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Where to find a replacement T1 for cobra 29

Discussion in 'General CB Services Discussion' started by longhaireddwb, Nov 15, 2017 at 2:11 AM.

  1. longhaireddwb

    longhaireddwb
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    W9WDX Amateur Radio Club Member

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    That pretty much is it. I found that T1 on this Cobra 29 LTD Classic is bad and I need to buy a replacement. Part number EI-28. Anyone know where to buy one? I know its bad as I took one out of another working radio and swapped it out and it came to life. Audio once again. But I'd like to have both radios working. Ha.



    BTW, The 25 I had been working on a month ago I gave up on. Its parts now.
     

  2. kopcicle

    kopcicle
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    Well for one audio output transformer failures behind a TA7222 are quite rare. Have you tested the windings out of circuit?
    The 25 uses the same output transformer ...
     
  3. longhaireddwb

    longhaireddwb
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    W9WDX Amateur Radio Club Member

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    The number on the transformer from the 25 are not the same. Now I guess its possible its the same one. But different numbers so I didn't try it.

    As far as why the transformer went bad...Someone ran the radio with a bad antenna for a long period of time. Took out the Driver and the D8 diode along with the transformer. Caps tested good but the resister that is connected to the driver was burnt toasty!

    Thanks for the reply.
     
  4. kopcicle

    kopcicle
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    I'm not positive but at first glance and my feeble memory the circuits are near identical. I found both schematics on CBTricks.

    Sry for the insta edit . I have seen several diode failures and the audio output cap fail but you have to all but weld the final to do that . Upgrade the cap and of course the diode is an easy test. Not like I don't believe but test T-1 out of circuit to be sure :)
     

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  5. longhaireddwb

    longhaireddwb
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    I believe your right as I've got both service manuals but with the different part numbers... Guess its worth a try. Dont think its going to hurt anything to give it a go.
     
  6. nomadradio

    nomadradio
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    Analog Retentive

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    Three good ways to toast the Cobra 29 audio transformer:

    1) MOSFET final

    2) 10 Amp fuse

    3) Or better, both.

    A junk radio will probably be the simplest route. It's a part that doesn't frequently go bad, so a 5 or ten buck yard sale radio is probably a safe bet for that part.

    73
     
  7. 338_MtRushmore

    338_MtRushmore
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    I have a parts 29 that you can have transformer if I can find it. I'll give a good look for it tomorrow

    Edit: mine is stamped TF-129 ?
     
    #7 338_MtRushmore, Nov 15, 2017 at 5:44 AM
    Last edited: Nov 15, 2017 at 6:26 AM
  8. longhaireddwb

    longhaireddwb
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    Thanks for the offer of the part but that is not the right number. Guessing I'll do some testing to see if there really is a difference between these transformers. They might have the same values in the end, just different numbers for the different radios. Who knows.
    I should be able to find another used radio around somewhere. I bet a new transformer, if possible to find, would cost as much as 20 bucks. Thanks for all the help and reply's on this.
     
  9. unit_399

    unit_399
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    EL CAPO

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    The transformer from a 25 is the same as the one in a 29. Maybe stamped with a different # but still the same.

    - 399
     
  10. longhaireddwb

    longhaireddwb
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    Great. Thanks for letting me know. I'll give it a try. When I get the chance. For now at least I know what the issues are and both will come to life soon.
     
  11. kaos513

    kaos513
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    i have 29 for parts if you need pm me i recently sold a user on here the audio chip. i just ask to pay shipping fees thats all if your intrested.
     
  12. 2315 Robert

    2315 Robert
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    Kaos sent me a working part. The radio I put it in has a gnarley final. Told Kaos that it was going to be my bench radio. Little to hot for that. Yes he only asked for shipping fees tip that man.
     

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