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. OldTech03

    OldTech03 Sr. Member

    Joined:
    Dec 15, 2017
    Messages:
    435
    Likes Received:
    574
    Well, I can't hear it but if it's deep in tone maybe AC hum maybe not? As it should or might also show up on XMIT? or not, something to consider it's tuff when you can't hear it in real time. I would suspect though that it's traceable you might start by making sure it isn't originating in the stages before the volume control you have a signal tracer use it to at the volume control with the tracer on high gain you may hear something if not use an audio dummy load or sufficient resistor to eliminate the speaker so you can turn the audio up full without a speaker this is to make sure it's inducing audio phonics or harmonics of any kind on the chassis. Just some things to try eliminating some possibilities. Unless you don't see it as something that is a problem for me it would be but I'm
    O-scar C-harlie D-elta.


     
    kaos513 likes this.

  2. kaos513

    kaos513 Well-Known Member

    Joined:
    Apr 10, 2014
    Messages:
    1,786
    Likes Received:
    408
    I think that super coil has something to do with it might have to put it back.stay tuned guys I'm not giving up
     
  3. OldTech03

    OldTech03 Sr. Member

    Joined:
    Dec 15, 2017
    Messages:
    435
    Likes Received:
    574
    ?????
     
    kaos513 and Robb like this.
  4. Handy Andy

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

    Joined:
    Apr 23, 2018
    Messages:
    2,059
    Likes Received:
    1,812
    I have already NUDGED you on what needs to be done, you have work to do, and I'm still seeing you complain about it...

    So fix it...

    I showed a hint of it here...uniden washington it's # 53 in post count on the thread...

    Here's more - apparently you did not do your research very well, everyone has been trying to help you - you need to follow through...
    Squealingwhy.jpg

    Did you fix the blue wire?

    Did you replace R197?

    Both of the above are pretty much the reason you have a "Tone squeal" in your radio.

    R 197 "mutes" when the radio is in an Out Of Lock Condition, but PIN 4 goes to the rear distribution "Buss" for speaker and PA functions - that does not belong there. You should remove that wire. Then restore it to the original condition it was set for, I attached a schematic to help.

    The Blue wire Pin 4 mod bypasses the Audio Amp - you inject (Re-inject actually) the output of the speaker BACK to the INPUT which is Pin 4!
    Bluewire.jpg

    So you wondered why you had the squeal, now you should be able to more forward and get it working right...

    Happy skies!
    LaplandCurrent.png
     

    Attached Files:

    #79 Handy Andy, Dec 30, 2018
    Last edited: Dec 30, 2018
    kaos513 and Robb like this.
  5. kaos513

    kaos513 Well-Known Member

    Joined:
    Apr 10, 2014
    Messages:
    1,786
    Likes Received:
    408
    Look at my picture under the board there is a plastic coil like I removed it to eliminate the power issue but I bet the final was the issue all this time.as for the coil had to put it back to have my recieve back strange radio .
     
  6. kaos513

    kaos513 Well-Known Member

    Joined:
    Apr 10, 2014
    Messages:
    1,786
    Likes Received:
    408
    Yeah I know blue wire has been fixed
     
  7. kaos513

    kaos513 Well-Known Member

    Joined:
    Apr 10, 2014
    Messages:
    1,786
    Likes Received:
    408
    Will update tomorrow thank you everyone.
     
  8. nomadradio

    nomadradio Analog Retentive

    Joined:
    Apr 3, 2005
    Messages:
    2,239
    Likes Received:
    1,845
    Sounds like a 5-pin mike socket with a 4-wire mike connected to it.

    The whistle, or more like Popeye's pipe "toot" comes up when a mike with only one ground wire gets hooked to a 5-pin socket that has two separate ground pins.

    The Washington has a ground on pin 2 that's meant for the mike audio only. The ground on pin 4 is for the transmit/receive switching only. A mike cord with only one ground presents you with three choices.

    Hook it to just pin 2.

    Hook it to just pin 4.

    Jumper pin 2 to pin 4 and connect the ground that way.

    The "toot" in SSB receive happens mostly when the first option is used.

    I think.

    But that's what the symptom sounds like. A mike with only one ground wire.

    73
     
    Robb likes this.
  9. Low_Boy

    Low_Boy Well-Known Member

    Joined:
    Jan 21, 2010
    Messages:
    827
    Likes Received:
    263
    Wouldn't a bad cap. also show the same symtoms?
     
  10. kaos513

    kaos513 Well-Known Member

    Joined:
    Apr 10, 2014
    Messages:
    1,786
    Likes Received:
    408
    The coil below in the picture had to be re installed back to align the radio again seems the receive died after removing it.
     

