I recall repairing a Yamaha Receiver where the Dolby board was shot.
The unit had smoked on the protection Board and took some effort on my part to get it functional again.
After repairing the Protection Circuit, I noticed none of the Dolby Functions worked.
As long as I bypassed it, it worked flawlessly, so I left it at that.
Was just something someone gave to me. I fixed it up the best I could as I wasn't about to try and chase down a dolby board for it. Wound up giving it to my Brother to use for tunes in the Garage,
Just mention the story as makes me wonder if the intermittent cutout on yours could be something similar. Meaning possibly a hardware issue in the Dolby Circuitry on it's way out?
DB8E/VHF Yagi rotor FM Bandstop ap-8700 preamp 8way split LG lcd.