted so it took some playing with the code to get it to work.

I spliced in a bare board to add the arduino processor. 

Here is the revised code for a basic version of this arrangement;

// Sunrise 7x96 Uno LED Array driver

// Easier to read code

// 4/4/2024 by Bob Davis

#define Data 7// Data pin

#define CLK 8 // Port B assignments 

#define OE  9 // 74138 pins 4 and 5

#define LAT 10// Latch

#define A0 11 // 74138 pin1

#define A1 12 // 74138 pin2

#define A2 13 // 74138 pin3

String text="ARDUINO+SUNRISE  ";

// This font from http://sunge.awardspace.com/glcd-sd/node4.html

byte font[][7] = {

0x00,0x00,0x00,0x00,0x00,0x00,0x00, // ascii 32

0x00,0x00,0xfa,0x00,0x00,0x00,0x00, // !

0x00,0xe0,0x00,0xe0,0x00,0x00,0x00, // "

0x28,0xfe,0x28,0xfe,0x28,0x00,0x00, // #

0x00,0x34,0xfe,0x58,0x00,0x00,0x00, // $

0xc4,0xc8,0x10,0x26,0x46,0x00,0x00, // %

0x6c,0x92,0xaa,0x44,0x0a,0x00,0x00, // &

0x00,0xa0,0xc0,0x00,0x00,0x00,0x00, // '

0x00,0x38,0x44,0x82,0x00,0x00,0x00, // (

0x00,0x82,0x44,0x38,0x00,0x00,0x00, // )

0x10,0x54,0x38,0x54,0x10,0x00,0x00, // *

0x10,0x10,0x7c,0x10,0x10,0x00,0x00, // +

0x00,0x0a,0x0c,0x00,0x00,0x00,0x00, // ,

0x10,0x10,0x10,0x10,0x10,0x00,0x00, // -

0x00,0x06,0x06,0x00,0x00,0x00,0x00, // .

0x04,0x08,0x10,0x20,0x40,0x00,0x00, // /

0x7c,0x8a,0x92,0xa2,0x7c,0x00,0x00, // 0

0x00,0x42,0xfe,0x02,0x00,0x00,0x00, // 1

0x42,0x86,0x8a,0x92,0x62,0x00,0x00, // 2

0x84,0x82,0xa2,0xd2,0x8c,0x00,0x00, // 3

0x18,0x28,0x48,0xfe,0x08,0x00,0x00, // 4

0xe4,0xa2,0xa2,0xa2,0x9c,0x00,0x00, // 5

0x3c,0x52,0x92,0x92,0x0c,0x00,0x00, // 6

0x80,0x8e,0x90,0xa0,0xc0,0x00,0x00, // 7

0x6c,0x92,0x92,0x92,0x6c,0x00,0x00, // 8

0x60,0x92,0x92,0x94,0x78,0x00,0x00, // 9

0x00,0x6c,0x6c,0x00,0x00,0x00,0x00, // :

0x00,0x6a,0x6c,0x00,0x00,0x00,0x00, // ;

0x00,0x10,0x28,0x44,0x82,0x00,0x00, // <

0x28,0x28,0x28,0x28,0x28,0x00,0x00, // =

0x82,0x44,0x28,0x10,0x00,0x00,0x00, // >

0x40,0x80,0x8a,0x90,0x60,0x00,0x00, // ?

