Sony_Trinitron TV problem!!!

Discussion in 'General Electronics Chat' started by ranatungawk, Oct 2, 2011.

  1. ranatungawk

    Thread Starter Senior Member

    Oct 30, 2008
    147
    0
    Im using old “Sony_Trinitron_KV-2192M3” TV. Since last few days, I found some channels are very unclear or no pictures at all ( see pic 1 to 3 ). Some channels which I watched very clearly (high gain ), can barely watched with shadows (see pic 4 & 5). However I didn’t find any other problems such as “screen width issue issue”, “power off issue”, or TV function problems. So I did following things :

    • Antenna connection (RF) directly connected to the Tuner unit ( BT-EG201) - problem remain same.
    • Tuner was removed from the mother bored and all DRY joists were re-soldered. - problem remain same.
    • Motherboard was re-soldered - problem remain same.

    Could you please give me a advice on fixing this ? what should I do next ?
     
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  2. #12

    Expert

    Nov 30, 2010
    16,317
    6,818
    The second and third pictures remind me of the frequency of the tuner being slightly out of adjustment. One cause could be in the AGC circuit.
     
  3. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,347
    Hello,

    It looks indeed to a tuning problem.
    The sensitivity is low and the AFC is not working correctly.
    It could also be there is a problem with the voltage reference (TAA550) of the tuner

    Bertus
     
    ranatungawk likes this.
  4. loosewire

    AAC Fanatic!

    Apr 25, 2008
    1,584
    435
    Are you on a building system or you have your own anteena.
    All the pictures could be signal problems.
     
  5. ranatungawk

    Thread Starter Senior Member

    Oct 30, 2008
    147
    0
    just forget the antenna connection, i get the same result even for the DVD player in put
     
  6. ranatungawk

    Thread Starter Senior Member

    Oct 30, 2008
    147
    0

    Does the reference voltage mean the B+ which supply the tuner ????
     
  7. debe

    Well-Known Member

    Sep 21, 2010
    947
    184
    Looking at the pictures there appears to be a darker band across the picture. It just might be caused by mains freq in the power supply. If its a smps check that the first electrolytic from the mains bridge rectifier is ok. If its playing up using a DVD player through A/V, then its not a tuner problem.
     
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  8. tom66

    Senior Member

    May 9, 2009
    2,613
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    Did you use an AV or RF connector for the DVD player?
     
  9. ranatungawk

    Thread Starter Senior Member

    Oct 30, 2008
    147
    0

    Good Question !! it's a old TV so there is only RF connecter
     
  10. tom66

    Senior Member

    May 9, 2009
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    In which case - the RF part may be faulty.
     
  11. ranatungawk

    Thread Starter Senior Member

    Oct 30, 2008
    147
    0
    Service manual is here!!!
     
  12. ranatungawk

    Thread Starter Senior Member

    Oct 30, 2008
    147
    0
    Thanks for the advice !! pls tell me, according to Mr debe's comments, can the bad filter cap cause is issue? because i saw B+ voltage go to the RF unit too. however apparently that cap is ok (not get swelled)
     
  13. manieceindia

    New Member

    Sep 29, 2011
    1
    0
    I think problem is in your tuning circuit which is the out of band of frequency, so it might be a problem of getting clearance. Check with that circuits.....
     
  14. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    Come back after a few hours. I will help you to locate the fault indefinitely.

    My god child's graduation is this evening. I will post back after that.

    First confirm to me if the problem is there at AV input. Double check with Audio Video Input and post back.
     
  15. ranatungawk

    Thread Starter Senior Member

    Oct 30, 2008
    147
    0
    thank for your help you sir, there is no any AV input, but only a RF input (antenna- input)
     
  16. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    760
    Seems I have a bit of time to spare.

    So this means the fault is at Tuner or IF.

    Here is another thing you should do.
    Near the tuner there will be an IF pack, Service diagram no, is IF201 / IFB-389

    IF Pack is a bit larger than tuner.
    Remove it and then remove the shield covering and then resolder every single joint. Do not leave a joint untouched.

    Clean the Board with any circuit PCB cleaner to remove the flux, inspect it for solder bridges thoroughly and solder it back.

    Remember to clean it and check with a magnifying glass.
    Any bridge not removed will cause picture failure and cause more symptoms.

    Post back after doing this.

    {ed}

    I wonder where OP is.
     
    Last edited: Oct 3, 2011
  17. loosewire

    AAC Fanatic!

    Apr 25, 2008
    1,584
    435
    Show a picture with the dvd hooked up,the photo's you have up
    all show signal or agc,have you checked with your cable company.
    You must have tried an other T.V. on your Input,we don't know.
    I would never agree to all the soldering,solder only when you have a
    good reason,you will only make more problems.
     
    Last edited: Oct 4, 2011
  18. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    It's ripple in the PSU. The Trinitrons have a central caged PSU under the tube neck, slide that out and replace the smaller electros in it but not the very large one.

    It's also worth cheking the marked points for the PSU voltages with your multimeter set to AC volts, as this will show ripple.
     
  19. tom66

    Senior Member

    May 9, 2009
    2,613
    214
    Usually in these TVs there is a 33V rail which provides power to the tuner. This is used to bias the tuner's varicap diode. Check if this is present.
     
  20. ranatungawk

    Thread Starter Senior Member

    Oct 30, 2008
    147
    0
    Thanks for the advice! I found 12V, B+ voltage goes to the tuner. hope this is the voltage you have mentioned here. can a bad "varicap diode" cause this issue ? could you please see the service manual i have attached herewith.
     
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