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Kenwood TS-450 Final Bias adjust

Discussion in 'Troubleshooting and Repair' started by Heliman, Nov 5, 2016.

  1. Heliman

    Heliman

    65
    13
    Feb 4, 2016
    I'm replacing the finals (2SC2879) in my Kenwood TS-450. The service manual described how to set the idle current using VR1 and VR2. My question is, where in the circuit is the ammeter connected. Ive been told by some to connect in series with the 12v line in but the manual says ANT on rear panel.
     

    Attached Files:

  2. davenn

    davenn Moderator

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    Sep 5, 2009
    what page/section in the manual did you read that ?
     
  3. Heliman

    Heliman

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    Feb 4, 2016
    Its in the service manual. I included a snapshot of the page.
     
  4. Heliman

    Heliman

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    Feb 4, 2016
    I'm sure the manual is in error. The snapshot I provided shows the final bias setting. The column shows measurement taking at rear panel on ANT terminal
     
  5. davenn

    davenn Moderator

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    Sep 5, 2009
    that's why I asked you to clarify, and I did find the manual

    it doesn't say in your above clip anything about measurement at the antenna .... really not sure where you are getting that from ??
     
  6. Heliman

    Heliman

    65
    13
    Feb 4, 2016
     

    Attached Files:

  7. davenn

    davenn Moderator

    13,330
    1,769
    Sep 5, 2009
    ahhhh

    hmmmm OK I see how that was read .... wonder of the horizontal dividing line was supposed to continue across
    between 4 and 5 ?

    I am not at home so don't have the manual handy, but I doubt that you will get a DC bias reading at the antenna
    because of series capacitors in the output filter stages
     
  8. Heliman

    Heliman

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    Feb 4, 2016
    I know, that's is what is confusing. Im sure its a misprint or even a error in translating the manual from Japanese.
     
  9. davenn

    davenn Moderator

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    Sep 5, 2009
    just downloading the manual again

    have you read anywhere in the manual the actual text for the measurement procedure,
    surely there is something more than just a test table layout ?
     
  10. Heliman

    Heliman

    65
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    Feb 4, 2016
    There's two 12 volt lines coming from the 12 volt in jack. 1 goes to the collector of the finals and the other goes to the on/off switch. I'm just going to put the ammeter in the line going to the finals.
     
  11. Heliman

    Heliman

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    Feb 4, 2016
    Havnt seen anything in the manual other than that image I uploaded
     
  12. Heliman

    Heliman

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    Feb 4, 2016
    This service manual is the poorest service manual Ive ever seen
     
  13. Heliman

    Heliman

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    Feb 4, 2016
    I looked at the service manual to my Kenwood TS-2000 and its really clear as what to do
     

    Attached Files:

  14. elebish

    elebish

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    12
    Aug 16, 2013
    Just hook an ammeter in series with your 50 ohm dummy load at the antenna terminals. I believe 250 Ma is the reading at idle according to you jpg sheet.
     
  15. davenn

    davenn Moderator

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    Sep 5, 2009
    That doesn't sound correct .... idle current is normally done in the collector supply line
     
  16. Heliman

    Heliman

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    Feb 4, 2016
    I ended up hooking the ammeter in line with the power in line. Turned both VR1 and VR2 all the way down. Checked idle current then added 250ma to each final. Turned out great. Puts out 100 watt and sounds great.
     
    davenn likes this.
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