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Thread: No Power iMac

  1. #1
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    Confused No Power iMac

    Bear with me, I am new to macs but I have a collected a bunch of stuff lately and the jewel (if it will work) is an Graphite iMac DV special edition, 400mhz slot loading machine with one problem. It will not power up. I do not know the history of this machine. Here is what I know, unit appears intact, currently no keyboard (got one coming from a friend), 1 memory card installed, no airport card, Li bat was flat, I replaced it and reset the PMU, no luck, fuse next to power suppy OK.How do I check the power supply itself? I get a faint sound like a capacitor charging when I plug in but no sound beep, humm, glow, etc when I press the power button , nor when I press and hold the power button. I am looking for any help to troubleshoot the problem so I can decide if it is worth fixing. How can I test the the system ot find the problem??

  2. #2
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    Default You should be very aware...

    And perhaps you are (since you have it apart). CRT's, any... can be deadly dangerous, even when unplugged.

    Its not worth the chances of touching something which can kill.
    MacBook Pro Uni 2.4GHz with express card slot

    iMac G5

  3. #3
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    Default

    Hi, I assume you have all the service manuals to work with.
    If not let me know.
    Imac,s are as buggy to work on as laptops IMHO.
    My trusty 333 went south a few days ago, and I had to re-assemble several times,(reinstall-RAM modules,reinstall-CPU module, etc.)
    Up and running again now.
    Best wishes,

    Dave

  4. #4
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    Unhappy

    Could be bad...

    Check this thread out, plus all the links in it.
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  5. #5
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    Default

    No Dave I have no service manuals, that would be something that would be very useful. It was a pain to figure out how to get all the layers of the case off. After the fact it would have been simple if I started in the right place.

    Yes, I know CRTs can be hazzardous to to one's health, I give them a heathly respect, reminders help me from getting complacent Thanks.

    Even if its bad, are there parts that I can use in others. and what a great learning experinece. I will go through threads you listed. After the iMac, I have a Power MAC 7500 that I what to get running. Currently I using a Beige Tower G3, 266mhz, 768mb, with a rev 2 motherboard running 9.1, that I am hoping to upgrade as best I can.

    Thanks Bob

  6. #6
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    Lightbulb

    I use the PowerLogix G3/1.0 on my Beige, ACard, runs 9.2.1 and 10.4.2. Just had to move Combo drive from G4 for DVD, and Tiger runs fine. One nice thing of the PL zif is I set the jumpers to 15x multiplier, no need for software to enable or anything.

  7. #7
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    Smile

    Service Manuals
    http://www.whoopis.com/computer_repair/
    A good link to keep,
    Dave

  8. #8
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    Lightbulb

    Also, there are a number of links in the Troubleshooting FAQ Guide in various areas.

    Apple Hardware Developer Notes (HTML, PDF)

  9. #9
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    Default

    Dave thanks, That link was excellent. I tried anothor site for "free Manuals" and down loaded 4 parts of a 7 part series on the iMac DV but when I tried to open then got nothing but unreadable character text. the file was named with a .rar at the end???
    I also downloaded manuals for G3 a desktop version. It turns out the what I have label as a Power Macintosh 7500/100 on the front of the case has a label on back that list it as a PowerPC G3 266mhz. Unfortunately this unit will power up (fan on power supply) but nothing else no LED no tone. Going through the list in the manual, checked jumpers, reseated voltage reg, process module, rom dimm etc, still nothing, so the manual says replace voltage regulator, then logic board. Any idea the cost of a voltage regulator, I hate the thought of pulling the regulator from my working G3 to test it. Are logic boards easy to come by?? I also tried resetting the Cuda chip and logic board no luck.

    Now for the iMac, looks like I need to start by replacing the power/analog/video board. I get no power to J9 or C10 and the fuse is good. any thoughts on availiblity and cost?

    Thanks Bob

  10. #10
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    Default

    Hi Bob,
    Looks like you are all over the problem
    One thing at a time for my old brain,
    Re: the Imac power/analog/video board.
    http://search.ebay.com/power-analog-...FvideoQ20board
    Should get you in the ballpark.

    Re:Power Macintosh 7500/100
    Sounds like a processer upgrade was installed if I read your post correctly.
    I would suspect bad RAM/ memory 1'st.
    But need more info...
    I would not advise spending much on this one..
    Regards,

    Dave

  11. #11
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    Default

    The service manual has section devoted to verifing the PAV, and makes the statement that most PAv sent in as Bad or DOA test out fine. then it just outines verification on the connections through out the board. They make no mention of how to actually test the board to isolate where the problem is. Any one have a way to test the board once it is removed??

    Dave the eBay link looks promising, but I still have the same question.They say the board has been check out as good? how did they do it??
    Bob

  12. #12
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    Default

    I would imagine that the unit is tested in a known working machine.
    I would also suggest contacting the Ebay seller and ask him the same
    question prior to purchase.

    Dave

  13. #13
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    Thumbs up Its Alive

    Guys thanks for all your help. The Imac lives. Although its not all back together yet it is up and running. I ended up installing a power analog video board that I got off of ebay. I was hoping to find a way to trace the problem with the board I had but could not find enough info out there. It amazes me that some people are out there trying to sell parts for far more than the whole machine is worth.
    Now any thoughts on the best OS for that machine, (400mhz, 13GB HD, 128 MB Slot load DVD) I am not sure what I plan to do with it just yet. I sort of like this old Beige G3 with its 17"monitor, cd burner, scanner, laserwriter II and its 768MB of memory. Might think of networking the whole mess.


