Apple CS II Guía de usuario descargar pdf (Pagina 278)

Fatter +5, +12, and Ground leads should protect you power supply and reduce

circuit noise.

If audio noise in your stereo card output and/or system bombing due to

noise glitches were problems, they may be eliminated. A lot depends upon which

cards you've installed, which slots they are in, and whether your IIgs is a ROM-

01 or ROM-03.

The motherboard circuit traces supplying power to each Slot are fairly

skimpy, especially on ROM-01 boards. A heavy power user in Slot 7 can produce

significant noise up and down the entire Slot 'backplane'.

The cure is to remove the motherboard and run leads to a couple Slots ...

First, flip over the motherboard and get oriented. Below is a quickie

sketch showing the Power Connector points as well as key power pins for a Slot.

The view is from the _Bottom_ with the _Back_ of the motherboard facing you:

Bottom of Motherboard

Power Connector Socket Slot

X GND +12V (pin 50) X X (pin 1)

X GND X X

X +5V .

X +12V .

X -12V

X -5V X X

GND (pin 26) X X (pin 25) +5V

.... Ground Plane Area (plug shields, etc. connected here) ....

|______________ Back Edge of Motherboard _________________________

A good way to make sure you know what's where is to use an Ohm meter to

check Resistance from pin 26 (GND) to a metal plug shield near the back of the

motherboard. (Set your meter to Ohms X1. Touch one meter lead to pin 26 and the

other to a metal plug shield. Resistance should read nearly zero. Reverse the

leads and repeat the check. Again, Resistance should read nearly zero.)

Repeat the check for R between pin 26 and the GND points on the Power

Connector socket. R should be nearly zero. Using a marker pen or white-out, mark

pin 26 (GND) on Slots 3 and 7. Also mark the GND points of the Power Connector

socket.

GND: On the bottom side of the motherboard, connect a Black #16 gauge wire from

one of the Ground points of the Power Connector socket to the Ground plane area

near the back of the motherboard. Run a short Black #16 gauge wire from pin 26

of Slot 3 to the Ground plane; run a short Black #16 gauge wire from pin 26 of

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Apple CS II Guía de usuario Pagina 278