KYORITSU KP-87B Peak Level Meter problem.

I got 2 of these that i never used and i'm trying to get them to work now. Does anyone have any info about them, like what voltage they need ?

Never saw these before.
From looking at them I'll say: The two big terminals above are for the audio signal. The two smaller ones below are probably for powering the leds so power these between 3 and 5 volts or so.
However, for the led meter to work there need to be some kind of driver circuit. I suspect that this is inside the meter. Maybe you can take a look inside?

It can also be that these meters need some kind of external driver card or so, depending on what you'll find inside them.

These are from ca 1988. It's a special verson of the standard KP-87 with built in Peak LEDs.  Costed about $125 each when new.

Looks like this inside.

Found it finally .... 20-24v DC.  And they look great 

I use them all day run it on 12V you vcan calibrate a lot in there. I did a recap job but did not replace the 741. I use them together with sifam VU's and calibrate the peak meters on 0dB for +6dBu. That works best for me.