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westcliff · 2nd Nov 2011, 12:58 pm

Last night the transformer was tested following Rich's suggestion. Only the dial lamp was in place when the set was switched on. The dial lamp lit, the set was left for five minutes, then switched off. The transformer was cool after this.

Back in went the valves and the unwelcome noise returned. I started substituting valves one at a time, with no difference to the sound. I have yet to try a different rectifier as the one in place was working well a couple of weeks ago, but I will try a different one next time. I will also check the wiring to the new smoothing capacitors and to the output transformer, and let you know what I find.

Gus.

2nd Nov 2011, 12:58 pm	#47
westcliff Hexode Join Date: Jan 2011 Location: Essex, UK Posts: 397	Re: KB FB10 "Toaster" Last night the transformer was tested following Rich's suggestion. Only the dial lamp was in place when the set was switched on. The dial lamp lit, the set was left for five minutes, then switched off. The transformer was cool after this. Back in went the valves and the unwelcome noise returned. I started substituting valves one at a time, with no difference to the sound. I have yet to try a different rectifier as the one in place was working well a couple of weeks ago, but I will try a different one next time. I will also check the wiring to the new smoothing capacitors and to the output transformer, and let you know what I find. Gus.