Sunday, July 20, 2014

LED Conversion of Magnifier Lamp

converted magnifier light

My Luxo magnifier light stopped working recently. It turned out to be a bad ballast. The light is a very expensive unit and has proved invaluable for lighting and magnifying various tasks in my shop. I needed to fix it, but unfortunately I could not find a replacement ballast. So I decided to convert it to LED lights.

the light

removed the bad ballast unit
removed the light housing

LED strip from Radio Shack

removed the protective silicone covering and
used foam tape to mount strip into light housing

had to make cuts to get it to follow the curve

used solid core wire to bridge the gaps

LED strip mounted in housing.  Not shown: soldered LED
wires to existing wires in magnifier.

LED strip requires 12v @ 1.5A.
Found this old Power Wheels battery charger in my pile of junk

spliced power supply into magnifier power cord

It works! Nice and bright.
Original power switch turns it on/off.

view from above

This light is back in action and I can finally see what I am working on again. 30 bucks to save a $400 magnifier, not bad. The light is just as bright as before, maybe brighter. If I decide to add a PWM controller, I can even adjust the brightness. I even have about 18" of the LED strip left over for a future project.

Monday, April 14, 2014

LCD HD Television Repair

working again

My inlaw's Vizio V037L FHDTV10A stopped working. When you turned it on, the picture would come on for a few seconds, then disappear. You could still hear the audio, but there was no video regardless of input. After some online research, it seemed like the backlight inverter board was to blame.

I found a used but guaranteed replacement on ebay for $16.30 with free shipping. For that price, even if I was wrong about the diagnosis, it was worth the risk.

remove the back cover

backlight inverter is in the lower left corner


remove top cover

remove inner cover

replace board and 4 wires

The entire process was very easy; it took less than 15 minutes total.  Note: if you look closely the boards are not the same. There are about three different part numbers that will work.  They are Phillips 6632L-0490A, 6632L-0504A, and 6632L-0506A. Buy whatever is available or cheapest.

Wednesday, March 19, 2014

Astro Invaders Arcade Restoration - Control Panel

Part I - Intro
Part II - Lights & Locks
Part III - Marquee Paint
Part IV - Power Supply Rebuild
Part V - Circuit Board Cleaning

Now it's time to get the control panel in shape. It works perfectly. But the buttons are dirty and scratched, and the paint is scratched in a few spots. Let's clean everything up and protect that cool artwork. The panel was removed easily by unhooking two latches inside the cabinet.

leaf switches

The panel is made up of leaf switches. These are pretty cool, much less noisy than the typical microswitch buttons found in most arcades today. They are durable as well as there isn't much to go wrong with them. The wiring is straightforward. One common ground and a separate wire for each button. All I did below the control panel was straighten one leaf and clean the contacts on the leaf switches with fine emery paper.

buttons removed and disassembled
these things are filthy

While the buttons were working fine, they were a little beat up. I started by disassembling them and cleaning with some Fantastik. That didn't help much. So I put them in my ultrasonic cleaner for two 8 minute cycles with heated simple green. That got them much cleaner, but the plastic was still stained yellow. I tried Goo Gone; no help. I tried a buffing wheel on my Dremel. That just turned the plastic red from the buffing rouge. 320 grit sandpaper worked OK but took forever. The plastic is soft and does not sand well.

new (L) and old (R) buttons

After too much time and several attempts, I gave up on restoring the old buttons. I found replacements for only $2.65 apiece. For under $20.00 delivered I could get new buttons in less time than I spent trying to restore these eye sores. Lesson learned. The new buttons are a slightly different design below but function exactly the same.

