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Old 12th Dec 2021, 1:23 pm   #64
DMcMahon
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Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
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Default Re: Grundig TK27 - Low audio output

The fact that the hiss level can be controlled by the volume control would indicate that the source of the hiss is before the volume control, i.e. around the two EF 86 pre-amp valves.

Certainly check for bad soldering around the valves and dirty valve base socket pins etc.

Using scope you should see the hiss on one or both of the EF 86's and hopefully home into problem area.

The TK 23 contacts are arranged physically differently compared to the TK 27 with most of the PB/Record switching being done on the long slide switch.

David
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