Super Famicom loud hum and slight graphical glitch.

First post so go easy on me.
I have a super Famicom I've had it for 4 months, I play it every now and then, and it looks like it has a decent amount of wear on it. I'm using hori RCA cables but I've tried other rca cables and X-video as well. now when I first got it I didn't notice any humming that was out of the ordinary now when there is a silence in the game it's extremely noticeable. Now my two other snes both make SLIGHT humming but it's nothing out of the ordinary and it's very minor. the other issue I noticed was with Super Metroid every time I get a power up or save and a black box with text comes up. the colour on the screens go all sorts of messed up. this goes away if I pause the game and unpause or go to a diffrent area. Now I am using a third party famicom adapter from Japan. it says AC100-240V 50/60ghz 20va Dc10v 850ma.

My first guess is something is messed up inside the SFC because it's old.
second. plugging the adapter in without a step down converter screwed up the system.
third, I need to be using a better power suply (original genesis) which I don't currently have.

EDIT: for some games I notice no problems then others I notice big problems with some layers fucking up. maybe it's a ppu issue

 

I also have a second question. My SNES when I hook up the S-video cables it's black and white, looks good aside from the fact of no colour, is there a easy fix to this?

 

I would try a different psu,the one you have could be a very cheap one.

As for no color on s-video the first thing I would do is adjust the red or green trim cap on the motherboard,it should be right be the crystal,just turn it will a small screw driver when the system on until you get color.

 

I'l try that for the S-video now. I'll look into charging, I connected my offical NES adapter to a converter and tried it to the same thing, but it's still the wrong kind of voltage is my best bet to try the original sega one? also I will say the buzzing is coming from the speakers, and it only comes on 10 seconds after super metroid turns on it's silent before then. it will go silent. then once I get a new item or save it's a loud buzz for 30 seconds.

 

tried the red crystal no change. Had it on turned with mario rpg in, someone on facebook suggesting the chroma was damaged.