Reset logic board

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    Posted: 19 June 2001 07:31 AM

    [Admin Note: This thread has been transplanted from our old forums. This post was originally made by George Young.]

    Dear Dave,

    I be using a PowerComputing clone: G3 750,160mb, 255MHz, 4.24gb Ultra SCSI, with ADB, serial, SCSI ports, CD ROM Toolkit drivers, no firewire or USB. I am using about 15% of available disk space.

    Recently, I have been experencing freezes at the Welcome screen during startup.

    I did a low profile format about two months ago and on June 3rd a simple format, plus running Disk Warrior, TechTool Pro 3.0.3, Disk First Aid and Conflict Catcher Demo. The internal power supply, processor and pRam battery were replaced about two months ago. Blasting the pRam and rebuilding the desktop have been included as well.

    I have heard that in addition to what I have done, that resetting the logic board may contribute to eliminating this problem. I do not know anything about resetting the logic board in respect to what it does to or contributes to the computer’s operation. The proceedure seems simple enough. Shut down the computer, remove the battery, push the power button, reinstall the battery after a full ten minute wait and then restart the computer and go to work.

    Can you tell me anything at all about this procedure? I will appreciate your comments.

    Thanking you, I remain

    Yours very truly,

    George D. Young

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    Posted: 13 June 2001 10:49 AM #1

    On 2001-06-13 08:49, George Young wrote:
    I be using a PowerComputing clone: G3 750,160mb, 255MHz, 4.24gb Ultra SCSI, with ADB, serial, SCSI ports, CD ROM Toolkit drivers, no firewire or USB. I am using about 15% of available disk space.

    Recently, I have been experencing freezes at the Welcome screen during startup.

    I did a low profile format about two months ago and on June 3rd a simple format, plus running Disk Warrior, TechTool Pro 3.0.3, Disk First Aid and Conflict Catcher Demo. The internal power supply, processor and pRam battery were replaced about two months ago. Blasting the pRam and rebuilding the desktop have been included as well.

    I have heard that in addition to what I have done, that resetting the logic board may contribute to eliminating this problem. I do not know anything about resetting the logic board in respect to what it does to or contributes to the computer’s operation. The proceedure seems simple enough. Shut down the computer, remove the battery, push the power button, reinstall the battery after a full ten minute wait and then restart the computer and go to work.

    Can you tell me anything at all about this procedure? I will appreciate your comments.

    Thanking you, I remain

    Yours very truly,

    George D. Young

    George—this problem sounds like an extensions conflict or, perhaps. a bad preference file for one of the extensions.  I recently experienced this same symptom on one of my machines and, after hours of reinstalling, troubleshooting, and such, I realized that it was a damaged “Display Preferences” file in my system folder.  While this may not exactly be the case with you, it’s possible.  There are two ways to get around this:
    [list]
    [*]Reformat and reinstall everything CLEAN
    [*]Copy new extensions into the system one at a time or use something like conflict catcher to do an conflict test
    [/list:u]
    This may or may not do it for you.  You can reset the CUDA on the logic board by shutting down and pressing the little red button on the logic board itself.  That resets more of the PRAM and such.

    Good luck!
    -Dave

     

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    -Dave Hamilton / The Mac Observer / Mac Geek Gab / Dave on Twitter
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  • Posted: 13 June 2001 05:17 PM #2

    Dave,

    I did the clean install with the simple reformat.  I had been having trouble gettintg TechTool Pro to run without freezing.  I finally achieved a good clean run with both TTP and Disk Warrior.

    I used the ConflictCatcher Demo but must have stumped my toe somehow because everytime that I ran it, I has to reset IE specifics.  I uninstalled it.

    Anyway, my start up freezes at the Welcome screen have vanished. 

    My interest in the PMU and/or Logic Board reset is now purely interest.  You wrote that this resets “more of the pRam and such.”  It is the “and such” that I want to know what is.  Can you elaborate?  I appreciate you time and help. 

    Thanks again,

    George

    <font size=-1>[ This Message was edited by: younggdy on 2001-06-13 20:35 ]</font>

         
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    Posted: 13 June 2001 07:24 PM #3

    George—

    Resetting the CUDA just resets a different section of the PRAM than the CMD-OPT-P-R does. The CUDA is responsible for the date, time and more.  I wish I had more specific details, but the documentation on the CUDA has been sparse at best, and that’s all we know.

    -Dave

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    -Dave Hamilton / The Mac Observer / Mac Geek Gab / Dave on Twitter
    When you find a big kettle of crazy, it’s best not to stir it.

         
  • Posted: 14 June 2001 06:20 AM #4

    Dave,

    Do enjoy the Mac Observer web site.  This is good reading through out. 

    Somewhere in this site is a question about format.  My 2cts holds content over appearance

    Jolly ta for the responses. 

    George

    <font size=-1>[ This Message was edited by: younggdy on 2001-06-14 09:21 ]</font>

         
  • Posted: 14 June 2001 09:22 PM #5

    Have you considered the fact that it may be bad Ram?
    I’m not totally sure (I could look it up) but your computer may be hanging at the point in the startup sequence where it checks all of the system RAM.

