After being helped by so many great "how tos" here, I've decided to document and create my first. I've disliked the florescent tube in my Stern pins and have wanted to change the backbox to LEDs. However, the cost of getting a pre-fab one done is a bit on the pricey side. Not that they aren't worth it, but I figured that making them could be something that I could handle. After some research and parts hunting, I figured that I could make one for about $50. Once I had assembled the parts and successfully made my first, I decided to document everything that went into making my second. All told, the cost was about $30 and takes about 4 hours (depending on how many times I had to get a beer, dig out a tool, or find where I put down tool). I'll be posting this in a series, outlining the parts (costs and where to get them), required tools, and step by step instructions with photos. I hope this how-to helps someone as much other people's how-tos have helped me. Your comments and feedback for how to make this better (or point out errors!) are appreciated.

A couple of photos to show the final results.

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The parts list:

Hardware store (Ace):
2x 6x32 3" rods ($0.40)
4x flange washers ($0.27)
2x 6x32 wing nuts ($0.59)
6x 6x32 nuts ($0.10)
2x small lock washers ($0.10)
zip ties ($1)
22 gauge wire ($1)
heat shrink tubing ($1)

Pinball life and/or Great Plains Electronics:
6-pin IDC (.156") connector ($0.45/$0.18): press fit or pins (press: http://www.pinballlife.com/index.php?p=product&id=1598, pins: https://www.greatplainselectronics.com/products.asp?cat=81 )
(optional -- depends on IDC connector style) 6 crimp contact pins (.156"): ($0.08) https://www.greatplainselectronics.com/products.asp?cat=80
6-pin IDC header (.156"): ($.35) http://www.pinballlife.com/index.php?p=product&id=1622

Ebay:
5M RGB LED 12V strip (300 5050 LEDs) $10 ebay.com link: itm)

Connecting wire for LED strips (Need one fewer than number of LED strips) can be bare or with quick connects ($0.25-$1) (ebay.com link: itm $3.25 for 10)

RGB remote controller ($3.50): ebay.com link: itm

Note: Just received one of these and the battery for the remote is NOT included! Required: CR2025

Batteries for RGB remote (44 key):

*CHANGE*
Get the 24"x18" plastic board from Home Depot. The slightly narrower width makes it easier to mount/unmount the backboard. Also, this negates the need to cut slots to wrap the wires around the board. For photos: https://pinside.com/pinball/forum/topic/how-to-make-an-led-backbox-for-30-for-modern-sterns/page/3#post-1898877
<original>
Foam core poster board cut to 25"x18"
Michael's sells 40"x32" for $8 (enough for two, or messing up one)
</original>

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Tools:

Phillips screwdriver #2: for removing florescent light tube holders
Box cutter: for cutting poster board
Straight edge/meter stick: for drawing and cutting straight lines
Tape measure: for measuring
5/16" box wrench: for tightening 6x32 nuts
Extra small screwdriver: for punching holes in poster board
Scissors: for cutting LED strip and poster board slots
Heat gun: for heat shrink tubing
Helping hands: for holding electronics
Crimping tool: for attaching crimp contact pins
Wire stripper
Wire cutter
Soldering iron and solder

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Directions for cable adaptor harness: Abbreviated

WARNING: do not connect or disconnect cables to a pinball machine while it is on. You could shock yourself or do damage to the boards.

Steps:
1. Locate 6 pin power IDC connector (J11) on cpu board. This is located in the upper left corner of the board
2. unplug and note pin labels:
1: +5V
2: GND
3: -12V
4: AGND
5: AGND (header pin clipped)
6: +12V
NOTE: The harness will add a bridge that has wires for pins 1 (+5V), 2 (GND), and 6 (+12V). For the back box LEDs, we will be using only the GND and +12V. The +5V may be used for other mods (e.g., addressable LEDs)
3. Cut 5 short wires that will be used to connect IDC header to connector
4. Cut three long wires that will be used to bridge pins 1, 2, and 6 to back board or other mods
5. Hold 6-pin IDC connector with helping hands
6. Solder 5 short wires to header pins 1, 2, 3, 4, 6
7. solder 3 long wires to header pins 1, 2, 6
8. cut and place heat shrink over the wires and exposed pins
9. heat and shrink with heat gun
10. pin small wires with crimp contacts if using an IDC connector that requires them
11. push pins/push wires into IDC connector
12. double check that you pinned the harness correctly
13. clip pin 5 from header so it can be plugged into connector J11

If you have an RGB color changing module, times to wire it to the harness.
1. Pop it open
2. Solder the ground and 12V wires from the harness as shown in the picture.
3. Test. If it doesn't work, try switching the wires.
4. Close it
5. Attached it to the head with double sided tape.

