Introduction

Full teardown of a cordless phone and accessories from 2001.

  1. 5rvIPCA1NZQMMKHW
    5rvIPCA1NZQMMKHW
    3qB5oFAAIZyibeix
    dg6jQ6NXUm3cocIU
    • This is a teardown of a GE 27990G3 cordless phone system from 2001. Sadly, while it still works, its 2.4 GHz wireless transmitter interferes with WiFi.

  2. jDKojPpUhVLJbuJN
    jDKojPpUhVLJbuJN
    rEQbK1ALKj1g12P6
    QMUCjIlJd6gWZB1T
    • Part I: The Handset.

    • Remove the battery door on the back.

  3. ReZkGHxxPIEncEJQ
    ReZkGHxxPIEncEJQ
    g4oKgiojZunqWdSC
    uxUenHQl5mntDocS
    • Use needlenose pliers to disconnect the battery connector.

    • The battery is a 3.6V Nickel-Cadmium rechargeable battery made up of 3 AAA-sized cells

  4. X2DMXU3YKOyI1vXf
    • Remove 2 phillips screws inside the battery compartment.

  5. WRDt3MTIvmguVHkm
    WRDt3MTIvmguVHkm
    EGbFLYDTwHws5o43
    xBvOvI5hkwAS2tf2
    • After some aggressive spudgering (the pictures make it look much easier), the back of the case can be removed.

  6. fi1pLK4UaZOAlEBn
    • The charging contacts can now be easily removed.

  7. E4JXKX3jPnOQYD2l
    E4JXKX3jPnOQYD2l
    2lsW3DQQhjEBfPOq
    • Remove 2 screws on what appears to be the wireless board.

  8. uLBKkQYjxuGQitb6
    uLBKkQYjxuGQitb6
    Dnigt6l153B1nU3t
    MAOnxdljpTKccikV
    • The wireless board can be flipped up, but is still attached to the main board by a short ribbon cable.

    • Remove 2 screws on the main board.

    • Remove 2 screws on the speaker.

  9. LLLyksV2lSsfkTpZ
    LLLyksV2lSsfkTpZ
    sp4onJKqtKSxyvvY
    • The mainboard assembly can now be removed from the front case.

  10. LZtEFk1I4MuQljL1
    LZtEFk1I4MuQljL1
    cWLUoXEefIe5g5Mr
    • The wireless board is attached by a soldered and hot-glued in ribbon cable, which must be cut off to remove.

  11. HRCUEKmSRTvqIBuV
    HRCUEKmSRTvqIBuV
    ZeNUiAPrRDUOK5CI
    • Components on the main board:

    • Speaker

    • Message indicator LED

    • Ringer switch

    • Electret microphone

    • Unknown potted 'Blob' IC

    • Piezo buzzer for ringer

  12. FqBOtjlfo26PRUkU
    FqBOtjlfo26PRUkU
    pyaAHw4ekAwnD2Vb
    tb2dftBPGKmvNiuD
    • Whoever designed the wireless module really didn't want anyone to know what was inside. The very thick EMI shield is soldered, crimped, and epoxied on.

    • The shield took about 20 minutes to remove with diagonal cutters, 2 pairs of pliers, and 3 metal spudgers.

    • Needless to say, the shield is irreversibly damaged and the wireless module will probably never work again.

  13. vXgtSFsSF1MMQGCg
    vXgtSFsSF1MMQGCg
    qo2QwDqRiRotdyVY
    • Components inside the wireless module:

    • Toshiba TB31261AF cordless telephone RF chip

    • Ceramic resonators

    • Unidentified square ceramic components with 2 cylindrical holes in them horizontally (anyone who has an idea what they are, please comment.)

    • The back of the board says that it was manufactured on August 29, 2001, making the phone 14 years old at the time of writing.

    • Interestingly, the Toshiba TB31261AF is designed for a 900MHz cordless telephone, but this is a 2.4GHz model.

  14. DJVYShQ4BoXN1HYw
    DJVYShQ4BoXN1HYw
    GeBnDMSQbbSYSET5
    • Repairability score: 6/10

    • Phone is held together with only phillips screws.

    • Battery, the most likely part to fail, is a standard component and is easily replaceable.

    • Case is difficult to open.

    • Wireless module is very hard to replace and impossible to repair.

    • All wires (except for the battery) are soldered to the circuit board instead of using connectors.

