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Re: Where does the negative wire go from pin to driver board

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In Reply to: Where does the negative wire go from pin to driver board posted by Carl B. on June 10, 2006 at 19:53:14:

RCA grounds are 10 and 8 respectivly and are made with 10 ohm resistors. Yes, you need to make sure 9 goes back to the quad cap ground. Also make sure the .02uF "3 legged cap" is connected to quad cap ground as well. Do you have the 1K carbon resistors shown between 22,23 & 1,2 actually mounted on the el34 tube sockets using pins 5 & 6?
Does your amp hum (or do whatever it is you call feedback) with RCA shorting plugs in place? What work was done to cause this condition?

Russ

Follow Ups:

Re: Where does the negative wire go from pin to driver board - Carl B. 08:51:01 06/11/06 (0)
dear russ, i thought the 470k resistor is connected to the - and + of the rca jack. where does the 10ohm resistor come into play?
Re: Where does the negative wire go from pin to driver board - Carl B. 04:58:31 06/11/06 (1)
ok, I got you. the 10,8 are for the rca ground. I have 1k resistors on 22,23,1,2. I am not sure about the .02uF "3 legged cap" connected to quad cap ground. I don't see any legged cap there. There are only 2 wires connected to my quad cap ground. The ground going to my driver board and the ground for my curcio cap board. I see only a ceramic round like disc cap with 3 wires coming out of it soldered to my 3 hole terminal strip that I purchased from curcio for his cap board. Can you email me at: carl.barbieri@sympatico.ca and I can send you pics of my amp.thanks
- That ceramic cap - Russ57 07:00:54 06/11/06 (0)
  with three 3 wires coming out of it should have the 2 outside legs connected to the center taps of the heater supply(s) and the middle leg needs to be connected to the central quad cap ground. This could be your main problem and would show up as hum. The cap is two caps built into one and can be replaced with 2 individual caps if needed.
  The stock design has the 1K resistors connected between the driver board and pin 5 of the EL34's. While that can be adequate it is not proper. It would be best to take advantage of the fact that pin 6 is not used on an EL34. What I advise is to run a short wire from driver board to pin 6 and then install the 1K resistor from pin 6 to pin 5. It is important that the resistor be a carbon resistor and not a metal film and that it leads be as short as possible, especially at pin 5. The 1K resistor is intended to surpress any oscillations which if audible could sound like a high pitched feedback type of whine.
  In the end it may become necessary to replace the stock driver board.
  
  Russ
10 and 8 go to the preamp sockets via the 10 ohm resistors, don't they? - Marshall W 21:23:44 06/10/06 (2)
The original dynaco diagram shows the RCA inputs grounded to two unmarked eylets just above 9 and 10 I think.
- Re: 10 and 8 go to the preamp sockets via the 10 ohm resistors, don't they? - Carl B. 05:31:38 06/11/06 (1)
  that's what I thought. they are unmarked and the top ends of the 10k resistors are not connected. I tried connecting my rca grounds there, no difference. I think russ is right(8 and 10 eyelets), but on the original dynaco diagram 8 and 10 is for the 10ohm resistors only. So I will have the 10ohm resistors and my rca grounds in there. 2 wires per eyelet? Does this make sense?
  - Re: 10 and 8 go to the preamp sockets via the 10 ohm resistors, don't they? - Russ57 07:08:40 06/11/06 (0)
    Terminals 8,9, and 10 are all a common ground so it really doesn't matter. Make sure to have a 10 ohm resistor, not 10K in series with the (between) the RCA outside shell and driver board ground on both sides with no other wiring attached to the RCA shell. There will be 2 extra 10 ohm resistor from the original mono/stereo switch that can be removed as well as any wiring.
    
    Russ

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