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Thread: NAC PSU weak voltage...

  1. #1
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    NAC PSU weak voltage...

    I hooked up my NAC PSU today to check the voltages...

    I'm getting good 120v, however my 12v was jumping between 10-10.8v, my +5v was jumping between 4-4.8v with the adjustment screw turned all the way up...and my -5v was just reading 0...unless I was using my meter wrong when i was checking for that...

    Here's some pics, it's a 400-5198-01Y:
    http://wiki.arcadeotaku.com/w/New_Astro_City_PSUs

    Astro PSU.1.jpgAstro PSU.2.jpg

    Any input on how to fix this up? Here's the numbers off the 3 chips that are attached to the heat sinks:

    K2236 5K...I think this is a voltage regulator?

    61 D15SCA4M...has diode symbols on it, I think it's a rectifier?

    58 D5LC20U...also has diode symbols on it...

    Cap list:

    50v 0.47uf
    25v 47uf
    50v 10uf
    200v 330uf
    10v 6800uf
    10v 6800uf
    16v 2200uf
    50v 10uf
    25v 100uf

    Do any of you guys have any advice on what you think I should replace to get these voltages back to where they are supposed to be??

    THE MADNESS!!!

  2. #2
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    Quote Originally Posted by ahcmetal View Post
    I hooked up my NAC PSU today to check the voltages...



    I'm getting good 120v, however my 12v was jumping between 10-10.8v, my +5v was jumping between 4-4.8v with the adjustment screw turned all the way up...and my -5v was just reading 0...unless I was using my meter wrong when i was checking for that...



    Here's some pics, it's a 400-5198-01Y:

    http://wiki.arcadeotaku.com/w/New_Astro_City_PSUs



    Astro PSU.1.jpgAstro PSU.2.jpg



    Any input on how to fix this up? Here's the numbers off the 3 chips that are attached to the heat sinks:



    K2236 5K...I think this is a voltage regulator?



    61 D15SCA4M...has diode symbols on it, I think it's a rectifier?



    58 D5LC20U...also has diode symbols on it...



    Cap list:



    50v 0.47uf

    25v 47uf

    50v 10uf

    200v 330uf

    10v 6800uf

    10v 6800uf

    16v 2200uf

    50v 10uf

    25v 100uf



    Do any of you guys have any advice on what you think I should replace to get these voltages back to where they are supposed to be??

    I have rebuilt two NAC power supplies, I start with all caps that's a must, after I check voltages and if it's not steady I change the voltage regulators. Last one I did 5v was fine, but 12v was at like 4 or less. Completely crapped out but after putting in a new one everything was great again. So start with caps then if needed swap the regulators. Not much to them so between those two things chances are you will be good to go again.

  3. #3
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    That was kind of my assumption as well...I ordered up the caps last night...

    I didn't have much luck googling the K2236 regulator though...anybody know where to find a compatible replacement for that??

    THE MADNESS!!!

  4. #4
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    Quote Originally Posted by ahcmetal View Post
    That was kind of my assumption as well...I ordered up the caps last night...

    I didn't have much luck googling the K2236 regulator though...anybody know where to find a compatible replacement for that??

    I'm sure I used an NTe equivalent if it's one I replaced, can you post a clear pic of it and I'll see if I can find the receipt in my email of where and what I bought, assuming I changed it...

  5. #5
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    Quote Originally Posted by Westcb View Post
    I'm sure I used an NTe equivalent if it's one I replaced, can you post a clear pic of it and I'll see if I can find the receipt in my email of where and what I bought, assuming I changed it...

    Yeah sure thing! I can do the repair...I'm just not smart enough to find a suitable replacement if the manufacture numbers don't match haha!

    Any idea if this controls the -5v as well? I wasn't reading anything when I tested that pin...
    001.JPG

    THE MADNESS!!!

  6. #6
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    NAC PSU weak voltage...

    On mine I didn't have to change out the 5v just the 12v, if you have the same psu as this guy I have seen several posts that said it fixed there -5v issue, it's at component IC3. Check out this link and see how he trouble shooted it. http://fgaddiction.blogspot.com/2012...gging.html?m=1

  7. #7
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    Quote Originally Posted by Westcb View Post
    On mine I didn't have to change out the 5v just the 12v, if you have the same psu as this guy I have seen several posts that said it fixed there -5v issue, it's at component IC3. Check out this link and see how he trouble shooted it. http://fgaddiction.blogspot.com/2012...gging.html?m=1
    Damn, different PSU...good read though...I'll see if I can follow it out like he did...

    THE MADNESS!!!

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