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