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Thread: DOA Main Board?

  1. #1
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    I'm about to either get some money back, or make a HUGE fool out of myself, so I thought I'd check by here first before I do something embarrassing. I have a beige G3 Rev 1 and wanted to upgrade it to a Rev. 3. I purchased the ROM Module, which works fine, and I purchased a Rev. 2 Main Board, which doesn’t work so well.

    In fact, I can’t get any reaction whatsoever from the thing. I purchased it off of eBay and it was delivered, sealed in an anti-static bag, and was well-packaged. As I am upgrading several components simultaneously, I wasn't able to conclude with 100% assurance that the problem was with the Logic Board. After making other purchases in search of a work-around, I feel I've been able to isolate the problem as this Rev. 3 Logic Board.

    Briefly, when the Board was installed, there was no evidence that any electricity was moving through it. I tried several different configurations, adding and removing PCI cards, RAM, hard drives and floppies, and swapping out the Logic Board Battery with a new one. None of these changes had any effect. I tried turning the computer on from inside the case, to make sure the button on the case actually made contact with the switch hooked up to the Main Board. I held down the CUDA button for half a minute hoping that would do something. I also plugged in an ADB keyboard and tried to turn the system on using its power key. Not one of these procedures yielded so much as a sound or any fan activity. It was literally as if it hadn't been plugged in, which I double-checked.

    The vendor assures me the board was operational when it was shipped and suggests that perhaps I shorted something out by being careless. I suppose anything is possible, although I did use a grounding wrist strap. But even so, I would expect to see SOME activity; SOMETHING should’ve blinked, squeaked, or popped, right?

    Thanks for the input!
    -Christopher

  2. #2
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    Christpher,

    Beige G3s have been known to have Voltage Regulator issues. Sounds like something is causing a no power situation, which shouldn't really be the mobo.

    You might download the service manual and do some testin' to see.

    You can get the manual at: http://home.wanadoo.nl/manual.man/manuals.html


    Hope that helps, sounds very frustrating being you right now.

    Rick

  3. #3
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    There's a jumper on the Beige G3 boards to set it to use the Apple power supply or a standard ATX power supply. Perhaps that jumper is set to teh opposite of how it needs to be?

    I don't know where the jumper is located, but I just read a thread about it somewhere. Oh, yes, I think on the XLR8yourmac formums in the Case Mods section.

  4. #4
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    Great! I'll be sure to check up on both of those things. I think I read something about that jumper setting, too. In fact, that would probably do it. But if that isn't the issue, would it be safe to assume the board was DOA? I mean, if I had inadvertantly zapped something important on the logic board, wouldn't I still expect the fans to start up, if nothing else?
    Thanks again,
    Christopher

  5. #5
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    It depends on what you may have zapped. And I"m not that familiar with the Beige motherboard. On a PowerSurge machine (x500, x600) you can destroy almost everything except the CUDA chip (341S0788) and the machine will still power up the power supply, though it won't bong, etc. You can even leave out the CPU and RAM and it will power on.

    I don't know if the Beige power circuitry is the same way. Are you sure that your power supply is good?

  6. #6
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    The jumper setting did the trick!
    I double-checked my Rev. 1 motherboard and found that it had been set to the ATX PS configuration. My computer must have been sold to me with a non-Apple power supply because I never made that change. At any rate, I took the new Rev. 3 motherboard and moved the jumper from the Apple setting to the ATX PS setting and it booted up just fine.
    But now I have another fear. I can't get any response from RJ45 connector. I am using a cable modem here and left all settings the same but was receiving no signal after I switched boards. I have since re-checked the TCP/IP settings numerous times and I know they are correct. Is there some test I can run to check the ethernet port? I don't have any spare PCI slots, so I really need this thing to work.
    Thanks,
    Christopher

  7. #7
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    Glad that worked! Thanks for reporting back. The feedback is useful.

    On the ethernet thing, I'd say to check the usual stuff. Does the ethernet cable, etc. work with your old motherboard?

    Also, does the Beige G3 have an AAUI port? If you're sure all your cable and configuration are good, you might wish to pick up an AAUI to UTP transciever and see if the AAUI port is working if the RJ45 isn't, assuming the Beige has an AAUI port.

    Oh, on testing, if you have another Mac and an ethernet hub or a cross over cable, hook the two together and see if file sharing works. Be sure to set the AppleTalk control panel to Ethernet. That will at least tell you if the ethernet port is working. If it is, then you can look to your TCP/IP stuff for the problem. If it isn't, then it's that much more likely the problem is in your ethernet hardware (though it still could be the cabling).


    [This message has been edited by trag (edited 08 April 2002).]

