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WRT54G Power Supply Chip

Discussion in 'Datasheets, Manuals or Parts' started by ParkingLotLust, Jan 3, 2007.

  1. mvs sarma

    mvs sarma Well-Known Member

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    Ok, can you parallel an extra elecrtolytic across the imput power (say 470uF )
     
  2. ParkingLotLust

    ParkingLotLust Member

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    Pardon? I dont understand what youre saying, or more off, what thats going to do.

    EDIT do you mean just connect a 470uF cap across the + and - leads coming into the board? What will that do? Im guessing filter the power? But wouldnt buzzing be more than just a dirty power supply, considering the buzzing is coming from inside the power supply?
     
    Last edited: Jan 5, 2007
  3. mvs sarma

    mvs sarma Well-Known Member

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    power brick but istead of breaking, i am trying to see whether buzzing will comedown-- if it reduces, then we may suspect the power brick. we need not spoil our asset(power brick by breaking) you can also supply external DC of suitable votage from any adjustable PSU if you have one -- this will help eliminate the possibilities, you see

    Sorry-- it may be mid night for you-- better tomorrow morning .
     
  4. dave

    Dave New Member

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  5. ParkingLotLust

    ParkingLotLust Member

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    I tried it with a computer PSU, and while it didnt buzz, the router still didnt work. I noticed something though, as marked in the picture (pink to make stuff show up). The yellow part is labelled:
    P30V
    JF34

    and on the other side:

    P30V
    IGOU or I6OU

    Voltages while hooked up to the computer psu (hooked up to 5v line):
    [​IMG]
    The other side shows 0v (in reference to ground) with or without the part (obviously without)
     
    Last edited: Jan 5, 2007
  6. mvs sarma

    mvs sarma Well-Known Member

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    Hi, perhaps the yellow part may be a polyfuse (i mean self re-setting type)

    what is the input power supply to the equipment(eqpt) ?

    now you try to see the output voltages from the regulator IC. generally it may be 5V or 3.3V in modern epqt. if this is complied we ahve to see for other failures,if any.

    check for too hot chips( unusual) better if you have a another piece for comparison. then check for failure of any line protection devices like transzorbs. generally these will be either two or three terminal devices. if they become short the unit under querry maynot function for that port and if in the common input entire eqpt may suffer
     
  7. ParkingLotLust

    ParkingLotLust Member

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    The input from the original power supply is 5v, so Im using a computer power supply, and connecting the router to the 5v rail. The bottom side of the yellow part is always 0v, even right at startup, i dont notice a difference. So if it is a polyfuse, could it be possible that something is blown and is shorting it out? Ive checked over the board with a magnifying glass, and there arent any shorts or torn traces.
     
  8. mvs sarma

    mvs sarma Well-Known Member

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    Hi, it appears, the power converter may be in the bottom plane and may be 5pin type very near to L3 torroid.

    or is it one of the 8pin dip ICs?

    whether the output is ok at saay 3.3V or so?

    FUSE F1 APPEARS GONE????
     
    Last edited: Jan 5, 2007
  9. mvs sarma

    mvs sarma Well-Known Member

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    Hi,

    REMOVE AN CHECK F1--- suspect it is gone

    also check DS1,ck1, CA3 and C3 for short-- whether any of them is warm or HOT??
     
    Last edited: Jan 5, 2007
  10. Oznog

    Oznog Active Member

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    I see no Full Wave Bridge Rectifier is apparent.
    So the supply takes in DC from the "wall wart" transformer.

    It is possible that the wall wart has either a bad filter cap or even a bad rectifier diode.

    Basically I'd rate liklihood:
    1. The big caps on the board
    2. The little caps on the board
    3. The cap in the wall wart
    4. The rectifier in the wall wart.

    You need some way to measure things. An oscilloscope would be ideal. You can measure the wall wart's DC output when the router is powered up but disassembled. You can try to measure the ripple with the AC scale on the meter but it may be very unreliable due to it being a higher freq than the meter was intended for. It'll probably read lower ripple than the actual value.
     
  11. ParkingLotLust

    ParkingLotLust Member

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    Ill check F1. No components are getting warm/hot. The power converter is a PWM chip, the small one in the bottom of the picture. It has been replaced with an equivalent chip. The one below it is the one I described on page 1, but I dont know what type it is and couldnt find any info on Google.

    As for the wall wart, oznog, it would buzz when connected, so Im using a computer power supply instead. As you can see from the picture, with the yellow thingy soldered in, the voltage of the 5v rail drops to 4.6v. With it removed, it goes back up to 5v, but breaks the circuit which would bring power to the board.
     
  12. mvs sarma

    mvs sarma Well-Known Member

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    Hi Oznog, you might have noticed that the DC input available at input of F1 is 0V at output. i presume F1 to be a polyfuse. thus it is possible that fuse is blown and evenif self resetting it wont unless the load or perhaps shrt at its output is removed( imean normalized) now see the possiblities-- hope you are also seeing the photo--- these mentioned components in my last post are all shunting to ground. if any of them is shoert it is perhaps possible that the fuse can not restore. now they could remove the supply and start a DMM check for ohms (low range) wrt ground across these points.

    also they cold gine current limited 5v supply , say witha 5ohms series resistor and try bypass the fuse wit a wire. automatically the faulty component will be revealed by thermal sense by a touch
     
  13. ParkingLotLust

    ParkingLotLust Member

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    Interesting. I removed F1 and tested it with a multimeter and it has <1 ohm of resistance, which is good. I reinstalled it, and now the torroid (or something near it) is buzzing. That CANT be good.
     
  14. ParkingLotLust

    ParkingLotLust Member

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    We've got it some more stuff worked out. It still doesnt turn on, but it doesnt buzz until I connect a multimeter to test volages, for example, across DS1 or D1. When I remove the multimeter it stops buzzing. If anyone else has any ideas, Id like to hear them.
     
  15. game.tech

    game.tech New Member

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    Hey there. I'm working on the SAME router. I thought the 'yellow' thing was a capacitor which it apparently isn't! It sure gets hot when I power it up, and then all the front led's go out. Also, I checked the power supply and found it to be 18 vac...I didn't even check what it was said to be on the case...is it supposed to be DC??? (I'm at the library and will check when I get home though)
     
  16. ben7

    ben7 Member

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    Yeah i would think that your power supply has a bad bridge rectifier in it. The router takes DC in.
    -Ben
     
  17. cento50

    cento50 New Member

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    help for my wrt54gl 1.1 power supply voltage diagram ??

    http://www.cento50 shopping.it/wrt54gl%20voltage%20voltaggi.JPG

    help for my wrt54gl 1.1 power supply voltage diagram ??
    pls help me for correct voltage ??
    thank's

    cento50
     

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