MiniSport Laptop Hacker - Vol #22.  July 1994 
To discourage pecuniary interests, Copyright (c) 1994 Brian Mork 
 
>>> ADMIN 
The MLHacker series is formatted to print out on 8.5"x11" sheets manual- 
ly fed into an Epson LQ-850.  I print at 8 lpi, which gives 82 lines per 
page.  Back issues are available from ftp.cs.buffalo.edu in the 
\pub\msdos\ham-radio directory.  E-mail server ham-server@grafex.cuper- 
tino.ca.us also has them in the directory \hamradio\newsletters.  Note 
in the signature block that my packet radio address has changed. 
 
>>> ALTERNATE BATTERY SOURCE 
In April Jim forwarded me results of his efforts to modify 9.6 volt 
Makita power tool batteries.  Cut directly from his Internet message, 
here are his observations (thanks Jim!): 
 
   "Just the other day I did something I've been dreading for 6 
   months.  I  removed the stock battery from my Zenith ZL-2 Minis 
   port and connected  a variable voltage power supply directly to 
   the computer's power  terminals.  After adjusting the supply to 
   six volts, I powered up the  computer and verified that it was 
   working properly.  Then, taking a  deep breath, I slowly cranked 
   the power up to ten volts.  No  explosions, no complaints from 
   the Minisport power supplies, It took  it just fine.  Great, now 
   I can use my 9.6 volt Makita batteries with  the laptop as part 
   of my portable packet station. 
 
   "Since the internal Zenith supplies are all switchers, current 
   drain is  inversely proportional to battery voltage.  This means 
   no power is wasted regardless of whether the voltage is 6.0 
   (stock Minisport battery) or 9.6 volts (as in my Makita pack).  I 
   measure 450 - 650 Ma drain with a 6.0 volt source (depending on 
   backlight brightness), but  with a 9.6 volt source, only 340 - 
   425 Ma is needed.  The Makita  batteries are about 1400 MAh ca 
   pacity and run my ZL-2 for 3 hours with  the backlight on full. 
   Obviously, a 7.2 volt external would work  also, with proportion 
   ally reduced operating time. 
 
   "I had to make a better way to get the external power to the ma 
   chine than the alligator clips I was using.  I thought I'd share 
   what I built with you all.  Here's how to make a fake battery 
   pack for your Minisport. 
 
   "Begin by cutting a 2 1/4" by 5 1/8" piece of single sided glass 
   epoxy Printed Circuit board material.  Remove 1/16" strips of 
   copper along five lines as shown in the following diagram. 
 
                |<-------- 2 1/4" ---------->| 
               >|---- 1 1/2" --->|           | 
               >|- 1 1/16" -|<   |           | 
               >|- 3/4" |<  |    |           | 
                5/16"   |   |    |           | 
               >|  |<   |   |    |           | 
       _______  _____________________________ 
          ^     |  |  o |   |  o |           | < drill holes for 
          |     |  |  + |   |  - |           |   power wires 
                |  |    |   |    |           | 
          |     |--|----|---|----|-----------| < remove copper 
                |  |    |   |    |           |   for 1/16" 
          |     |  |    |   |    |           | 
                |  |    |   |    |           | 
          |     |  |    |   |    |           | 
                |  |    |   |    |           | 
          |     |  |    |   |    |           | 
                |  |    |   |    |           | 
          |     |  |    |   |    |           | 
                |  |    |   |    |           | 
          |     |  |    |   |    |           | 
                |  |    |   |    |           | 
        5 1/8"  |  |    |   |    |           | 
                |  |    |   |    |           | 
          |     |  |    |   |    |           | 
                |  |    |   |    |           | 
          |     |  |    |   |    |           | 
                |  |    |   |    |           | 
          |     |  |    |   |    |           | 
                |  |    |   |    |           | 
          |     |  |    |   |    |           | 
        __v___  |__|____|___|____|___________| 
                   ^    ^   ^    ^ 
          Remove copper along these four lines 
 
   "Drill the two holes close to the edge so solder will not inter 
   fere   with the power contacts on the machine.  Only the two 
   small rectangular areas with holes will actually be energized. 
   Isolating these minimizes the possibility of short circuiting the 
   battery.  Nevertheless, you should always disconnect the external 
   battery when the fake unit is removed from the computer. 
 
   "You can remove strips of copper by double scoring the material 
   1/16"  apart along the indicated lines, then gouging out the met 
   al with a  knife or wood chisel.  With some patience, you can 
   also do it with a  hacksaw or a hand grinder.  My favorite method 
   is using a 1/8" drill  bit in a small drill press as a router.  I 
   raise the table until the  PC board is just touching the drill 
   bit.  Then one or two thickness of 3 x 5 card under the board 
   raises the copper just enough so I can route out metal along the 
   lines by moving the board under the bit while it's turning at the 
   highest speed.  I have a piece of wood with a vertical fence 
   screwed to one edge that I can "C" clamp to the drill table to 
   help guide the PC board while routing. 
 
   "You will need to solder a power cable directly to the board, or 
   glue some sort of jack on the board to accept a power cable 
   through the battery cover hole.  The NEGATIVE terminal is nearest 
   the front of the Laptop.  The POSITIVE terminal is the rearmost. 
   You won't need a connection to the center terminal, it is used by 
   the Minisport charging circuit.  Use a minimum amount of solder 
   and file the solder bumps down smooth. 
 
   "Complete the fake battery by gluing a block of wood about 1 inch 
   high to the glass side of the PC board.  This takes up the slack 
   in the battery compartment so the board is pressed firmly onto 
   the computer's power terminals.  You will have to sand the block 
   to just the right height, or glue on strips of cardboard for ex 
   tra height if it's too short. 
 
   "One problem with using a higher than six volt battery with the 
   Minisport is that the low battery voltage alarm doesn't work.  It 
   appears that by the time the 9.6 volt pack is discharged far 
   enough to trip the alarm, it's going down so fast that there 
   isn't time for an indication.  Save your work often if you're 
   near drop out time.  It should be possible to construct a sepa 
   rate discharge alarm on the fake battery board that will trip at 
   a higher voltage and give a couple of minutes warning. 
 
   "I have also created a real battery pack for my Minisport by us 
   ing one of these routed out PC boards, and hot gluing five "C" 
   size nicads to the top.  It works as well as the 1700 MAh Minis 
   port batteries but I have not figured out a way to use the Minis 
   port charger.  Also the exposed battery power terminals on the 
   bottom require care to avoid short circuits. 
 
>>> DRIVE EXPANSION PINOUT 
On the back of the Minisport is a small plug with a rectangular external 
form and an internal "D" shape.  I have been unable to identify a source 
for this connector, but several people have asked for the pinout.  Here 
it is, compliments of wa8wzx.  The top row of pins 1 through 19 are all 
sequential odd numbers.  The bottom row has pins 2 through 20.  Pins 4, 
10, 12, 19 & 20 are all ground.  Others are: 
 
      1 Disk Change       2 Side Select       3 Read Data 
      5 Write Protect     6 Track 0           7 Index 
      8 Write Enable      9 Write Data       11 Step 
     13 Direction Select 14 Drive Select 2 
     15 RPM              16 Motor On         17-18 Vcc 
 
Please provide feedback!      * Direct data 1-509-244-9260 
                              * ARO Net KA9SNF@ka7fvv.#ewa.wa.usa 
                              * Internet bmork@opus-ovh.spk.wa.us 
73, Brian                     * 6006-B Eaker, Fairchild, WA 99011 
