Amstrad 3in drive spares
ard at p850ug1.demon.co.uk
Tue Nov 2 15:30:07 CDT 2010
> Cheers for the link. Now I just need to fix the PCB on the 231 (some
> idiot has gone and ripped a few tracks and pads off the board) and steal
> some parts (a PCB mounting screw!) from the 156...
Is there soemthing special about the screw? Why do you need to take it
from another drirve?
> Given its wiring, I suspect SW1 is the drive select switch (it isn't
> fitted on either of my drives). What I don't get is why it's got three
> pins plus common. Common goes to the "SELECT" input on the controller
> chip, 1 goes to /SEL1 (pin 4), 2 apparently goes to /SEL0, and 3 carries
> the READY signal from the drive (?!). JP1 allows SEL0 and SELECT to be
> bridged without the switch present.
> The only way this would make sense is if switch pin 3 was open-circuit...
The schematic I have to hand shows SW1 as switching bwtween drive select
0 (pin 4 of the connecotr) and drive sleect 1 (pin 6 of the connector.
The common connection goes to the D-SELCT/ input of the main ASIC. There
is indeed a jumper to connect up Drive Select 0 if the switch isn't fitted.
Alas the manual doesn't show PCB layouts, just a schematic So I have no
idea if there's an exta non-connected pin on the switch.
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