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About ADSL Splitter

By on April 14, 2009

Recently my company fax machine does not have tone and customers could not send their fax to our office. Since the internet line was working i did not suspect it was the ADSL splitter fault. Later when i used another good working ADSL splitter to confirm it i found that indeed the ADSL splitter phone circuit have problem but the modem  line was working. I opened up the splitter and found only five components inside. The splitter consists of only two resistor, one capacitor and two coils. This is a cheap ADSL splitter and cost about USD3.00.

Then i check on the components and guess what? found a small coil that have open circuit when i tested it using multimeter Ohm’s range. Here are the photos of the ADSL splitter internal section and the faulty coil:

 adsl splitter

 adsl splitter



  1. senaka alahakoon

    April 29, 2009 at 3:15 pm

    Thanks for your web information.
    I have the same adsl splitter problem.
    I want to know the values of coil , resistors and capacitors as I cant read them on my splitter box. My splitter has same as yours 5 components.
    If you can send me those I will be very much thankful.

  2. admin

    April 30, 2009 at 10:13 pm

    Hi Senaka,

    I have thrown away the cheap spiltter after i got another new one which is much more reliable and stable. As for the coil value you can compare it with another similar coil in the splitter.


  3. minimos

    April 24, 2011 at 9:13 am

    we're facing exactly the same issue.
    our splitter is simpler: a capacitor parallel and a coil serial to line.
    our problem is that since coil is faulty, the circuit is open so the phone doesn't hear the tone at all!
    do you know what is the value of coil so we can repair it?
    and i really prefer to repair it!

  4. admin

    April 25, 2011 at 5:04 am

    HI Minimos,

    Sorry i do not know the value but it has to be in the microhenry range since the coil is so small.


  5. catz

    May 25, 2011 at 1:15 pm

    Try cutting that insulation safely and check whether u can find the disconnected point very closer to the terminals. If so remove the enamal of the remaining coil and solder new wire to it. Then solder that wire to termianl.

  6. Boonyarit Tangkakarn

    July 17, 2012 at 10:09 pm

    I faced the same trouble as you are. I opened the box and found the very similar thing in the box.  I bought another one and suspiciously pry out open to ensure that I have the right one. This time, I found a better circuit design. The proper one need to have 2 transformers so that he signal will not interfere with each other.  I notice that the coil one will not last and it will eventually cause trouble. It means at the end we have to change to a new one.  From now on, when I have to buy this type of ADSL splitter filter, I will be very cautious about the circuitry design.

    • Jestine Yong

      July 19, 2012 at 8:41 am

      Hi Boonyarit,

      Thanks for the info. My office now using high speed broadband (Fiber optic lines) thus I no longer using the ADSL splitter.


  7. sally

    August 31, 2012 at 7:57 pm

    Hi friend,
    About your problem,you can choose a good adsl splitter,also you can use the fiber optic products.

  8. shekar

    October 6, 2012 at 8:55 am

    I have a nice ADSL spliter UST 0018 can any who has this please send me inside pic of am curious to know the diferance of these.

  9. friend

    January 15, 2013 at 12:27 pm

    i see adsl splitter in your web site
    i want to get circuit diagram that you show in above

    • Jestine Yong

      January 16, 2013 at 12:15 am

      Sorry I do not have the schematic.


  10. Kushan

    December 28, 2014 at 2:16 pm

    Replace these two inductors with two 4.4mHen once…surely it will works

  11. Hameed

    May 31, 2017 at 5:06 pm

    The coil value is 330uh..and the capacitor value is 0.0033mfd resistor value is 1ohm...

  12. jraju

    July 7, 2021 at 4:54 pm

    Hi, Oh, nice of you for touching inside of the dsl splitter.
    But is there a way from checking , if the splitter is working correctly to adsl and phone.
    How do we find out without opening as opening involves techniques. Normally there is no screw to be seen outside.
    If you say, I will check and then buy a new filter


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