> 5) Don't mess with the PCMCIA guides. They are a ^@#* to put
> back in.
> I think this is *why* Apple invented the dummy cards (so they
> could put
> them in while assembling the darn things!)
>
> Jim
Jim,
Actually, they are very easy to remove/replace... ...if you know the secret.
Ssshhh! Don't tell anyone this but the metal bars that connects the two
sides of each PCMCIA slot are removable. When the two sides are separated
from each other the fitting is soooooo much easier.
Now, as far as the test points are concerned. TP31-34 are just conveniently
placed for access to the touchscreen connections in-situ.
TP35-38 functions are unknown based on the scant info on the voyager chipset.
Just from a physical connection point of view and using some educated
guessing, I have determined the following:
TP35 goes to U6.63
TP36 goes to U6.64
TP37 goes to U6.62
TP38 goes to GND
Generally, though there are exceptions, related functions or pins are
grouped together. It is, therefore, a fair assumption, in the absence of
hard data, to postulate that these are used for a factory calibration procedure.
U6 (CL-PS7020-VC-A) looks after a number of analog functions, the back-up
supply (goldcap) provides power to this chip during battery changes. It is
likely that screen calibration values are held in a small amount of ram or
registers inside and would account for the need to screen cal after prolonged
power loss.
Interestingly, the 32.768kHz crystal that, I believe, runs the RTC, connects
to U9.130/131 but this chip has no connection to the goldcap! It may derive
it's connection in another way but I haven't the patience to map it all out.
This is where a data sheet would be of help.
The goldcap is a 'double layer' device. It is not the same as an electrolytic
capacitor. It is made from activated carbon and consists of a solid anode
and cathode with a liquid electrolyte in-between. The double layer is by
virtue of the solid-liquid liquid-solid interface. It has a life of >1M cycles
and works by ion exchange not chemical changes. An aluminum electrolytic,
on the other hand, has an aluminum anode with a very thin aluminum oxide layer
that is sitting in an electrolyte that forms the cathode.
Two different technologies.
The goldcap won't leak but it is sensitive to temperature, typically losing
half its' life for each 10deg rise in temperature. The converse is also true
so please put your Newtons in the refrigerator between uses. ;)
Regards,
PCBman
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