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Thread: No power off pulse.

  1. #1
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    No power off pulse.

    I just recently bought a new M4-ATX power supply for my car PC and it seems to be having issues with sending an off pulse to the motherboard’s power switch header. It turns on perfectly fine, but won’t send an off pulse when the car is turned off. I have the dip switch configured for P1, so it should send the off pulse within 5 seconds of the ACC power being switched off. I verified with a multimeter that the ACC ignition power wire does cut out to 0 volts when the ignition is turned off. I also decided to see if it was a problem with the computer by connecting the original chassis power button to see if it would turn off when I press it and it does.

    What do you guys think? Defective unit?

  2. #2
    Maximum Bitrate kegobeer's Avatar
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    Have you checked the proper polarity of the connector? Some power supplies won't operate correctly if you have the positive lead connected to the negative lead. Remove the connector, turn it around, and plug it back in, and see if the on/off cycle works.
    1999 Mercury Grand Marquis GS with: ASRock E350M1 w/4GB RAM, 80GB Intel SSD, Opus DCX3.120, Visteon HD Radio + HDR-USB, PL-18N wifi, OBDLink Scan Tool, BTA6210 BT, BU-353, Win 7 Ultimate, CF 4.0, Alpine MRP-F240 + MRP-T220, RF Punch 1572s, Kicker 8" Comp.

  3. #3
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    I did follow the instructions and connected the positive lead to the outside terminal and the negative to the inside. Would it not power up at all or fry if I had it reversed? The ACC ignition wire is tied into the center terminal.

    I saw one other post by some user who had the same problem but never got an answer. That makes me think this may be a defect. Any other ideas before I start trying to seek a replacement? Does anyone have experience working with mini-box.com support?

  4. #4
    Maximum Bitrate Mickz's Avatar
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    You could try increasing the time of power on/off pulse. It may just be on the edge for that MB.
    You need the USB connection to the M4 and the free control app to simply extend the width of the pulse.
    Make sure you disconnect +12 to the M4 after changing the setting to force it to update.
    GA-Z77N-WIFI, i5-2400S, 8GB, Intel 520 128GB SSD, M4-ATX Modified, 2 Rev Cams, 2 Web Cams
    8" 16:9 TRANSFLECTIVE, Win8-64, Dual GPS RX and Garmin PC + Odyssey Nav, FM-DAB+, BB-Rec
    T-Screen HVAC control, custom microcontrollers, code and FE. CarPC Project

  5. #5
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    Thanks for the tip, but no dice. I suppose what I can do is buy another M4, swap it out and see if it works. If it doesn't, then I'll just return it and manually hibernate the system through Centrafuse.

  6. #6
    Maximum Bitrate Mickz's Avatar
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    Yes a strange one. The fact that you can turn it on indicates that the M4 is capable of outputting the pulse. Only other thing I can think of would be to have a look, with the same app, at the delay before turnoff for Mode 1 in case it’s corrupt.

    Have you tried doing a reset of the unit? I had a problem at one time when it just went nuts, a reset to defaults (via USB command) before entering the new values fixed it.
    GA-Z77N-WIFI, i5-2400S, 8GB, Intel 520 128GB SSD, M4-ATX Modified, 2 Rev Cams, 2 Web Cams
    8" 16:9 TRANSFLECTIVE, Win8-64, Dual GPS RX and Garmin PC + Odyssey Nav, FM-DAB+, BB-Rec
    T-Screen HVAC control, custom microcontrollers, code and FE. CarPC Project

  7. #7
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    Ahhhh I was an idiot. I thought down was up and up was down on the switch so I had the switches reversed from where they should have been. Everything works perfectly now.

    I made the assumption that the power supply came from the factory with all the switches set to off, but they were actually all set to 'on' to begin with. That's what threw me off.

    Sorry about that guys and thanks for the help!

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