Again, from the recycle pile, I found something very nifty. It was a broken Amazon Kindle 2 with 3G cell modem. The screen was very messed up. I attempted to charge it, which seemed to work. I was able to connect it to my computer, and see the files on it, so I knew it was somewhat working. A quick search on ebay showed a used, working eInk screen was $20. I asked around on a few Kindle boards online about repairs, or getting Amazon to repair it, and the basic overall response was "just buy a new one". That wasn't the point.
I eventually decided to drop the $20, order the screen, and take my chances that the main unit works and has decent battery life. A few days later, I received what you see above. I love how eInk displays hold their last image. It's a pretty good sign that this one has a standard Kindle startup image showing on it.
Lots of screws holding this thing together. After assembling and reassembling it a few times I got pretty fast at doing the whole procedure. I wouldn't have been able to do it without resources like iFixit who provided teardown and disassembly procedures.
The battery removed from the left. You can see, left to right, Battery bay, 3G sim card slot, cellular modem. The orange bit at the top is the display screen ribbon connection.
The inside of the upper case, showing the orange flex cables for the side buttons and such.
Just for good measure, here's the entire board, removed from the casing.
That explains the bad screen display.
All in all, it took about an hour. I had to disassemble and reassemble it a few times to get the display flex cable seated properly, but once it was, it all just worked. Battery life is still excellent on it, the 3G service works great, and I've loaded it up with a bunch of books to read.
I hacked it a little to change the sleep display images but other than that, it's pretty stock. Not bad for $20 and some manual labor!
I should note that about a week after I performed this operation, it suddenly decided that it would constantly press the "4" key for me. Very nice of it, but not very convenient. I disassembled it all again. The keypad buttons all looked okay to me. I even removed the '4' key from the main board to examine it, but it looked fine. Something about that process, however, seemed to have fixed the problem. It is currently working perfectly, and other than the battery dying on me, after 4 months of use, it has performed excellently. :D
I got this knockoff JAMMA Ms Pac-Man arcade board many years back. It's got two ROMs instead of the authentic board's 6 (9 for Ms Pac), and is substantially smaller than the "real thing". The only issue is that the audio is poor... REALLY poor. It makes sounds but they're... wrong and noisy.
I took over some desk space at Interlock and got to work. (I should note that the beverages you can see here are other people's, not mine. ;)
I traced the audio circuit on a real Pac-Man schematic (seen on my laptop's monitor), and buzzed it out on the Yenox board to try to corrolate the two.
I had to trace four similar paths from a quad flip-flop, through a quad bidirecional switch, to the audio output. It got really confusing at times, and took me probably a bit longer than it should have. For the most part, they were pin-for-pin correct as far as how they were wired. These chips have the same device (eg, a flip flop, or a logic gate) repeated 4 or 6 times. In some cases here, the Yenox board had a different one of these devices hooked up, which added to the confusion.
This portion of the circuit uses 8 resistors to make a digital-to-analog converter. These generally work by having different resistance levels, usually something like multiples of eachother, eg, 10k ohm, 22k ohm, 47k ohm then 100kohm. I traced out all of the lines on the Yenox board and I found out that not only were the resistors in the wrong order on the board, but they were also wildly wrong (47 ohm instead of 4.7k ohm), which you can see in this table I made:
You can see these resistors here on the Yenox board, right next to the JAMMA connector. They start from the left with R1 (my notation.) The printing on the board completely matched the resistance values that sat on them, so it's obvious that the engineer who made this board seriously screwed it up in the design stage.
I replaced resistors R3 - R7. I put them in with the gold band closer to the JAMMA connector, rather than the other way around.
And now it sounds near-perfect. There's a little bit of popping left, but I was getting tired and decided to head home for the night. I'll hook it up to an oscilloscope at some point and see if i can figure out which line is causing problems.
For what it's worth, I also did the same as this on the video path DAC, seen in the above picture as the next three groups of resistors. In the above, the group of four and then the group of five are for audio, then the next group of three is for the "red", next three for "green", next two for "blue", and the remaining two are for the sync. Again, there were some 47 ohm resistors mixed in, and notice two of the three in the "green" section are identical (red-red-brown)... which is surely wrong. Color is now perfect on the board too!
