NetNews Usenet Archive 1992 #16

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Newsgroups: comp.sys.3b1 Path: sparky!uunet!noc.near.net!wellesley.edu!lhawkins From: lhawkins@olaf.wellesley.edu (Lee Hawkins) Subject: How to upgrade BOTH types of Unix-Pc/3b1 1Mb motherboards to 2Mb. Message-ID: <1992Jul25.205914.27053@olaf.wellesley.edu> Keywords: upgrade 3b1 unix-pc 7300 memory Organization: Wellesley College Date: Sat, 25 Jul 1992 20:59:14 GMT Lines: 558 Below is an article that I have put together with the help of Robert Dalla Costa and Franco Barber on how to upgrade the two different types of Unix-Pc/3b1 1Mb motherboards to 2Mb. It is rather long, as I decided to include not only instructions on the upgrade itself, but also a set of useful references and detailed instructions on getting the motherboard out of and back into the machine. I am also sending a copy of this to Dave, in hopes that he can include it in the RAMupgrade file at the OSU archives. Hopefully, this file will make it a bit easier for those who have 1Mb motherboards to upgrade them. Enjoy! ------CUT HERE--------CUT HERE--------CUT HERE-------CUT HERE--------CUT HERE What follows is a list of the necessary parts and instructions for converting a 1.0Mb. Unix-Pc to a 2.0Mb Unix-Pc. Please note: =*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=* DO THIS AT YOUR OWN RISK. IF YOU HAVE NEVER SOLDERED BEFORE, OR HAVE LIMITED EXPERIENCE, OR NO EXPERIENCE WITH SOLDERING/ DESOLDERING ON IC CIRCUIT BOARDS, STOP _NOW_ AND FIND SOMEONE WHO HAS TO ADVISE YOU! I CANNOT BE HELD RESPONSIBLE IF YOU FOLLOW THESE DIRECTIONS AND STILL DESTROY YOUR MOTHERBOARD. =*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=* Also, please print out a copy of this and read it over twice before trying it. It's bloody hard to read it if the only computer you have is your Unix-Pc, and you've already started wrenching on it! Now, with that said, this is one of the easier Unix-Pc memory upgrades, as you don't have to desolder any chips to do it! You just need to desolder the holes for the extra memory, capacitors, and resistors that are necessary, add the additional components, change a few jumpers, and voila, you have a 2.0Mb Unix-Pc, just like Ma Bell used to make. I have listed several suppliers. I have no connection with them, except as a satisfied customer. Prices are only to give folks a ball-park estimate of what all this will cost. This upgrade should take around 6 hours depending on your experience level. I recommend splitting that into three sessions: 1) Motherboard removal and hole desoldering. 2) Capacitor, resistor pack, and decoder installation. 3) Memory installation, patches, reassembly, and testing. I also recommend that, if you haven't already done so, that you apply the DRUN patch and install a new battery in a battery holder, so that changing batteries later will be easier. Refer to the Unix-Pc/3b1 FAQ on how to do these things. Note that there are two different types of 1Mb motherboards. The only things that are different between the two are the jumpering changes. My gratitude goes to Robert B. Dalla Costa (rbdc@ihlpe.att.com) and Franco Barber (feb@febpc.cmhnet.org). Robert supplied the jumpering changes for the old style 1Mb board, while Franco supplied the jumpering changes for both the old and new style boards. These changes are obscure, and almost impossible to divine from the schematics. If you use these instructions and they are helpful, be sure to send them a note of thanks! Article 2839 of comp.sys.3b1, posted by Nick Miljkovic (nmil@phoenix.princeton.edu), included only the patches for the new style motherboards, but it is unclear who originally wrote the article. In any event, thanks to Nick for posting it! The parts: 1 1.0Mb Unix-Pc motherboard. I assume that you had realized this already, but, well, one never knows.... 