  15. qM2YJtLYyKDty1RX
    qM2YJtLYyKDty1RX
    uqEqpZrJnXCn3iSe
    • Part II: The Secondary Base Station

    • Remove 2 phillips screws on the bottom.

  16. jiBHSLixDB1S3T5n
    jiBHSLixDB1S3T5n
    wDwdPsTOEqQ6nobH
    PcxNyGQEJWsL6Dh2
    • The top case can be removed with some spudgering.

  17. FZh2FnAdX3ZwglBg
    FZh2FnAdX3ZwglBg
    dSlJaXCcdJZsipBs
    FlMLMmwyXOssvIwk
    • Remove 1 screw to remove the wireless module.

  18. 5ehhlYOhB6oSDC6R
    5ehhlYOhB6oSDC6R
    SbdYcKJbsPrQnJsI
    AZFH1PkLW1MG3kE5
    • Just like in the handset, the wireless module is connected to the main board with a soldered ribbon cable. I'm sensing a theme here.

    • Remove 2 screws that hold down the main board.

  19. MLxxnuV6LsdcFE3I
    MLxxnuV6LsdcFE3I
    DnnbJNZpKNYBKKDQ
    PmeKTs2bHMWEJUlQ
    • The main circuit board can be removed from the bottom case.

    • Remove 4 screws holding in the button board and charging contacts from the top case.

  20. rGVn2kEGF4trjkyL
    rGVn2kEGF4trjkyL
    FuZSSX5RENPmJjUC
    qPX23DCXvnYsZqAR
    • The wireless module can be cut away from the logic board.

    • This wireless module is identical to the one in the handset except for the fact that it used coiled wires instead of straight wires for antennas.

  21. gf3ZXMoPlwtnFi1P
    gf3ZXMoPlwtnFi1P
    jGVmq3mIJQqOjarc
    • Remove 2 screws to remove the support for the wireless module.

    • The plastic pieces used to hold down the board can also be removed.

  22. 5CAxSKDKsIYt2Qpx
    • The button board contains a lonely button, 2 LEDs, and is connected with a soldered ribbon cable reinforced with hot glue.

    • This board appears to have been manufactured on April 17, 2001.

  23. IKvtVecqkNgnLIiD
    IKvtVecqkNgnLIiD
    wgxaChPaT6ZcmlvI
    • Components on the main board:

    • 4 MHz crystal

    • Reed relay

    • Variable capacitor

    • Small audio transformer

    • Miniature fuse

    • Varistor for surge protection

    • This board was manufactured on September 3, 2001.

  24. cSjcrsHGIFvXRB54
    cSjcrsHGIFvXRB54
    dwOOoK1AVVsU6Wwi
    • Repairability Score: 4/10

    • Secondary base station is assembled with only phillips screws.

    • Circuit boards use mainly through-hole parts, so repair of individual components is easier.

    • Case requires lots of spudgering to open.

    • Removing the board requires a long screwdriver.

    • Wireless module is very hard to replace and impossible to repair.

    • All wires and ribbon cables are soldered to the board and reinforced with hot glue.

  25. VAfg1jKXPGOytCTN
    VAfg1jKXPGOytCTN
    CwcAEGmA6sZ4YI3r
    QnMRjkAqgQQIPtxA
    • Part III: The Main Base Station

    • First step: remove 4 screws.

  26. bcES3SVOoD3xChhw
    bcES3SVOoD3xChhw
    GeDrBwRgBJxUqNXV
    GHEXnVPeGwpSBnHk
    • The case for the main base station can be opened, but it requires 2 spudgers and much more force than the other one.

    • Remember how I said soldered ribbon cables were becoming a theme here? I was right.

  27. a2RqBgBb6ZoeSyvt
    a2RqBgBb6ZoeSyvt
    i5xeyQifJqESDPE6
    • Remove the buttons from the side of the case.

  28. FLRc4NBhJvtx4B2u
    FLRc4NBhJvtx4B2u
    kkMLkBvrsNrQMaLG
    PAC1L44sTLAHm4If
    • Remove 2 screws holding down the wireless module.

    • Remove 2 more screws holding down the plastic pieces attached to the circuit board.

  29. PLFMZGnra2GEQYiL
    PLFMZGnra2GEQYiL
    knYUSxOiuRPVarhl
    • Remove another 2 screws on the other side of the board.

    • Remove the microphone from its holder.

  30. OccZgksPQd5Vff1U
    OccZgksPQd5Vff1U
    Ujj1jVeQO5jGwYUl
    YLrHIs4KbydNtNZe
    • In order to remove the board from the bottom case, you have to carefully reach in and free each one of the plastic pieces attached to the board from a clip on the bottom case.

