EL34 Grid Stopper resistor

[ca7922303]

One sec. Can you see the OT output wires and where the go to the board ?

R45(100k ohms), R46(4.5k ohms), yellow resistor in between r45/r46(0.7 ohms).

[ca7922303]

R45(100k ohms), R46(4.5k ohms), yellow resistor in between r45/r46(0.7 ohms).

Showing you those readings because they are right at green/blue points that I desoldered.

[catalin gramada]

Or better tie it at the jack, is more robust. Twist together with orange 16 ohm wire and run directly at the 16 ohm jack. Keep those short black wire from jack to board pad

[ca7922303]

Disconect common black wire OT common output from where it is. Tie the black common wire in the red point.

I see the red point you made, can you point me to the black common wire? Thanks.

[catalin gramada]

You must find its end yourself, I don't see you output transformer. From you output transformer you should able to see in one side red wire 4ohm, brown wire 8 ohm( this are tied under the board) , then orange 16 ohm and the black one which is common. Twist together orange and black and run to the edge if chassis connecting the ends of the jack. Orange exactly where is conected now and black in the red point of the jack. Those short black wire from jack to the board must keeped there.

[ca7922303]

You must find its end yourself, I don't see you output transformer. From you output transformer you should able to see in one side red wire 4ohm, brown wire 8 ohm( this are tied under the board) , then orange 16 ohm and the black one which is common. Twist together orange and black and run to the edge if chassis connecting the ends of the jack. Orange exactly where is conected now and black in the red point of the jack. Those short black wire from jack to the board must keeped there.

I believe you are talking about the black wire which is connected to lug(P16). Can I run a wire from where it is connected on top of board to 16 ohm output jack?

[ca7922303]

You must find its end yourself, I don't see you output transformer. From you output transformer you should able to see in one side red wire 4ohm, brown wire 8 ohm( this are tied under the board) , then orange 16 ohm and the black one which is common. Twist together orange and black and run to the edge if chassis connecting the ends of the jack. Orange exactly where is conected now and black in the red point of the jack. Those short black wire from jack to the board must keeped there.

Here is P16 on top of board.(photo)

[catalin gramada]

If the common black is conected to lug p16 is perfect , no need to change it. ...huh...

[ca7922303]

If the common black is conected to lug p16 is perfect , no need to change it. ...huh...

Should I run a wire from P16 to 16 ohm output jack?

[catalin gramada]

Should I run a wire from P16 to 16 ohm output jack?

You allready have a wire there, the short black one. I thought the strange nfb circuit caused instability but was wrong. Now you amp is open loop and still osscilate...hmm.

[ca7922303]

You allready have a wire there, the short black one. I thought the strange nfb circuit caused instability but was wrong. Now you amp is open loop and still osscilate...hmm.

Anything possible with the presence pot?; It has no effect on brightness or volume?

[ca7922303]

You allready have a wire there, the short black one. I thought the strange nfb circuit caused instability but was wrong. Now you amp is open loop and still osscilate...hmm.

Could the boost trim pot be set to high cause oscillation? Hum balance pot?

[catalin gramada]

You don't have a problem with power stage as time as you test is not osscilate with the input shunted to ground.

[ca7922303]

You don't have a problem with power stage as time as you test is not osscilate with the input shunted to ground.

Can you rephrase that, I don't understand what you mean?

[catalin gramada]

Do you have say 100k resistor at hand ?