EL34 Grid Stopper resistor

[ca7922303]

Did you tried to pull v5 out to see if osscilate? Oh you said the volume increased with 100k feedback resistor? then your wires to power tube inputs should be reversed. It is possible those wires to be reversed by mistake ? hope you used 100k from orange wire to blue point without those link on board you removed( blue-green)

Removed V4, same condition as V5 removal, channel two(2) oscillates, channels one(1) & three(3) do not oscillate.

[ca7922303]

Did you tried to pull v5 out to see if osscilate? Oh you said the volume increased with 100k feedback resistor? then your wires to power tube inputs should be reversed. It is possible those wires to be reversed by mistake ? hope you used 100k from orange wire to blue point without those link on board you removed( blue-green)

Removed V3, channel three(3) oscillates, channels two(2) & one(1) do not oscillate.

[ca7922303]

Removed V3, channel three(3) oscillates, channels two(2) & one(1) do not oscillate.

Removed V2, no oscillation on all three(3) channels, but only have output on channel one,(1), no output on channels two,(2) & three(3)..

[catalin gramada]

What are you saying I need to do with the power tube input wires? Can you point me in the right direction with that? Thanks.

I talk about the wires to control grid resistors, those 4.7K soldered at the power tube socket. It is possible the wires to be reversed ? Because is not normal to have more volume when injected nfb., you should have less...If was reversed you have to swich it: the wire to left tube to the right tube and the wire from the left tube to the right one. There is no reason to get more volume with nfb injected other than you negative feedback is actually positive one. Switch the input wires between power tubes as well to correct the phase it if is so...

[ca7922303]

I talk about the wires to control grid resistors, those 4.7K soldered at the power tube socket. It is possible the wires to be reversed ? Because is not normal to have more volume when injected nfb., you should have less...If was reversed you have to swich it: the wire to left tube to the right tube and the wire from the left tube to the right one. There is no reason to get more volume with nfb injected other than you negative feedback is actually positive one. Switch the input wires between power tubes as well to correct the phase it if is so...

Let me make sure I understand. I'm going to switch the green wire and blue wire that is currently attached to underneath of board(photo). That should correct what you are talking about or is there more to do?

[ca7922303]

Removed V2, no oscillation on all three(3) channels, but only have output on channel one,(1), no output on channels two,(2) & three(3)..

Removed V1, channels two(2) & three(3) oscillate, channel one(1) has no output.

[catalin gramada]

Yes dark blue and green those are the wires. I just wonder if was not reversed by mistake ? It have connectors on board. It is possible somehow to be reversed from initial position ?

[catalin gramada]

Or it is possible to be reversed from mistake the wires from output transformer to power tubes ?

[catalin gramada]

Judging by you picture the wires are posed in original position. But still you may try to switch the connectors of dark blue and green to the board. Be aware you amp may severe oscillate if I.m wrong, so keep an eye on it to cut the power off quick if happen.

[ca7922303]

Or it is possible to be reversed from mistake the wires from output transformer to power tubes ?

What color wires go from output transformer to power tubes?

[catalin gramada]

I don't see very clear in the picture you sent and I want to confirm: the track on board is how I draw it in red line ?

[ca7922303]

I don't see very clear in the picture you sent and I want to confirm: the track on board is how I draw it in red line ?

Can you describe in more detail what I am to do here? Thanks.

[catalin gramada]

Don't disconect nothing yet. It is possible the original feedback circuit to not be disconected completely removing those link. The picture was not clear. Please to confirm if the track on the board looks like what I drawled in picture above ?

[catalin gramada]

Just look at the track on the board and tell me if is how I drawled with red. It is a black wire in front I cannot see

[catalin gramada]

Or get a better picture perpendicular to the board. If there are wires in front I cannot guess how the tracks looks behind. Same frame but a better angle..just move those black wire a bit to see how the track behind it looks like