Sherwood S-5000 restoration

Discussion in 'Tube Audio' started by bberkom, Jun 22, 2017.

  1. bberkom

    bberkom AK Subscriber Subscriber

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    That’ll be a DC rating. Can’t remeber exactly what I used, but it was probably 400 or 450 VDC
     

     

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  2. HowardK

    HowardK New Member

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    Hello,
    Ive just did a total recap and removed the selenium rectifier, added the diodes for the bias/heaters on a S-5000. The amp sounds fantastic thanks to this website and people who share there knowledge. My question is, what wattage does the dropping resistor have to be after the diodes on the bias/heater power supply because down stream from the dropping resistor I added there is 33 ohm 7w resistor going to the phono stage heaters?
     
  3. HowardK

    HowardK New Member

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    I meant phone stage bias not heaters!
     
  4. gadget73

    gadget73 junk junkie Subscriber

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    If there is already a drop resistor and the voltage comes out in spec, I wouldn't worry about it.
     
  5. HowardK

    HowardK New Member

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    49
    I ended up with -19.65 volts going to the bias on 6bq5's using a 1w at 19.65 ohm dropping resistance, -20.7 going to 12ax7's pono heaters. Does that sound good?
     
  6. gadget73

    gadget73 junk junkie Subscriber

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    What does the schematic call for? I don't have it in front of me.

    Phono heater voltage sounds reasonable though.
     

     

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  7. HowardK

    HowardK New Member

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  8. gadget73

    gadget73 junk junkie Subscriber

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    Bias is good then, phono heaters are a little low, may be worth making sure that 33 ohm resistor is still on value. If it is, then I'd honestly just leave it alone.
     
  9. HowardK

    HowardK New Member

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    There was actually a 47 ohm resistor going to the phono section. I changed it to 33 and the voltage came up to -22.5 which is in the right direction.
     
  10. gadget73

    gadget73 junk junkie Subscriber

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    That sounds reasonable. 11.25 per tube heater should be enough to get the job done.
     
  11. HowardK

    HowardK New Member

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    Can a 5y3gt be substituted for the 5ar4 in this amp to bring B+ down and run the 6bq5? The 5y3 draws a 10th more amp than the 5ar4, also with the dc bias on 7189 the B+ only says to draw 100 ma.
     

     

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  12. gadget73

    gadget73 junk junkie Subscriber

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    Much less current capacity with a 5Y3. I wouldn't recommend it honestly.

    100ma is probably total, so 25ma per tube.
     

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