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Carver M-400 display problem

Hi, I have a Carver M-400a amplifier and the led peak reading meter refuses to work. There are two columns of LEDs that are supposed to light up in succession with increasing power. The bottom 2 LEDs light up with power on and the surge of a start up flickers the upper LED's so I have hope the display board is good. have the service manual but it does not address any issues with my "new power supply" version.

All suggestions appreciated......

Re: Carver M-400 display problem

Could be a bad display driver IC (IC2, on the display board). I would first check for the - and + 12 volts at pin 3 and 4; this is measured to chassis ground. If either one of those is missing you won't have a display. Carver used kind of an odd way to get those voltages: the +12 volts comes from the +25 volt supply and is regulated by ZD1 (zener diode) through a 2 watt 280 ohm resistor; -12 volts comes from the -80 volt supply and is regulated by zener diode ZD2 through a 4700 ohm resistor.
If any of the diodes are shorted or the resistors are open the circuit will not work.