1. You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.

Cobra 142GTL Loud Popping Sound When Turned On

Discussion in 'General CB Services Discussion' started by DJboutit, Dec 7, 2017.

  1. DJboutit

    DJboutit
    Expand Collapse
    Active Member

    Joined:
    Nov 30, 2006
    Messages:
    423
    Likes Received:
    33
    My house flooded during hurricane Harvery today is the first day I turned on my 142gtl I am getting a loud poping sound from it. When I hooked up a coax cable to the antenna jack no antenna I get a loud popping sound I was just trying to see I could hear anything. Anybody have any idea what could be wrong I am thinking the radio might have taken a little bit of moisture from the flood??


     

  2. nomadradio

    nomadradio
    Expand Collapse
    Analog Retentive

    Joined:
    Apr 3, 2005
    Messages:
    1,129
    Likes Received:
    618
    Hmmm.

    A radio that's between 30 and 40 years old.

    Wouldn't want to underestimate how many things it might be after that many years.

    Do you know if the popping sound is coming out of the speaker? If you still hear it with the mike unplugged, it's not coming from the speaker.

    Does turning the volume down have any affect on the sound?

    If it does, this points to a problem upstream from the volume control.

    If the sound remains unchanged when the volume control is turned, that would point to a problem downstream from the control.

    This is not a fault I associate with the usual electrolytic capacitor age failures.

    Might be what's causing it, just the same.

    And if the sound is NOT coming out of the speaker, remove the top cover and look for the blue flashes that accompany the popping sounds.

    High humidity is almost as unhealthy for a radio as getting it wet will be.

    73
     
  3. DJboutit

    DJboutit
    Expand Collapse
    Active Member

    Joined:
    Nov 30, 2006
    Messages:
    423
    Likes Received:
    33
    No sound without mike it has always been this way and with a external speaker I still get the popping sound
     
  4. nomadradio

    nomadradio
    Expand Collapse
    Analog Retentive

    Joined:
    Apr 3, 2005
    Messages:
    1,129
    Likes Received:
    618
    Ummm.

    Volume control?

    73
     
  5. DJboutit

    DJboutit
    Expand Collapse
    Active Member

    Joined:
    Nov 30, 2006
    Messages:
    423
    Likes Received:
    33
    Volume control works it just makes the popping sound louder or quiter.
     
  6. nomadradio

    nomadradio
    Expand Collapse
    Analog Retentive

    Joined:
    Apr 3, 2005
    Messages:
    1,129
    Likes Received:
    618
    That means the sound is not coming from the audio power chip. If it were, the volume control would not affect it.

    Does the squelch control make the sound go away? The answer to this question might serve to narrow down where in the radio's audio circuit the noise comes from.

    73
     
  7. nomadradio

    nomadradio
    Expand Collapse
    Analog Retentive

    Joined:
    Apr 3, 2005
    Messages:
    1,129
    Likes Received:
    618
    Just realized you say the volume control makes the sound "quieter".

    Does this mean that you can't make the sound go away completely when the volume is all the way down?

    73
     
  8. DJboutit

    DJboutit
    Expand Collapse
    Active Member

    Joined:
    Nov 30, 2006
    Messages:
    423
    Likes Received:
    33
    When the volume is turned down the popping sound will not go away.
     
  9. kaos513

    kaos513
    Expand Collapse
    Well-Known Member

    Joined:
    Apr 10, 2014
    Messages:
    816
    Likes Received:
    104
    When you first turn on the radio does it make the poping sound? or the sound stays on constanly ?
     
  10. sonoma

    sonoma
    Expand Collapse
    Sr. Member

    Joined:
    Sep 14, 2005
    Messages:
    1,475
    Likes Received:
    500
    have you tried running the radio on an external power supply yet. have seen the internal supply put out to much voltage and the radio would make all kinds of weird noises.
     
  11. kaos513

    kaos513
    Expand Collapse
    Well-Known Member

    Joined:
    Apr 10, 2014
    Messages:
    816
    Likes Received:
    104
    Try cleaning the volume control with deoxit.
     
  12. nomadradio

    nomadradio
    Expand Collapse
    Analog Retentive

    Joined:
    Apr 3, 2005
    Messages:
    1,129
    Likes Received:
    618
    We still don't know what (if any) influence the squelch control has on it.

    If this radio was made in 1978 it could have the original "TA7222" audio power chip, and NOT the one with the letter "A" at the end of the part number.

    I remember some odd noises coming from that original-type chip 35 or more years ago. Pretty sure replacing it with the "A" fixed this.

    And if the chip has that letter "A" after the "TA7222" markings, that's probably not it.

    It's not just the miles, it's the years, too.

    We test for noisy electrolytic caps by bridging a new cap across each of the caps C112 (4.7uf) and and C115 (22uf). If the noise goes away or gets reduced in a big way with the new cap touching the foil pads, that one is causing the noise. C114 (47uf) is a possibility, but I can't remember seeing that one cause this fault.

    73
     
  13. DJboutit

    DJboutit
    Expand Collapse
    Active Member

    Joined:
    Nov 30, 2006
    Messages:
    423
    Likes Received:
    33
    I just want to know it is worth it to get fixed or or not. This radio has a ufo frequency hooked up to it that has nothing to do with the weird sound I am heard. I have no way to test with a external power supply I lost a of my cb radio connectors and misc items after the flood.
     
  14. sonoma

    sonoma
    Expand Collapse
    Sr. Member

    Joined:
    Sep 14, 2005
    Messages:
    1,475
    Likes Received:
    500
    do you at least have a volt meter so you could check the voltage at the main on off switch to determine if the voltage is at 13.8 volts or at least close to that.
     
  15. Robb

    Robb
    Expand Collapse
    Yup

    Joined:
    Dec 18, 2008
    Messages:
    10,340
    Likes Received:
    2,105
    That is the question you must ask yourself. Is it otherwise in good shape? Do you have the money to send it to a shop and give it the attention that it would need? That is the REAL question; isn't it? Sounds like a $150/up bill to me. Yeah; its worth it if they fix the problem, recap, and realign the radio for that much. That radio is easily worth that much when repaired right.
     
    #15 Robb, Dec 9, 2017
    Last edited: Dec 9, 2017

Share This Page