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Old 24th January 2019, 07:54 AM
snowman_al snowman_al is offline
Join Date: Nov 2016
Location: West Wales
Posts: 89
Default Re: Problems with K5881 MK2

Hi Dave,
Two things to look at then.
First is the amplifier drawing more current than it should be? Have you checked the voltages on the 5881 cathodes (pin 8)? You can work out the current through each valve then using ohms law. The circuit has 56 to 60mA per valve.

Second is the mounting of the transformer and the end bell.
Are the red washers there, is the transformer mounted directly to the chassis or on rubber grommets etc.? If you slacken or tighten the bolts does it improve or worsen the buzz etc.?
You might have to rework the mounting.

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