    You could check by removing all but one DIMM and see if it will startup. If it does, keep adding DIMMs until it freezes again. If it still won’t, then swap the simgle DIMM for another. The chances are pretty remote that you would have 2 bad DIMMs.

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    "ignorance more frequently begets confidence than does knowledge" - Charles Darwin

    What’s the difference between a Mac and a PC? Macs are designed, PCs are assembled.

         
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    Posted: 15 June 2001 06:40 AM #6

    On 2001-06-15 00:22, Photodan wrote:
    Have you considered the fact that it may be bad Ram?

    He indicated that a clean install solved his problems, but yeah, these symptoms could most definitely lead to it being bad RAM.  No doubt.  For anyone else experiencing this problem, check RAM as well.  Thanks Photodan!

    -Dave

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    -Dave Hamilton / The Mac Observer / Mac Geek Gab / Dave on Twitter
    When you find a big kettle of crazy, it’s best not to stir it.

         
  • Posted: 15 June 2001 08:12 AM #7

    Photodan,

    I did do the clean install but that was over a month ago.  I am not sure what redeemed my startup capabilities.  They stopped just after getting a good clean run with no freezes with Techtool Pro, Disk Warrior and Conflict Catcher Demo.  That was a couple of days ago.  However, this morning I rested for five full minutes on the Welcome screen before doing a
    CMMD+CONTROL+POWER BUTTON restart which danced me right through the start up.  Looks like the redemption was short lived or maybe, the five minute wait was not long enough?

    I have not considered bad RAM.  That will certainly be something that I will check when the lid comes off of this box.  Getting into this machine is simple enough.  Getting access to it to get into it is not, I want to collect as much info as possible before disturbing the tranquillity of it’s residence. THE DIMMS in this computer must be installed in pairs.  I have two 16 mb DIMMS and two 64 mb DIMMS.  Is pulling down to one DIMM still the way to go? 

    By the way, here are my computer specs.  Power Computing G3/750, Mac clone;160 mb, 255MHz, 4.24 gb Ultra SCSI, ADB, serial, SCSI ports, CD ROM Toolkit drivers, no firewire or USB, OS 9.0.  I am using 14% of available memory.

    I am hoping to get more info on the PMU chip and resetting the logic board before opening this thing up.  I used the links on this site to do more research but, so far, I still do not have a complete picture in mind as to what all this procedure accomplishes.

    Thanks for your input about the DIMMS.

    Dave,

    Thank you for the follow up.  I am confidant that to the bottom of this, we will get.

    George

         
  • Posted: 18 June 2001 08:58 AM #8

    All . . .

    I will follow up on my other post because I see a good bit of interest in this subject as depicted by the number of visits to this site.

    I found these by following the links in this web site header:  Links+Accelerate Your Mac+GOT QUESTIONS+TroubleShooting G3 Upgrades+Q:  What is the CUDA chip, when should I reset it, and how do I reset it?+CUDA Reset: Definition and How To+: CUDA Button Location and How to Get to It

    PRESENTING THIS HERE DEMANDS THAT A STRONG WORD OF CAUTION ACCOMPANY THIS POSTING.  I MUST EMPHASIZE WHAT IS POSTED BY A CERTIFIED APPLE TECHNICIAN IN ANOTHER FORUM, “You shouldn’t be mucking around with this unless you know what you’re doing. It isn’t “just like zapping the PRAM or rebuilding the desktop”. You can damage your computer if you’re not careful.”

    By the way, I have not yet used this procedure as my problem has disappeared.  I think now that it may have been caused by an extension conflict but of course cannot be sure.

    Many thanks to all here for the help, and input and for providing a great instrument for communication and knowledge and a place to exchange ideas.

    George

     

         
  • Posted: 18 June 2001 09:42 PM #9

    THE DIMMS in this computer must be installed in pairs. I have two 16 mb DIMMS and two 64 mb DIMMS. Is pulling down to one DIMM still the way to go?

    I’m afraid that I’ve never worked on a PowerComputing clone before but if its design is similar to the mac 7300 series it is not mandatory to install the DIMMs in pairs, its just a bit faster (about 10-30%).
    To be safe, you could just yank a pair to see if it helps your problem.

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    "ignorance more frequently begets confidence than does knowledge" - Charles Darwin

    What’s the difference between a Mac and a PC? Macs are designed, PCs are assembled.

         
  • Posted: 19 June 2001 07:31 AM #10

    Photodan,

    Cool.  This will work fine for assessment.  This was a G3/750 9600 series until the processor was replaced.  Then, it became an 8500 series.  Either way once inside the number of DIMMS necessary to be pulled can be.  This is a definite to do the next time the box is opened.

    Thank you for your input. 

    George

    <font size=-1>[ This Message was edited by: younggdy on 2001-06-19 10:32 ]</font>