Nexus-s Rev2.2 & onboard IR circuit

  • Hi, all
    i was trying something with my nexus-s 2.2
    i was trying to replace the sensor of the original remote control receiver with new one , and i did it, and it worked great
    but when finalizing the circuit and while the card was pluged to my pc and running the white wire of the IR(5 VOLTS- i think) touched the ground wire, after that the IR circuit stoped responding


    i've tested the old sensor and the new one, and i can tell that they work perfectly on another remote circuit.


    i've sent pm to UFO, Thomas, and randy , and as a result for their advices i guess there is a broken transistor between the IR connector on the nexus board and the av7110 IR_IN, or the av7110 IR_IN itself is damaged.


    so, what do you think folks?
    if there is a defected transistor, how can i know it?
    i dont know how to trace a circuit, HOWEVER i have some good experience with SMD soldering (did the memory mod ,and the budget patch by myself)


    if some one who faced this problem before could send me some info on that issue , i'd be thankful


    also i want a simple site that teaches tracing and messuring circuits(in english please) .


    many thanks in advance


    mas0h..
    .

    Intel 865Perl, P4 2.4, nVIDIA GeForce 4 128 MB, WD 160 GB, Maxtor 80 GB, SBLive 5.1
    Nexus-S Rev 2.2 (4MB) OSD
    Debian Sarge ==> Kernel-2.6.10
    Fedora Core 3 ==> Kernel-2.6.10

  • Zitat

    Original von mas0h
    but when finalizing the circuit and while the card was pluged to my pc and running the white wire of the IR(5 VOLTS- i think) touched the ground wire, after that the IR circuit stoped responding


    Hm - in your PM you wrote that the red wire touched the ground. So what? It makes a big difference!


    Please check the voltage on the white (5V) wire. If it is 0V you killed the SMD resistor which limits the current on the white wire. This resistor saved your card. :D


    CU
    Oliver


  • Hey, UFO
    Actually, i cant remember which wire touched the other
    i mean, the red or the white touched the ground , or both of them.


    anyway, i did some search online, and found that a simple remote receiver unit consists of:
    -IR Receiver (Sensor)
    -Capacitor
    -Voltage Regulator
    -Resistor
    -Universal Diode


    So, by ruling-out IR Receiver (because it is not defected).
    the defected part could be one of the rest of the components
    capacitor, Voltage regulator, Resistor, and Universal diode.


    also i've tried to messure the voltage between the (Red, white) and ground while the card was running( i dont know if that is correct or not)
    by adjusting my multimeter to 20 DCV.
    and here is the result:


    the voltage between the ground and the white is 5 VOLTS
    the voltage between the ground and the red is 4.8 VOLTS


    and i tried to push any button from my remote control while messuring
    and i noticed that the voltage dropped from 4.8 to 4.3 between the ground and the red.


    that all i can do according to my little info about messuring with multimeters


    BTW, where is this SMD resistor on the board?
    i hope to hear good news from you.

    Intel 865Perl, P4 2.4, nVIDIA GeForce 4 128 MB, WD 160 GB, Maxtor 80 GB, SBLive 5.1
    Nexus-S Rev 2.2 (4MB) OSD
    Debian Sarge ==> Kernel-2.6.10
    Fedora Core 3 ==> Kernel-2.6.10

  • I found some friend who has some electronical skills, and he suggested that the transistor in the picture ( the bottom arrow ) is broken


    so i left it for him to test it and he said that it is really defected.
    now i want to know what that transistor is responsible for, you will find another one in the picture with the exact shape, and size on the top of the picture ( i've removed the defected one, so you will notice that the arrow is pointed to an empty place)


    even i cant read the nubers on it to search for it online or on some broken old boards.


    is that transistor is a voltage regulator ? or what.


    please help me


    thanks


  • The transistor inverts the signal of the ir receiver. On my Nexus 2.1 it is labelled "SA" (really hard to read so I might be wrong). According to http://www.tkb-4u.com/code/smdcode/smdcodeS.php "SA" is a BSS123 (N-channel mosfet).


