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Reading pin out voltages

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Rottingfishguts
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2024/10/02 07:41:45 (permalink)
I have a Supernova 750 G2 80plus gold Power supply.  I recently had a lightning strike that took out my mother board but the power supply appeared to be functional.  I put the paperclip in the two pins to activate the supply and take voltage readings.  Some pins are spot on while a few are not.  Are these voltages always supposed to be steady and will reading with a digital voltmeter have an effect on them?  It seems strange that one pin that is marked 3.3 volts is right on while another that is also supposed to be 3.3 is 1.5.  Don't they all connect to the same 3.3 volt source?  My CPU pins are all 12 volts as they should be but the pins on the motherboard connector that are supposed to be 12 are 6 and 1.5.  Again, don't they pull from the same source?  I just want to confirm whether this is a condition of reading with a digital meter or I do have some kind of internal failure of the PS.
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    Cool GTX
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    Re: Reading pin out voltages 2024/10/02 07:44:08 (permalink)
    Welcome to the EVGA Forums


    Sorry to here about your lightning damage.  Might be time to review your renters/ homeowners policy for coverage
     
    Consider having a licensed electrician check your entire property for damage to appliances like your HVAC, refrigerator, outlets, wires ....... 
     
    I've had lightning strike a rain gutter downspout on a home before & the amount of damage can add up; licensed electrician inspection adds peace of mind & is a requirement for most insurance claims
     
    Was the PC & network connection protected from surges?  How was it protected?


     
    I've seen a PC get zapped through the unprotected network cable, even though PC was connected to a UPS
     
    Digital meters are usually too slow to pickup quick changes, so analog meters can be better for troubleshooting
     
    I'm not sure if the PSU is toast; though it sure sounds like it.
     
    Your test lead contact quality when testing (or lack of) can make an impact at low voltages
     
    Place a small load on your PSU -- think fans or AIO & test again, also test any removable drive
     
    Remove MB from case to test.... place on cardboard or other nonconductive surface & inspect MB closely with a good light ..... a damaged USB, drive ... can all stop a MB from working ..... the naked bench test is the best way:  MB, CPU & cooler, 1-RAM at a time.... does it boot, unplug & add GPU - then test,  next test add mouse & KB
     
    ck your PC case for sign of arcing ... the peripherals could be damaged
     
    FAQ How do I test my power supply?
     
    FAQ What are the voltage tolerances of each of my power supply's rails?
     
    ATX standards specify that power supplies have a +/- 5% maximum variance tolerance on each rail. For each rail, the voltages should be in between:
    5 VDC
    +4.75 V to +5.25 V
    −5 VDC
    –4.50 V to –5.50 V
    +12 VDC
    +11.40 V to +12.60 V
    −12 VDC
    –10.8 V to –13.2 V
    +3.3 VDC
    +3.135 V to +3.465 V
    +5 VSB
    +4.75 V to +5.25 V
     

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    Rottingfishguts
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    Re: Reading pin out voltages 2024/10/02 08:33:24 (permalink)
    Thanks for the information.  By "rail" does that mean that all 12 volts fed to different pins is coming from a single 12 volt source, same with 3.3, 5 volts, also?  If this is the case, then I have another issue since not all my 3.3 Volt pins are 3.3 but SOME are. Any of the voltages that are off are off by a significant amount.  I'll dust off my analog meter and see if that changes things.  Currently, with the PS attached to the motherboard, no fans driven off the MB function.  Could also be that the chipset got fried but I'm sorting one thing at a time.  Doesn't seem like anything controlled by the MB is working except it does turn on the PS.
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    Cool GTX
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    Re: Reading pin out voltages 2024/10/02 10:46:21 (permalink)
    EVGA - Product Specs - EVGA SuperNOVA 750 G2, 80+ GOLD 750W - spec sheet
     
    correct single rail PSU (advantage, you do not have to manually balance (move) your device loads across several rails)

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    chrisleviss
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    Re: Reading pin out voltages 2024/10/02 19:39:51 (permalink)
     
    It sounds like your power supply might have taken some damage from the lightning strike. The voltages should be stable when using a digital voltmeter, so if you're seeing significant differences (like 3.3V on one pin and 1.5V on another), that suggests an internal failure.
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    post edited by chrisleviss - 2024/10/02 19:52:35
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