Question about the TI motherboard shield

[jrhodes]

My current (and i suspect also the one i have coming from ebay) systems have the motherboard with a shield.

I have never removed that shield. I've had the unit taken apart twice for cleaning.

If i was to remove the shield, do you think i could leave it off if i give all the major chips (cpu and vdp for sure, maybe ram?) a stick-on heat sink?

[Ed in SoDak]

It was primarily intended for RF shielding, in TI's typical tank-like design norm. Seems the FCC used to care about such trivial things as obliterating TV and radio reception. These days, not so much!  But the metal enclosure did perform double-duty as a heatsink for the VDP. Plenty of alternatives for that. Your finger will tell you which chips would benefit. As to losing the RF containment, your wife will let you know all her TV shows have wavy lines now.

-Ed

Edited December 8, 2019 by Ed in SoDak

[Tursi]

In earlier machines the 9904 also attached a heatsink, and even without it also runs pretty warm. But QI machines ditched the top shield entirely and the VDP just has a clip-on heatsink there.

 

[HOME AUTOMATION]

I've had a bad experience operating w/o shielding...

 

...on some case bottoms there is a steel leaf-spring that helps support the shielding and thus the main-board, near the expansion port. There can be a bit of play on the main-board when connected to that giant, heavy P-BOX connector! This can cause contact between the leaf-spring and  the main-board, resulting in a short!

 

So if you do remove the shielding, remove the leaf-spring as well, before reassembling the case, then be careful to check alignment when using the expansion connector.

[apersson850]

Being a designer of electric systems for machines, where many of them are exported to the US, I can tell you that the FCC is concerned about interference just as they used to be.

Actually more than before, since they have now adopted some of the more modern European style rules to the concept as well.

[wierd_w]

The primary rationale USED to be to protect broadcast signal bands (which used to be easily smashed by leakage) to assure that the Emergency Broadcast System could function (this was especially strongly enforced in the 80s, when the cold war was still going).

 

These days, it's more to protect likewise sensitive bands used for government data communications and pals, with prevention of smashing cellular communication bands a strong second.

 

It does not have near as much "national security!!" weight behind it as it did in the 80s, but yes- it is still strongly enforced.  Most of the time, the sheilding demanded is good medicine for devices anyway. The sheilding works both ways, and with lots more energy being pumped out in the 2.4ghz band (Cumulatively, by all the consumer devices using it within a small area) it makes sense to protect devices from getting saturated. With that short a wavelength, you do not need a very long conductor at all to unintentially intercept those signals, and get spurrious inputs on logic circuits and the like, especially if your design includes amplifiers.

 

The niave thing is expecting the world outside to be radio-quiet-- and thus, have no need for RF sheilds at all.  

[Tursi]

Even so, these regulations are for manufacturers... you don't have to worry about a knock on your door because you removed the RF shield. Not yet anyway.

 

Weird_w does make a good point about the reverse though -- the shields also protect your machine from everyone else's noise.  I haven't had any trouble with my plank TI though.

[apersson850]

Well, if somebody reports to the FCC, or similar authorities over here, that they have noise preventing radio reception, then an on location investigation could take place, in which case your modified electronics could be found as the culprit, in which case you could be held responsible. But there are many "could" in that chain of events.

One of the main reason the FCC was so worried about this in the old days, compared to nobody caring back then in Europe, is the general state of everyday technology in the US being some 50 years behind Europe. Here, FM broadcasts took over from the much more sensitive AM radio broadcasts in the 1950s. Thus there wasn't much concern about electromagnetic noise until all the computers coming in everywhere put the first requirements for legislation similar to what you had in the US in place in 1995.

[Omega-TI]

One of the funniest stories I ever heard was about a cable provider in Rainier, Oregon.  Apparently there were a few consumer complaints about an Amateur Radio operator 'messing with their TV channels".  So, to pass the buck, the company reported the Ham to the FCC.  The FCC comes out, inspects the mans station and finds him in full compliance.  The FCC then decides to inspect the cable providers system, and it's leaky as all get out and deemed a hazard to aviation.  One million dollars in upgrades later, the cable company puts a disclaimer on one of their stations that basically said, if you get any interference on certain channels, there is nothing that can be done about it.

