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WAG54G rev1.2, ADSL problem [hardware]

Discussion in 'Other Linksys Equipment' started by nopsoft, Jan 1, 2008.

  1. nopsoft

    nopsoft LI Guru Member

    WAG54G rev1.2, ADSL Annex-A problem [hardware]

    - hot ADM6996L chip causes hot the whole board (eth. 100Mbps does not work, only 10Mbps) - this is still not solved here
    - after power-up sequence power LED is blinking (green) and finally flashes red color, Internet LED flashes red also, ADSL does not detect the signal (ADSL LED does not flash)
    - sometimes combination of RESET button and power-up sequence makes finally power LED flashes green and ADSL works

    - high temperature causes changes in properties of capacitors (electrolyte)
    - high noise in power voltages (oscilloscope tests)

    - add on bottom of the board a small 2.2uF/25V (but here is 1.8V only) tantal capacitor parallel to C36 (33uF/16V, near huge L2 inductance in front of the board, under PCMCIA WIFI card)

    I hope it helps somebody...

    best regards
    Janusz U.
  2. HiSpeed

    HiSpeed Network Guru Member

  3. nopsoft

    nopsoft LI Guru Member


    For WAG54G rev1.2 it is C136 capacitor (near ADM chip and Y1 quartz). Because there is a little bit difficult to replace the capacitor (pad is directly connected to a huge plane of the ground) I added parallel to one 22uF/6.3V (here is 2.5V) tantal capacitor on bottom side of the board. It helps and the ADM chip is not so hot but still it is (52*C, also U18 ADSL chip is hot 48*C).
    Also after C36 modification I notified the Internet link speed-up and WiFi link is more stable (noise before?)!
    Now I have WAG54G (3 years warranty, I bought it on 7th April 2005, probably I could replace the whole router in a service but they will only paid me money back...) like new :biggrin:

    Should I care about high temperature?

    best regards
    Janusz U.
  4. HiSpeed

    HiSpeed Network Guru Member

    Temperature is bad for the lifetime of capacitors...
    This is the reason why the current MBs use now new solid capacitors.

    When a capacitor is bad it is much better to replace it !
    If it is difficult to unsold it, you can cut the pads and resold a new one.
  5. nopsoft

    nopsoft LI Guru Member

    I cut the old capacitor C136 and removed it. With 22uF tantal it works very well also. Temperature is still high :/

  6. HiSpeed

    HiSpeed Network Guru Member

    33uF should be better...
  7. nopsoft

    nopsoft LI Guru Member

    I know but I prefer to use tantalum capacitor instead of electrolyte... I haven't got 33uF currently. Tantal is better because it has smaller ESR (the old 33uF probably is not low series resistance) and it is less temperature sensitive (polymer structure instead of liquid, operating temperature is usually -40...+125*C and eg. +85*C without derated voltage). Also the capacitor reduces more noise - important here. The router was made in China - low cost -> low cost of elements also (almost all capacitors are the same!!! it is not normal in reliable devices...).
    In datasheet there is nothing about the capacitance...

    Does new router WAG54G have also so high temperature?

    best regards
  8. HiSpeed

    HiSpeed Network Guru Member

    The high temperature is proper to WAG54G v1.x only specially when wireless is on. It requires a fan on top but in summer only.
    The other WAG are less hot...

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