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CRT TV Mitsubishi CT29AS1 Vertical deflection problem?

Discussion in 'Troubleshooting and Repair' started by Gpit6903, Jan 25, 2020.

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  1. Gpit6903

    Gpit6903

    11
    0
    Jan 25, 2020
    Hi all

    I've been scratching my head for days to work this out.

    My mitsubishi Crt TV CT29AS1 has gradually deteriorated. The top 1/3 of the picture is stretched. If I display a service test picture for geometry the circle ends up looking like an egg at the top. I have the service manual and have tweaked the service mode. However, I cannot adjust anymore.

    Can someone help me by advising if it is the vertical deflection circuit and a bootstrap capacitor before I take it all apart and discharge?

    Any advice would be amazing!!

    Thank you

    G
     
  2. Gpit6903

    Gpit6903

    11
    0
    Jan 25, 2020
    I have no dismantled the TV and discharged it. Before I start recapping the whole board can anyone advise me of the deflection circuit and usual problems or capacitors that might go?
     
  3. bertus

    bertus

    256
    82
    Nov 8, 2019
  4. Gpit6903

    Gpit6903

    11
    0
    Jan 25, 2020
    OK great thanks for this. I have a copy of the schematic but I can't identify what capacitor to esr test
     
  5. bertus

    bertus

    256
    82
    Nov 8, 2019
    Hello,

    I tried to download a schematic and got an elbe E19 schematic.
    Is this the deflection part of your TV?

    Elbe E16 deflection.jpg

    If so have a look at Q301,Q302, C307 and C308.
    If not, do you have a link to the schematic?

    bertus
     
  6. Gpit6903

    Gpit6903

    11
    0
    Jan 25, 2020
  7. bertus

    bertus

    256
    82
    Nov 8, 2019
    Hello,

    It looks like the vertical deflection is done by a TDA8178S:

    E16 deflection.png

    There are some scope test images in the schematic.

    Bertus
     
  8. Gpit6903

    Gpit6903

    11
    0
    Jan 25, 2020
  9. Gpit6903

    Gpit6903

    11
    0
    Jan 25, 2020
  10. bertus

    bertus

    256
    82
    Nov 8, 2019
    Hello,

    What happened in this corner?

    E16_20200125_200133_part.jpg

    It looks like someone tried to solder something and touched the plastic frame.

    Bertus
     
  11. Gpit6903

    Gpit6903

    11
    0
    Jan 25, 2020
    Woah, so has it been repaired before?
     
  12. bertus

    bertus

    256
    82
    Nov 8, 2019
    Hello,

    It looks like they tried to solder this region:

    E16_20200125_200133_part2.jpg

    So to see it is in the audio part.

    Bertus
     
  13. Gpit6903

    Gpit6903

    11
    0
    Jan 25, 2020
    Hi,

    Yes they have!!!! Why on earth would someone do that. Either way I don't use the audio on the TV as it runs via my amp.

    In regards to the vertical deflection, will I need a professional to scope it? Or can I just replace the capacitors?

    Many thanks
     
  14. Gpit6903

    Gpit6903

    11
    0
    Jan 25, 2020
    So upon inspection q550 solder was dry with supplies vpos. However upon putting it all back together the linearity is still poor. Any other ideas?
     
  15. Gpit6903

    Gpit6903

    11
    0
    Jan 25, 2020
    Update

    After turning the TV on and testing voltages unfortunatly my avo meter grounded 2 pins on the ic. This took out a resistor, I have subsequently replaced the resistor and also 2 capacitors in the vertical ic.

    The picture is now a white line which i presume is the Ic tda 8178s burnt out because I grounded it accidently.

    1. At least the TV turns back on now after replacing the capacitors (bad values tested with esr meter)

    2. I have managed to source a TDA8178S for the mitsubishi deflection circuit.

    3. Not sure when it will arrive but is there any other caps I should check to ensure no other problems?

    Any advice on the white line would be great!!!!

    Thanks
     
  16. Gpit6903

    Gpit6903

    11
    0
    Jan 25, 2020
    Advice anyone?

    I'm about to start replacing the ic today.
     
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