Tom and Lisa's Weird Web Page
I got into a "Duo mania" a while back, and now have enough parts for several units. It has been fun playing around with these simple sub-notebooks and seeing how they are put together.
Before I start, let me say there is a very good list server for Duo and powerbook 2400 topics that you can join by going to www.lowendmac.com and finding the correct link. The listerver has been a great source of information about Duos.
If you want to see the King of Duo modifications, I suggest take a look at this link: http://www.liethen.com/firebook-mana/index.html
What I set out to do was much simpler. There are 6 things I will describe on this page:
- Overclocking your Duo
Here is a view of a Duo 280/280c motherboard (they are the same part):
#1 is the CPU
Here is a close-up of the motherboard, centered around the oscillator that controls the CPU speed:
The oscillator will run the CPU at half the frequency of the oscillator, so the stock 66.6666 MHz part in the picture above runs the CPU at 33.3333 MHz. By removing the oscillator and replacing it with another, faster part, your CPU (and bus speed) will increase. The oscillator controls the bus speed but to the best of my knowledge you cant change the bus-to-CPU speed multiplier.
- A 23 Watt (or so) soldering iron with a fine tip. A 15 Watt
iron might not have enough oooommph to desolder.
* a 75 MHz part worked for me. You may want to try a slower or faster part (70-80 MHz) depending on how lucky you feel.
Once you have overclocked the duo, I highly recommend adding some thermal paste between the CPU and the heatsink; this will help soak up the extra heat generated by the faster CPU.
Cleaning the Duo keyboard: One of the most common questions about Duos is where to buy new keyboards or how to fix the old ones you have. All the Duo keyboards I have come across have been repairable. The keyboards either tend to get gunk on the mylar contacts, or a small break develops in the metallic traces on the mylar sheets. Either can be fixed.
This is the keyboard as it appears in a pristine state:
Using the tool pictured above, or carefully using your fingers, it is possible to remove all of the keys. If you remove the keys you will see that beneath the keys there is a rubber mat:
The mat is removed freely after all the keys are off. Beneath the mat are 2 layers of mylar plastic that have metal traces on them:
In an ideal word I would show a complete keyboard disassembly, but it takes a while to get all the keys on and off. Please note that some of the keys have metal stiffeners which are attached to the keyboard and the keys; so don't be surprised (although they are easy to get on and off).
These metal traces can get dirtied and require cleaning to get functional. To clean them, I suggest gently rubbing along the traces with a clean eraser (use rubbing alcohol to clean them). Watch out not to knock off the green CAPS LOCK LED; it is easily dislodged. Also be careful not to get a fold in the mylar sheet from rubbing to hard and too fast.
If keys are still not working after cleaning the traces, there may be a
break in one or more circuits.
Replacing the Green Caps Lock Light: I took this idea from a Japanese page that used a blue LED in place of the green CAPS LOCK LED. Unfortunately, I can't find the appropriate blue LEDs to use (the only SMT ones I found were 4.9 V which is too much for the keyboard, which is limited to 2.5 V or so). I did find red LEDs that work (www.digikey.com part #L62211CT-ND).
Remember what I said above about not knocking off the CAPS LOCK LEDs ?
Well it's real easy. If you want to replace the LED, a small amount
of pressure is enough to pop it off the top mylar sheet (I am assuming at
this point that your keyboard is completely disassembled).
Adding a hard drive activity light:
This is the toughest mod I have done for a duo, and probably one the most
fun. I originally saw this idea on a Japanese web page, but
unfortunately the details were very slim. After a fair amount of
time tracking parts down and getting a refresher in basic electronics, I
managed to figure out how to do this.
The lower left hand pin of the set of 8 pins is the drain, or negative
point of the circuit I built. The source, or positive point of the
circuit, is any one of the 3 pins surrounding the drain pin. These
pins are also used for SCSI ID, but using them as a source does not affect
the SCSI ID.
Pretty simple, eh ? If you select the correct parts, you don't
even need a resistor before the LED. After some trial and error, I
find that either digikey part# L62211CT-ND (red) or L62411CT-ND
(red) works well. Digikey part # L623007CT-ND (yellow)
probably works but I haven't tested it. Unfortunately, I cant find a
proper part with a blue color. These are SMT parts and require some
sort of mounting surface. I used Digikey part# 6103CA-ND (a
"surfboard") to mount the parts on.
When put together, the whole thing looks like this:
The item on the left is the surfboard with the LED soldered onto it, and the item on the right is the socket I cut from an old IDE 2.5" drive socket, with wires soldered to the socket.
I also like to put some heat shrink tubing on the connection to the
surfboard (not shown above).
Here is a pic of the wiring in place, below the trackball:
The first thing I did was to take a power on card and remove the top epoxy layer that covers the copper layer (I used a dremel). If you don't remove the copper layer, this will short the 4 ADB pins to each other. I used a concentrated FeCl3 (ferric chloride - Radio Shack used to sell this stuff) solution to etch the copper off. You could also use a dremel tool.
After etching the copper off (if you etch off just the parts around the 4 signal pins, you can use the copper plate near the mounting pins to solder the socket down, although this is not absolutely necessary) , and drilling some holes out to mount the ADB socket this is what it looks like:
I used some epoxy to glue the port down onto the card. Adding some hot
glue cant hurt.
Once put together, the wiring on the backside of your Duo should look something like this:
The pins on the ADB socket are marked 1-4. According to Peter Leithen's web page,
Pin 1 on the ADB socket goes to Pin 83 on the PDS socket on the
Don't get the numbers mixed up.
Repairing the AC adapter port: A
few people have noted that their Duos wont run off of AC adapter. I
had one duo that had this problem. A careful inspection showed that
the AC socket was loose and made only intermittent contact with two of
three mounting pads I could see sparks when I jiggles the AC plug when