If you don't have an RGB color changing module, you can wire directly to the back box LED lead. For white, bridge the RGB inputs together and connect to the negative wire. 12V+ to the 12V on the LED strips.

Completed harness

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Directions backboard: Abbreviated

1. Cut foam core poster board to size (25"x18")
2. Measure and poke holes for mounting posts
3. Remove yellow tabs holding in florescent tubes
4. Remove florescent tube
5. Remove florescent tube holders
6. Tuck florescent tube holders behind florescent tube mounting plates
7. Remove florescent tube starter
8. Screw in 6x32 3" rods into florescent tube mounting plate
WARNING: Make sure it is in far enough so that the ends don't hit the translite!!!
9. Put small lock washer on rods
10. Tighten 6x32 nut against lock washer to hold rod in place on mounting plate
11. Put two 6x32 nuts onto each rod, about halfway down. These will be the backstop for the poster board
12. Tighten the two nuts against one another to lock them in place
13. Test fit the poster board in the back box (adjust as necessary -- you can bend the rods widen holes, start over)
14. Cut light strips (lengths of twelve sets of three LEDS for the one shown in this example)
15. Measure poster board to space LED strips. (Number of strips + 1)/18". For the 6 strips shown here, that is ~2-9/16" from end to first strip and between each strip
16. Cut slots in edge of poster board to run wires for the LED strips
17. Remove backing and apply LED strips.
NOTE: Since you will be tapping into the 12V power on the cpu board (right board on SAM systems), it will be easiest to leave a connector free on the upper right side of the poster board (with the LEDs facing you)
18. Connect wiring in serial.
NOTE: doing steps alternating steps 17 and 18 help make sure that you orient the LED strip (12V top or 12V bottom) correctly. Exactly how to connect the wires depends if you have quick connects or solder. This example uses both.
NOTE: if soldering, make sure to tin (put solder) on the LED strip pads and the wire before soldering together.
NOTE: if using quick connects, I noticed a fraction were shorted or made bad connections
NOTE: Test the lights and the color channels as you go, this makes it easier to find and correct problems
19. Pull wires through slots
20. Tape wires to back of poster board
21. Glue flange washers to rod holes on poster board (protects the holes)
22. Connect to power, mount, enjoy!

Completed backbox:

_{Post edited by lyonsden: Added abbreviated directions for backbox}

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Making the wiring harness: Detailed

Note: Thanks to Kris at Firebird Pinball for pointing out that you can just run wires from the accessory plug located near the coin door. That should be safer for your CPU board and take less time to make. I'll post details on how to do that on the next machine I do, but the parts list are further down in the thread.

Step 1. Locate 6 pin power IDC connector (J11) on cpu board. This is located in the upper left corner of the board
Step 2. Unplug and note pin labels:
Pin 1: +5V
Pin 2: GND
Pin 3: -12V
Pin 4: AGND
Pin 5: AGND (header pin clipped)
Pin 6: +12V

NOTE: The harness will add a bridge that has wires for pins 1 (+5V), 2 (GND), and 6 (+12V). For the back box LEDs, we will be using only the GND and +12V. The +5V may be used for other mods (e.g., addressable LEDs)

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Step 3. Cut 5 short wires that will be used to connect IDC header to connector
Step 4. Cut three long wires that will be used to bridge pins 1, 2, and 6 to back board or other mods
Step 5. Hold 6-pin IDC connector with helping hands (I love this thing!)

Note: I labeled the pin numbers for pins 1 and 6 on the IDC connector. It is relatively easy to wire this backwards.