    Bob

  14. #14
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    Thumbs up

    Nice.

    Replacing the PAV board means gutting the whole thing, which is quite a project, at least the first time through. Congrats.

    If you can scrounge up a bit more RAM to get to at least 256, I would say 10.3.9 would be good. Even 10.4 is good, but it really needs more RAM, and some eye candy that the imacs can't do because of video card limitaions.

    Verify firmware is current, and install away. No other limitaions on this model.
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  15. #15
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    Default Verify Firmware???

    How do I go about verify firmware, and how do I know what is current. I plan to Zero the hard drive and start from stratch with the operation system. I plan on using the beige G3 with OS 9.1 so I am thinking the Imac will be strickly an OS 10.? machine. I shoul have some more Memory on the way shortly.
    Thanks Bob

  16. #16
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    Default

    You have to boot to the HD (ideally with OS 9). Open System Profiler in the Apple menu, and dig around a bit in the Hardware Overview...look for Boot ROM Version (if memory serves...). If the number is lower than 4.1.9, you need to update. If it is 4.1.9, you are ready for OS X.

    Apple has a nice firmware chart that includes links for all machines that need a firmware update - not all do, but imacs are on the list.



    FYI: installing any flavor of OS X can kill an imac that has not had the firmware updated...turning it into a non-booting door stop. Or boat anchor if you prefer.



    Click on the link for the imac 4.1.9 update (they are all the same) and read through it. Pretty straight forward, but you need to boot to OS 9 and run the firmware update file from the hard drive.

    Once you are up to 4.1.9, boot to your OS X CD, initialize, and install away.
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  17. #17
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    Default

    Ok now I am a bit confused.
    1 Lets say that I have the required Firmware update on the Imac already. Can I then boot from an OS X cd, initialize the Drive "zero it" an then start the install of OS X only, without a OS 9 partition, and go on my way?

    2 The imac does not have the current firmware I download the updated firmware on my Beige G3 burn it to a disk, install it on the Imac, but wait the install for the update says it need 9.1 and the Imac is running 9.0 can I continue? All the choices listed for the firmware updates need for my Imac list 9.1 as needed not 9.0?? if the firware does install then I can boot from the OS X cd and intialize and start the install etc.?

    I am thinking that the firmware is not keep on the hard drive but is installed to the install ROM????

    Am I missing something?
    I think changing out the PAV board was easier than this software stuff, at least I can see whats going on and have pictures to follow.
    Thanks again
    Bob

  18. #18
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    Default

    In the system profiler I see under:
    Mac OS overview
    Finder 9.0
    System 9.0
    Active enabler Mac OS ROM 3.1.1

    As a side note the Beige G3
    Mac OS overview
    Finder 9.1
    System 9.1 US
    Active enabler none
    Bob

  19. #19
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    Default

    Howdy,

    OK, you are close. And yes, you need to update: Mac OS ROM 3.1.1 will not cut the mustard for OS X.

    Here's what you need. Update from 9.0 to 9.1. Here is the link to the update. Download and run it. Don't worry to much about details - we just need to boot to 9.1 long enough to update firmware.

    Once you have updated the OS to 9.1, then you can run the firmware update. Very important: you must run the updater while booted to 9.1 on the harddrive, and the firmware updater file must be on the hard drive, not a CD ROM. It does not matter where on the HD, even the desktop is fine.

    Question:
    I am thinking that the firmware is not keep on the hard drive but is installed to the install ROM????
    Yes, you are correct that the firmware lives on a ROM chip, not the hard drive. The Firmware Updater is a little self contained application that updates the information on the ROM chip. Same as flashing the BIOS in a PC, except completely automated as long as you have: the right updater and the right OS.

    So just read through and follow the firmware update instructions. After you hold the programmer button and get the firmware tone, the rest is automatic, and the machine will reboot itself after you see a progress bar on a blank screen. Once booted at the OS 9.1 desktop again, you will see a verification notification that the update was successful. If you want to see for yourself, go back and verify your ROM number again - you should see 4.1.9.



    Once that is done....



    Yes: you can boot to your OS X CD, erase the drive, install OS X, and never look back to OS 9. You will never need OS 9 again, nor do you need to partition the drive, or use any helper tools to install OS X. All slot loader imacs fully support OS X - once the firmware is up to date.

    Or you can install both 9 and 10, run 9 in classic mode, and still be able to boot to OS 9 if you like. Just remember to check the box when you are initializing with Disk Utility to Install OS 9 Drivers. If this box is not checked during the initialization you will not be able to boot to OS 9, but you can still run classic mode.
    Last edited by unclemac; 09-10-2005 at 03:35 PM. Reason: added some details
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  20. #20
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    Default Shrinkwrap Engine error

    When I down load the firmware update, afterg the download is complete I get:

    Shrinkwrap Engine has reported and error

    Error -58

    I have not tried to do anything with the down load yet , the file appears to be there. got this error both times I downloaded form the apple site?
    Bob

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