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

Saturday, January 18, 2014

Astro Invaders Arcade Restoration - Power Supply Rebuild

Part I - Intro
Part II - Lights & Locks
Part III - Marquee Paint

Time to rebuild the power supply. Every time I think I have the game working, it proves me wrong. The game will work for extended periods and then the screen will go red & black. And now it loses the sound as well when it does it. Best I can tell, all of the problems stem from the power supply.

power supply

I know there is a bad connector, some questionable wiring, one resistor is burned out, the diodes look like they got hot, and the filter capacitors are probably bad. I could replace just the bad parts and hope for the best.  However, the rest of the parts are so cheap, it makes sense just to replace everything.

power supply schematic

Luckily the machine came with a complete set of paperwork, including schematics for every board. The service manual is available online, but I have never seen any of the schematics. I looked over the schematics and the board and made a list of parts. Good thing I did because for some reason, capacitor #3 (5V filter capacitor) is not listed on the schematic. I have since updated the schematic and added C3. Sourcing all of the parts was a pain, especially the 6800 µF and 15000 µF capacitors. I ended up ordering half of the parts from Newark Electronics and the other half from Great Plains Electronics. I probably could have ordered everything from Newark, but it is much easier to find things on the GP website and they had better prices on a few things.

the naked pcb and pile of old parts

With the parts ordered, I began stripping the power supply. I removed everything except the potentiometer, fuse mounts, test points and output header pins. I used a solder sucker to remove the solder from the components. Then I just pushed the leads through with a hot soldering iron. With the board bare, I cleaned it with some circuit cleaner. I finished the prep by re-drilling all of the holes by hand to make sure the leads inserted with no problem.

burned circuit trace

One of the header pins was badly burned; to the point that some of the copper traces were damaged. I scraped away as much of the burn as practical and soldered in a piece of solid wire to replace the damaged trace.

As I was removing the parts, I noticed that R5 was a 13Ω, 5W resistor. On the schematics it is listed as a 25Ω, 5W. This resistor goes to the input of the 7905 -5V regulator. So which part is correct? I asked for some advice on the All About Circuits forum. It looks like that resistor limits the amount of current that can flow through the 7905. The 25Ω resistor only lets about 0.5 amps through. Perhaps that was not enough current for the CPU board and someone swapped it out. I had already ordered the 25Ω resistor and didn't feel like paying the shipping just for one resistor. So I went to a local electronics supply shop and found a 15Ω resistor. That's close enough and should provide plenty of power to the CPU.



The parts arrived in a few days. Installing the new parts didn't take long. I mounted the resistors and diodes well above the surface of the board to hopefully help dissipate any heat. I increased the one burned out resistor from 1/4 W to 1/2 W. I finished by spraying some contact cleaner in the potentiometer and working it back and forth a few times.

With the board rebuilt, all that was left was to replace the contacts. The four and six pin plugs were so loose that touching them would make the screen go haywire. I decided to replace the standard contacts with Trifurcon contacts. They grip the pins on three sides instead of one and provide a much more secure connection. I replaced the contacts for all of the plugs on the power supply board. Even with the Trifurcon contacts, the four pin connector is still touchy. I will need to replace the plug and pins as well.

Time to re-install the board. I screwed the board down and attached the connectors. I powered up the power supply without plugging in the output connectors and adjusted the voltage to spec. Then I plugged in the output connectors and nervously hit the power switch. I watched for the magic blue smoke but all was calm. No smoke, but no game either. I checked the test points and all of the voltages were OK. I unplugged the CPU boards and quickly cleaned the contacts. I also found two resistors on the board that had their leads touching and may have been shorting out. I separated those, put the boards back in, powered up and voila! The game works.

Next I'll pull out the CPU boards and give those a good cleaning. A few decades of dust and corrosion can't be good for the game. Check back soon.

