Re: Hacking: bisection of IIC motherboard to install IIC in Mac casing

[fishern3485@cobra.uni.edu]

> Last year, I installed a harddrive in a classic Disk ][ casing.  Now, I
> am thinking again about installing a IIC inside a Mac casing.  The Mac SE,
> in particular is very roomy.
> 
> The obstacle remains the fit of the IIC motherboard inside the
> Mac case.  Its slightly too big.  But I am considering butchering the
> IIc motherboard by slicing it in half, using spacers to "double-deck"
> the two halves, then running soldered wires to connect the corresponding
> points at the split edge of the motherboard.
> 
> HACKING QUESTIONS:
> 
> (a) Is it feasible to split the motherboard, then reconnect the tracings
> with soldered wire jumpers?  I have silver solder and have successfully
> desoldered RAM chips from the IIC board.

I have repaired several VCRs with cracked motherboards.  Lemme tell you
that there are a LOT of traces in a very short run of board!  It took me
about a week to repair a motherboard with better than 75 broken traces.
(I count myself VERY lucky, it worked the FIRST TIME!)

I cannot say for certain, but I believe the //c is a dual-sided motherboard,
with traces on both sides.  If you DO manage it, it will take several weeks
of work.  BTW, the big chip that is soldered to the motherboard, (KBD)
is CMOS. (static sensitive)  Hope you have a CMOS safe soldering iron....
(I had to replace mine - THAT was not fun)

Lotsa luck.


> (b) Assuming that all severed points on the motherboard are reconnected
> successfully, are there any electrical complications?  For example, any
> circuits which will be messed up by several inches of additional wire in
> their circuits?   Another anticipated complication is the possibility that
> the motherboard is multi-layered with buried tracings.  Anyone know for
> sure?  In other words, are the tracings along the surface (where wires can
> be attached), or are they buried inside the green resin board?

Again cannot say for certain, but it probably is not going to cause severe
problems.  1 mhz is not too terribly high frequency.  Now if this were an
IBM, I'd say don't even bother trying. (distance is very important in
high-frequency applications)  All traces run on the outside of the
board, but many will go through holes to the other side. (sometimes
SEVERAL times to get where they are going)


> (c) The direction of the cut will be in areas of the board with the lowest
> density of traces and components.  Any suggestions?

That seems wise.  I'd also avoid cutting anything NEAR the TMG chip or either
ACIA port chip.


> 
> (d) The board will be cut with a sharp hacksaw blade on a power saw.
> Will the vibration of the saw be risky to components or traces, or should
> I saw the board manually instead?

High speed, thin blade.  You do realize you are going to tear the traces,
right?  They are tougher than the board, and are not held on with much.
A high speed hand-saw (power) with a VERY thin and fine tooth blade
is your best bet.  The higher the speed, the less likely it will be to
rip the traces off the board.  BTW, take into account the width of the
blade, which will be eaten away.  It would be good to have another
motherboard handy to reference!


> Hardware hackin' advice: sought and appreeciated!      Hakker Sebugg

oh it's YOU!  (will be getting the disks out EVENTUALLY....)  You are
crazy.  Owell if you must, GOOD LUCK!



Here is a crazy fantasy to ponder - you find this wierd acid that will
dissolve circuit boards, but nothing else.  You place the motherboard
into the acid and all the board is eaten away.  Then you pull the tangled
web of chips and traces out and spray with another magical thing, penetrating
laquer, which coats the surface of all metal contacts, pins, and traces,
insulating them from eachother.  Then you just pop the ball of wire/chips
into your shirt pocket.....

yes I'm crazy too.


-- 
Nathan Fisher
  FISHERN3485@COBRA.UNI.EDU