Fender tweed bassman 5F6 no sound

[eschertron]

Enzo, not knowing which ended I should lift of the 27K I lifted both. The one that is closest to the speaker jack has .3 ohms to ground the other is open.
Across the output transformer from black to green it measures .3 ohms.

Where the feedback resistor meets the bottom of the long tail resistor (this is a 5f6a, right? not a 5f6 where the feedback goes to the tone stack?) there needs to be a small resistance to ground, I'm thinking 2.2k? Without that resistor, there's no path to ground except through the transformer secondary.

[pontiacpete]

I'm not sure if this is a 5f6 or a 5f6a, I don't have the cabinet here. I have been using the 5f6a schematic. Where would the 2.2K resistor be?

[Chuck H]

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[pontiacpete]

Thanks chuck, I was just looking at the 5f6 and 5f6a. This amp is definitely like the 5f6a in that the 10K resistor was not grounded like it is in the 5f6 schem. That connection was under the board and there's no chassis solder point above the 10K. I did pull that you can see it is above ground now.

[eschertron]

I'm not sure if this is a 5f6 or a 5f6a, I don't have the cabinet here. I have been using the 5f6a schematic. Where would the 2.2K resistor be?

My bad, the ground reference is the presence pot. :Brain fart:
Still odd is that if you have a 5f6 and not a 5f6a, how the NFB is related to the PI at all. On the 5f6a the NFB resistor and the presence pot connect to that 10k tail resistor. Did some one start to mod from one version to the other and then get confused?

[Enzo]

When you lift a resistor or other part, you are disconnecting an end. It really doesn't matter which end, it is disconnected. There would then be two end points where the resistor had been. In your case, the one spot would be the one connected to the speaker winding of the OT. That would have a VERY low resistance, as you found. The other end point would be the top of the presence pot and as well the bottom end of the middle pot. On the drawing, there ought to be 5k to ground from that point - the presence pot. You got open. That means either your presence pot is open, or it is miswired. Or the ground connection is missing. That is the 5F6.

In the 5F6A, that point is still the presence pot, though now it is the ground path for the phase inverter too.

[J M Fahey]

You-are-missing-the-cathode-resistor.

Circuit is closed through the feedback resistor, when and if you connect it, but you still have a wiring error.

PLEASE answer the questions posted in #3.

G1, Chuck H and Escherton are also worried about that but you donīt yield

[pontiacpete]

Thanks guys, Got to the bottom of this issue for sure.
The presence pot was most certainly wired wrong. The pot was going to ground through the .1 cap, or should I say, not going to ground because of the cap. Also the pot was the wrong value, 50K instead of 5K. So now when measuring at the top of the presence pot it's 5K.
So with or without the feedback resistor lifted the amp makes good sound.
Voltages are way better now. The plates of the PI are at 260 and 285vdc. The cathode 53v and about 35v on the grids.
Also, clipped out the 56K at the top of the middle pot that went to ground.
Many Thanks to you all for seeing me through this repair.