In that case that would be one difference between the 850 and 850a.
I don't have the service manual for the 850a so I based my comments on the 850.
Also, I thought I saw the fuses when I had my 850a opened for the fan swap. I am going to review the photos to see if the breakers were captured.
Edit: Okay, I remember right about seeing the fuses, found the photo. The breakers for for the transformer primary protection, the fuses are on the transformer secondary, to protect the rectifier bridges. You can see the 2 fuses in the bottom right corner.
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