I won't lie to you. Having an arcade machine is a lot of fun. I used to have about 6 of them, but I'm down to two, due to space restrictions and general sanity. The two that I still have are a TRON Mini/Cabaret, and a generic full-size cabinet into which I can put one of a few game motherboards that I have. (Dig Dug, Mortal Kombat, Klax, Rampart, and a few others.) But one of the less glamorous sides of collecting machines is troubleshooting and repairing these 30 year old beasts.
I bought the Tron Mini in the late 90s as an empty cabinet. I was having a difficult time back then finding an affordable Tron board/control set to install, so I instead put Satan's Hollow into it.
Tron Cabaret cabinet with Satan's Hollow - Note the red joystick and white "shield" button instead of the standard blue stick and spinner from Tron.
Over time, I found all of the parts needed including a few tricks to restore this. When I put the Satan's Hollow boardset in, I rewired/hacked/brutalized the wiring in the cabinet to accommodate SH. Although SH used the same boardset, the controls were wired differently. Once I got the Tron board, and realized how rare this machine really is, I re-wired it using a wire harness from a junked Tron machine. I also found the correct power supply to install, repaired by a fellow collector. The controls were also out of another junked machine. Over time, I got the machine as restored as I could get it.
Tron uses a boardset, three boards connected together, from Bally/Midway called "MCR-2". It consists of a CPU/Program board, a Video/Graphics board, and a Sound/IO board. Midway used this boardset for a few games, including Tron, Satan's Hollow, Two Tigers, and a couple other ones. If you have a ROM programmer (which I do), you can buy one of the cheaper boardsets to use as a replacement for one of the more desirable machines. Tron boardsets, when I was last looking, sold for about $75-$150. Two Tigers sold for about $40. The boardset I have Tron running on right now is a Two Tigers boardset.
When restoring a game, there's a line to walk with respect to what parts to put into it. This machine has some vinyl veneer on the sides, which are somewhat damaged. It also has a fair bit of wear on the front edge of the control panel. I could have tracked down a replacement/reproduction for these parts, but I'd rather keep it factory original. It's not like the damage is too severe for either issue. I'm actually very happy with the overall condition.... except for the monitor.
The cabaret/mini cabinet uses a 13" monitor, compared with the full-size's 19" monitor. The monitor on this one showed a wavy haze, distorting the image a little, and mucking with the brightness across the screen, which you can kinda see here:
I was given a solution about 11 years ago, involving modifying one of the boards in the monitor (the "neck board", which connects directly to the back of the picture tube) but never did it, and lost the parts a few years ago. I instead bought a "cap kit" from Amusements Plus around 3 years ago, and decided to install it. The last time I did one of these was in 2001, so it's been some time.
Love that desoldering iron! The pump just clears out all of the solder super fast!
All of the caps in the cap kit have been replaced. Shiny new caps on the board. Old, dusty, puffy caps in the plastic bag. I'm not entirely sure why I kept them...
Thanks to the awesome desoldering tool at Interlock, I was able to do this in about 45 minutes, rather than the 3 hours it took me years ago.
The board is mounted into the monitor framework, and reconnected to the picture tube.
Just about all of these knobs needed to be tweaked to get the picture looking its best!
After some calibration of adjusting all of the controls (focus and drive on the flyback transformer, and R/G/B Drive and Cutoffs on the neck board), the picture looked better than it has ever looked before! Which you can't really tell from these pictures, but trust me, the picture is sharp, colors bright, and the imagery is stable. It's like it's a new monitor!
The boardset I had in it at first was the Satan's Hollow with my ROM hack so that it will work as a drop-in for TRON arcade cabinets with no rewiring at all.
Yeah, a horrible high score, but just let me practice and remember my old strategies!
The above pictures were taken before I realized how much dust had accumulated on the picture tube and shroud. I've since removed the artwork glass as well as the tinted plexi below that, and cleaned off those items as well as the picture tube itself. That eliminated all of the haze, and improved the picture as well!