    • All of the cables to the main board can now be cut and the wireless module can be cut off of the main board.

  31. D4L62ZHguxh1kmTU
    D4L62ZHguxh1kmTU
    dUTVvjXrSQVEdG43
    • Components on the main board:

    • LM324 Quad Operational Amplifier

    • Electret microphone

    • Small audio transformer

    • Reed relay

    • Same potted 'Blob' IC found in the handset

    • HEF4053 triple SPDT analog switch

  32. CptF1ndZVeKSHqSL
    CptF1ndZVeKSHqSL
    omEWPYknSHIVQ1oR
    • The main board in the base station has patches of an unknown yellowish-brown substance on it that appears to be some kind of weak adhesive, and it seems to be scattered in no obvious pattern.

  33. OcjxMgIPWAjEXw6t
    OcjxMgIPWAjEXw6t
    xDYBNuWOL3ojKJcZ
    • Remove 2 screws to remove the charging contacts in the upper case.

  34. JowQjM1wkVFAvm3W
    JowQjM1wkVFAvm3W
    hnoQThmuWcl331hS
    feCNxFyqTEOI4GkO
    • Remove 3 screws to remove the speaker cover.

    • This speaker cover appears to have been designed to accomodate both a low-profile speaker and a speaker with a larger magnet on the back.

  35. oLNKaadnDyYiSnyN
    oLNKaadnDyYiSnyN
    NbYBysiZaenXEZM3
    • The upper case board can be removed by removing 5 screws.

  36. 5rRVYiPsAq11NUiW
    5rRVYiPsAq11NUiW
    prVPZAsqkQPiCfij
    • Remove 4 screws on the mysterious metal box.

  37. WwnZRpduke6SMnXc
    WwnZRpduke6SMnXc
    AiHaESHyYlfDWOJX
    • The entire top case assembly can be removed from the printer after using a spudger to free the large buttons from clips in the top case.

  38. UIAcBttXjqdsokxC
    UIAcBttXjqdsokxC
    tTEpyOKTCHniGA1y
    JLgini43v5egYn4u
    • So what is inside the mysterious metal box?

    • Samsung K9F4008W0A-TCB0 512x8 Kb (512 KB) flash memory (designed for digital audio recording)

    • Crystal oscillator, covered in the same unusual substance found on the main board.

    • Unknown IC D16529CAC11CQC. Googling it turns up nothing that makes any sense.

    • This board is probably where the messages are stored.

  39. DpXxuTuq4ay1Aobt
    DpXxuTuq4ay1Aobt
    LK2PEjyXQoNH31Z4
    SZCUhLatUr64fcUI
    • The major components on the top case board:

    • Dual 7-segment display

    • LM386 audio amplifier

    • Message indicator LED

    • This board was manufactured on July 27, 2001.

    • The speaker is a standard 2" low profile 8 ohm 0.25 watt speaker.

  40. arZ4wZ2q3tJbELWU
    arZ4wZ2q3tJbELWU
    veDoNdCpkEIRei22
    • All of the boards in this phone system have terrible solder quality. I was able to cleanly remove the 7-segment display, about 20 capacitors, 3 voltage regulators, 1 transformer, and 2 crystal oscillators without damaging them using needle nose pliers.

  41. kjVv3BWrN4tCQKTO
    • Repairability Score: 3/10

    • Base station is only held together with phillips screws.

    • Circuit boards use mainly through-hole parts, so repair of individual components is easier.

    • Removing the top circuit board is difficult because the buttons are attached to the top case with clips.

    • Opening the case requires 2 metal spudgers and a lot of force.

    • Removing the bottom circuit board is difficult because the case is still attached with soldered ribbon cables.

    • Wireless module is very hard to replace and impossible to repair.

    • All wires and ribbon cables are soldered to the board and reinforced with hot glue.

  42. RgkXJdjfEheqqXnt
    • Overall repairability score: 5/10

    • The handset battery, the most likely part to fail, is a standard component and is easily replaceable.

    • Circuit boards use mainly through-hole parts, so repair of individual components is easier.

    • Entire phone is held together with phillips screws

    • Cases are difficult to open and require heavy spudgering.

    • Most parts were not designed to be repaired.

    • All wires and ribbon cables are soldered to the board and reinforced with hot glue.

jdp23

Member since: 23/08/13

1302 Reputation

0 comments