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Thread: Sproggy is ALIVE

  1. #21
    Constant Bitrate
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    Just curious, are you using Low-ESR capacitors? From the pix they look like the regular variety.

  2. #22
    FLAC Mastero's Avatar
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    Hey be sure to check out the LM1084 pinout they are different from the regular 7805 also the LM1084-5 is a 5amps regulator...

    check the diode if its connected correctly on pin 14 ...

    mastero

  3. #23
    Maximum Bitrate
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    Yah, I crossed the ground and output pins using some heatshrink to keep them from shorting... I imagine the diode is right or I wouldnt see the keyboard light up when I first plug the sproggy in (right?)

    I dont think they are Low ESR capacitors but I will check when I get home... Any idea where I could get some if I wanted to replace with Low ESR's?

    Finally, last night I replaced the 470 microfarad output caps on the 3.3 and 5 volt line with 1000 microfarad and 2200 microfarad caps I removed from an old powersupply... The only thing that happens differently now is the relay goes on then off very fast when I first hit the power button where as before, it wouldnt even turn on... Either the board needs a higher voltage (as I noticed all the lines are on the low side of nominal) or there could be some debouncing nessicary on the PS on line?

    Mike

  4. #24
    LDO
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    Mike I am with Mastero on this one, as from your pictures it looks like your diode on pin 14 is the wrong way around...hard to tell though.

    Edit: My mistake. I just had a closer look, and it looks correct.

    Edit 2: Oh never mind. Just ignore me! It has been a long night...... You can't even see your diodes on your pin 14 line....

  5. #25
    Maximum Bitrate
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    Well, the picture is very blurry but the white line is on the output side...

    One other question, why is the sense line on the max787 & maxx788 connected right after the first inductor and not the second? Wouldnt it give us a closer 5volt and 3.3 volt line if it could see the output voltage with both inductors being included?

    Mike

  6. #26
    Constant Bitrate
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    While testing the sproggy with another motherboard, I had a similar problem where the machine would start up for about a second after pressing the power button, and then shutdown. I temporarily bypassed the diode on the 5vstb and the machine started normally. I didn't have the exact diode specified, so maybe the voltage drop is too high on the one I am using.

  7. #27
    Constant Bitrate
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    I think I ordered my low ESR's from Mouser.com. They are sometimes hard to find and definitely more expensive.

    I don't know the exact characteristics, but they apparently provide a cleaner and more stable regulated output.

  8. #28
    Constant Bitrate
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    The atx spec also calls for de-bouncing the ps-on signal. This is the mechanical effect of the on switch oscillating on and off until finally latching to on. If the input is "bouncy", maybe the motherboard is going into a failure state.

  9. #29
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    well, I am gonna go home after work and remove the diode off pin 14 and move the sense line on the max chips all the way to the output pads and see what happens...

    Mike

  10. #30
    Maximum Bitrate
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    Well, I am tired of messing with the sproggy for now... I was watching the voltages when it is turned on with the computer and they all sag pretty bad...

    So I decided to make a nice little 12 volt regulator for now so I can at least use my computer in the car..

    Check it out:



    Mike

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