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.
    Dismiss Notice

uniden washington

Discussion in 'General CB Services Discussion' started by kaos513, Dec 23, 2018.

  1. kaos513

    kaos513 Well-Known Member

    Joined:
    Apr 10, 2014
    Messages:
    1,862
    Likes Received:
    457
    hello guys I have a uniden washington has no am ,USB lsb no carrier but modulation swings is 100% and recieve works well any help would be appreciated.


     
    Sonar likes this.

  2. nomadradio

    nomadradio Analog Retentive

    Joined:
    Apr 3, 2005
    Messages:
    2,508
    Likes Received:
    2,218
    Sounds like it might be TR34. It's originally a 2SC1419, but later production might use a different type.

    This transistor is a TO-220 bolted to the heat sink panel near the right-rear corner. Should have 13.5 Volts DC or so on the collector, the center pin.

    With the mike keyed in AM, the leg nearest the front should have 6 or 8 Volts DC on it. If not, TR34 may be bad.

    See what this check turns up.

    73
     
    NZ8N likes this.
  3. kaos513

    kaos513 Well-Known Member

    Joined:
    Apr 10, 2014
    Messages:
    1,862
    Likes Received:
    457
    Final,driver and tr34 have correct readings
     
  4. Handy Andy

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

    Joined:
    Apr 23, 2018
    Messages:
    2,068
    Likes Received:
    1,864
    Well, hopefully it's something really SIMPLE , like maybe a wiring swap or something with a Blown cap preventing power from getting to the AM carrier thru D42. It's a Germanium diode 1N60 - so if that quit - threre goes the carrier but you'd have audio - so something in that line...even the AMC Sense line that feeds TP7 and TP8.

    WashingtonCobra142.jpg
    I've also found R185, that 220ohm 1/2W resistor - played with, you may want to put that back in. Or at least check to see if it's in value.
     
    #4 Handy Andy, Dec 23, 2018
    Last edited: Dec 23, 2018
  5. SIX-SHOOTER

    SIX-SHOOTER Well-Known Member

    Joined:
    Oct 2, 2010
    Messages:
    467
    Likes Received:
    365
    I have a Sam's Photofacts CB repair manual for it if you need one.I owned the radio several years ago but no longer have one nor will I be.

    SIX-SHOOTER
     
  6. kaos513

    kaos513 Well-Known Member

    Joined:
    Apr 10, 2014
    Messages:
    1,862
    Likes Received:
    457
    I felt the final get super hot so I turned it off right.
     
    SIX-SHOOTER likes this.
  7. OldTech03

    OldTech03 Sr. Member

    Joined:
    Dec 15, 2017
    Messages:
    517
    Likes Received:
    741
    Well try unsoldering the finals collector and then see if you have any signs of life coming from the driver, You know, like RF maybe even transmitting into another radio on the bench. Even if the final is bad the driver may still be kicking and it would be modulated " ASSUMING TR34 IS GOOD" so you would hear it in another test radio which I'm sure you have. I'm suggesting this based on your testing of the transistor Nomad was talking "34" about but if you are simply looking at the internal modulation meter and seeing full deflection at least the rectifier circuit for the mod meter is working and most likely some stage of the final section is might be working. which to make a short story longer most likely means the final is bad? There I Know I could have drug that out even more but I was getting carpal tunnel...
     
    Shadetree Mechanic and Robalo like this.
  8. kaos513

    kaos513 Well-Known Member

    Joined:
    Apr 10, 2014
    Messages:
    1,862
    Likes Received:
    457
    ok it doesnt get hot any more i cleaned up some bad solder job but still do not get am power or on usb and lsb .whem i turn radio off front meter does refelect back
     
    #8 kaos513, Dec 23, 2018
    Last edited: Dec 24, 2018
  9. kaos513

    kaos513 Well-Known Member

    Joined:
    Apr 10, 2014
    Messages:
    1,862
    Likes Received:
    457
    very strange now when i turn on radio front meter is pegged
     
  10. kaos513

    kaos513 Well-Known Member

    Joined:
    Apr 10, 2014
    Messages:
    1,862
    Likes Received:
    457
    i downloaded the block diagram hopefully i can get it to work
     
  11. nomadradio

    nomadradio Analog Retentive

    Joined:
    Apr 3, 2005
    Messages:
    2,508
    Likes Received:
    2,218
    Any time the meter pegs after work is done to the circuit board around the final, look for a solder bridge across adjacent foil traces. A bright light and a magnifier help a lot.

    If the meter did NOT peg before you cleaned up the soldering, this is almost certainly the cause.

    Sure would be nice if you had a way to test the final transistor. Does make it sound as if the fault that made it get hot has damaged it.

    If it checks bad, you should also check R163, a ten-ohm 1/4-Watt resistor on the final's input side. You don't have to unsolder it to do this, just place the two probes on each foil pad, and measure its resistance in the circuit. Most any reading under 12 ohms is probably okay.

    73
     
  12. 9C1Driver

    9C1Driver Sr. Member

    Joined:
    Aug 13, 2008
    Messages:
    3,143
    Likes Received:
    858
    Just a thought if I understand what you said here correctly. USB and LSB has no carrier but modulation swings to 100%. Since SSB has no carrier and is all modulated watts then your saying SSB seems to work?

    My Madison is doing this right now, AM does not work but it's perfect on LSB which is where I talk 90% of the time. Dropped it off to the local tech yesterday.
     
  13. kaos513

    kaos513 Well-Known Member

    Joined:
    Apr 10, 2014
    Messages:
    1,862
    Likes Received:
    457
    When I whistle to the mic I get only modulation in am mode only as for usb and lsb I get no audio or carrier as well but the receive works very well and all the front buttons work as well .
     
    #13 kaos513, Dec 24, 2018
    Last edited: Dec 24, 2018
  14. OldTech03

    OldTech03 Sr. Member

    Joined:
    Dec 15, 2017
    Messages:
    517
    Likes Received:
    741
    One of the reasons I didn't necessarily think that TR34 was bad was exactly for the reason that you said the modulation meter was showing modulation while not developing output, "IT STILL NEEDED TO BE CHECKED for the sake of getting that possibility out of the way" I didn't bring up the schems but, in these radios the mod meter is driven by a pure audio signal and maybe a half wave rectifier circuit that drives the meter so without TR34 working that meter most likely would not show anything or very little. This is why I focused on the final section and whether or not the radio showed any signs of RF from any stage in the final section including the pre-driver. These are not hard steps to take it a simple logical approach which often times leads you to the problem.
    So I read after posting this and went to the schems and if the meter is pegged most likely it's close to tr44 or maybe r169 is now shorted with solder.



    OldTech
     
    #14 OldTech03, Dec 24, 2018
    Last edited: Dec 24, 2018
    NZ8N and kaos513 like this.
  15. kaos513

    kaos513 Well-Known Member

    Joined:
    Apr 10, 2014
    Messages:
    1,862
    Likes Received:
    457
    Ok will check tonight and post my finding thank you
     

Share This Page

  • About Us

    The WorldwideDX Radio Forum was originally established in 2001. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. We are working every day to make sure our community is the best Radio Hobbyist's site.
  • Like us on Facebook

  • Premium VIP Member

    The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. Care to buy us a beer? We'd really appreciate it!

    Donate to us!