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samrebel

RF Shielding - Replate or toss?

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Hi all,  first post, first TI-99/4A.  Just won a silver and black TI-99/4A with an lovely Alps keyboard off of eBay for $30, including the power cord and joysticks, which I think was a fair deal.  I didn't even bother testing the machine when I got it, as I didn't have a video cable at that point. A few scuffs on the aluminum top, but hey what do you expect for an almost 40 year old machine.

 

I disassembled the machine and found the biggest issue right away, which was that the RF shielding was extremely rusty, which left rust stains on the ground plane edges of the mainboard, and rust stains on the bottom of the case.  I scrubbed the mainboard edges with IPA and small squares of 3M green pads, and used Barkeeper's Friend powder on the inside of the case (tip from a boating board for cleaning the inside of coolers, lol).  I washed the mainboard, power supply board and keyboard with dish soap and water, which cleaned up a treat.  The boards honestly look brand new. I was going to retrobrite the keys to get the lettering whiter, but I was afraid it would dull the black and they look great otherwise.  I went ahead and put the machine back together without the shielding, and once I got a cable, fired it up.  Holy moly, it works!  

 

My question is, what do I do with the RF shielding?  I'd like to put them back in to keep the machine original, but I've soaked them in a phosphoric acid rust remover to clean them up which has removed what's left of the plating.  Does anyone know a good cheap plating shop that will accept and ship parts by mail?  All the chrome shops around here focus on automobile restoration and are both expensive and don't like bothering with small jobs.  Should I just toss them?

 

Sam 

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Seems like a lot of work and expense for no real gain.  I understand people like to keep things original, but you will likely only find one in a million where the RF shield is in perfectly shiny and chrome condition.  Plus, no one cares.  If you have chips with heat sinks on them, usually the VDP, then the shield provides some cooling functionality.  As well, the expansion port fingers connect to the shield and can help with grounding and shielding on the one or two original TI components you might never use.  The nenoPeb, the Jedi32k (Matt's 32k,) the side-port SAMS, really none of the home-brew stuff use the expansion port grounding fingers.

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This was asked a while back on another topic header, but I think the result was, who's inside looking? I think most agreed to just clean it and move on. Lol

But, if it's something that is going to be jewelled up, that's another game.

 

 

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Hey All! :-)  What exactly is the "RF-shielding" on the Ti99 console?  Is it that silver , snap-together part that the keyboard sits on (when console is assembled)?  And, shouldn't the PS (in the console) REQUIRE RF-shielding (and grounding, too)?

 

Jt

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To answer your questions:

Yer, the RF shield is that metal can around the main board that the keyboard goes over.

No, the power supply doesn't care if you have an RF shield. The FCC might care, but it is doubtful.

Edited by JB
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