potentially very stupid questions....

[dperry]

In circuit ? You can't measure those in-circuit.

Seriously, test your tubes (pull them out, set up a jig with suitable anode voltage, you can get this from your signal generator's supply) and make sure they're allright, Once you're sure of that look for problems elsewhere.

Its definately not either v1 or v2....i bought a new tube for each and plugged them in....still doesn't work.

Incidently, the power valve 6x4 (v3) now sparks full of bright light, so i assume its come to the end of its life.

 

[Arnulf]

In this case you have no alternative but to measure tube's operating points (measure voltage at the cathode and current across cathode resistor), compare them with sane values and locate the offending component in this manner.

Report back with readings for all sections of V2 (and V1 if you get around to it).

 

[kevinkr]

Its definately not either v1 or v2....i bought a new tube for each and plugged them in....still doesn't work.

Incidentally, the power valve 6x4 (v3) now sparks full of bright light, so i assume its come to the end of its life.

This may be a pretty good indication that one or more of the power supply capacitors is bad. Arcing in a previously good rectifier does not always signify tube end of life although due to internal damage the tube now will have to be replaced - this usually if not always signifies a bad component elsewhere. Before ruining another rectifier I strongly recommend you replace ALL of the electrolytics in this thing. (IMLE 6X4 is a pretty reliable rectifier, I've almost never had one just "wear out" - failure was almost always due to an external cause or excessive load current)

Don't you have a scope and the basic skill set to use one? It should be pretty obvious what is going on with just a little judicious probing, but please first replace those caps!! Make sure the power supply functions properly before proceeding further. (Cart before the horse??)