Riviera amp with a mysterious fault

[hylaphone]

Hi folks,Wondering if you can help me with a strange issue in this Riviera Venus Deux I'm looking at, which is not passing signal.Attached schematic seems close, though V1 sections are reversed in this amp.
I have no anode voltage at the first triode (second triode is fine)I'm reading 30 ohms to ground from the anode pin, with or without the tube removed.
I'm having a hard time envisioning a fault in the tone stack that could cause this condition.. any ideas? No sign of damage on the PCB or tube socketThanks ---

[tubeswell]

no anode voltage at the first triode (second triode is fine)

As both triodes source their high tension voltage from the same filter cap node, then the problem will be in the 1st triode - either missing one or more of the required connections between the plate, the plate resistor and the filter cap, or the triode itself is defective.

[hylaphone]

no anode voltage at the first triode (second triode is fine)

As both triodes source their high tension voltage from the same filter cap node, then the problem will be in the 1st triode - either missing one or more of the required connections between the plate, the plate resistor and the filter cap, or the triode itself is defective.

Right, that's the mysterious part. I have HT (325V) at the top of both anode resistors. I measure 100K across either resistor, and from the top of each resistor (HT side) to pins 1 and 6.  Both cathode resistors measure correctly from pins 3 and 8 to ground.Then there's this 30 ohm to ground business on the non working anode. I'm stumped what could cause this

[DummyLoad]

no anode voltage at the first triode (second triode is fine)

As both triodes source their high tension voltage from the same filter cap node, then the problem will be in the 1st triode - either missing one or more of the required connections between the plate, the plate resistor and the filter cap, or the triode itself is defective.

Right, that's the mysterious part. I have HT (325V) at the top of both anode resistors. I measure 100K across either resistor, and from the top of each resistor (HT side) to pins 1 and 6.  Both cathode resistors measure correctly from pins 3 and 8 to ground.Then there's this 30 ohm to ground business on the non working anode. I'm stumped what could cause this

PCB issue - anode pin/trace shorting to something something else?

--Pete

[tubeswell]

So you tried another tube yet?

[tubeswell]

If you’re reading 0V on the plate, then there’s no current at all going through the triode. And as there is HT voltage at the power rail for this stage, then there’s an open connection somewhere between the power rail and the plate. (If everything was connected but the tube wasn’t conducting, we’d expect to see the same voltage on the Plate that is on the HT). So it’s a bad connection.

[hylaphone]

Thanks everyone, I needed the sanity check before committing to removing the PCB, which is no walk in the park on this amp..Once done, I found a giant flux creature, spanning several joints near the plate resistor.Scraped and cleaned, and the amp is playing nicely now.I appreciate your help!