Hi all,
I have a Mac Classic with a checkerboard pattern. I have recapped the analog and the logic board. I have proved the analog board works with a known working logic board (Board B) and I have proved the Logic board (Board A) also doesn't wok with the known working Analog board.
The symptoms I am getting are the checkerboard (with two different ROM chips being tried). The power rails are as follows measured at the 19 pin connector on the back of the logic board :
-12v is good at -12v
+5v is good at +5v
+12v is bad only measuring 1.8v
So my question is what component controls the +12v once it enters from the analog board ? The Analog board must be passing the right voltage as Board B (working logic board) works ok with the Analog board and this board (B) is showing +12v at the pin 8 using the same analog board.
Does VR1 have something to do with this next to C8 ?
Logic Board is 630-0390-C
I have a Mac Classic with a checkerboard pattern. I have recapped the analog and the logic board. I have proved the analog board works with a known working logic board (Board B) and I have proved the Logic board (Board A) also doesn't wok with the known working Analog board.
The symptoms I am getting are the checkerboard (with two different ROM chips being tried). The power rails are as follows measured at the 19 pin connector on the back of the logic board :
-12v is good at -12v
+5v is good at +5v
+12v is bad only measuring 1.8v
So my question is what component controls the +12v once it enters from the analog board ? The Analog board must be passing the right voltage as Board B (working logic board) works ok with the Analog board and this board (B) is showing +12v at the pin 8 using the same analog board.
Does VR1 have something to do with this next to C8 ?
Logic Board is 630-0390-C