G4 Cube revival help?

[TJ812]

I picked up a complete, cosmetically nice Cube this weekend for very cheap. The seller was the original buyer and had photos of it booting within the past few months. The final FB listing said 'it does not currently boot' and it is 'likely the hard drive as it was making some odd noises'.

I included the matching monitor, speakers, PSU, etc. All cosmetically near perfect.

I have several old Macs and other vintage computers which I've revived, so I thought this would be a fun challenge.

But this Cube is, in fact, not booting.

Symptoms: power button LED will light bright and then flash off and on slowly. there is no sign of video out from the Apple monitor or from a VGA monitor.

What I've tried so far: replaced PRAM battery, pressed the PRAM rest button, reseated RAM modules, disassemble to the point of removing VMU, video card, modem card, and reseated them all. disconnected the drive power connector with video card/modem/ram removed, same flashing power.

The power supply brick seems ok and is steady 28vdc on both sets of pins. the DC on the drive connector on VMU shows near nothing. My guess is the power module VMU.

Any tips on what else to look for?

Thank you.

 

[phunguss]

Here is a maintenance manual. It does not sound like yours are "flashes" as they are defined as 1/4 second. If it is slow pulsing, not sure what that could be.

• Two Flashes: No memory is installed or detected.
  • Troubleshooting: Make sure the RAM is securely in its slots. If no memory is installed, install the correct type.
• Three Flashes: Incompatible memory types are installed.
  • Troubleshooting: The Cube only supports PC-100 or PC-133 SDRAM, not ECC or registered memory. You can identify incompatible memory by counting the chips - an odd number suggests it's incompatible. Remove the incompatible memory.
• Four Flashes: No memory banks passed testing.
  • Troubleshooting: This could mean faulty RAM or memory slots. Check for bent pins on the logic board's memory slots and contact Apple for replacements if needed. If there are no bent pins, try resetting the logic board by removing the video card and pressing the S1 reset button

 

[François]

Did you test it outside of its enclosure? The power button is very finicky, and sometimes detects a touch when there is none. When a normally functioning Cube is put to sleep, the power led pulsates slowly, like the slow breath of a person sleeping. The problem might be the power button malfunctioning and the Cube goes to sleep directly?

 

[TJ812]

Did you test it outside of its enclosure? The power button is very finicky, and sometimes detects a touch when there is none. When a normally functioning Cube is put to sleep, the power led pulsates slowly, like the slow breath of a person sleeping. The problem might be the power button malfunctioning and the Cube goes to sleep directly?

Thank you both for your replies.

I have the bottom switch panel loose and unscrewed.

Mine is missing the grommet around the button, but I read that is ok.

is it possible to trick the unit via the connector to power on for testing, bypassing the switch?

 

[ScutBoy]

Since it seems you have one of the matching acrylic displays, you should be able to use that power button even if the one in the Cube is disconnected.

 

[François]

Do you have the USB speakers? Does the Cube chime?