36 41256-15 DRAMs. About the cheapest you can find these days, and they can often be had used for as little as $15/meg. Chips faster than 150ns should work fine also, as should 4256's. I suggest you buy used ones off the net or at ham fests. They are much cheaper, and I've bought several megs with no bad chips. Total Price: $15.00 40 Slim-line 16-pin machine-pin sockets. Get good ones, as they are more reliable. They can, however, cost more than used 41256-15 memory chips. Make sure they are narrow enough to fit side by side on the motherboard. Some Augats are too wide. DigiKey part number: ED3316 Total Price: $28.92 4 74F258's Note the F. No substitutions allowed. These are decoders for the second bank of memory that you add. DigiKey part number: 74F258APC Total Price: $3.36 4 33-Ohm resistor packs. You want the type that have four separate, unconnected resistors in one in-line package. The markings on the package of these are misleading. They are usually marked 330, which I assume means 33.0, but to a novice is easily mistaken for 330 ohms. These are used as pull-ups for the 4 74F258's that you add. DigiKey part number: 770-83-R-33 Total Price: $1.28 20 .1uF monolithic capacitors. These are small and are usually marked 104, for 10^4 pico farads. DigiKey part number: P4887 Total Price: $5.24 16 .01uF monolithic capacitors. As above, but marked as, you guessed it, 103, for 10^3 pico farads. DigiKey part number: P4881 Total Price: $2.56 The equipment (required): 1 Weller EC3001 or equivalent soldering station. These cost around $150 and are well worth it. If you absolutely can't afford/get access to one of these, one of the modular soldering irons that Radio Shack sells with the 23 watt heating element and the small tip from the special-order surface-mount tip set will do IF YOU ARE VERY CAREFUL. These irons are apparently made by Ungar, and can be had from other vendors (Techni-Tool, Jensen) with a wider range of tips. If you are really worried about static damage, special order the grounded handle. Radio Shack part numbers: Handle: 64-2080 Grounded handle: 64-2077 23W heating unit: 64-2081 Surface-mount tips: 64-2074 Total Price: $17.47 Total Price: $21.90 (grounded handle) 1 Radio Shack Vacuum Desolder Pump. Cheap, but works about as well as any I've used. Paladin also make a good line of these. Radio Shack part number: 64-2098 Price: $5.99 1 pair small flush-cutting pliers. If you really don't want to pay the price for the Diamond Brand cutters, the Radio Shack Nippy Cutters look like they will work. DigiKey part number: GA54 (Diamond Brand) Price: $22.70 Radio Shack part number: 64-1833 (Nippy Cutters) Price: $3.79 2.5oz. .032 diameter Rosin Core solder. If you need more than 1/2 this, you're using WAY too much solder! Radio Shack part number: 64-005 Price: $3.19 1 Can Radio Shack Solder Flux Remover Spray. Used to get rid of any excess rosin after you solder the new components in. Radio Shack part number: 64-3324 Price: $2.99 1 Oral B #60 or equivalent toothbrush. Used for brushing excess resin off the board. Price: $2.89 1 Large anti-static bag. Used for storing the board when you are not working on it, and giving your work surface an anti-static top. Buy this at a ham fest, shouldn't be over $2.00 1 Firm-but-soft work area. I use a stack of PCWeek's and Open Systems Today's. Price: Free! 4 paper towels. Price: Not enough to mention. 1 5x magnifying lens. The ideal thing is one of those circular fluorescent lights with a big lens in the middle. Barring that, a good loupe will do. Price: About $10.00 (for a good loupe). Lots of light. Price: About $0.04/kWhr., depending on your location. 1 3/16" Nutdriver. For removing the RS-232 port standoffs. 1 1/4" Nutdriver. For removing the printer port standoffs and the four motherboard standoffs. 1 #1 Phillips screwdriver. For removing the motherboard hold down screws and any expansion board retaining screws. 1 #2 Phillips screwdriver. For removing the cover and chassis screws. 1 small straight screwdriver (some people call it a flathead). The equipment II (optional, but nice): 1 3-inch or equivalent muffin fan. Used to carry away all those nasty solder fumes. Buy at a ham fest. Price: $7.00 or less 1 IC insertion tool, 14-16 pin. For putting all those chips in. If you use this, though, be careful to check carefully for bent pins! DigiKey part number: K153-ND Total Price: $7.87 1 IC Pin Straightener. Used to straighten any bent pins on your chips. Radio Shack part number: 276-1594 Price: $3.49 1 Anti-static wrist grounding strap. Some of you will, no doubt, recoil in horror that I don't mention this as a required item. Fact is, I've worked on lots of boxes, from Commodores to PC's to Mac's to DECstations, and I've seldom