Sony APS-111 power supply Vout adjustment

Discussion in 'General Technical Questions and Answers' started by AA7EJ, Mar 30, 2010.

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  1. AA7EJ

    AA7EJ Ham Member QRZ Page

    I have this 12V / 34A power supply (came from Cisco router) and like to adjust the output to float a battery ( 13.8 V). Unfortunately the Vout adjustment shuts the power supply down at about 12.8V. There are other adjustments on the board but without a schematic or operating manual it is a challenge.
    Since this is my first switching power supply project I could use some help.
    FYI - I did Google it and found no schematic or manual.
    Any constructive comments are as always appreciated.
    Thanks for your time.
    73 Vaclav
  2. W9GB

    W9GB Ham Member QRZ Page

    This is VERY Common.

    The power supply is a Switch-mode design (SMPS) and these supplies have an overvoltage trip point wired into the supply. Meanwell 12 V supplies have that trip point ~ 12.8 and their 13.8 VDC supplies have the trip point ~ 14.5 VDC.

    Unless you are well versed in SMPS designs and IC usage, you will need a schematic. Since Cisco purchased this from Sony (OEM supplier) -- Cisco will not have the schematic!

  3. AF6LJ

    AF6LJ Premium Subscriber QRZ Page

    There maybe an over voltage protection circuit (crowbar circuit) you will have to look for that adjustment.
    Rather you can get the power supply up to the required voltage is another issue...
  4. AA7EJ

    AA7EJ Ham Member QRZ Page

    Thanks for confirming my suspicion in needing a schematic.
    I found total of 5 adjustments on the board.
    Marked “PFC V.ADJ”, “Fain ADJ”, “DC ADJ” ,”C5 ADJ”,“V.OUT ADJ”.
    If some power supply designer can give a hint what they could be that would really help.
    I just do not want to adjust some switching frequency or such, by mistake.
    I'll do some more search on net.
    As said , the over-voltage “crowbar” may be fixed.
    73 Vaclav
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