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cobra 29 wx nw st

Discussion in 'General CB Services Discussion' started by randl, Jun 18, 2017.

  1. randl

    randl
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    I received a cobra 29 with burnt out finals. I put a mosfet kit in it. The IC4 audio chip gets very hot. I replaced the chip and it still gets hot. I checked the solder joints and they look good. I don't know if the IC4 is getting hot from what I did or from the previous damage. Any ideas on where to go next?? The IC4 chip has 12.6 volts across the the terminals. Is this to high?//


     

  2. Bow

    Bow
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    Bastard Modulation Engineering

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    You replaced the IC, did you put the thermo-grease on it before mounting it?

    You need a copy of this:
    http://www.cbtricks.com/radios/cobr..._st/graphics/29ltd-st_29wx-st_sm_pg1_pg11.pdf

    http://www.cbtricks.com/radios/cobr...st/graphics/29ltd-st_29wx-st_sm_pg12_pg34.pdf

    it has the voltage charts in the Second link

    And he is some more 29 porn for you...

    http://www.cbtricks.com/radios/cobra/29ltd_29ltd_st_29wx_st/graphics/cobra_29ltdwx-st_29ltd_sch.pdf
     
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  3. randl

    randl
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    Yes, I did put the thermo grease on them. Thanks for the links!!
     
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  4. Bow

    Bow
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    Bastard Modulation Engineering

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    Yes sir!

    Hope it is helpful.

    The Good news is, its a 29.... there is SSSSOOOO Much information on those, should be a great project to get going again.


    I'm currently playing with an Old Superstar 3900, and a SBE Catalina II 23 channel!
     
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  5. randl

    randl
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    This is the first radio I am working on. It was a freebee. It was not working when I got it.
     
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  6. Bow

    Bow
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    Bastard Modulation Engineering

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    Well, there you go.

    If you play your cards right, you might get a great radio for the price of a couple components, your time, and your sweat.

    Post up your findings as you go and I'm sure someone else may chime in with ideas
     
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  7. randl

    randl
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    Yes, I am determined.
    It is frustrating. I found out that with the different models of cobra 29 that the wire diagrams and audio chips are different. I am having a hard time finding the right wire diagram for my model. Unfortunately, I don't have to much spare time. But, I will keep posting what I find.
     
  8. sonoma

    sonoma
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    here is about every radio that cobra has put out. even has a wiring diagram for the 29radios. see if you can find what you need here. shows all the chips used by cobra. I have used this info for about every cobra 29 I have ran across. it also has the info for the newest cobra 29 radios. I put the wiring diagram here for you also so you do not over look it.

    http://downloads.cobra.com/CB/Models/29-SERIES/

    http://downloads.cobra.com/CB/Models/29-SERIES/29LTDwiring.pdf
     
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  9. randl

    randl
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    Thanks very much! It is very helpful.
    The one thing I have not been able to figure out yet is where it shows capacitor C42. On my radio it is actually C41. And where the scamatics show C44 mine is C39 no matter what year the radio is.
    I will keep posting. This is a slow works in progress for me.
     

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