Thanks for the information on the UCC capacitors. I hadn't come across these types and the light blue Ducon's. Are they originals?

With regards to the electrolytics. The cans had been disconnected a long time ago and replaced with the ubiquitous Brown Ducon's.
I had removed them to make it easier for me to trace the circuit.
My plans are to hide the new electrolytics in the cans.

So far - I've found no show stoppers - all coils & transformers test Ok (without power).

The circuit looks straight forward apart from the changes that some one made to the cathode bias of the RF & IF stages and also inserted a 70 ohm resistor between the centre tap of the HT winding and chassis! There is no back bias on this set - each stage has (or had its own cathode bias resistor). I haven't see anything similar in contemporary sets and I have trawled through lots of circuit diagrams from the early 30s to try and work out what was the most likely original set up.

If you are not sure of a NP cap, the best thing to do with it is to get an insulation tester & see if it leaks (one end out of circuit) I have one standard for them: If it leaks its a dud.

I suspect that those wets are in circuit. As I see washers under them, beware. Fibre washers indicate that both will be above ground. One is leaking so the seal may be cactus. That's a definite do not power.

It looks like Heinze 57 varieties of caps from the sixties onward. Do be aware that RB caps with their wires left a bit long, do mount well on sockets.

To stop & tidy up wire fraying; circuit board lacquer is good. On valve fly leads shrink tube when renewing, or a small ring of shrink tube. Cloth covered wire is around.

Apart from the white UCC "Hi-Qual"s, all your caps are polyester from the late 1960s. Do not replace them, they WILL be OK.

If there is a 70 ohm resistor between CT and chassis that's back bias.

It would be pertinent to see the whole of the circuit including the PSU

I have sent PDF of 6B7 to Brad for comparison with the AGC, 2nd detector circuit. This is the same as 6B8; Only the base is different.

RCA 6B7 Valve

Document uploaded to Post 19.

Brad thanks.

Do be aware that the battery's are in part to help conceptualise the circuit and show which polarity one would expect. Do be aware that there were sets made quite late, that for some reason persisted with a cell in the grid circuit. As an example; where a resistance is shown cathode to ground as on these sheets, this is self biased and the cell is to be ignored.

Unfortunately, when a set has been Monkeyed with, it often makes the fixers job, that much more difficult & time consuming. Positively annoying is the STC here with 0.4V on a 6U7 plate and the correct volts on the two switch terminals that feed it: You get em... Typically one wants to shoot the designer after you realise the crazy places he put the adjustments in a massive chassis?

Obviously had links to the European car industry, where, given an engine they will build a car around it. In one case I know of you need to remove the engine to change the spark plugs.