SET Asylum

Posted by audiowill (A) on April 01, 2007 at 22:36:50

I have a homebrew 45 amp made by a hobbyist that i've been enjoying for a few months now. It uses the 45's along with 4 417a input tubes and a 5v4g rectifier. Just today, I turned on my amp and the right speaker started to make loud popping noises. I quickly turned it off but the popping continued while I turned off the amp. I put the amp on a few minutes later and now there is nothing coming out of the right speaker. I tried switching the input and output tubes but there doesn't seem to be a problem with them. Then I switched speaker cables and indeed the speaker is fine but the amp's right channel has no output. The only thing I didn't do is change the rectifier since i don't have a spare. Even though this is unlikely, can a bad rectifier cause the loss of one channel? I think it's something in the amp and in that case i would have to bring it to my local tech. Otherwise if anybody can troubleshoot this for me that would be most helpful.

• Re: Help, the right channel of my 45 tube amp is out - Janos 00:27:47 04/02/07 (4)
  In Reply to: Help, the right channel of my 45 tube amp is out posted by audiowill on April 1, 2007 at 22:36:50:

  Hello,

  The rectifier should be fine, otherwise there would be no sound from either channels.
  It could be the tube pin conncetions, or coupling cap going bad.
  Test if there is continuity between the leads leading to tube pins and the pins themselves. Check if the caps in that channel are shorted or not. Check the resistors values. Check if the OPT is shorted. If you do not know the original values, compare one side tho the other, and if there's a difference, you have found the culprit.

  Good luck!

  Janos
  
  
  

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  • Swap the output tubes; then the input tubes... - Interstage Tranny 08:38:19 04/02/07 (3)
    In Reply to: Re: Help, the right channel of my 45 tube amp is out posted by Janos on April 2, 2007 at 00:27:47:

    I know that you must be scared to try the amp again, but troubleshooting is easy on SE amps. If you think that your speakers are in danger(very unlikely with 2 watts)try a different pair, less costly.
    Swapping the tubes from one side to the other, one tube type at a time, might clear this question up, quickly. If swapping the 45s brings the noise(or silence, now) to the other channel, voila, it's that tube that was now tried in the known good channel.
    Likewise, swapping each stages' 417A, you might find the culprit.
    This is before you dive underneath and check voltages. This way, you can simply call the tech and, hopefully, only need a tube.
    If you want to try troubleshooting voltages, let us know. Resistances must be checked with the unit off...
    
    
    

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    • Re: Swap the output tubes; then the input tubes... - Janos 16:37:25 04/04/07 (0)
      In Reply to: Swap the output tubes; then the input tubes... posted by Interstage Tranny on April 2, 2007 at 08:38:19:

      Great point: if a channel goes out, never hook up the other speaker! Maybe the amp has blown/damaged the speaker, and when you hook up the other of the pair, that one will be also blown. And vice versa: when you hook a blown speaker to the working channel, if it shorts the channel, the OPT will be damaged.
      Always keep a pair of RS speakers (or plain drivers) to hook them up if you suspect something.

      good luck,

      Janos
      
      

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    • Re: Swap the output tubes; then the input tubes... - Ron Oehlert 10:41:12 04/03/07 (1)
      In Reply to: Swap the output tubes; then the input tubes... posted by Interstage Tranny on April 2, 2007 at 08:38:19:

      Read the OP. *I tried switching the input and output tubes but there doesn't seem to be a problem with them.* = he already tried that.
      
      

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      • Re: Swap the output tubes; then the input tubes... - maxhifi 18:08:02 04/03/07 (0)
        In Reply to: Re: Swap the output tubes; then the input tubes... posted by Ron Oehlert on April 3, 2007 at 10:41:12:

        Did you try swapping the left and right signal cables feeding the amp? This has been a problem for me more than once.
        
        

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