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Step 6. Solder 5 short wires to header pins 1, 2, 3, 4, 6

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Step 7. Solder 3 long wires to header pins 1, 2, 6

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8. Cut and place heat shrink over the wires and exposed pins.

Note: I used different diameter tubes for the single and double wires. Having a kits with different sizes helps.

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Step 9. Heat and shrink tubing with heat gun

Note: Heat guns are awesome. Surprisingly dangerous, but awesome!

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Step 10. Pin small wires with crimp contacts if using an IDC connector that requires them.

Note: Having a ratcheting crimping tool helps a bunch. I used to do this with needle nose pliers, and then I got this: ebay.com link: itm ($19)

I will never, ever go back.

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Step 11. Push pins/push wires into IDC connector

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Wiring harness complete.

Note: Header pin 5 has been clipped. The connecter in the machine for J11 is keyed by having pin 5 blocked.

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Step 12. Double check that you pinned the harness correctly.

Note: The missing wire on pin 5 should line up. If it is on pin 2, the harness was pinned backwards. Time to start over.

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Step 13: Clip pin 5 from header of your new harness so it can be plugged into connector J11.

Note: The connector for J11 is keyed with the hole for pin 5 blocked. You need to remove this pin from your wiring harness' header in order to plug it in.

_{Post edited by lyonsden: Added photo}

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If you have an RGB color changing module, time to wire it to the harness. These modules are 12V so will run straight off the 12V+ power of your pin.

Step 1. Pop it open
Step 2. Solder the ground and 12V wires from the harness as shown in the picture. You will be soldering to the underside of the board where the 12V DC plug is soldered through.
Step 3. Test. (You will need the completed LED backbox or strand of lights with the appropriate connector. Your 5M LED strip should have connectors attached to each end). If it doesn't work, try switching the wires. I did this and nothing bad happened. Of course, it took me 30 minutes to figure that out.
Step 4. Close it
Step 5. Attached it to the inside of the head with double sided tape. The upper right-hand corner has space.

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If you don't have an RGB color changing module, you can wire directly to the back box LED lead. For white, bridge the RGB inputs together and connect to the negative wire. 12V+ to the 12V on the LED strips.

In the photos, I bridged the RGB cables of an LED wiring harness by twisting them together. I then attached 1 pin molex plugs to all the cables to make it easy to connect and disconnect (so I can upgrade the second machine with a coloring changing remote). The second photo shows this harness connecting the 12V+ and the ground wires from the CPU board to a finished backbox.

Note: The in the photo, the 12V+ from the CPU board harness is red and is connected to the black (12V+) of the LED wiring harness. The colors on those LED strips can be confusing if you are not paying attention.

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Directions for the backbox: Detailed

Step 1. Cut foam core poster board to size (25"x18").

Note: I found that using a straight edge (in my case, a piece of wood) to guide a box cutter worked well for cutting through one side of the poster board. I then bent the poster board at 90 degrees and cut through with a second pass of the box cutter.

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Step 2: Measure and poke holes for mounting posts. This will be 9" from the top (or bottom) and 1" in. The holes need to be 23" apart. I used a small phillips screwdriver for poking holes.

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Now it is time to remove the florescent tube from the backbox, get the mounting hardware installed, and see how the poster board fits!

Step 3: Remove the yellow tabs holding in florescent tube.

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4. Remove the florescent tube.

Note: You need to twist the bulb until the pins on it are lined up with the slot in the front of the tube holders. It is a bit delicate and I have broken holders without much force.

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Step 5. Remove florescent tube holders. There is a phillips head screw. Remove it.
Step 6. Tuck florescent tube holders behind florescent tube mounting plates. There is no need to cut the wires running to them.

Note: The screw hole will be used for the backbox mounting hardware.

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Step 7: Remove the florescent tube starter from the left side. This is removed by turning (counterclockwise, I believe. Or the other way.)

Note, it is a bit tight due to a lot of wires running behind the mounting plate, but you can still get the florescent tube holder tucked out of the way.

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Here are your liberated parts. Save them in case you want to revert back to original (or the next owner does.)

