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President AR144 no tx rx

Discussion in 'General CB Services Discussion' started by Mk121, Sep 4, 2018.

  1. Mk121

    Mk121 Member

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    Ok so the radio powers on but that's it. No carrier on am, nothing on ssb and no receive. I did notice that when keying the mic the tx/rx light doesn't turn red. It just goes out. Also the radio did die on me and then came back to life on its own. The channel display and meter light went out for a few seconds but came back. I'm thinking the tx/rx relay circuit isn't switching? Then I thought maybe the voltage regulator is going? Any thoughts? Thanks in advance.


     

  2. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

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    When I leave an old radio on the bench for a couple of minutes from power on just to observe,

    Your symptoms alone suggest a recapping, as in a lot of the older Electrolytic cans have or are failing.

    The Quick on, to off, then on again usually means one cap after another are failing - in this case more than likely the power supply caps are causing your power supply to commit a fault sense and "trip" in a effort to reset a possible short condition.

    So looks like you have your hands full, start by buying and replacing caps and use a DVM long the way to determine if voltage appears or not.

    Try here for some guidance...

    http://www.cbtricks.com/radios/uniden/index.htm

    President too...

    http://www.cbtricks.com/radios/president/index.htm

    They are for AX - the bigger brother with SSB but should offer some help in knowing the era of technology and what may become of it...

    There may be a board or two from Uniden that will line up close to what you need.

    :+> Andy <+:
     
  3. Mk121

    Mk121 Member

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    Ok thanks Andy. Looks like I'll start working on the caps. Are all caps the same or should I stay away from the cheaper Chinese ones?
     
  4. nomadradio

    nomadradio Analog Retentive

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    I have zero data on the "AR" radio.

    I'll guess that "AR" doesn't stand for "ArmaLite Rifle".

    Tech data for that radio seems to have fallen into a black hole.

    73
     
    Robb likes this.
  5. Robb

    Robb Yup

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    Nomad:
    Aren't they similar to the 122's?
     
    #5 Robb, Sep 4, 2018
    Last edited: Sep 4, 2018
  6. Mk121

    Mk121 Member

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    Yea from what I have read similar to the pc122 and almost identical to the pc244. I have a pc244 at home that I'm going to open up and see if indeed they are the same.
    Can anyone suggest a good capacitor assortment to buy for radio work? I rather just buy a large lot instead of getting a kit for each individual radio. I have a couple radios that need attention so I'm sure it would be more cost effective to get in bulk. Thanks
     
    Shadetree Mechanic likes this.
  7. Robb

    Robb Yup

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    There are people that sell cap kits for your radio on eBay. Klondike Mike (forum member) sells these kits too, and he uses top grade caps in these kits.
     
  8. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

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    Most of the caps during that era were of the 10V types, which made them small and compact which would fit the profile and hole pinout left behind. Lead spacing and diameter profile is main importance . Their EPIC failure rates are 10 years so you're in the ballpark.

    Nowadays, you'll have to "compare" because I'm still using Sprague from the late 1990's - unused - so I too will have to gather up some in the near future.

    I bought various ranges but the better ones are also the most common values...

    1 uF 16V or greater - as long as it fits
    4.7uF 16V or greater - as long as it fits
    10uF 16V or greater - as long as it fits
    47uF 16V or greater - as long as it fits
    100uF 16V or greater - as long as it fits

    Now, you don't always need 100% correct values but the above list will help you get started...

    Many of the above values correspond to power filtering and RF bypass - which usually the DISC style ceramics handle RF and hash noises better and don't always fail but you'll need a good selection of those too usually 103 (0.01uF) 50V as well as 104 (0.1uF) 50V and of course 102 (0.001uF) 50V.

    So if you've got someone locally to help you out -that's great because they're now your best friend to keep that radio running - else eBay - but only due to convenience because I don't trust them all the time.

    Any DOT COM site direct should be ok but pay attention to the required minimum as well as flat rate shipping - I got my last ones from All Electronics Corp., it does well. As well as many of the direct sites those (name) DOT (com) ones - else eBay may soak you for shipping which you may be better off sticking with your local or buy another radio outright to replace the one you're working on.

    Why the "as long as it fits"?

    Because as the technology advanced, they left a lot of discretes behind - you should pay more attention to the pinout so it'll fit THEN worry about the working voltage - because many of them today are so common they will work just about anywhere and provide a good working value - there may be a hiccup or two in the tuning portions and you need to pay attention to those including the types, like Tantalum or NPO's. Or if working around the ACG sections, 10uF 16V is a particularly fussy one. Please take the time to identify those so as long as you can locate a schematic pretty close to it (your radio) you can see and compare for yourself and settle for, or pay for, the convenience.
     
    Mk121 and Dmans like this.
  9. William C. Colvin

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    If I am not mistaken it is the same as the ax144 which there is information for.
     

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