HELP Sony STR-V4 No Sound Right Channel

Discussion in 'Solid State' started by CavScout, Mar 14, 2019.

  1. CavScout

    CavScout Well-Known Member

    Messages:
    638
    Location:
    Medicine Hat
    I bought this receiver in great shape but no sound in the right channel.
    I checked the 2 fuses and put a lot of deoxit in the Vol,Bass,Treble, Balance and toggle switches with no result.

    Any suggestions ?
     

     

    Please register to disable this ad.

  2. CavScout

    CavScout Well-Known Member

    Messages:
    638
    Location:
    Medicine Hat
    I am wondering if it is a bad balance potentiometer.
    When I turn it ALL THE WAY to the right, I can still hear a little bit of sound on the left
     
  3. avionic

    avionic " Black Knights " F-15 Eagle Keeper Subscriber

    Messages:
    47,831
    Location:
    Fort Dodge, Iowa
    Try the headphones..
     
  4. CavScout

    CavScout Well-Known Member

    Messages:
    638
    Location:
    Medicine Hat
    Same result with headphones.
    I noticed when I have the balance pot cranked to the right I get distorted sound at 3/4 volume.
     
  5. avionic

    avionic " Black Knights " F-15 Eagle Keeper Subscriber

    Messages:
    47,831
    Location:
    Fort Dodge, Iowa
    Check your right channel emitter resistors out of circuit. Before I jump to conclusions about the balance pot. Need to verify that the right channel amplifier is working.
     
  6. CavScout

    CavScout Well-Known Member

    Messages:
    638
    Location:
    Medicine Hat
    I'll have to figure out what you are referring to somehow .
     

     

    Please register to disable this ad.

  7. avionic

    avionic " Black Knights " F-15 Eagle Keeper Subscriber

    Messages:
    47,831
    Location:
    Fort Dodge, Iowa
    Think you can find R725 and 726 They are .47Ω ceramic /cement wirewound 5 watt resistors.
     
  8. century tek

    century tek Super Member

    Messages:
    3,810
    Location:
    The Evergreen State
    You prolly shouldn't be poking around then! :no:
     
  9. CavScout

    CavScout Well-Known Member

    Messages:
    638
    Location:
    Medicine Hat
    Tested them out of circuit and they appear fine ( .5 ohms )
     

    Attached Files:

  10. avionic

    avionic " Black Knights " F-15 Eagle Keeper Subscriber

    Messages:
    47,831
    Location:
    Fort Dodge, Iowa
    Reinstall those and check the two for the other amplifier.(right channel)
     
  11. avionic

    avionic " Black Knights " F-15 Eagle Keeper Subscriber

    Messages:
    47,831
    Location:
    Fort Dodge, Iowa
    These two are for the left channel.
     

     

    Please register to disable this ad.

  12. CavScout

    CavScout Well-Known Member

    Messages:
    638
    Location:
    Medicine Hat
    Yes, went ahead and checked those also. All good
     
  13. avionic

    avionic " Black Knights " F-15 Eagle Keeper Subscriber

    Messages:
    47,831
    Location:
    Fort Dodge, Iowa
    Great. Next,we need to check the power supply voltages powering the Rt channel.
     
  14. sax6

    sax6 Loudness always ON

    Messages:
    2,069
    Location:
    Province de Québec
    Check preamp to power amp jumpers if any.

    edited...


    Sorry, checked out some pics and ... no jumpers ...
     
  15. avionic

    avionic " Black Knights " F-15 Eagle Keeper Subscriber

    Messages:
    47,831
    Location:
    Fort Dodge, Iowa
    +/- 45 vdc should be present on the output transistors collector. Center pin or metal " batwing "tabs.
     
    Last edited: Mar 16, 2019
  16. avionic

    avionic " Black Knights " F-15 Eagle Keeper Subscriber

    Messages:
    47,831
    Location:
    Fort Dodge, Iowa
    Does the bias adjust on the Rt channel?
     

     

    Please register to disable this ad.

  17. CavScout

    CavScout Well-Known Member

    Messages:
    638
    Location:
    Medicine Hat
    I got the following readings :

    Q713 - 44.5 VDC
    Q714 +44.5 VDC

    Q763 0.00 VDC
    Q764 - 44.5 VDC
     
  18. avionic

    avionic " Black Knights " F-15 Eagle Keeper Subscriber

    Messages:
    47,831
    Location:
    Fort Dodge, Iowa
    There is your problem..Should be +44.5 vdc
     
  19. CavScout

    CavScout Well-Known Member

    Messages:
    638
    Location:
    Medicine Hat
    So just replace with new transistor?
    Then what? Adjust bias ?
     
  20. avionic

    avionic " Black Knights " F-15 Eagle Keeper Subscriber

    Messages:
    47,831
    Location:
    Fort Dodge, Iowa
    Looks like it may be a broken wire or solder connection. Or..... burnt trace:rolleyes:
     
    Last edited: Mar 16, 2019

Share This Page