From: tomc@oas.olivetti.com (Tom Carlino) Subject: TECH: A Nintendo Saga: Power Glove Extender Cable Alternative Date: Thu, 28 Jan 93 14:50:50 PST From reading this newsgroup, I gather that this has happened to a number of people before. I found the July 1990 Byte article on the Power Glove interface and connected the glove as directed. Right from the start it worked fine with the Rend386 demos but there were two problems. First, I couldn't find one of those evasive extender cables anywhere so I went ahead and hacked the 7 pin connecter off of the cable from the glove black box to make the connections. The problem is that the box cable is too short so I had to leave the PC in a partially disassembled state with things dangling out everywhere and the black box sitting right in the middle of the PC guts. Another annoying thing which I didn't condsider to be related at the time was that the glove image was very jittery, apparently acquiring a mind of its own somewhere in the process. After getting the run around from Nintendo, Curtis, Pacific Computer, etc. trying to find a Super Extendo cable to match up the 7 pin connector, I decided to take matters into my own hands. Picking up a nearby MIDI cable I counted, let's see, 1 - 2 - 3 - 4, hey, 5 pins! That's just the right number. Not only that, since the MIDI interface was designed to be used with 5 volt logic and cables in excess of 25 feet, the cables are shielded to boot. What a deal. You can get a MIDI cable at just about any music store, and for the economically minded, you can often get a used one for about $3 or $4. So I say, death to the evil 7 pin connector. Hack that bugger off and put a decent God-fearing upright and honest citizen in its place. So I chopped about two feet off the end of one of my MIDI cables and hooked up everything. Not only could I close up the PC and get the black box out of it, now I have an easy connect and disconnect. And as an added surprise, the glove image suddenly turned rock solid. Now it only moves when I do. I haven't analyzed the circuit in detail, but it certainly looks like taking the black box out of the seriously electrically noisy PC chassis environment makes a world of difference. And having a shielded cable inside the chassis is certainly a boost for signal integrity. If you're still with me, this is going to continue on for some time. I've provided the details below and some explanations of why I did the things that I did. First, you need a little bit more that the MIDI cable. MIDI cables have the same male connector on both ends so you need a female end too. You should be able to get one of these at any electronics parts shop. Even Radio Shack sells them and calls them a 5 pin DIN jack. The Radio Shack version is $1.69 but I found one at a local electronics place (Fry's in the SF bay area) for 79 cents. The only problem I found with it is that the contacts seem to be coated with some sort of super solder resistant plating and I had to scrape the hell out of them with an exacto knife before they yielded to reason. The next thing you have to know is that there are several common types of MIDI cables. You have to get one with die-cast metal connectors because they have solder contacts and you can't rework the ones with molded ends. Then there are two varieties of the die-cast connector types. One type has only three pins wired and the other has all five pins wired. You need one of the five wire varieties. How can you tell from looking? You can't. Either bring an ohmmeter with you when you buy one and check for continuity on all five pins, or bring a small flat blade screw driver. With the screwdriver, you can remove the small screw that holds the connector together and push the core forward out of the shell to look at the wires. Be careful not to let that screw get away because it will immediately follow one of the fundamental laws of physics and travel at nearly the speed of light in the direction which can carry it the maximum distance away from you in a straight line where there are the least number of objects to impede its progress. Just as an observation, some keyboard extender cables have the same 5 pin DIN connectors but I don't know any more details about them. Now for the wiring. I listed all of the wire colors as I found them on the Power Glove and they agree with the Byte article. The MIDI cable wire colors might be different, so you might have to improvise slightly there. Pick your own colors but make sure that the shield is connected to pin 2. I took the MIDI plug apart and rewired the whole thing. In fact I bought another DIN plug for 69 cents and used that for the glove so that I could salvage my original MIDI cable. Talk about cheap. Note that the MIDI connector pin numbering is funny, the order being 1 - 4 - 2 - 5 - 3. This is shown in the Byte article on page 288 and it's molded into the plastic connectors in raised numbers. You know, that would make a good firing order for a 5 cylinder piston engine. Didn't Volvo make one a few years back? Pardon me, I digress. Glove side: MIDI connector Controller cable (black box) 1 ------------ RED (+5 volts) 2 ------------ BLACK (Ground) 3 ------------ YELLOW (Latch) 4 ------------ GREEN (Data out) 5 ------------ ORANGE (Data clock) --------------------------------------------------- Computer side: Power Supply MIDI connector +5V --------------- 1 (red, +5 volts) Ground --------------- 2 (shield, Ground) Parallel Port MIDI connector 18 --------------- 2 (shield, Ground) 3 --------------- 3 (white, Latch) 13 --------------- 4 (green, Data in) 2 --------------- 5 (black, Data clock) Well, that's it. What? There's that nagging question about +5 volts again. I found that the disk drive power supply was the cleanest nearby source. Also my PC has a spare unused disk power supply connector and I was able to get an extender cable for that and hack it appropriately. I can't help you any further with that except to say that no wire is sacred. If you must, splice into it and exuberantly grab that life giving power which is rightfully yours. Don't cut that black box cable too short. I opened the box up and found that you could rewire directly to the circuit board inside if necessary, but there are a few ugly analog type chunks of metal in there that I shrink back from in sheer terror. I guess that there must be some very strong magic inside because even though I opened it and gave plenty of opportunity for the magic to escape, it still works. Come to think of it, just about that time was when my watch stopped. Maybe that's where the jitters escaped to. While soldering things, keep the male and female DIN connectors plugged together so that as you apply excessive heat and the plastic in the connectors starts to flow freely, the pins stand a better chance of keeping in line so they don't end up like a pile of pick-up sticks frozen in grotesque position for eternity. The shield conductor must be connected to ground to make electrical shielding effective. Pin 2 of the connector is ground to conform to MIDI specifications. Why conform to MIDI specifications? Keep reading. The MIDI interface specifications only designate pins 2, 4 and 5 as connected so that's why many cables only have three wires. Using pin 1 for the 5 volt supply should not cause any conflict with any MIDI instrumentation conforming to the standard MIDI specifications. Beware that some MIDI system designers went ahead and exceeded their authority and used one or both of the unconnected pins for their own devious ends. I can't tell you off hand where you might find such deviants, but be warned that they do exist. Why do I bother bringing this up at all? Because I know that some of you who own MIDI equipment at this moment have an overwhelming burning desire to build this cable and plug in every conceivable combination of devices, in the interest of science, of course. I would tell you to forget about it, but that would only encourage you more. I have tried to make the cable as innocuous as possible, but I'm sure someone will find a way to defeat my efforts and I declare no responsibility for what happens as a result. And don't tell me about it, I don't want to know. Another note, as an added measure of security to prevent you enterprising youngsters with an inquisitive mind from plugging your MIDI equipment into the glove just to see what happens, I suggest putting the male connector at the computer end and the female one at the glove end. I did this, even though I would naturally never try such a stupid thing as plugging in other MIDI equipment myself. I guess this actually prevents mating MIDI equipment with the wrong computer cable more than anything else. In fact, that makes it easier to plug a wandering MIDI cable into the glove. You just can't win. Another danger is that the pins on the male end which are active could short together if you drop metal things into the connector or crush it, which could lead to a distressful situation for your 5 volt power supply. So either be careful or plug in a dummy DIN jack when the glove is not plugged in or ignore this paragraph completely. Did you find this article?... 1. Very useful 2. Somewhat useful 3. Cryptic and irrelevant 4. None of your business 5. Electronic toilet paper Send replies and any other gripes you might have about anything else to: Bill Clinton, The White House, Washington, D.C. USA