You're on the wrong track because the pin 3 could have 3 to 7 vdc.
This value depends on the motherboard, not really from the psu.

The basic voltage for the main board and external tuners are 12/5 and pin 10 3.3 vdc.

Nevertheless you need give more information as,
Failure of all tuners, in/external.
Failure of the external tuners.
Failure of the motherboard tuners.
Other issues..
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Johnny B.

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