  8. #8
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    I seem to recall that ethernet, or other devices on the PCI bus could sometimes act weird if you had the bus set to 83 MHz (instead of the default 66 MHz). If you're overclocking, that's something to check. While this motherboard can be set to 83 MHz, not everything always works okay at 83 MHz.

  9. #9
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    That's interesting...

    I would assume that the jumper block I have is valid; it’s the one off of my Rev. A board, and therefore is probably set to the 66Mhz configuration. But maybe I should try a new one. I was disappointed to learn that XLR8 doesn't supply bus jumper blocks anymore (I think I saw a picture of one of theirs equipped with dipswitches for each connection.) as I was hoping to tinker around with different speeds. Does anyone know off hand where a jumper block like this can be found?

    Unfortunately, I don’t have another Mac around to test the Ethernet port via Appletalk and no, I don’t have an AAUI port either. The cable is probably good because it is the same one I have been using all along. In fact, the only variable that changed was the Ethernet port (via the motherboard). I really don’t know how these things work. If the port has been hit with some static electricity, does that mean that the circuitry is physically damaged, or would I be able to flash it with some firmware update, assuming it exists, to bring it back to life?

    Thanks once again,
    Christopher

  10. #10
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    I thought all XLR8 ZIFs had jumpers. Is this what your refering to? The jumpers control the ratio that the cpu runs to the motherboard ram bus speed. The ram bus speed is controlled by the jumper block on the motherboard.

    What do you have installed as a cpu in your G3?

    Rick

  11. #11
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    I'm currently in the process of upgrading my system from a Beige G3 233 Rev. A to an XLR8 G4 500 (Beige Rev. C). I want to make sure, however, that every component is working before I throw them all together. I have the XLR8 package, but have yet to install it. I am currently working on the motherboard.

    You are right, ricks, the XLR8 G4 CPU does come with jumpers for the processor itself, but I remember hearing somewhere here that system performance might be better achieved by speeding up the system bus itself. The jumper configuration I'm currently using for the system bus came from my Rev. 1 motherboard, which is therefore probably 66MHz. I was interested in trying other bus speeds and heard that a jumper block to do so generally shipped with XLR8 packages.

    At any rate, with regards to the Ethernet port, I tried a couple of extension updates from Apple with no success. I'm interested in seeing if changing the system bus setting, as ndp suggested, has any effect. Does anyone know if a jumper block like the one I described in my last post exists, or was that another one of my hallucinations?

    -AR

  12. #12
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    Christopher,

    This is the XLR8YourMac page on the jumper block settings for the Beige G3
    http://www.xlr8yourmac.com/G3_OC/tims.html

    I disagree with your statement that changing the jumper blocks, and in doing so changing the motherboard speed, is the best way to speed up a Beige G3. In changing motherboard speed you change ALL your speeds including RAM, memory controller and PCI bus. Lots of stuff may not work when you do that. It comes down to a minimal gain in performance versus all the hardships that come with everytime you install a PCI card wondering if the mobo speed is why it won't work.

    Certainly folks have had success boosting motherboard speeds. All the way to 83mhz in some cases. More folks have not had success. Also, you will probably need at least PC100 ram to do this. You may not benifit your cpu speed at all. CPUs are rated to run at a certain maximum no matter what the ram speed is. Boosting the mobo speed to 75 will mean you will have to turn down the CPU speed to the CPUs operating range. A 500 G4 is not likely to run at 575.

    Stability is more important than a 7% increase in performance. Before you try overclocking I would seriously consider setting up at stock speeds and getting the whole thing stable and burned in. Then working your way up slowly to a higher bus speed can be tried, usually by slowing down the cpu first so you'll be able to tell what component fails to operate at a higher speed.

    You mentioned XLR8 including jumper blocks to control motherboard speed, that's only on the carrier cards(and those are actually switches).

    Your Beige G3 only takes the zif portion of the upgrade unlike the older daughtercard Vintage Macs. With the vintage Macs the switches that control motherboard speed are on the adapter card that converts the daughter card slot to take a zif. The only jumpers on a zif (and only XLR8 zif at that) are to set the cpu to bus ratio. There are only four jumper positions on the zif and on the Beige they set the ratio from 4.5:1 to 8:1.

    Wish I had some way to help on the ethernet problem, I'm wrastling with the same thing with a Macally 100baseT PCI card in my 8500. It lights up but won't connect no matter what I do. I know everything else works because I can switch the cable to the 10baseT built in and connect no problem. Oh well, such is the life of a computer junkie, huh?

    Good luck, ought to be fun setting this up to run.

    Rick

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