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Step 8: Screw in 6x32 3" rods into florescent tube mounting plate
Step 9: Put small lock washer on rods
Step 10: Tighten 6x32 nut against lock washer to hold rod in place on mounting plate with the 5/16" wrench

WARNING: Make sure it is in far enough so that the ends don't hit the translite!!!
Second WARNING: Obey the first warning.

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Mounting rods installed.

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Step 11. Put two 6x32 nuts onto each rod, about halfway down. These will be the backstop for the poster board
Step 12. Tighten the two nuts against one another to lock them in place

Note: you want some clearance from the boards. Some of those components get hot and will melt the tacky adhesive used to tape the LED strips in place. (Ask me how I know. . . )

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Step 13: Test fit the poster board in the back box (adjust as necessary -- you can bend the rods widen holes, start over.)

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14. Cut light strips. Length: in this example, twelve sets of three LEDS.

Note: The strips of LEDS are arrayed in sets of threes with very obviously places to cut (exposed metal pads for making contacts). When you cut, cut on the black line to give equal contact space to each side. This is important when connecting wires the the LED strips.

Note: How many strips should you use? Up to you. These strips are dimmable (there are inline dim controllers for ~$1-2 and the color remote has dim control too). I decided to err on the bright side and use 6 strips which I could dim later.

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Step 15. Measure poster board to space LED strips. The formula to use is:
(Number of strips + 1)/(height of poster board)

For this example, I used 6 strips and the height of the poster board is 18". That is ~2-9/16" from board end to first strip and between each strip.

Note: I made marks on each side of the poster board for these measurements. However, the picture doesn't show them and is not very exciting, so it has been omitted.

Step 16. Cut slots in edge of poster board to run wires for the LED strips.

Note: I made two cuts at the edge of the poster board at each mark, about 3/4" long. I then pushed the material through the cut and snipped it off.

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Step 17. Remove backing and apply LED strips.

NOTE: Since you will be tapping into the 12V power on the cpu board (right board on SAM systems), it will be easiest to leave a connector free on the upper right side of the poster board (with the LEDs facing you). The roll of LEDs has a connector attached at each end.

NOTE: If you are tapping into the accessory power source located near the coin door (see message from Firebird) of the pin, leave a connector free on the lower right corner so you can run the wires along and up the right side of the cabinet.

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_{Post edited by lyonsden: Add note about connecting to the accessory power near coin door.}

Step 18. Connect LED strips by wiring in serial.

NOTE: Alternating steps 17 and 18 help make sure that you orient the LED strip (12V top or 12V bottom) correctly. Exactly how to connect the wires depends if you have quick connects or solder. This example uses both.
NOTE: If soldering, make sure to tin (put solder) on the LED strip pads and the wire before soldering together. This makes it much, much easier and is to lessen the time you apply heat to the LED strips.
NOTE: If using quick connects, I noticed a fraction were shorted or made bad connections. You can pop them apart and try to fix them. A small flat head screw driver was my friend.
NOTE: Test the lights and the color channels as you go, this makes it easier to find and correct problems,

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This shows the different LED RGB connectors. One with quick connects on both sides, and one with a quick connector on only one side. After doing one backbox with each, I like the one with only one quick connect. Of course, this depends on how much you want to practice your soldering skills versus playing the game of "finding the short circuit".

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Step 19. Pull wires through slits
Step 20. Tape wires to back of poster board

Note: I just used scotch tape and have no idea how it will hold up.

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Time to test!

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Step 21. Glue flange washers to rod holes on poster board front and back (protects the holes)
Step 22. Connect to power, mount, enjoy!

Note: I've also found that the flange washers also help with the mounting of the board in the machine.

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That is pretty much it. If you have the RGB remote control, you'll need to pay attention to the antenna on it. Make sure it isn't tucked away where it can't receive a signal. Also, I have found that you need to know where it is so you can put the remote very near it.

Here are some final picts. This is lame of me, but I forgot to get before picts (I'm including one from when I unboxed IM and first turned it on. However, it is during the day so isn't a great comparison). Hopefully the comparison of IM next to a fully LEDed TOM will emphasize how bright this can be.

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Next time, how to wire up the backbox for flashers! Of course, posting this took about the same amount of time as making a backbox LED kit, so it may be a little while.

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