Properly treat rusted shield plates

I've bought this Sega Master System II (PAL, Sonic and that non-Sony VDP chip) and been looking into restoring it.
It's fully funcional, I gave it a good wash (plastics only) and now I'm into treating the metal and electrical components. The board looks ok, so I'll probably just degrease some spots and blow some canned air into the cart slot.
Now, it's shielding case is in a pretty mess. Top side of the upper piece is all rusted, not sure how deep, though the bottom side of it is ok. The bottom piece is ok.


Top shield piece. Rust on the outside only.


Rust as spread to the RF Modulator. Though it can't bee seen in the pics, the rf modulator has a kind of knob (which can be turned either ways with a flat head screwdriver). My earlier model doesn't have this knob but the rf modulator shield has the hole for it already. I could't properly test any difference since I had just the board connected to the power & tv without the shield. I've read it does nothing to the image and the plates are just there to comply with elecromagnetic legislation. I'll test it later with shielding on and on a different tv before reassembling it.

What's the best way to treat it, considering it's size? Any alternative to vinegar/electrolysis? What finishing process should I consider for preventing the rust to re-appear, besides avoiding humidity (how harmful would it be to throw a silica bag inside the console, taped to a safe place, since it has many storage place left?) Whick material are the shield plates made of?

Here's some pics for comparsion with my first system ever, Sega's PAL SMSII with Alex Kidd (which I'll swap some plastics to have it in the best shape I possible).


My other (first) SMS II. Shield is ok. Feels harsh at the touch and the top right of it shows some rust, which I plan to treat it also.


It's respective board. There's some stains, don't seem to me to be degradation. I'll report back after cleaning it.


A side-by-side of there two versions, just for hardware p0rn purposes.

Thanks for any help!

Long time lurker, first time poster, absolute electronics beginner yey!

 

Hi, those shields aren't smooth inside, they're kinda brushed so they're porous and rust easily. that shield isn't too bad, just surface rust. A little Brasso ought to take it out.

 

ive used a Fiberglass Scratch Pen on rust before and its fantastic , its good for small areas though


it would suit the RF Modulator you have there............

 

Handheld grinder with brass wire brush attachment always works. Don't use steel as it will scar the metal.

 

I use a fine sandpaper or like takeshi a brass wire brush.

 

Motor oil will stop it from coming back too.

 

You can get rust treatment from car parts shops, but it'll turn the metal black. Your best bet is to just clean it off with wire wool or a wire brush, really. Don't worry about it too much, though - it's just a shield. Some countries didn't have them.

 

I would honestly just toss them, they're not worth the effort.

 

And on top of that aren't necessary to allow the console to function. My bet is most of the shielding was installed to prevent EMI emissions.

 

If you have a decent air compressor; get this:

Mac Tools Speed blaster



It will remove that rust and get into all the porous areas and make it look new.

 

Is that a sand blaster?

Thank you all for the tips. It turns out I had a car battery charger and am considering electrolysis again. I wonder if motor oil is enough to prevent it from rusting. Plating is a bit overkill and I'd rather keep them as original as possible. I'll probably remove the rf module while rgb modding this unit. It's rusted inside also and that explains some video issues I'm having.

 

Seriously, if you're looking to RGB mod it you might as well save time and dump the shielding.

 

@ ElectricCo.
the motor oil is a sound suggestion.
had an a500 shield get slightly rusty (nothing like your md effort) so i used a scouring pad to sand it clean (without the abrasiveness of glasspaper) then with a porous cloth, used a small amount of oil, just enough to smear the surface of shield, NOT dowse it!
underside of shield shouldn't require coating so replace the rust-free cleaned shield and polish it's exterior with a STRINGENT amount of motor oil!
(axel grease is good for warding off moisture/rust but it's WAY too solid and stodgy)
...
brasso is good for the cleanup too...but a smear-coat of oil should suffice in the long run! (do as much assembly as possible so when the shield is coated with oil, you need not touch it and electronics getting fingerprints all over the show!)
...
hope you salvage that pup! :friendly_wink:
....
[edit]
typo....

 

Use some gun oil like Rem-Oil. Or you could get a cold bluing kit, but that will make it black like a gun barrel. Or you could just get some silver spray paint or clear coat.

 

So... you want to keep it as original as possible, but you're going to take the RF module out and RGB it? Not very original, then!

The RF shielding is to stop RF interference. If you take out the RF module, you're not going to get RF interference now, are you? Cleaning the shielding is going to be a complete waste of time. That said, it's possible a chip in the audio circuit could pick up something like a mobile phone signal and cause noise. Just try it without the shield rather than dumping it then regretting it, of course!

 

I usually throw shields of mega drive and sms1 in the garbage but never threw sms2 shields cos I tought they could have the function of heat sinks having never found heat sink in sms2...am I totally wrong?

 

RF shields are useless. They're only there to conform to certain country's laws concerning RF emissions. The original systems in Japan don't have them at all.

 

Not until VCCI started (1988). Nintendo partially adopted it in 1988 with the VCCI Famicom and fully in 1990 with the Super Famicom. EMI is generated and transmitted even even if the system has no RF modulator part. It comes from the digital switching and signaling within the system and may cause *OTHER DEVICES* to malfunction. It's not there to protect the game system from other devices but to protect other devices from the interference *IT* generates.

 

I get that. But really, what are you going to be using in your immediate area that's going to be affected by EMI while you're playing one system or another?