imac rev a - motherboard boot (in a colour classic)

Discussion in 'Macintosh Computers' started by Ansel_Tk1, Jan 14, 2005.

  1. Ansel_Tk1 macrumors newbie

    Jan 14, 2005
    Hi All - wondering if someone out there could give me a few tips...I realize this is something of a technical post.

    I am trying to do an iMac 333 motherboard upgrade on a Colour Classic :)

    I am relatively proficient with hardware and minor electronic projects, but I can't figure out if I have a dead iMac mobo or not! I have a 333 mobo with a daughtcard with 1 sodimm sdram 128mb in the upper slot. I have wired the PS (a 1U ATX PS) that is testing the correct voltages at all the pins. I turn it on and I get nothing.

    Now, if I take the daughterboard out, I get 1 beep (memory not found). Okay, so there is some life...put the card back on, nada. no beep no chime.

    I guess my question is - does an iMac modo need to be connected to anything else in order to boot? does it need to be connected to some sort of video output (thats the only thing I am not sure of) I have wired the outs on the mobo to a d15 connector and connected this to a monitor. Still nothing. Maybe a ground other than the black PS wires?

    Any thoughts?

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