FIRST WATT BIAS SETTING FOR F-5............Not turbo !!!

Look here...

https://www.firstwatt.com/wp-content/uploads/2023/08/prod_f5_man.pdf

DeKay

Dekay:    Thanks for your input but I have already been there, My amp I think is about the first version of about 5 different f-5 boards.............I have also contacted Nelson Pass and they are looking into it................So I thought that maybe someone else would have a odd unit like mine...............Thanks  

Wow, I just went down the F5 rabbit hole @ DiyAudio.

Hopefully Pass (class act) will recall the details.

DeKay

@autospec

Does it make any sense to return your amp to First Watt and request they bring the amp up to current F-5 spec?  Or, maybe upgrade your amp to the current F-5 version?  This might be the safest solution and money well spent  

FYI - The F5 model has had various modifications and upgrades over time, such as the “F5 Turbo” upgrade that improves power supply safety and performance, adds better filtering, and allows higher power output (e.g., up to 50 watts per channel with proper heat sinking). These upgrades can enhance reliability, safety, and audio performance without fundamentally changing the classic Class A topology of the amp. 

Click here to for F-5 link