    CU
    Oliver

  • Zitat

    Originally posted by UFO
    The transistor inverts the signal of the ir receiver. On my Nexus 2.1 it is labelled "SA" (really hard to read so I might be wrong). According to http://www.tkb-4u.com/code/smdcode/smdcodeS.php "SA" is a BSS123 (N-channel mosfet).


    CU
    Oliver


    Ok, now we know where is the defective part, and yes it begins with SA.


    does this mean that any transistor that starts with SA will do the job ?
    and is there any equivalents ot that part ?


    thanks, again.

    Intel 865Perl, P4 2.4, nVIDIA GeForce 4 128 MB, WD 160 GB, Maxtor 80 GB, SBLive 5.1
    Nexus-S Rev 2.2 (4MB) OSD
    Debian Sarge ==> Kernel-2.6.10
    Fedora Core 3 ==> Kernel-2.6.10

    Dieser Beitrag wurde bereits 1 Mal editiert, zuletzt von mas0h ()

  • now, i have another problem.
    when i tried to order one of these online, i found something called minimum order, and that varries between 20 and 30 $.


    can i found these transistors on any type of broken boards, like hard disk, main board, VGA ...etc


    thanks.

    Intel 865Perl, P4 2.4, nVIDIA GeForce 4 128 MB, WD 160 GB, Maxtor 80 GB, SBLive 5.1
    Nexus-S Rev 2.2 (4MB) OSD
    Debian Sarge ==> Kernel-2.6.10
    Fedora Core 3 ==> Kernel-2.6.10

  • Zitat

    Original von mas0h
    now, i have another problem.
    when i tried to order one of these online, i found something called minimum order, and that varries between 20 and 30 $.


    can i found these transistors on any type of broken boards, like hard disk, main board, VGA ...etc


    Well, how should we know what you can find on your broken boards?
    IMHO any N-channel mosfet should work.


    Look at your boards and find a N-channel mosfet.
    Using the link above you can check whether
    - a transistor is a n-channel mosfet
    - the pins are wired the same way as the BSS 123.


    CU
    Oliver


  • Hey, UFO
    calm down please, i told you before that i dont have any experience with electronics except soldering.


    i searched on my old boards, and i found 1 transistor marked 1A, so i returned to the link you gave to me:
    http://www.tkb-4u.com/code/smdcode/smdcode1.php


    and found 5 ones named 1A including this


    1A IRLML2402 IR F SOT23 n-ch mosfet 20V 0.9A


    and, the one on the card (the broken one) is


    SA BSS123 Sie M SOT23 n-ch mosfet 100V 0.17A


    actually, that is very confusing to me, i dont know if the (1A) transistor could do the job of the (SA).


    and one more thing, there are in the same table in the link above another 4 transistors beginning with 1A and are not n-ch mosfet


    for example


    1A FMMT3904 Zet N SOT23 2N3904
    1A MMBT3904 Mot N SOT23 2N3904
    1A BC846A Phi N SOT23 BC546A
    1A BC846AT Phi N SOT416 BC546A


    sorry for the long post
    thanks

    Intel 865Perl, P4 2.4, nVIDIA GeForce 4 128 MB, WD 160 GB, Maxtor 80 GB, SBLive 5.1
    Nexus-S Rev 2.2 (4MB) OSD
    Debian Sarge ==> Kernel-2.6.10
    Fedora Core 3 ==> Kernel-2.6.10

  • Thanks, it's done !
    By getting another SA transistor from the nexus board itself.
    the one connected to the big CI connector at the end of the board.
    Since, i dont use that CI connector, and i'll never do.


    And the card is running as a charm from three days with its own onboard remote circuit.


    one last question, will this affect the card on the future by anything?
    thanks again.

    Intel 865Perl, P4 2.4, nVIDIA GeForce 4 128 MB, WD 160 GB, Maxtor 80 GB, SBLive 5.1
    Nexus-S Rev 2.2 (4MB) OSD
    Debian Sarge ==> Kernel-2.6.10
    Fedora Core 3 ==> Kernel-2.6.10

    Dieser Beitrag wurde bereits 1 Mal editiert, zuletzt von mas0h ()