I repost my old post from xboxhacking - general here as it's a better place to have help ...
I want to make a tri-boot using an SST39SF040 chip, soldering it above the original SST39SF020 chip with her original firmware.
However, looking at differents schemes presents in the forum I'd like to be sure that I'm not doing a supid operation.
I choose an SST39SF040 (70-4C-NH) to make the "tri-boot" I was speaking of. So I want to choose between the original chip and the SST39SF040 one AND between bank 0 & 1 of this SST39SF040 chip.
But schematics showing us how to solder a second chip on the original one (I used the following picture) show that we have to solder pins A18 & VDD together.
However the tutorial "TightMod360 by LittleJonny tells us to join pins A18 or VDD (or both) to pin CEx on the lower original SST.
AND if I want to choose between bank 0 and 1 of the ST39SF040 I have to leave A18 and VDD WITHOUT
permanent contact (the switch decides what bank will be used)
The first question is : do I have to solder just pin A18 or VDD to make the tri-boot possible ?!?!?! I'll solder pin A18 with the other A 18 from the original chip, then to a couple of resistor and finally to each CEx of each chip (SSTSF020 and SSTSF040) : is it right
The second question is relative to the tuto of the pic used ( http://www.chipper.se/forums/index.php?showtopic=5011
) : it tells us to cut a track on the DVD mobo :
I never heard to cut that track on xbox hacker BBS >>> what's this manipulation so
Third question : on the schematic shown before it's shown that pins A18 & VDD are connected together and with the original chip ; it's just a resistor that makes the link between this differents pins and the two CEx (who are connected together thrrough two 10kohms resistor on the schematic => is it all ok
) => is this schematic right for the tri-boot i want to do
Is this final schematic is right for what I want to do
(in this scheme I placed green and orange LED before the switch as I found in a previous scheme => does it take power from the chip or will I have to lace LED after the switch using power from the PCB of the DVD Drive
Thanx for the future answers .... and for an eventual schematic to show me the way to do (^_^);