ADD MODULAR TELEPHONE JACKS TO YOUR TANDY 200 v. 1.9 TELJAX.200 Copyright 1989 by Jeremy Nichols (73527,2164) All Rights Reserved GRAPHICS Download JAXPIX.200, a text file containing a BASIC program. It will draw a diagram of the installation process on the Tandy 200's hi-res screen. INTRODUCTION It took me only a short time to get tired of Tandy's modem adapter cable and wish for built-in modular jacks. I first considered removing one of the connectors I don't use and putting the phone jacks in its place but was concerned about such an obvious violation of Murphy's Law (removing an "unused" connector causes a need for it). Eventually, I discovered that the portion of the case above the various connectors was mostly empty space. After poking and prying and thinking it over, I decided to put the jacks in the case just above the printer connection. This is how I did it and how you can, too. WARNING This project involves cutting holes in your T200. You may not want to do anything so permanent. The rigidity of the case is not compromised, though, and no other functions are affected in any way. Soldering is also required but it's relatively easy to get at the locations to be soldered and most people with a little experience should have no trouble. If you have no experience soldering, get a friend to help. PREPARATION This is the most important part of the project. If you know what you're going to do in advance, it'll go smoothly and you'll like the results. The only tools needed are simple ones most people are likely to have - screwdrivers and pliers, a hacksaw, a sharp hobby knife, and maybe a file. You'll also need a soldering iron with a small tip and some rosin-core solder. Don't use acid-core solder - it can ruin electronics. The object is to cut a pair of holes, or perhaps they could be called notches, in the back case, and install in each notch a modular telephone jack. A total of three wires from the two jacks will be soldered to the 8-pin DIN jack labeled PHONE. That's all. You'll be turning off all power to the computer before beginning the project. Remember to save every file you want to keep. PARTS The modular jack you will be installing is a standard RJ-11 line cord jack, part number 623P. The jack has grooves on the sides which will hold the edges of the slot you're going to make in your Tandy 200. It would be wise to have the jacks in hand before beginning to cut your case. The jacks should be available from most telephone equipment manufacturers. You may have to search a bit to find a retail outlet, though. Graybar Electric is a good source for telephone parts, although they usually are wholesalers only. You may be able to sweet-talk them into selling you two jacks. Gary at the San Jose store was very helpful to me and turned out to be an M100 owner to boot! AMP, Inc., on the other hand, wasn't at all nice; I'd recommend avoiding them. Another option is to buy the jacks from the same place I did: Halted Specialties, 3500 Ryder St., Santa Clara, CA 95051. The 632P jack is Halted part number 9436. Like most surplus items, the supply is limited. Halted has a $10.00 minimum mail order so you'll have to buy something else to make up the balance of the order. They'll send you a catalog for a dollar; mostly surplus new and used electronic components, PC-XT clone kits, etc. TAKING APART THE TANDY 200 1. Turn off the power switch. 2. Turn off the Memory Power switch on the bottom of the computer. 3. Remove the AA batteries. 4. Remove the cover over the LCD screen's cable and hinges. Push in at top center and slide it down (not as easy as it should be, unfortunately). 5. Remove the ribbon cable from its socket on the display's green PC board. WARNING: The black thing on the green board is NOT a plug; it's a socket! The ribbon cable has no real plug, the bare end just slides into the black receptacle. Grip the cable carefully with a thumb and finger on each side and pull it down and out of the socket. 6. Remove the four phillips-head screws from the hinge assembly. Note that two of the screws are longer - remember which go where! 7. Carefully lift up the LCD screen and pull it off of the hinges. Put the screen away in a safe place. The metal tabs stay on the main case. Bend the tabs down in the "closed" position so they'll be out of the way 8. Turn the computer upside down on something soft and remove the phillips screws in the four corners which secure the top and bottom halves of the case. Don't worry about the cases falling apart; they're also held together by tabs in the plastic. 9. Turn the Tandy 200 right-side up. Carefully pry the upper half of the case up and out from the lower half with a thin screwdriver or knife blade. The tabs are in the middle; there's one on each side. 10. When all four tabs have popped, you can carefully lift the top case off of the bottom. WARNING: Don't turn the bottom half of the case over: the keyboard will fall out as it's not held in except by the top case. Now you're ready to operate. Put the bottom half aside and turn the top half upside down on your work surface. CUTTING THE NOTCHES See the diagrams in JAXPIX.200. The Tandy 200's back wall is two layers thick. Conveniently, the inner wall is the exact thickness needed to hold the modular jack. The notches can be almost anywhere in the back wall. Logically, they should be close to the PHONE socket and in between the "ribs" connecting the inner and outer walls. If you put one notch on either side of the word "PRINTER," you'll have plenty of working room without destroying the PRINTER label. Both walls can be cut at the same time. Then the inner notch can be enlarged carefully to provide the correct fit for the jack. The initial cuts should be 0.44 inch wide and 0.75 inch high. The width of the inner notch is more critical because the jack has to slide into it. You can make the vertical cuts with a hacksaw blade held in your hand. It's prudent to make the cuts a bit small and enlarge as necessary. Because the hacksaw won't go around corners, make the cross cut by using a one-sixteenth inch drill to make a series of holes across the bottom of the notches. Use the hobby knife to finish cutting out the notch and smooth the edges with the file or the knife. Now use the hacksaw blade to increase the width of the inner wall's notch at the open end to 0.5 inch wide and 0.4 inch high so it will clear the sides of the jack. Try the jack for fit and trim the notch as necessary so the jack slides in smoothly. If you get the notch too big you can always glue the jack in place. WIRING Each jack has four wires. Only two leads, the red and green ones, are used. They go to the middle two pins or wires of the jack. Cut the other leads off. If your jack uses different colored wires, make sure the ones you choose go to the middle pins of the jack. If the wires have terminals on the ends, cut them off. The wires need to be long enough to reach from the top case to the bottom case. Four inches should be enough. Strip 0.25 inch of insulation from each wire and twist the red wires together as they are "common" to the circuit. Look at the round, 8-pin DIN jack labeled "PHONE" as if it were a clock. The pins to be used are pin 1 at 3:00, pin 3 at 9:00, and pin 7 at 2:00. The pins aren't numbered but the Tandy adapter plug's pins are numbered. You can take the plug apart and see which pins it uses, just to be sure. Examine the inside of the DIN jack until you have figured out where the metal pins go and which ones you want. Use an ohmmeter to help if necessary. Carefully solder the red pair of wires to pin 3 at 9:00 and one green wire to each of the other pins (at 2:00 and 3:00). Solder quickly: the jack is plastic and will soften if the pins are heated for too long. Don't slop solder and cause a short. REASSEMBLY Slide the jacks into their slots. It doesn't matter which jack goes in which slot. The telephone line will plug into the jack that's wired to pin 7 (the 2:00 pin). Your telephone plugs into the other jack. Remember to label the jacks. Now carefully flip the top case over and settle it on the bottom half. Be sure to slide the ribbon cable for the LCD through its slot. There's plenty of room for your new wires but make sure they aren't pinched. As the top goes on check that the keys, especially the function keys, aren't stuck. When everything is clear, snap the halves together. Then reverse the rest of the disassembly instructions. Be careful with the LCD cable and the cable cover so the cable doesn't get bent or pinched. FINISHING TOUCHES After you replace the batteries and make sure it all works, plug a telephone line into the new "Line" jack and try it out. Now put your old adapter in a drawer and enjoy your modification. I carry a six-foot modular cable in my Tandy's case for occasions where I find a telephone jack but no wire. COMMENTS Please email me with your comments, questions, and suggestions.