Parts List

22 µF, 35V x 4       $1.22
15000 µF, 16V       $5.91
1000 µF, 35V         $1.03
0.1 µF, 50V x 10    $0.32 (only 1 needed)
0.01 µF, 50V x 10  $0.27 (only 1 needed)
6800 µF, 35V         $6.32

1N4004G x 4     $0.76
6A4 x 4              $1.40

12Ω, 500 mW x 10    $0.27 (only 1 needed)
5.6Ω, 5 W                  $0.35
25Ω, 5 W                   $0.35

0.156" Header, 24 Pin x 4                                            $5.40 (only 1 needed)
Crimp Contact, 0.156", Trifurcon, 22-26AWG x 100   $8.00 (only xx needed)
Crimp Contact, 0.156", Trifurcon, 18-20AWG x 50     $4.00 (only xx needed)

Voltage Regulators
7905T    $0.45
7815T    $0.45
7812T    $0.35

S&H + tax  $10.99
Total  $46.64 (price is actually higher than needed because I ordered extra of some parts)

Astro Invaders Arcade Restoration - Marquee Touch-Up

Part I - Intro
Part II - Lights & Locks

In a previous post I repaired my marquee light. With the light shining through, the missing paint was now much more noticeable. Actually, it's not paint. I believe it was screen printed. Over the years the ink had dried out and was starting to crack. In some of the worst spots, it was flaking off. So I decided at the very least, I should preserve the sign in its current condition. With any luck, I might even be able to make it look a little better.

flaking ink

I started by cleaning the back of the marquee. Years of dust had accumulated over the ink and was probably muddying some of the colors. Because of the compromised condition of the ink, I couldn't simply scrub the sign clean. So I sprayed the marquee with Fantastik and let it soak for a minute. Then I rinsed it under a very light stream of water. That removed much of the grime. I followed by very lightly wiping the ink with a damp paper towel. That did pull off a few flakes of ink from the worst area but it got the rest of the marquee much cleaner.

Before (top) & After (bottom)

With the sign sufficiently clean I needed to protect the ink so that it wouldn't crack or flake anymore. I read on a forum that Krylon Triple-Thick Crystal Clear Glaze is the best option for preserving old pinball marquees and backglass. I found a can at Michaels and applied it per label directions over the ink; two heavy coats. The glaze dried clear and left a nice thick protective coating. Now I don't have to worry about the marquee getting any worse. More importantly, I could try and repair the missing ink on the sign without fear of ruining the sign. Any mistakes could be wiped away.

If you read the arcade/pinball forums, you will find most people advise against repainting translucent marquees.  Even if you match the colors perfectly, the translucency will likely differ and your repair might actually be more obvious than the damage was. While trying to decide what to do, I came across a 24 pack of Sharpie markers at home. For some reason I thought they might be suitable for repairing the marquee art. I tried them along the edges of the marquee, hidden by the brackets. The colors ended up being too transparent; even with multiple coats.

So next I decided to try fine point Sharpie oil-based paint pens. I picked up a few colors that were close to the marquee colors and tried them out along the hidden edges of the sign. I tried two colors to touch up the purple area of the marquee. The colors weren't an exact match but the repair looked OK...until I put it up to the light.

repair lighted from the front

same repair lighted from behind

With the light shining through the marquee, any spot of paint that was over the original ink made the area more opaque and painfully obvious. IF I could get paint that was a closer match, and IF I could get the paint ONLY on the clear areas without getting ANY paint on the ink, the repairs might be OK. But those are a lot of ifs.

Luckily, the black paint is completely opaque. Repairs made with the black paint pen were completely invisible. The area of the marquee with the worst flaking is actually black and light blue. If I can at least touch up the black, the missing light blue might not be that noticeable. So I carefully went to work with with a black extra-fine point Sharpie paint pen.

before (top) & after (bottom)

The resulting repair isn't perfect, but it looks pretty good. I've got two things going for me. Most of the flaking paint is light blue which blends well with the clear areas. And the worst part is in the area of an explosion. So the bits of flaked and missing paint almost look intentional. This will do for now. Maybe in the future I will play with those light blue areas again. The final step in the touch-up will be polishing the front of the marquee with some Novus plastic polish. But that will wait until the rest of the cabinet is finished.

back on the arcade

The difference is subtle. From 5 feet away, nobody would probably notice the difference. But it is certainly better than it was. And most importantly, the marquee will be protected for the next three decades. Next up, I'll rebuild the power supply.

Krylon glaze      4.49
Paint pen           2.50
Total              $6.99