[Tursi]

2 hours ago, apersson850 said:

Well, if somebody reports to the FCC, or similar authorities over here, that they have noise preventing radio reception, then an on location investigation could take place, in which case your modified electronics could be found as the culprit, in which case you could be held responsible. But there are many "could" in that chain of events.

Your TI motherboard doesn't put out a strong enough signal for the FCC to find you with their radio sniffer from the street. It's unlikely it's even strong enough to get through the paper-thin wall to my neighbors. You can prove this for yourself. Tune an AM radio to a local station, and see how close you have to get to your open TI before you can hear it.

 

Now my microwave, THAT throws off a hell of an interference pattern. The FCC can have it if they want it.

 

[+OLD CS1]

On 12/11/2019 at 12:59 PM, Tursi said:

Your TI motherboard doesn't put out a strong enough signal for the FCC to find you with their radio sniffer from the street. It's unlikely it's even strong enough to get through the paper-thin wall to my neighbors. You can prove this for yourself. Tune an AM radio to a local station, and see how close you have to get to your open TI before you can hear it.

I would, however, love to "hear" what the TI's motherboard is capable of picking up from the ether.

 

About ten years ago I postulated using sound and radio for random number generation.  It is still sitting on my "shelf" waiting for me to head to grad school.

[+save2600]

On 12/11/2019 at 11:59 AM, Tursi said:

Now my microwave, THAT throws off a hell of an interference pattern. The FCC can have it if they want it.

 

I had a microwave (an expensive built in) that when used, would knock out my wireless router and they were several rooms apart! I'd need to reboot my router afterwards. Thought my ISP was flakey before realizing the pattern.  lol

[jrhodes]

1 hour ago, save2600 said:

I had a microwave that when used, would knock out my wireless router and they were several rooms apart! I'd need to reboot my router afterwards. Thought my ISP was flakey before realizing the pattern.  lol

Nothing ruins a movie faster then getting up to get a fresh bowl of popcorn and coming back to no working internet to continue the movie.

Edited December 13, 2019 by jrhodes

[+save2600]

55 minutes ago, jrhodes said:

Nothing ruins a movie faster then getting up to get a fresh bowl of popcorn and coming back to no working internet to continue the movie.

Now that, I wouldn't know about. Haven't used a microwave for popcorn since it was a "thing" in the 80's. yuck

 

I make mine on the stove top! Whirlypop or not, just add a little olive oil, popcorn and... yum!  
 

 

[Omega-TI]

One corner of my den has a microwave for late night coffee and popcorn production.  It's about 7 feet from my router and I've never experienced any degradation of the WiFi signal.  Maybe it's close proximity overcomes any RFI.

 

[wierd_w]

3 hours ago, save2600 said:

Now that, I wouldn't know about. Haven't used a microwave for popcorn since it was a "thing" in the 80's. yuck

 

I make mine on the stove top! Whirlypop or not, just add a little olive oil, popcorn and... yum!  
 

 

 

You should try avocado oil;  Takes higher heat, and with a bit of seasalt, tastes a lot like movie theater popcorn.

[+save2600]

7 hours ago, wierd_w said:

 

You should try avocado oil;  Takes higher heat, and with a bit of seasalt, tastes a lot like movie theater popcorn.

I'll look into that! The way I make it (with olive oil) already tastes better than theater popcorn though. I don't buy just any old kernels either. Gotta be the small, lighter stuff. Usually petite white. The popular stuff like Redenbacher pops too large, looks funny coloration wise and is too chewy for my tastes. 

[wierd_w]

Beware though-- Not all brands are created equal!!  Some are made from pressing the avocado skins, and taste terribly pine-tree like. Blech.  Not good on popcorn.

 

Others are mild and fantastic for popcorn.

 

For reference, this is the one I get.

 

Stay away from this one, unless you happen to like oil that tastes faintly of turpentine.

 

(And if you want TeensyWeensie popped kernels, try airpopping milo (AKA, sorghum). :))

(Video is for hot oil method, which tends toward burning. I have better luck with an old 1980s air popper when doing milo.)

Edited December 14, 2019 by wierd_w