The monitor glass is easy to remove once the control panel is removed. So I decided to clean the glass and monitor. With the glass removed I could see the monitor bezel was severely faded. I removed it, cleaned it, and sprayed it with satin black spray paint. The bezel was then stapled back in place. It's a small detail but it makes a difference in the look of the cabinet.

bezel before

bezel after


Next I cleaned up the control panel with some Fantastik. To finish things off, I touched up some of the scratches with a paint marker. Finally, I reinstalled the monitor glass and control panel. Next time I'll work on touching up the cabinet.

back together

Sunday, March 2, 2014

Hexacopter Power Distribution Board

New PDB. It ain't pretty but it should work.

Recently my hexacopter crashed. Luckily I had a GoPro strapped to it and I saw one of the motors stop in flight. You can also hear a"pop" just before the failure.

After the crash I plugged the suspect motor into a good speed controller (ESC) and it worked fine.  So I plugged a good motor into the suspect ESC and it did not spin. Therefore, I concluded that the ESC had failed. I took the ESC apart to see which component failed but I couldn't find anything out of the ordinary.
But when I installed a new ESC, it didn't work either! After a little checking with my multimeter, I discovered that the positive terminal on the power distribution board (PDB) for that ESC was not getting power from the battery. Upon closer inspection, I could see that the circuit traces had burned out. This was a bit surprising considering that the board is rated for 90 amps and my motors should only be pulling around 45 amps max.

Note the 3 burned copper points around the lower right solder pad.

I had a few choices to fix it. Purchase the same thing again, purchase a different one, or make my own. I couldn't put the fate of my several thousand dollar hexacopter in the hands of the same component that failed once already. Other brands were an unknown and probably would not fit as well. I really liked the form factor of the original so I decided to make my own based on that design. I could etch my own PCB but I was concerned that it couldn't handle the power. So I decided to make a new PDB out of a piece of 0.025" copper plate. That's five times thicker than the original copper traces. It should have no problem handling the current.

I choose a piece of 0.093" polycarbonate to insulate the positive and negative sides. I marked and cut the plastic the same size as the original PCB. Then I cut out two pieces of copper plate larger than the plastic.

I glued the copper pieces to the plastic with 5 minute epoxy then trimmed the copper even with the plastic.

Each copper plate is almost as thick as the old PDB!

With that finished I drilled the mounting holes with a 1/8" drill.  I'll use nylon mounting screws to avoid any shorts. I followed by drilling a hole for the negative battery lead. The negative lead was passed through the bottom of the board and soldered to the top. I soldered a set of 3x6 header pins to the negative side of the board for the ESC receiver wires. All of the negative leads are wired together. The positive leads are separate. One positive lead is wired to the power supply wire for the flight control system. And the wiring harness from the old PDB was soldered to the signal wires.

Ready for ESC's
Finally, the six ESC's were soldered to the board. I covered the entire board in several coats of liquid electrical tape. Once it was dry, I screwed the new PDB to the center plate and attached the receiver leads. It fits the hexacopter exactly like the original. It is a little heavier, but this one can handle much more power. Now I just have to slap it back together and get her back in the air.

Ready for reassembly.

Tip: If you've never soldered to copper plate before, you need lots of flux and lots of heat. Coat the area to be soldered with flux. Heat it thoroughly with your soldering iron. Keep touching solder to the area until it melts. When it does, run your soldering iron in circles around the area to tin it with solder. Once you have a small layer of solder on, it will be much easier to solder your leads. Don't try to solder leads directly to bare copper plate.

Sunday, February 16, 2014

Floating Airsoft Targets

A few years ago I received this Floating Target Shooting Gallery as a gift. The concept is pretty cool, shoot the floating balls as they bounce around on a column of air. The problem is, the dart gun is so inaccurate that if you hit the target it is only by pure luck. So I decided to build an upgraded floating target system for use with a more accurate airsoft gun.

floating target toy

Obviously the targets need to be light, so I chose ping pong balls. I also picked up some plastic practice golf balls. They are about the same size but a little heavier. With ping pong ball in hand, I took a trip to the hardware store to select the parts. Check the picture below for the parts. The 1" x 1/2" bushing serves as a cup to hold the balls. The ball valve controls the amount of air flowing through the pipe and thus, the height of the ball. I opted for five targets, but you could make as many as you want so long as you have enough air to supply all of the lines. The vacuum adapter will differ based on your air source.