used one and have never statically destroyed a chip. You might not be as lucky, though :) Radio Shack part number: 276-2397 Price: $3.29 The suppliers: DigiKey 701 Brooks Avenue South PO Box 677 Thief River Falls, MN 56701-0677 Ph. 800-344-4539 Radio Shack Nearly one per every damn street corner. Useful references: AT&T Unix-Pc Reference Manual. Hard to find, but worth it. This one has the schematics and discussions on component-level troubleshooting, along with general discussions on how this box works at the hardware level. AT&T Unix-Pc Service Manual. Also hard to find. Pretty pictures and descriptions on how to get the case apart. Most of the troubleshooting stuff in this manual is useless, as most of the solutions end with 'Replace the logic board.' It even suggests this approach for a dead battery! HWNotes01-15. A file on the OSU archives by John Milton on various Unix-Pc/3b1 hardware hacks. Well worth getting and reading many times. RAMupgrade. Also a file at OSU. How to upgrade a 512k expansion board to 2Mb, and how to upgrade a 512k motherboard to 2Mb. Lots of good advice--these are what got me into all this. s4test.info. Once again, at OSU. Info on the "expert" mode of the diagnostics. The upgrade thus costs about $70.00 if all you need to buy are the components, solder, and flux remover. You can cut this down quite a bit if you can find sockets and other components for a low price at a ham fest. My upgrade only cost about $33.00. Removing the motherboard: 0) Reboot with the Diagnostic Disk, and park your hard drive, then power off and remove the power cord from the computer. 1) Place the computer on a table such that the rear edge is hanging off the edge of the table, and remove the two #2 Phillips screws at the rear that hold the monitor on. Repeat this process for the one/two #2 Phillips screws (depending on model) on the left and right edges of the computer. 2) Remove the two #2 Phillips screws in the rear that hold the cover on. Then tilt the monitor assembly forward and off. Lay it down on its back behind the computer. I prefer to take the monitor off, since it is easier to get the cover back on in pieces as opposed to all at once, and you are less likely to pinch the ac wires. 3) Use the small straight screwdriver to pry off the cover screw covers located on the top of the keyboard posts on the front of the computer. Remove the #2 Phillips screw under each of them. 4) Pull the cover off and tilt it back so that it is sitting vertically between the monitor and the rest of the cover. On some models this requires that you do a little prising on the front edge to get the cover to come up. 5) Remove the three #2 Phillips screws from the front edge of the metal chassis. 6) Remove the #2 Phillips screw at the left rear of the chassis that is holding the monitor cable down. 7) Remove the power supply connector from the power supply at the right side of the chassis. 8) Remove the power cables from both the floppy and hard drives. 9) Tilt the pan up a couple of inches and reach into the left side of the chassis and unplug the monitor cable. 10) Tilt the pan up a bit more and reach in and unplug the floppy and hard drive cables from the motherboard, noting the orientation of the connector. Pin 1 is on the left of each connector on the motherboard, and pin 1 is usually marked with a red or blue stripe on each of the cables. 11) Now remove the pan completely and set it aside. 12) Balance the case on its front and remove any expansion cards, being sure to put them in an antistatic bag. 13) Remove the four 1/4" standoffs in the central quadrant of the motherboard. 14) Remove all the #1 Phillips screws around the outside edge of the motherboard. 15) Remove the two 1/4" standoffs on either side of the printer connector. 16) Remove the two 3/16" standoffs on either side of the RS-232 connector. 17) Remove the four #1 Phillips that hold the chassis back on. There are two on the bottom and one on either side at the back edge of the chassis. 