Transgenic X5-655

Q: PowerMac 7500 Hesitant Startup

My PowerMac 7500 has a really odd power up issue, and it's done this every since I owned it..  Too bad back in the 90's I never took advantage of the warranty and now am interested as to WHY it does it.

 

What it does, is when I press the power button, it always never boots.  It comes on, but the screen remains blank and no signal.  If I force a reboot, Command Control Power on the keyboard, then it boots up and proceeds to run without issue.  It does occasionally freeze up bad, with no mouse cursor movement, but every classic Mac I've ever used that was PowerPC has always seemed to do that.

 

I do not know why it does this though, always requiring a force reboot just to turn on..  It has done this since day one of owning this brand new, literally, but was always shrugged off cause it worked otherwise.

 

It has now since been upgraded to a 1GHz G4, with 1GB RAM, and Mac OS 9.2.2 (through some tricks), but even with all new other components on the motherboard, it STILL does this.

 

So the other day, I found another 7500 logic board.  I stuck it in, and well what do you know, it does the SAME thing!  I'm confused now.  Was this a common problem with these machines?

 

On a side note, where can I even find a OS 9 CD that will BOOT on this Mac?  I lost my original OS 9 CD that I got for it when it first came out, but every OS 9 CD I find has 9.2.2 and won't boot on it.

 

It still has it's original 1GB hard drive that is SCSI, and I really want to replace the drive, but I can't until I at least have an OS to put on it.

PowerMac, Mac OS 9.2.x

Posted on Mar 18, 2012 5:01 PM

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Q: PowerMac 7500 Hesitant Startup

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  • by Transgenic X5-655,

    Transgenic X5-655 Transgenic X5-655 Mar 18, 2012 6:30 PM in response to Transgenic X5-655
    Level 4 (1,160 points)
    Mar 18, 2012 6:30 PM in response to Transgenic X5-655

    I ran MacTest Pro on it, and it passes all 1GB of RAM perfectly.  What doesn't pass however is the SCSI controller it seems..

     

    Both logic boards do this though..  Can this truly be related, or is this something else?

     

    http://img.photobucket.com/albums/v395/Evilweredragon/IMG_0183.jpg

    http://img.photobucket.com/albums/v395/Evilweredragon/IMG_0184.jpg

  • by Jeff,

    Jeff Jeff Mar 18, 2012 11:33 PM in response to Transgenic X5-655
    Level 6 (11,559 points)
    Mar 18, 2012 11:33 PM in response to Transgenic X5-655

    I have (2) 7500s, (2) 7600s, and (4) 7300s.  I never experienced any startup quirks with any of them, and I upgraded all with an Apple 604e/233 MHz processor card, a 1 MB L2 cache card, and a 2 GB hard drive.  What you describe is often symptomatic of a very weak/dead PRAM battery.  Have you ever replaced the 3.6-volt ½AA lithium battery on the original board and on the replacement board that you recently installed?  Did you overclock the system bus with the G4 processor upgrade?  The system freeze could be caused by an electronic/mechanical problem with the old 1 GB hard drive.  Do you hear any unusual sounds when the computer freezes?  As for replacing the SCSI hard drive, you can find used pulls (small capacity), but given the age of any hard drive of that vintage, the remaining service life may be short.  Depending on the amount of $$ that you care to invest in this 7500, you could check eBay for an Acard AEC-6280M ATA-133 Mac controller PCI card.   It would give you the option of installing a much larger and newer IDE/EIDE hard drive.   The retail/universal OS 9 installer disk (white with a large yellow-orange "9" on it) should boot the 7500.  Avoid the grey machine-specific restore disks sold by many dealers.

  • by Transgenic X5-655,

    Transgenic X5-655 Transgenic X5-655 Mar 18, 2012 11:46 PM in response to Jeff
    Level 4 (1,160 points)
    Mar 18, 2012 11:46 PM in response to Jeff

    Well, being it did this brand new back in the 90's, I doubt it was a PRAM battery then, but I did just replace the PRAM battery today since it started complaining about the clock, so that's been resolved today.

     

    No overclocking on the bus, it's still 50MHz, as the Sonnet Crescendo was designed to do.  Once again though, back in the 90's wen this machine was new, it still did this.

     

    When it freezes, it just freezes, no HD activity required. Usualy when it freezes if anything, it wasn't even accessing the HD, but I was clicking on some dialog box.

     

    On a side note, I did just purchase a Sonnet Tempo ATA/100 PCI card for this Mac, so I can run a modern IDE card in it, or at least a Disk On Module, a form of SSD on the IDE bus.

     

     

    Remember, it did this  NEW back in the mid 90's..  So it's not age related.  But it could have been a defective part, but upon trying another logic board, it doesn't seem to be that, unless I got two bad logic boards in a row.

  • by Transgenic X5-655,

    Transgenic X5-655 Transgenic X5-655 Mar 19, 2012 2:58 PM in response to Jeff
    Level 4 (1,160 points)
    Mar 19, 2012 2:58 PM in response to Jeff

    Ok so I tried something..  I removed ALL cards, and all cables off of the logic board, including ram, vram, and cpu..  Turned it on, pressed on the CUDA switch.  It turned itself off as expected.

     

    I then hooked up all the stuff back to it, pressed power, and voila, it turned on first start!  Used the computer, turned it off, came back later and turned it on, and boooooo, it wouldn't turn on again.

     

    Seems CUDA related then..