Yamaha CS1D Operating Manual page 409

Hint
These buttons are linked with the METER [PRE]
switch in the METER section (MASTER block) of
the CS1D top panel, and their setting will also affect
the level meters in the meter bridge block.
When the PRE EQ or PRE FADER button is on, the
METER [PRE] switch LED will light.
When the POST FADER or POST ON button is on,
the METER [PRE] switch LED will be dark.
The peak hold function will be momentarily
cleared when you change the metering point.
4 PEAK HOLD
This button is linked with the METER [PEAK
HOLD] switch of the METER section (MASTER
block) on the CS1D top panel, and its setting will
also affect the level meters of the meter bridge block.
If this button is on (the METER [PEAK HOLD]
switch LED will light), peak levels of each meter will
be held.
When this button is turned off, the peak level display
that had been maintained until then will be cleared.
METER functions
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