Hopefully, I'll get 30 more years of life out of if!
Soon, I need to mount a bunch of UV LEDs in the cabinet to illuminate all of the art work. That's one of the features of the full-size cabinet that I really miss.
Some nights when I head to Interlock, rather than having one single project, or a part of a larger project to work on, I have a bunch of little things I want to get done. They have the tools and materials I often need to do this. This past Tuesday was one such night. I had four things I wanted to work on, and I got all four done!
1: I like to put handles on things. My favorite handles are from Lowes or Home Depot, and are called "wire drawer pulls" as seen in the image above. They're relatively inexpensive at about $2, and are simple to install. Generally they would be put on drawers in a modern kitchen or a clinical-type setting, but I like to put them on everything. If something is portable, it should have a handle. I just drilled two small holes in the plastic parts bin seen above, shoved the screws in from behind with some washers, and done! I've used these handles for portable drive carriers, and other now-more-portable things.
2: Jasper sometimes breaks his toys. I usually am the one who fixes them. Above are two wood bolts from his workbench. The threaded screws came out of the bolt heads. I just scraped out the glue from the holes, and cleaned up both sides with a rasp and some other things that probably weren't designed for such things. I added some wood glue, threw them in these clamps, and returned the screws to Jasper in the morning.
3: I had tried to fix my DLP projector a few weeks back. There was something in the light path making half of the image dim such that if you shook the projector, it would clear up a little. I tore it down, and right between the spinny color wheel and the mirrors in front of the DLP chip is this little mirror tube collimator. The glue holding the four front-surface mirrors to the rectangular metal box had failed, and the mirrors became loose. A couple weeks back, I had tried gluing it back together with epoxy, and it seemed to work, but a new, harsher shadow was in the projected image. I needed to get some dental tools, mainly the little mirror tool, to see what was going on. Sure enough, this little guy was aligned incorrectly. A bunch of futzing with it later, and it is now fully functional!
4: I have been building little breakout boards for my stepper motor controller-turned-arduino boards. I decided that for the animatronic bird project, I wanted to have a way to input joystick data. I made a small adapter to go from PC Gameport Joystick to the widget. I followed this project here for the correct circuit -- basically just some pullups on the digital button inputs, and some pulldowns for the analog axis inputs. I only wired up the first X/Y pair as the widgets only have two analog inputs available. It was relatively simple to build. I had built the main breakout board the night before at home, and i made the orange-wire to Gameport connector cable at Interlock. With help from Nick, providing the old joystick, before I left i had written an auto-scaling display of the current joystick state. More about this to come in future posts.
All in all, it was a densely packed evening, with four mini-projects completed. Huzzah!
I like to collect old pocket computers and gadgets. One of the things I encounter often is exploded batteries. I recently rescued a Canon Powershot A520, and it seemed to be completely dead, probably due to poor battery contact due to the previous batteries exploding.
I've read stories of other people using watered down vinegar to remove the alkaline, but I instead use just vinegar. I dip a paper towel in it, and saturate the affected areas. If you listen closely, you can hear it fizzing. Ssszszszsszszszs!
After a few saturations and wipes with paper toweling, I had removed most of the alkaline gunk. From here you can clean it with a baking soda paste, but for this, I just decided to scrape the contacts a bit.
Once it was cleaned up, I put in some old AA batteries and it powered right up! I dropped in my old 2 gig EyeFi Geo card ($20 from Woot many moons ago), and it worked! I recharged some high capacity AAs overnight and dropped them in. Then things started going badly...
It would power on, then immediately turn off. I tried my second set of rechargables, and the same thing happened. I re-cleaned the contacts, but that didn't seem to help. It was at this point that I thought I knew why it had been dropped in the recycle pile.
Then I realized that my AA rechargables put out 1.2v each, rather than the 1.5v of alkalines. The camera has a requirement printed on it of 3.15 volts. 1.2 plus 1.2 does not equal 3.15.... I found a fresh pair of alkalines and dropped them in, and sure enough, it works perfectly!