    Attached Files:

  11. kaos513

    kaos513 Well-Known Member

    Joined:
    Apr 10, 2014
    Messages:
    1,786
    Likes Received:
    408
    Seems like I'm missing r197 maybe that is why I get the squeal
     

    Attached Files:

  12. nomadradio

    nomadradio Analog Retentive

    Joined:
    Apr 3, 2005
    Messages:
    2,239
    Likes Received:
    1,845
    No. R197 serves to mute the receiver audio when the radio's PLL is not locked on frequency.

    Leaving it out should not cause a squeal.

    If you're sure that the mike cord has all five wires, and the two ground circuits are properly isolated, then that's not the cause.

    But it's a common side effect of wiring a mike with a 4-wire cord to a 5-pin mike plug.

    73
     
  13. Handy Andy

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

    Joined:
    Apr 23, 2018
    Messages:
    2,059
    Likes Received:
    1,812
    If you can - better look again. The "Coil" is part of the clarifier "swinger" mod...

    No - you do not need it, but since they ripped out the part that would be in there, you have no choice at the moment...

    Not all is lost though...
    You can rebuild this, but the "Choke" has be removed so you can rework that section back to OEM and then once done, you can reinstall the mod properly - ok?

    The 10K (R143) and 470uH choke in the line needs to be there. Look over the pic - the schematic can help you.

    PC385Clarifierfix.jpg

    The swinger choke can be re-installed later, it goes in IN SERIES with that 470 uH choke - the MB3756 has RX and TX feed to here, your are missing one of the diodes - it's clipped by JP34 - more than likely its D35 or D36 of the two I presuming D35 - because it is from the TX side, so they went looking for 8V constant - that is the mess under that coil. D35 is the one from the Voice Lock.- for fun trace it back to R187 in your top photo - then review your schematic.

    Now as to why you really should have those R143 and R187 resistors in there - they are your best line of defense when it comes to drifting clarifier and temperature compensation.
    ClarifierTrim.jpg

    There is a reason why things are done at the factory that are not always on the books or schematics, simply due to linearity issues - production line feedback problem resolutions as well as mid-production changes due to lack of sourcing or otherwise...

    They did not always draw all the support parts in the same region for one particular piece of equipment. R187, which is intact - is the Pull-Up resistor for the Varactor. Green-Blue-Red - 5.6K 1/6th W. But this pull up is AFTER the Voice Lock wiper - meaning that this "Swamps" a voltage feed to raise the voltage higher to the Varactor to affect slide. LEAVE the part R187, ALONE for now. For it does serve a purpose. IT works with R143 - again part of the tuning from the Voice lock, but is a Pull-Down - part of the voltage divider the Voice Lock sends power to R187, R143 - float a voltage to the Varactor for the Voice lock side.

    So fix the thing, bring it back to stock, once that is completed, you can then decide to (or not) make changes and do the job right this time.
     
    #88 Handy Andy, Dec 30, 2018
    Last edited: Dec 31, 2018
    Shadetree Mechanic and kaos513 like this.
  14. kaos513

    kaos513 Well-Known Member

    Joined:
    Apr 10, 2014
    Messages:
    1,786
    Likes Received:
    408
    I'm almost there now I now see 2 wires that have been cut on front panel below is the picture
     

    Attached Files:

    #89 kaos513, Dec 31, 2018
    Last edited: Dec 31, 2018
  15. Handy Andy

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

    Joined:
    Apr 23, 2018
    Messages:
    2,059
    Likes Received:
    1,812
    Those two are for you Clarifier/Voice Lock. Orange is the one that goes to R415 - and then to GROUND.

    The White Red stripe is the SOURCE from RX side (means that it only has voltage when in RX)- else it DIES on TX - So that board supplied the power and offset trim resistance for the Voice lock pot.. ORANGE is your RETURN wire from Voice Lock back to board and to the offset resistor 3.3K THEN to GROUND.

    So they sourced constant from somewhere else - more than likely direct from the Pin 1 of the MB3756. It's in another one of your photos see (Red wire) the foil side...When all they had to do is unsolder White / Red stripe wire and re-source it back to the PLL's own sourcing by L501 - that Ferrite Bead - and relocate R187 across Source ... From L501 - ACROSS - to wiper as pull up offset - everything else could be left alone.

    This is a best guess, but you will need to rework R187 - make a decision to restore ORIGINAL condition and keep R187 in place or REMOVE R187 and REINSTALL across SOURCE and WIPER for Voice Lock pot AT THE POT

    The board has all the rest of the support parts to RECENTER your Voice Lock pot if it still has one - that 3.3K is the offset trim resistor to force the pot to slide more towards positive voltage range towards SOURCE.

    VoicelockRebuild.jpg
     
    Shadetree Mechanic and S&W357 like this.

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!