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Thread: Presslabs Psu Modification

  1. #1
    FLAC Mastero's Avatar
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    Presslabs Psu Modification

    Ok guys i am getting in to this mess of modifying the psu ...

    got the transformer thing done .. the main problem is how to connect to the optocouplers???

    i cant find any on the board or is it not there i dont understand this can anyone help me with this optocoupler thing cause then i am good to go ..

    can some one tell me where should i find this on the PSu ?


    Mastero

  2. #2
    Variable Bitrate mp3hombre's Avatar
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    Look for a 6-pin chip, 3 pins on each side.

  3. #3
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    look under the small transformers.. if its not there, then good luck..
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    register another account and you're gone for good.

  4. #4
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    In a pinch you can just connect the voltage feedback wire to the 3.3V output. You probably will have to change the feedback resistor R6 to a 220 ohm to get the range out of the potentiometer.

    For the on/off control wire you can just short it to ground to make the supply work. It won't turn on and off with the ATX switch though, so if you can find the on/off circuit on the secondary side try to trace where it connects back to the primary. With a multimeter try to find where the output of the on/off latch circuit is and connect the on/off wire there. The opto is the easiest place to connect it, once you find it connect the opto emitter to ground and then connect the on/off wire to the collector.

    Hope that helps.

    Presslab

  5. #5
    FLAC Mastero's Avatar
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    Presslab i am using a AT psu as experiment ... so i dont think it has the optocouplers ... looked very hard ..

    I just ripped the transformer ...! (NEVER have done this before)

    transformer has 3 pins on one side and 6 on the other side

    After ripping the tapes

    The 3 pin side comes first (guessing its primary )

    Three pins 1 2 3 taking in consideration the 2 is the center pin which is not connect to the PSU pcb.

    Pin 2 takes 20 wraps and connects to Pin 3

    Then there is a copper plate connected to pin 1

    Then come the time to unwrap the 6 pin side

    1 2 3 4 5 6

    Pin 5 takes 4 wraps and connects to pin 1

    Pin 2 takes 4 wraps and connects to pin 3

    Pin 3 & 4 takes 3 wraps and connects to the ground of the PSU DC side comming out from the top of the Transformer .

    Pin 5 & 6 takes 3 wraps and connects to the ground of the PSU DC side comming out from the top of the Transformer .

    so pin 3, 4, 5, 6, takes 3 wraps and comes out together and soldered to ground on the dc side of the PSU !

    Then another copper thing

    Then back to the primary 3 pin section

    Now pin 1 takes 20 wraps and connects to pin 2

    Thats it

    What do you advice / suggest i do ?

    Shall be posting the pictures tommorow.

    Thanx

    Mastero

  6. #6
    Variable Bitrate
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    ooohhhww Mastero,

    I sure hope you took my advice and noted which way the turns were wound (CW or CCW). You didn't describe it in your last post, so I'm fearing the worst....

    As you describe the prim. side I think you should have 40 turns in all. If they are connected like mine, and I think you are saying this in your post :

    pin1=> coils=> pin2(not connected)=>coils=>pin3

    If all is ok then the coils between pin1/pin2 are wound the same way around as the windings between pin2/pin3. so this means you have 40 turns on your primary side, which means that you can follow arby's tutorial (almost) to th letter...

    BTW the link you emailed didn't work, I hope you were reffering to this post...
    If at first you don't succeed.........
    destroy all evidence you tried

    for info on t6369c LCD or Presslab's powersupply check:
    http://www.namms.tk <=updated!!

  7. #7
    FLAC Mastero's Avatar
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    marjell i did take your advice and noteed the side it went ..

    dont worry about that ..

    I am just confused about which is my secondary winding?

    cause there are some going to the ground from top of the transformer..

    thanx

    Mastero

  8. #8
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    The secondard windings are everything that isn't a primary winding..

    All you have to do if double the number of windings as you wind them back on (new ones) connecting to the same pins as you removed them from..
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  9. #9
    FLAC Mastero's Avatar
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    Kid i understand that very clearly

    My problem is very confusing

    Primary side is OK (understood)

    Secondary side HUH


    Total 6 pins

    PIN 1 COILS => PIN 5

    PIN 2 COILS => PIN 3

    PIN 3 COILS => GROUND

    PIN 4 COILS => GROUND

    PIN 5 COILS => GROUND

    PIN 6 COILS => GROUND

    The point the coil leaves the transformer form pin 3,4,5 & 6 they are and soldered together to the ground on the DC side of the PSU at the same point where you connect the ground for the supply to the mobo etc...


    Now my confusing is why is there so many ground i was guessing does the psu controll the negative volts also?

    I assume the pins that dont go to the ground are for +12 and +5 as this is a AT PSU so no 3.3 ..

    Sso should i just redo the secondary winding exactly the way it was just making it x 2 and connect the PINs 3,4,5,6 to ground.
    as it was before i ripped it.

    Kinly advice !

    Mastero

  10. #10
    Variable Bitrate
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    Mastero, your inbox is full!!

    but yes, keep the secondary side allmost the same as it was, but double the number of turns, so 3=>6 turns 4=>8 turns... I guess you'll understand...
    that's all there is to it, ignore the fact if it is logicall or silly just do it. My secondary turns (ATX) were 4,7,8,10.. figure out what voltages each represents... I couldn't so I just did as it (presslabs thread) said and it work perfect...
    If at first you don't succeed.........
    destroy all evidence you tried

    for info on t6369c LCD or Presslab's powersupply check:
    http://www.namms.tk <=updated!!

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