18) Remove the chassis back. The only thing holding the motherboard in now is the expansion bus connector. Disconnect the volume slider from the volume pot at the right front edge of the motherboard, grasp the motherboard, and gently pull it free of the bus connector and out of the chassis bottom. Performing the upgrade: 0) Set up the board on a firm-but-soft work surface topped by the antistatic bag, in a well lighted area. Situate the fan so that it gently blows over the board so as to carry any solder fumes away. 1) Set your soldering station on about 680 degrees F, and desolder, from the back (solder) side of the board, the following: a) Locations 2A-10D b) The locations marked CW and CX associated with 2A-10D c) Locations 11B, 11C, 11D, and 12A. d) Holes for RP1, RP3, RP7, and RP8. Heat each hole until you see the solder flow, then suck it away with the desolder vacuum. This should take no more than 10 seconds/hole. Be sure to stop occasionally and clean out your solder vacuum. Also be sure not to cock the vacuum while it is over the motherboard. This can result in little pieces of solder all over your motherboard! 2) Examine the holes that you have just desoldered, along with the area around them, for solder bridges and splashes. Use the magnifying lens, and clear off any stray solder. Make sure to check both the top and bottom of the holes! 3) Insert a .1uF (104) capacitor in each of the positions marked CX, and a .01uF (103) capacitor in each of the positions marked CW, and solder them in. Clip the excess leads close to the solder, using a pair of flush-cutting pliers. The fourth row of these (nearest the original memory chips) will probably already be in place, leaving you with 4 .01uF and 5 .1uF capacitors left over. 4) Insert and solder in each of the resistor packs, and trim any excess leads. Make sure that pin 1 of the packs faces the front edge of the motherboard. In this case, it doesn't strictly matter, but it IS a good habit to get into. Not all resistor packs are symmetrical. 5) Solder in the sockets for the 4 additional decoder chips, at positions 11B, 11C, 11D, and 12A. As you solder these in, be careful of solder splashes and bridges. Make SURE that there are no solder bridges on the top (component) side of the board, because once you have soldered the sockets down, they will be difficult to find. 6) Solder in the sockets for the new memory chips at positions 2A-10D. See cautions for 5) above. 7) Place the front edge of the motherboard on the paper towels, solder side up, angle the motherboard about 60 degrees from the horizontal, and spray flux remover over the pins that you have just soldered in, going from top to bottom. Then gently brush the pins with the toothbrush to remove any stubborn resin. Spray again, then use your muffin fan to dry off any remaining residue. DON'T use the paper towels to dry the board--they will rip up on the sharp pins and cause a mess. 8) Insert the four 74F258 decoders into the sockets at 11B, 11C, 11D, and 12A. Make sure not to bend any pins, and check to make sure that pin 1 faces the front edge of the motherboard. 9) Insert the 36 new memory chips in their sockets at positions 2A-10D, observing the cautions for 8) above. 10) Perform the following patches (thanks, Robert & Franco!): First, determine whether you have an old or new style 1Mb board. The old style is characterized by a jumper from pin 11 of 13B to pin 15 of 25F. The new style lacks this jumper. Once you have determined this, perform EITHER the old: or new: instructions below, BUT NOT BOTH! a) old: Remove the jumper between pin 3 of 6J and pin 1 of 6K. new: Remove JR10 b) old: Disconnect the jumper from pin 15 of 25F. new: Insert JR9 c) old: Reconnect pin 15 of 25F with its hole in the motherboard, using the piece of jumper wire that you removed in a). new: Remove R145 d) old: Connect the jumper that you removed from pin 15 of 25F to pin 8 of 25F. The other end of this jumper should still be connected to pin 11 of 13B. new: Insert JR5 11) Perform any other patches (battery holder, DRUN) that you need to. 12) Recheck both sides of the motherboard for solder splashes and bridges, then check to make sure all the chips are inserted in the correct direction, then check to make sure you applied all the motherboard patches correctly. Reassembly: 1) Align the plastic insulator and metal shield holes with those in the chassis bottom. 2) Replace the motherboard in the chassis bottom, being sure to completely insert the forward edge connector into the expansion bus slot, making sure to also put the volume slider back on the volume pot. 3) Screw the four 1/4" standoffs back into the center quadrant of the motherboard. 