Help, No sound from Turntable

Check to make sure the tonearm signal wire LEMO connector is fully seated into its output box. Where the red dots line up.

Mute button?

Do you have a volt meter?

Thank you everyone of the comments.  I've been traveling so haven't had a chance to really try any of the suggestions until today.  I tried previously to shut down both the preamp and the phono preamp and restart in hopes of the problem fixing itself.  No Dice.  

I tried plugging the tonearm cables directly into the Preamp.  No Dice.  

I do here a low "pop" when I turn on the motor to the turntable which is something I've always heard but when I put the needle to the record it's dead as a door nail.  I'm going to try a new cartridge.  I was looking to upgrade anyway.  Anything you would suggest under $2k for a MC cartridge?   

I would think it would be very rare for a cartridge to go completely dead without a bit of sound. I’ve heard of them becoming quieter, or becoming distorted, etc. But going completely dead quiet? That would seem quite the anomaly.

Before going out and purchasing. $1,500 cartridge, I would suspect something else. A wiring failure somewhere in the turntable/tonearm would be my first thought.

But, if you have no back-up cart, I would go out and buy the cheapest MM cart I could find, ‘bolt it on’, and see if you get sound.