As a sidenote, I also set up my computer at home to host the EyeFi software, and it drops the downloaded pictures into a Dropbox directory. Now, all of the pictures taken with the camera are instantly shared when I'm home. I have no reason to manually sync the card physically now. Yay!
Our kitchen timer has been acting up recently, and with Thanksgiving quickly approaching, I needed to do something about it. The push button for the start/stop function has been getting harder and harder to use. In the past, I've cracked it open and cleaned out the pad underneath the rubberized button membrane, but this time, doing this didn't work. I also wanted a more permanent fix.
I decided to replace the membrane switch for that function with one of these tactile buttons. I just had to make sure that the solder pads would line up. I worked out an orientation in which the solder pads would match the pushbutton pads, as you can see in the next image.
The only issue is that rather than the rubber membrane sitting flush with the board, it now had to accomodate the shape and size of the switch along with the button which extended out quite far. I used a pair of diagonal cutters to nip away at the rubber from behind to recess the switch into the button itself, Ben Heck style.
You can see this in the top right of the gray membrane. The two contact pads have been removed, and instead there is the hole, into which the switch recesses. The hole was made fairly crudely, but it works!
It's been accidentally abused over the years, and as a result, the screws on the bottom no longer hold it together as the plastic has broken enough. The strip of electrical tape around the base does well to hold it together while still looking super stylish! NOTE: It's not actually very stylish, but rather, functional and should last for many years more to come. No reason to throw it out, when an hour or so of work will get it fully functional again!
Amiga 1000 computer (1985) with an Amiga 3000 "pregnant" mouse.
One of the fun things about owning retro computers is that you get to repair them yourself. (Perhaps this isn't a fun thing for some of you, but I really enjoy it.)
About 6 years ago, my Amiga 1000 started showing some strange behaviors but only in the green levels of the video. If you dragged the green slider, instead of it stepping up gradually from dark to bright, it would get brighter, darker, brighter, darker, much brighter, a little darker than that, and so on. The following video shows this...
About 5 years ago, I had opened it up and replaced two '244 latches in the video output section. I kinda did this blindly by looking at the schematic...
Video output circuit on the A1000
Left to right: Denise coprocessor, '244 latches, resistor ladders, and output transistors.
...and replacing the two latches, assuming that one of them had gone bad. After doing the repair, the problem persisted and I just gave up on it for a while.
Green section is at the top. The two '244 latches are now socketed and replaced.
A few days ago, a comment on the above video re-sparked interest in this project and I decided to bring the Amiga over to Interlock and really get to the bottom of the problem. I hooked it up to a scope and followed the paths according to the schematics.
Amiga 1000 apart, hooked up to a scope and a LCD monitor.
The video circuit is on the left edge of the board, just under the power cable.
I traced the lines from input on Q2 (where all of the four resistors in the D-to-A resistor ladder are joined, and back through to the latch, and then continuing back to the Denise video generation coprocessor.
I tried jumpering across various portions of the resistor ladder to try to track down exactly where the issue was. It gave some pretty interesting results, but really only helped me track down where the issue is. I eventually came to the realization that something on the R55 data path was drawing it down to ground, or at least close to ground. (Where the left alligator clip is attached in the above picture.)
The "Green" section of the video generation circuit in
the Amiga 1000 with notes
I tried pulling out the pins on the Denise's G1 output (pin 29) and soldering it directly to pin 15 of U6A, and it didn't change anything. I then pretty much realized that the issue was on the other side of U6A -- the connection between pin 5 of U6A and the left side of R55 (4k resistor). I decided to leave the above wire "flying" and pulled the resistor leg, soldering it directly to pin 5 of U6A.
This did the trick! It worked. I probably could have restored the flying wire back to the original traces on the board, desoldering the wire, re-seating the chips, but I had flexed those pins in and out a lot, and decided to not stress out the pins anymore, and just leave it. -- "It works... don't touch it!"
After 5 years of it sitting on a shelf, my trusty 'ol Amiga, my favorite computer, is finally is working again!
