TS-850 Receiver Problem

Discussion in 'General Technical Questions and Answers' started by N4GKS, Oct 16, 2019.

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  1. N4GKS

    N4GKS Ham Member QRZ Page

    An issue with my TS-850. The problem caps have been replaced and a newer chip board was installed. All seemed good. It may take a few hours or a few weeks, but the audio starts distorting through the internal and external speakers. More volume more distortion. However here is the weird part. If I plug in headphones, I hear no distortion at all through them. If I turn off the radio for an hour, no distortion anywhere. Is there a cap for the speakers that could be the culprit?
     
  2. WB3BEL

    WB3BEL Ham Member QRZ Page

    The circuitry is pretty much in common for the speaker, headphones and external speaker connections.
    Other than the connections in the cables, the headphone jack and speaker itself there is little different.
    Check to see if it works fine with an external speaker.
    If that is OK, then check to make sure the wiring connections to the internal speaker are fine.
    If that is OK, then really I think all that could be wrong is that the speaker itself goes bad as the radio warms up.

    You can get the service manual from here:
    http://www.repeater-builder.com/kenwood/pdfs/ts-850s-svc-man.pdf

    The speaker connection schematic is shown on page 161. The audio amplifier is IC6 on this IF Unit board and the path to the speaker and headphones are shown through C187 and L37.

    So I see you already mention that the external speaker also does not work. Maybe there is something in the headphone jack or wiring or maybe there is something weird about C187 when used with the speakers only.
     
    Last edited: Oct 16, 2019
    KA9JLM likes this.
  3. KA9JLM

    KA9JLM Ham Member QRZ Page

    What happened to your other thread on this exact subject, Where the answer was given by the Master of Kenwood ?

    Good Luck searching for a better answer. Maybe you should turn off your ignore feature. :rolleyes:
     
    KD0CAC likes this.
  4. N4GKS

    N4GKS Ham Member QRZ Page

    It wasn’t the problem. I also place the question in a couple of places. I have no ignore on. Thanks for your help.
     
  5. KA9JLM

    KA9JLM Ham Member QRZ Page

    OK.

    It just gets hard keeping up with multiple threads, What help you have been given, And what you have tried.

    You may want to replace C187

    Good Luck.
     
  6. N4GKS

    N4GKS Ham Member QRZ Page

    Caps were replaced.
     
  7. KA9JLM

    KA9JLM Ham Member QRZ Page

    What value cap did you replace C187 with ? Was it a NP type ?
     
  8. N4GKS

    N4GKS Ham Member QRZ Page

    All I remember is increasing operating voltage from 16 to 25.
     

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