KONTAK CLEANER

" Easy to use, simply apply and allow to dry. Once Kontak has been applied, contact resistance between the connectors drops to virtually nothing, enhancing signal flow and conductivity."

https://www.musicdirect.com/equipment/kontak-contact-cleaner-aluminum-bottle

"  Also can i use it to clean my electric posts on my amp , preamp and cdp?"

isnt that what you bought it for ???

I have used it and used plain white paper towel to wipe the items until things were clean. 
I “did not” simply apply the cleaner and let it dry ...(coat the dirt?)
Try it and see the tarnish come off. 

addyson815...... Thanks....I didnt even think of the electric posts on my amp ,preamp and cdp until it came. I was just thinking about my speaker cable spades and power cable plug ends. I guess you can use it on any metal connections. 

@ tattooedtrackman

"  Thanks....I didnt even think of the electric posts on my amp ,preamp and cdp until it came. I was just thinking about my speaker cable spades and power cable plug ends. I guess you can use it on any metal connections. "

I would do one thing and then give it a few days before adding it to other connections.     that way if there is a change that is not good, you will know what piece you did.

addyson815.... Thanks i will do that... BTW, what do you clean with it?