Posted by RAFG (A) on May 21, 2008 at 15:37:06

Hi,
the other day we finally turned on the LUX and to my dissapointment the sound was awful. The friend that built it for me measured the amp and told me to ask you about the following strange readings he found in the amp:
I'm an electronics illiterate, I hope to be able to transmit and translate his doubts correctly.
1. In the schematics of the Power Transformer the short purple wires read 200v but he measures 400v. Is this normal?
2. In the general schematics of the amp we cannot see a 1k resistor that goes to the post 9 of the ef86, but it's in the step-by-step instructions.
3. In the schematics the 3 and 8 posts of the ef86 are not joined whereas in the step-by-step instructions, they are.
We suppose that the consequence of all of those is that...
4. Post 6 of the ef86 reads 450v instead of the 185v. expected.

Hope you can give me some directions...
Thanks in advance,

Raul

• RE: Problems building my LUX - GTCharlie 19:44:05 05/22/08 (2)
  In Reply to: RE: Problems building my LUX posted by RAFG on May 21, 2008 at 15:37:06

  Hallo Raul. Pin 9 is the "control grid" and the 1k resistor is just a "grid stopper" to prevent oscillation. You can take it out if it does not oscillate. You can go as high as 5k, 10k... (I use a Tantalum 3k3 which I got from Brian). Pin 3 is the cathode and is shorted to Pin 8, the suppressor grid. Pin 6 is the anode. Your 450v reading is with respect to what?
  
  

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  • RE: Problems building my LUX - RAFG 01:10:02 05/23/08 (1)
    In Reply to: RE: Problems building my LUX posted by GTCharlie on May 22, 2008 at 19:44:05

    Thanks GTCharlie for giving me a hand. I'm no expert, but I'm almost sure my friend -who is building the kit for me- told me it was with respect to ground.
    
    Raúl
    
    

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    • RE: Problems building my LUX - GTCharlie 20:23:24 05/23/08 (0)
      In Reply to: RE: Problems building my LUX posted by RAFG on May 23, 2008 at 01:10:02

      Hmmm. EF86 max plate voltage is 300v.
      
      

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• RE: Problems building my LUX - bcherry 23:11:14 05/21/08 (0)
  In Reply to: RE: Problems building my LUX posted by RAFG on May 21, 2008 at 15:37:06

  hello Raul
  1.the HT wires are Center tapped so it is 200 plus 200 equals 400 V.
  2.this is an added grid stop resistor. The step-by-step instruction is correct
  3. The step-by-step instructions are correct.if you would like to e-mail me I can send you a circuit diagram that shows some of those details.
  4. I would suggest to double check the wiring around the EF 86 cathode anode to make sure that it is conforming to the step-by-step wiring diagrams. None of the above three points seem to relate to the problem.
  if you would like to take a close-up picture of the wiring around the EF 86 and send it to me, I'll take a look.
  Regards
  Brian
  Take control! DIY.
  
  

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