In post #86 you wrote:
Quote:
Originally Posted by Humptydumpty
... looking at the schematic dia it looks like both 5 and 6 pins are on the same voltage 200DC voltage to run from v8 Just checked both pins again 5- 6 5 = 210 dcv 6 = 170 dcv .
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Not that it has any relevance to your hum problem, for the sake of accuracy, the schematic does not in fact show that pins 5 & 6 are fed from the same point and on the same voltage. If you look again at the schematic, you will see that pin 5 is fed directly from the output of the two rectifier diodes, whereas pin 6 is fed from the output of R37, and thus, the voltage will be lower. Though the voltage of pin 6 isn't shown on the schematic, 170V seems about right.
In the attachment below I've highlighted the relevant part of the circuit, showing the HT path to pin 5 of V8 in red, and to pin 6 in blue.
Given that you now have 6.5V on pin 2 of V8, and apart from the excessive hum the set is working well enough, that suggests that the output stage is now working as it should.
Turning to the hum problem, as I said in post #40, I feel that the most likely source will be the reservoir and smoothing caps and I’d reiterate that to investigate that further, my approach would be to temporarily substitute those caps, of which there are three in a single can - all 40uF, the nearest modern value being 47uF caps. If that cured the fault, it would be up to the individual whether or not to leave the triple can C40/41/42 disconnected and to fit replacements under the chassis, leaving the redundant can in place for appearance sake, or whether to disgorge the contents of the can and to re-stuff it.
It’s a matter for you whether you feel competent and confident enough to do these tests yourself, and if need be, to permanently replace the three caps in question.
Every good wish for a successful conclusion.