4) Replace all the #1 Phillips screws around the periphery of the motherboard. 5) Replace the chassis back, chassis back screws (four #1 Phillips), and the serial and parallel port standoffs. 6) Replace any expansion cards that you removed. 7) Replace the pan and reconnect the disk drive cables (3). Be CAREFUL not to bend any pins or offset the connectors to one side. 8) Tilt the pan partially down and reconnect the monitor cable. 9) Tilt the pan the rest of the way down and reconnect the power supply cable, along with the power cables for both disk drives. 10) Replace the three #2 Phillips screws along the front edge of the chassis that secure the pan, along with the #2 Phillips screw that secures the monitor cable to the chassis. 11) Replace the bottom part of the cover, being careful not to break off any of the fingers that press against the hard drive shield, or to pinch any wires. 12) Replace the two #2 Phillips screws on the keyboard posts at the front of the cover, along with the covers that conceal them. 13) Replace the monitor onto the cover. 14) Replace the two #2 Phillips screws that hold the cover down at the rear of the machine. 15) Move the computer so that one side is hanging off the edge of a table, and replace the corresponding monitor hold-down screw(s). 16) Repeat 15 for the other side of the computer. 17) Move the computer so that the rear is hanging off the edge of the table, and replace the remaining two monitor hold-down screws. 18) Replace the keyboard and power cord and boot the diags. They should report that you have 2Mb. of memory. IF NOT, GO DIRECTLY TO "In case of trouble", below. Testing: 1) Type s4test at the diags menu prompt. This takes you into expert diags mode. 2) Type 100:0,0 This will run the memory tests approximately all night. Turn the brightness on your monitor down, and if it still hasn't caught an error when you wake up the next day, you should be ok. Pat yourself on the back for a job well done! 3) If you got errors, go to "In case of trouble", below. In case of touble: 1) OOPs, something is amiss, several things are possible: 2) If the computer doesn't come on, you have probably managed to short +5 to ground. CUT OFF THE POWER IMMEDIATELY, or you will fry your power supply. Remove the motherboard and check for solder splashes and bare places on your jumper wires. 3) If the computer still only recognizes 1Mb, your patches might not have worked, you might have a bad decoder chip, or you might have solder splashes and/or bridges that are causing the problem. Remove the motherboard and check for all these things. 4) If you get errors during the memory tests, you might have solder bridges in the memory area or a bad chip. Try replacing one row of memory at a time. When the problem goes away, take the row that you just removed and replace a chip at a time until the problem returns. Then remove the chip that you just put in and cut it in half so that you never make the mistake of using it again. (I once had a professor who threw known bad chips back into the parts box. What a pain.) If the error doesn't go away, remove the motherboard and look for solder splashes. 5) If none of these solutions work, feel free to give me a call/email. I doubt I'll be able to help much, but I'll try. However, I said it before, and I'll say it again: =*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=* DO THIS AT YOUR OWN RISK. IF YOU HAVE NEVER SOLDERED BEFORE, OR HAVE LIMITED EXPERIENCE, OR NO EXPERIENCE WITH SOLDERING/ DESOLDERING ON IC CIRCUIT BOARDS, STOP _NOW_ AND FIND SOMEONE WHO HAS TO ADVISE YOU! I CANNOT BE HELD RESPONSIBLE IF YOU FOLLOW THESE DIRECTIONS AND STILL DESTROY YOUR MOTHERBOARD. =*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=* And once again, thanks to go to Robert and Franco for the patches needed to make this all work! Good luck! --Lee ________________________________________________________________________________ R. Lee Hawkins lhawkins@annie.wellesley.edu Department of Astronomy lhawkins@lucy.wellesley.edu Whitin Observatory Wellesley College Ph. 617-283-2708 Wellesley, MA 02181 FAX 617-283-3642 ________________________________________________________________________________