I read that the SBX1637-11 can be bypassed with 2 4.7uf capcitors
posted he

http://tipsmaster.ca/hottips-1.htm

I removed SBX1637-11 and soldered in the 2 4.7 uf caps, both positive
to pin 12 and negative to 10 and 11 as stated in the instructions,
but no joy. I never had any audio problems until it went completely
dead the other day. From what I've read, the SBX1637-11 goes staticy
before it dies. The only thing I can think of that was different in
the last couple of days before the audio died, was the family was
over and the little ones had the TV turned up loud because of all the
talking in the backround. The TV worked for a couple of days after
that, then it died. I'm wondering if maybe something on the amp
board went?

By the way, the TV is not in SAP mode, I checked that before I started
ripping it apart.

Any other suggestions?