Pioneer SD-5046 shuts down
 

Came across an unusual problem in this PTV, if I crank the B+ *up* to around
150v the set stays on and works fine other than the picture shrinking a bit,
but if I turn it down towards 135v specified the set shuts down. Where
should I look? Usually when I have a set shutting down it's because the
voltage is too high, but this one has to be too high to stay on.