parts diagram

Eventually I would like to use a built-in air source to make the unit self-contained. But for now, I'm just using the exhaust from my shop vac. I used a narrow adapter that fit into the tee to get the vacuum hose to attach to the manifold. I added some duct tape around the adapter for a snug fit. The unit was glued together with PVC cement and mounted to a board with pipe clips.

completed assembly

With everything together, it was time to test it out. I closed all of the ball valves and fired up the shop vac. Then I opened each ball valve just a little until the ball was floating. I adjusted the valves until each ball was floating stably. With my 6 HP Craftsman shop vac blowing around 170 mph, I was able to get each ball floating comfortably about 4 inches above the cups. You could adjust the valves so each ball is at a slightly different height.

floating targets

Now let's see how it works as a target system. I loaded up my WE Hi-Capa 5.1 R and took aim. With each good shot the balls popped off the air column. The air holds them steady enough that a glancing shot is not enough to knock them off. It takes a good square hit.

cracked and dented balls

The ping pong balls hold up OK to the airsoft shots. Once in a while they crack. I tried the plastic golf balls. They dent but don't crack. The golf balls also seem to be a little more stable. I'll keep searching for a better target that can withstand multiple shots. The air flow is just a little erratic. Sometimes the balls pop off the air column on their own. I'll work on making the air column more stable. But for now, it's ready for some range time!

Monday, January 20, 2014

Astro Invaders Arcade Restoration - Circuit Board Cleaning

Part I - Intro
Part II - Lights & Locks
Part III - Marquee Paint
Part IV - Power Supply Rebuild

circuit boards in "card cage"

Now that the game is working, I want to make sure it is working as well as it possibly can. Decades of dust and corrosion on the circuit boards, pots, and IC pins can lead to sub-optimal performance. I'm not sure if it will help, but it certainly can't hurt to give everything a good cleaning.

(L to R) video, CPU, & sound boards

I started by pulling out the card cage containing all of the circuit boards. I sprayed each with circuit cleaner and scrubbed them with a soft toothbrush.  Any IC's that could be removed were worked back and forth in the sockets to clean the pins. There are 8 exposed potentiometers on the sound board. One is the master volume and then I believe each game sound has it's own volume control. I marked the position of each one with a silver Sharpie before cleaning . Then they were sprayed with contact cleaner/lube and worked back and forth. I found a capacitor and resistor whose leads were touching and perhaps causing problems. I corrected that and checked for the same problem on the rest of the components. I finished up by cleaning the board contacts with 0000 steel wool. As I worked I looked closely for any signs of failing components. Everything looked good. I blew the boards dry with compressed air, cleaned the card cage and put it all back together.

someone didn't want to find an adapter for the ground plug

cracked power cord

While I was at it, I changed the power cord. The ground pin was broken off of the plug and the cord was starting to crack. I was going to pick up some 3 lead cable and make my own power cord. But buying wire by the foot is expensive. So instead I purchased an extension cord. With the plug molded in, the cord looks more professional anyway.

I kept the cord 11 feet long, like the original. I just cut off the female end and wired the cord to the connector with some new female crimp terminals. I kept the original warning card in place and added a zip-tie as a strain relief. The new power cord is much heavier duty than the original. In fact, if I were doing it again, I would probably go with 16 gauge wire. It was hard getting the 14 gauge wire into the connector. But this will stand up to years of hard use.

new cord in place

Luckily the game still works and it seems like the sound is less scratchy than before. The game also used to have a few errant pixels lit up on the screen during game play. That seems to be gone as well. Next up I'll pull out the control panel and restore that.

PS - I didn't even waste the cut portion of the extension cord.

Extension Cord   $15.96