Dynakit ST70 - No Output - No Bias

[Pio1980]

This can help that tube last!

View attachment 2550079 View attachment 2550085

Doubled 1N4007 in series, and jumper tab #4 to tab #6.

 

[jefferylhenr]

Doubled 1N4007 in series, and jumper tab #4 to tab #6.

What does this do electronically? Block the back ripple? I have a bunch of these diodes.

 

[Pio1980]

What does this do electronically? Block the back ripple? I have a bunch of these diodes.

Blocks back emf, the jumper parallels the tube sections as doubled capacity time delay ramping series resistance elements for the solid state rectifiers.
Also would recommend a CL-90 soft start MOV in series with the power transformer primary if not already present, two might be better for 125 VAC with the OEM PA-060 power transformer.

 

[Shadowdog]

UF4007 will work also and the CL soft start MOV's are a great addition.

 

[jefferylhenr]

So found a good known rectifier tube and everything came up as expected. Set bias and playing sweet