My Macintosh Quadra 700 Clean Up and Fixes

[jmacz]

Gonna try diagnostic mode next. Have to make a null modem cable first.

 

[jmacz]

Ok, made my own DB8 to DB8 null modem cable and got diagnostic mode working by jumping the two edge connectors together on the motherboard (pad 1 and pad 2). Pad 1 goes to VIA1 pin 2 (otherside of the board near the Nubus slots). Pad 2 is ground.

Gathered info:

• Machine Identification: *APPLE*00007FF40A00*I* - the I in the string identifies this as a Quadra 700
• 0x84, 0x85, 0x86 SCC Tests - passed
• 0x87 VIA Test - passed
• 0x89 Sound Test - passed
• 0x8A PRAM Test - passed
• 0x8C SWIM Test - passed
• 0x94 EGRET Test - this keeps showing a skip (Result: FFFFFFFF0000) - tried with and without ADB devices connected and it's a no go.
• 0x95 Sound Test - passed
• 0x97 VRAM Test - passed
• 0X9A SCSI Test - passed

I don't see any Nubus related tests, so unfortunately didn't get much out of the diagnostic mode.

 

[jmacz]

Hmm, everything looks fine. I have been running the system with the Radius card and I cannot reproduce the one freeze I had with it. That must have been a fluke. Tried a SuperMac card and no issues. But this E-Machines card prevents the Quadra from booting (very early in the boot process before it even looks for a disk). The same card works fine in two other IIcis. Must be some strange incompatibility? Going to put this on the shelf for now. Too many other projects.

 

[LazarusNine]

The trick here was to find a PSU with the appropriate current on the -12V line

I could not source ANY ATX psu with a rated -12v of over 0.5A

What is the implication of using an ATX PSU that only has 0.5A on the -12V line? Will it damage the motherboard, result in uncertain performance, or simply disallow the computer to function?

 

[Phipli]

What is the implication of using an ATX PSU that only has 0.5A on the -12V line? Will it damage the motherboard, result in uncertain performance, or simply disallow the computer to function?

Worst case, sound and serial wouldn't work properly.

How likely you are to have an issue depends how short you are (of the current rating, not height).

 

[jmacz]

Donor PSU: I purchased the Logisys Micro ATX 350W Power Supply from Amazon. It was small and fit all the specs.

Circling back on this after half a year.

For future readers, please do NOT get the Logisys PSU mentioned above as a replacement. I am seeing some issues on my IIcis that are using this ATX PSU. Although on paper, the specs seem ok, in practice in a IIci with multiple Nubus cards and an accelerator, I'm seeing voltage issues. I am not sure what I'm going to replace it with at this point, but just wanted to add this courtesy note to not get this particular PSU as a replacement.

 

[Phipli]

Circling back on this after half a year.

For future readers, please do NOT get the Logisys PSU mentioned above as a replacement. I am seeing some issues on my IIcis that are using this ATX PSU. Although on paper, the specs seem ok, in practice in a IIci with multiple Nubus cards and an accelerator, I'm seeing voltage issues. I am not sure what I'm going to replace it with at this point, but just wanted to add this courtesy note to not get this particular PSU as a replacement.

Does it have any adjustment? Can you tweak up the 5v at all?

 

[jmacz]

Does it have any adjustment? Can you tweak up the 5v at all?

Unfortunately, no. I have three of these PSUs right now and all of them have the same issue.

 

[Phipli]

Unfortunately, no. I have three of these PSUs right now and all of them have the same issue.

Bleh. That's a shame.

Hopefully you can find another use for them.