Etching a board set for my HRM build...

[ic-racer]

So, if it is wired per the usual non-CF schematics, the white test point eyelet and the orange eyelet are redundant. They are at the same potential, assuming the test point is wired 'straight down' to the main board.

Now, if MR D wired the last stage before the HRM stack as a CF, then the test point and the orange eyelet are at different potentials, and the test point is not redundant.

This diagram shows a hypothetical situation (or perhaps the 'real way?') of wiring the last stage before the HRM stack as a CF. There would be no visual external clue of the difference. All the wires to the tubes are the same. The only difference would be under the goop.

https://tubeamparchive.com/download/file.php?id=10588

[ic-racer]

So, specifically, the usual V2b cathode resistor and capacitor would be absent. The resistor "18" in the diagram is shifted from its usual place next to plate resistor number "17" and now serves as the CF resistor. Then the appropriate jumpers are added to complete the circuit.

Any of these changes would be invisible under the goop.

[jelle]

Signal should come from the cathode end of the CF resistor and then go to the TSC.

Right now it comes from the ground end of the cathode resistor.

I have tried this before...sounds very much like a JCM800.

Does anyone know if this was done in a Dumble?

Jelle

[ic-racer]

Signal should come from the cathode end of the CF resistor and then go to the TSC.

Right now it comes from the ground end of the cathode resistor.

I have tried this before...sounds very much like a JCM800.

Does anyone know if this was done in a Dumble?

Jelle

Good pickup, I'll have to change it.

[ic-racer]

I have been working on this very slowly, due to other projects.
But I finally got the power supply board done.