0x4c,0x92,0x9e,0x82,0x7c,0x00,0x00, // @

0x7e,0x90,0x90,0x90,0x7e,0x00,0x00, // A

0xfe,0x92,0x92,0x92,0x6c,0x00,0x00, // B

0x7c,0x82,0x82,0x82,0x44,0x00,0x00, // C

0xfe,0x82,0x82,0x82,0x7c,0x00,0x00, // D

0xfe,0x92,0x92,0x92,0x82,0x00,0x00, // E

0xfe,0x90,0x90,0x80,0x80,0x00,0x00, // F

0x7c,0x82,0x82,0x8a,0x4c,0x00,0x00, // G

0xfe,0x10,0x10,0x10,0xfe,0x00,0x00, // H

0x00,0x82,0xfe,0x82,0x00,0x00,0x00, // I

0x04,0x02,0x82,0xfc,0x80,0x00,0x00, // J

0xfe,0x10,0x28,0x44,0x82,0x00,0x00, // K

0xfe,0x02,0x02,0x02,0x02,0x00,0x00, // L

0xfe,0x40,0x20,0x40,0xfe,0x00,0x00, // M

0xfe,0x20,0x10,0x08,0xfe,0x00,0x00, // N

0x7c,0x82,0x82,0x82,0x7c,0x00,0x00, // O

0xfe,0x90,0x90,0x90,0x60,0x00,0x00, // P

0x7c,0x82,0x8a,0x84,0x7a,0x00,0x00, // Q

0xfe,0x90,0x98,0x94,0x62,0x00,0x00, // R

0x62,0x92,0x92,0x92,0x8c,0x00,0x00, // S

0x80,0x80,0xfe,0x80,0x80,0x00,0x00, // T

0xfc,0x02,0x02,0x02,0xfc,0x00,0x00, // U

0xf8,0x04,0x02,0x04,0xf8,0x00,0x00, // V

0xfe,0x04,0x18,0x04,0xfe,0x00,0x00, // W

0xc6,0x28,0x10,0x28,0xc6,0x00,0x00, // X

0xc0,0x20,0x1e,0x20,0xc0,0x00,0x00, // Y

0x86,0x8a,0x92,0xa2,0xc2,0x00,0x00, // Z

};

void setup() {

  Serial.begin(9600);

  Serial.println("Arduino is ready");

  pinMode (Data, OUTPUT); // Data pin to output

  pinMode (CLK, OUTPUT);  // Clock pin to output

  pinMode (OE, OUTPUT);   // Out Enable pin to output

  pinMode (LAT, OUTPUT);  // Latch pin to output

  pinMode (A0, OUTPUT);   // Address pin to output

  pinMode (A1, OUTPUT);   // Address pin to output

  pinMode (A2, OUTPUT);   // Address pin to output

}

     

void loop() {

    if (Serial.available() > 0){

      text=Serial.readString();

      text.toUpperCase();

      Serial.print(text);

      }

    // Select the Row

    for (int r=0; r<8; r++){

      // select the character

      for (int ch=17; ch>-1; ch--){

        // select the column within character

        for (int c=5; c>-1; c--){

          digitalWrite(Data, HIGH); // Data is inverted!

          if ((font[text[ch]-32][c] >> r+1) & 0x01==1) digitalWrite(Data, LOW);

          digitalWrite(CLK, LOW);  // Toggle Clock

          digitalWrite(CLK, HIGH);

        }

      }

      // This row is done so display it

      digitalWrite(OE, HIGH);  // Turn off display

      digitalWrite(LAT, HIGH); // Latch  data

      digitalWrite(LAT, LOW); // Ready for next latch

      digitalWrite(A0, LOW);  // Update Row 

      digitalWrite(A1, LOW);

      digitalWrite(A2, LOW);

      if ((r & 0X01)==1) digitalWrite(A0, HIGH);

      if ((r & 0X02)==2) digitalWrite(A1, HIGH);

      if (r > 3) digitalWrite(A2, HIGH);

      digitalWrite(OE, LOW);  // Display back on

      }

    }

Here is a picture of the wiring from the back side.

InMoov Compatible Hand Design Upgrade

I am working on a InMoov Compatible Hand Design Upgrade.  The main goal is to put all the servos in the hand.  Years ago I printed out a hand only to discover that all the servos are in the forearm.  Recently I though I could do better.  So far I am on my third hand.

This is what it looks like so far.  I used the one piece finger segments and printed them laying down with supports to plate only.  The servo arms will need to be two sided or 3D printed.

Onthe left are the first three attempts to print the improved hand.  In the latest version the servos are indented 6mm so they stick out the back side of the hand slightly.