Bias Trimmer for Pro Reverb

Discussion in 'The Workbench' started by SigurdTheGreat, Jul 15, 2010.

  1. Lane Sparber

    Lane Sparber Well-Known Member VIP Member

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    If you haven't marked the folder as "private," I believe you can just send me the link to the folder.

    -Lane
     
  2. MajorNut1967

    MajorNut1967 New Member

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    What do you know about Ultra-Linear LOL! If you looked at the OT you would have seen the screen were fed via the taps from the OT, not a separate supply. Duh

    Major
     
    Last edited: Mar 25, 2012
  3. ournative

    ournative New Member

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    Here's the link, Lane. There's 20 photos but I'm not done yet. There'll be alot more. Let me know if there's any specific areas I need a better picture of. Some photos are good, some are not too good. My hand isn't as steady as it should be....

    Pictures by ournative - Photobucket
     
  4. MajorNut1967

    MajorNut1967 New Member

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    The Tube Balance pot is a Hi-Fi idea where as you could make up for unmatched tubes by using that POT. Now according to lane's schematic its supposed to have 6L6GC's in it they have a plate dissipation of 30 watts and screen dissipation of 5 watts for a total of 35 watts. so if you were look to hit 70% of the plate that would be 21 watts, whats the issue?
     
    Lane Sparber likes this.
  5. Lane Sparber

    Lane Sparber Well-Known Member VIP Member

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    I never said anything about a separate supply...I know that the screens are fed from the OT. I have a UL Fender myself (Bassman 70) and I love the sound of it. I also will never claim to have 1/10 the UL experience you do. Anyway, the OP had a separate issue, which we solved...over a year ago.

    -Lane
     
  6. MajorNut1967

    MajorNut1967 New Member

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    oh OKAY "NEVERMIND" LOL:naughty::naughty:
     
  7. Lane Sparber

    Lane Sparber Well-Known Member VIP Member

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    Just to fill you in on the backstory, the OP wanted me to help him convert from a "bias-balance" like you talked about to a "standard" bias arrangement.

    -Lane
     
  8. MajorNut1967

    MajorNut1967 New Member

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    but why?
     
  9. Lane Sparber

    Lane Sparber Well-Known Member VIP Member

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    Some owners like the traditional bias arrangement. If they have matched tubes, it's usually not an issue. He'd have to give you the final answer there, Major. It was his amp. :)

    While I think a combo of BOTH is best, since CP tubes are kind of all over the place spec-wise, if I have to go with just one method I too prefer the traditional bias circuit. This is because as long as the tubes are matched, then with the standard arrangement I can controll the overall dissipation level of the tubes a bit better than with the "balance" method alone. To each their own, though.

    -Lane
     
  10. ournative

    ournative New Member

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    Lane,

    Here's the back panel pics. It is a 1979 Pro Reverb. As you can see, whoever started in on this monster deleted the output tube balance circuit and the line out circuit. However, the hum balance pot is still there but has only 1 wire on it and it doesn't look stock. I don't see a new pot for bias anywhere...like I say, it's a mess, so I have no problem fooling with it. I'm an electrician by trade and an excellent wireman and certified solder junkie. Bring it on! To keep the UL OT? or buy a MMagnetics?

    Rick
     

    Attached Files:

  11. MajorNut1967

    MajorNut1967 New Member

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    didn't he say it was pulling 22 watts? And 21 watts should be the goal. It's only one watt off?
     
  12. Söulcaster

    Söulcaster Well-Known Member VIP Member

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    Hey at least he is trying to help. No need to be an asshole.

    I dont see ppl laughing at your sad attempt of a forum.
     
  13. MajorNut1967

    MajorNut1967 New Member

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    Hey did you boff the neighbors cat or something? I know the guy and it was a bloody joke and he knew it! And he does know about Ultra-Linear because I taught him about it and he knows it well.

    What are you talking about? "your sad attempt of a forum" I don't have a forum, and the only one I belong to is this one! you really showed what a true wanker you are, with screaming colors!
     
  14. ournative

    ournative New Member

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    Where do you live at? I travel quite a bit...Europe and the US. I'd like to talk this over in person. You're my kind of gguy.
     
  15. ournative

    ournative New Member

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    Give me your address.
     
  16. Söulcaster

    Söulcaster Well-Known Member VIP Member

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    You either left or they booted you? which was it? Your posts are still there.

    I know who you are. Someone even started a thread about your absence.

    And yea Ill defend any member on this forum from apparent smart ass dickheads. I will concede I didnt get the joke.

    Whos the Major Dunce now?
     
    Last edited: Mar 26, 2012
  17. Lane Sparber

    Lane Sparber Well-Known Member VIP Member

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    I'm in Queens, New York. Coming to the East Coast soon?

    -Lane
     
  18. pdman

    pdman New Member

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    Just joined the forum. I have a Pro reverb with the ultralinear Xfmr. I'm interested in the Bias Mod. Can you post some info here on the forum on exactly how the Mod is done? Much appreciated.

    Thanks
     
  19. Thejason2013

    Thejason2013 New Member

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    Hello everyone,

    I just discover this forum and treat that is very useful and unique in the web !!!

    I have just purchased a Pro reverb silver face with Master push pull, mid, treble, bass in both channel, and solid state rectifier.

    The amp was just reviewed by a tech, the power tube were Tung Sol 6L6GC STR.
    Don't know exactly from which year it is but Serial Start with F106 XXX.

    I purchase this on ebay, but unfortunately while shipping it (from Germany to France), the amp was broken. Mainly the 2 power tube were broken, and the cabinet.

    I fix the cabinet, then buy some new tube Electro Harmonix 6L6GC and put them in, then turn the amp ON, and wait 2min, then the amp smoke .....
    I switch it off.
    then when stop smoking I open it, and see the wire that link the different tubes burn.
    Don't know exactly why.

    [​IMG]

    http://www.flickr.com/photos/96545255@N02/8859375748/

    Is that something link to different voltage between the tungsol and elecro harmonic tube ?
    In addition I also put 240 volts before it smoke ...... then decrease to 220 :-(

    I have bought some wire to replace, but what else should I check and replace ?

    Thanks in advance for your advice.

    Jason
     
  20. RussBert

    RussBert Active Member

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    Running it at 240 volts may have destroyed the power transformer. Seeing the melted AC wiring sure makes me think so. What fuse do you have in there? Is it not the correct one?
     

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