Armorers usually have their own particular specialty. My specialty is electronic scoring machines. Here's some information on a couple of the boxes I've examined.
Technical Details
Taking apart the box is fairly straightforward and is accomplished by removing four screws, two on each side of the box. After lifting off the cover, you will see the main circuit board with 9 IC chips on it, along with gobs and gobs of discrete resistors and capacitors. The manufacturing is terrible--the circuit board has no solder mask which makes the board susceptible to oxidation. Assembly was done by hand, as evidenced by the horrible solder job. I wonder how many machines fail the QA tests.
The machine is based on TTL logic chips, which means the machine cannot be upgraded to support new rules. These machines do not follow the reversed scoring lights rule that recently was instituted.
The nonstandard 7-volt light bulbs cannot be found in the Radio Shack catalog, and they must be ordered from American Fencers Supply. The machine could be modified to use 6-volt bulbs by replacing the 7808 8-volt regulator chip with a 7806 6-volt regulator chip. If the voltage is not enought, a diode or two inserted between the middle lead of the regulator chip and the circuit board would jack up the voltage slightly.
Comments
Note that the transformer that comes with the machine does not last very long. Symptoms of transformer failure include dim scoring lights and erratic operation. When you buy a replacement transformer, make sure it can source at least 1 Ampere.
Schematic
If you have have the resources to repair the machine, contact me and I can send you the schematic.
Technical Details
You have to take apart the box in order to change the light bulbs, unfortunately. Remove the screws from around the perimeter of the front of the case, and the top half of the box comes off. You need to
remove the volume
control before the case will come off, on some models. Gently pry off the yellow cap off the knob, unscrew the hex nut, and pull the knob off.
It seems that the high price may be caused, in part, by the expensive surface-mount manufacturing, which is quite high-quality. The SG-12 is a fairly complex machine with lots of surface mount chips and components. The folks at Fencing Technologies have removed the part numbers on all the chips to prevent others from stealing their design. The machine contains a Phillips 8085 clone microprocessor running at 12MHz.
Comments
The machine is upgradeable--for about $50, an upgrade chip is available to update the foil timings.
Technical Details
To take apart the box, remove all the screws on the perimeter of the faceplate, but don't do this unless you really have to because the machine is hard to reassemble. After removing the screws, lift the machine out of the clamshell case and turn it over. Remove the four screws on the metal EMF shell and lift it off. You will then be presented with a crammed circuit board which is the guts of the Triplette box. The machine uses an Intel 8085 clone microprocessor, and has several support chips and a lot of small resistors and capacitors. The firmware is upgradeable to the latest rules.
Comments
I have two gripes about this machine. Fencers are often confused with the single button that is used to reset the machine, change weapons, change manual/automatic reset modes, and select alternate saber
programs. The indicator lights for each weapon light red to indicate manual reset mode, and green to indicate automatic reset mode. Or is it the other way around? Some machines have it one way, others have
it the other way. The other problem is with the transformer. If you plug the transformer into the wall, and then plug it into the scoring machine, it's possible to accidently touch the plug to one of the
two mounting
screws for the power jack. When this happens, the power plug shorts and blows the fuse in the transformer, leaving you with a useless scoring machine. Triplette tells you to plug the transformer into the machine before plugging it into the wall, but I would coat the screws with nail polish.
Technical Details
To take apart the box, remove the screws from the bottom of the box, then pry the two halves of the case apart; be careful because the machine can be hard to put back together again. The first thing I noticed is that the memory chip containing the scoring machine program is soldered onto the circuit board, which means the machine cannot easily be upgraded. I also noticed that although many of the chips are surface mount, there are no registration marks on the board which means that the machine is completely hand-assembled. The circuit board itself is poorly manufactured, and the solder job isn't exactly great either. The board also has several Russian chips on it, which are impossible to obtain in the United States. This means that if your machine gets broken, you'll have to ship it back to Russia to get it repaired.
Comments
The machine does not follow all of the rules. The off-target lights are yellow, which contradicts the rules which specify white off-target lights. When I was testing the machine, I noticed a "hole" in part of the logic involving the foil anti-fraud circuit. When a fencer grounds his weapon against his lamé and his opponent hits the lamé, several things can happen depending on the resistance between the foil and the lamé: For high resistances, you get an off-target signal, and for low resistances, you get an on-target signal. With the Amico box, there was a small range of resistance which did not set off the scoring machine at all. This is forbidden by the rules and the scoring machine test sheet. This machine does not have yellow grounding lights, which is unusual for a 3-weapon machine.
Technical Details
Remove all the little screws on the back of the case and pop out the back panel (You need to do this anyway to mount the wall mount version). You will get to see the inside of the machine with several circuit boards. The manufacturing quality is about average, but it has a "cheap consumer electronics" feel to it. The firmware is indeed upgradeable, which is good. Take a look at the buzzer, which is glued to the case next to the main circuit board. It's actually meant for smoke detectors, which explains the sheer volume of sound produced by it.
Comments
The size of the lights is a plus. Unfortunately, because the LED lights are not well diffused, side visibility is impossible. Get the extension lights. Also note that the off-target lights are yellow, which is against the rules. I don't like the case. It's made of cheap polystyrene, commonly known as "toy plastic" because it's used in the cheap toys you get at burger joints. It's probably okay if you mount it on a wall, but it can get beat up if you are taking it to tournaments. The front panel is complicated, and many fencers and referees get confused by the buttons and lights. With this kind of machine, you need to read the manual before using it.