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  1. Thread: 5F6A low volume

    by vinceg
    Replies
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    6,044

    Update It seems that the cause of the hum is...

    Update

    It seems that the cause of the hum is heater wires. I got up heater wire from V2 with a chopstick and hum has significantly reduced but not completely gone.

    What can I do to get better?...
  2. Thread: 5F6A low volume

    by vinceg
    Replies
    202
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    6,044

    Now it is correct V3 pin1 255 pin3 41 pin6...

    Now it is correct

    V3
    pin1 255
    pin3 41
    pin6 252
    pin8 41
  3. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    Believe me, I got confused. I think that tubes...

    Believe me, I got confused. I think that tubes fall down because low heater voltage
  4. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    Update Heater problem is resolved, the cause...

    Update

    Heater problem is resolved, the cause was fuse holders. I noticed that moving heater wires pilot lamp went out. Now I've wall voltage of 230V and heater voltage of 6.1V

    Also I change the...
  5. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    Yes, the V3 cathode voltage of 18V is with the...

    Yes, the V3 cathode voltage of 18V is with the tube that made the amp lower in volume and quiet but the same tube before works fine and amp had hum.
    I do not know how to do
  6. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    I want to give you an update. I tried to remove...

    I want to give you an update. I tried to remove V1 and hum is still there, I remove V2 and hum is stille there slightly quieter, I remove V3 and hum is disappeared. Then I swap V2 and V3 without...
  7. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    Yes, my PT has a 6.7V unloaded heater voltage...

    Yes, my PT has a 6.7V unloaded heater voltage with the correct 240V primary voltage.
    This morning I measured unloaded heater voltage directly at PT wire by open fuse holder and this was 6.2V
    This...
  8. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    Now, wall voltage is 220V, heater voltage at PT...

    Now, wall voltage is 220V, heater voltage at PT unload is 6.2V and load 5.6V

    I did some tests. I measured voltage at V3 pins and I discovered that there is a 28V at pin 8 cathode.

    I changed V3...
  9. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    No, other tube is bad, it broke and has air in. I...

    No, other tube is bad, it broke and has air in. I can try another new tube.




    The other day I had a 218V wall voltage and all out voltage of PT unload were about 8% less that nominal. Heater...
  10. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    Yes, I replaced all three preamp socket. This...

    Yes, I replaced all three preamp socket.

    This morning I turn on amp and I can confirm that volume is low compared to before.

    I measured voltage at pin 5 of power tubes and it is -44VDC. Is this...
  11. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    I'm amazed! I discoverd that V3 tube was too hot,...

    I'm amazed! I discoverd that V3 tube was too hot, then I swap it with new tube. Background hum and whistles are disappeared but amp volume is slightly decreased.

    Let's say that the volume that...
  12. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    I refer to background hum like not to whistles,...

    I refer to background hum like not to whistles, even if this is a problem. Anyway, the whistles disappears after few minuts

    Hum is not affected by controls.

    Only V2 tube is noise on speaker...
  13. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    This is a small video that you hear background...

    This is a small video that you hear background noise. Can you help me to find problem?
    https://youtu.be/vx6LWXCLwwQ
  14. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    Probably, if I used a PT with 220VAC primary...

    Probably, if I used a PT with 220VAC primary winding, like my house wall voltage, I would have a higher heater voltage, but I would have to spend a lot of money. Or would it be better to use a...
  15. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    About heaters voltage, considering that I have a...

    About heaters voltage, considering that I have a wall voltage of 220VAC, PT input voltage 240VAC, it is 5,7 VAC with all tubes in. How can I increase hetars voltage?
  16. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    Update Finally the socket has been delivered. I...

    Update
    Finally the socket has been delivered.
    I changed V3 socket and now voltages at pins 1and 6 are right, about 230VDC.
    The amp seems sound fine.
    I noticed some pop when I touch wires around...
  17. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    I do not konw, I'll check tomorrow Sorry,...

    I do not konw, I'll check tomorrow



    Sorry, but because of my bad english I do not understand what do you mean.
  18. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    Voltage at pins 2 and 7 is 24V. Plate resistors...

    Voltage at pins 2 and 7 is 24V. Plate resistors are correct.
  19. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    Update I read new voltages: AC: 328+328 VAC...

    Update

    I read new voltages:

    AC: 328+328 VAC
    HEATERS: 2.8+2.8 VAC
    B+: 431VDC

    V1
    PIN1 195
  20. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    Since I have to buy new noval sockets from...

    Since I have to buy new noval sockets from tube-town, can you advice me a good preamp tubes from this site? @Helmholtz
  21. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    Sorry, I mean plate, and no, I do not folded pin...

    Sorry, I mean plate, and no, I do not folded pin 8 on the tube, I folded pin 8 of the socket.
  22. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    Ok, I extract the tube and I measured voltage at...

    Ok, I extract the tube and I measured voltage at grid and it is 405V, without the tube. Obviously voltage at pin 8 is 0V. Then I checked for unwanted contact at pin8 and I simply folded the pin down,...
  23. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    Well, I had marked the value but frankly now I do...

    Well, I had marked the value but frankly now I do not remember and I do not think the same situation occurs. Surely I had 0v at grid and cathode. At the plates... voltage it was however higher than...
  24. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    Perhaps I could identify the voltage drop. While...

    Perhaps I could identify the voltage drop. While I moved the V3 tube, there was a pop and and the amp was silent. Then I measured pin's tube and I detected 0V at pin2 and pin7 grid, 0V at pin8...
  25. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    I noticed that if I move V3 tube there is same...

    I noticed that if I move V3 tube there is same sintoms with pop. Do you think the socket is bad?
  26. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    Can freeze spray help me find one of these...

    Can freeze spray help me find one of these possible causes? I never used freeze spray, how do I recognize a problem?
  27. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    Tomorrow I'll buy a freeze spray. Can you tell me...

    Tomorrow I'll buy a freeze spray. Can you tell me how to use?
  28. Thread: 5F6A low volume

    by vinceg
    Replies
    202
    Views
    6,044

    I do not have an analogue tester. However, it is...

    I do not have an analogue tester. However, it is difficult for me make this measurement.
    I should get somebody to help me.
    What voltage should I control?
    I noticed that everything I touch with a...
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