To shield, or not to shield?

[Beeblebrox]

1 hour ago, Havok69 said:

Being a HAM myself, I of course shield. 

 

It's also always a good idea to reduce your exposure to EMF (also why I'll never buy an EV!)

 

https://pubmed.ncbi.nlm.nih.gov/27012122/

It's funny because humans repeatedly put themselves in far worse health wise positions in everyday life than emf (air pollution, smoking, drinking, bad food choices).  Electric vehicles are the least of our worries... Apart from Cybertrucks..😬😁😉

Edited January 23 by Beeblebrox

[Havok69]

Admittedly the EMF from an Atari is miniscule, but I figured I would put my 10 dollars (2 cents adjusted for inflation) worth in.

 

Now where did I put my aluminum foil body suit again?

[Overange]

16 minutes ago, Beeblebrox said:

It's funny because humans repeatedly put themselves in far worse health wise positions in everyday life than emf (air pollution, smoking, drinking, bad food choices).  Electric vehicles are the least of our worries... Apart from Cybertrucks..😬😁😉

Both gullibility and narrow-mindedness do not help and the internet, particularly through social media, serves as a fertile ground for these tendencies.

[+mytek]

1 hour ago, Overange said:

Both gullibility and narrow-mindedness do not help and the internet, particularly through social media, serves as a fertile ground for these tendencies.

Be careful now, because the gullible ones might take offense 🙄  I jest, but unfortunately what I said is probably not far off the mark.

 

Sooooo... getting back to the original question to shield or not to shield your Atari, I'd say leave them in if you don't plan to do much if any upgrades and/or plan on using the RF output. However for those wishing to install some of the latest greatest gear such as the U1MB, VBXE, ect., it would be far easier to just leave it out. And if you have concerns about radiating, then the conductive paint options would be a good way to go (this is how many of the Atari ST Monitors were shielded).

[351cougar]

given their druthers, Atari would have preferred to use no shields, but they knew they would need something. How much isnt known until FCC sent back the test results. But for what it was initially intended , id think there is little use for it now. 

[_The Doctor__]

comical. this all had been covered before. It was noted observed and a topic of conversations. Even as much so that the firming up of keyboards etc was done by Atari and you have pictures of the supports added as a result. 130XE's with no shielding definitely flex and feel flimsy and some make those creaking noises when missing the structure. XL's had the added support material. The shielding makes a great deal of difference depending on where you live and the environment around the Atari. Radio/TV/Ham and other towers just a few miles away spell trouble for some people and their Atari. You want the best video, the best way to keep your Atari keyboard and pcb going for another 30 years? Keep them on. If you want to go with valiant but limited location redo of some quick short term testing and then remove it all, um ok. I'll stick with what time has shown and borne out to be true to this very day. The bridge held up today, but the engineer said it won't last, lets drive over enough times and see if and when it will fail. Even though we have seen similar in the past and measures were taken to try and abate the problems. Let's see if we know better, It looked good today as we checked a repeat of doing the bridge that failing way, it and all the conditions were perfect, the test said so. So sorry the cars fell in and you can no longer cross the river. Many of my Ham friends have dealt with this kind of topic ad nauseum for a number of what we now call retro electronic devices.

 

I also find it funny that when so many people have found the XE keyboards so flimsy, flexy and bouncy, and it is also a topic of discussion, that weakening it further is ever a suggestion. It feels and works much better when properly supported, the case posts and shield tangs properly engaged or shimmed to help out. I have seen people remove the added posts for upgrades and that works great for them at first, I also don't recommend that.

 

Having fixed too many of these things over the years I don't think anyone would like the kind of extra business and headache of doing repairs often as a result of bad practices returning for a new generation of hobbyists. Repair centers of old have been there and done that. Let's not repeat this part of history.

Edited January 25 by _The Doctor__

[Beeblebrox]

Points taken :), but as I say for some upgraded a8s it's virtually impossible to reinstate the sheilding. To reiterate my earlier point a 600XL's often one piece clamshell shielding will never fit back if you have U1MB, VBXE, Stereo, and other upgrades installed. Same goes for the XEGS, which when an U1MB has been installed, I simply cannot get the shielding back on.

 

Also, for my own A8s I am tinkering so often that having to continually remove and put back shielding is a pain.

 

One other point I've noticed in the PAL 600XL's I've had through my hands, (too many to count), is this. In all of these 600XL's where I've just upgraded the Ram from stock 16k to 64k, and added Chroma to it, 100% of them have a stock video output which is fantastic, even without the shielding present. I've never had a problem running them without shielding. So I am happy in that respect.

 

I've no doubt if there were external factors near me which would cause interferance, installing the shielding would help. But since I've not had an issue in that respect, I don't need to worry.

 

I'll personally continue to leave off the shielding for my XE line of A8s, as well as the XEGS, the 600XL, 800XL. I'll be keeping the sheilding (where upgrades allow) for my 1200XLs.

 

And obviously for my 400 and 800s the shielding/faraday cages are integral to the structure anyways so they are always present. (I've done many incognito upgrades and the latter sits well alongside the sheilding so removing it is never a consideration).

[+mytek]

Ok granted there are a few edge cases where the shields add structural integrity to the keyboard and possibly prevent bending. However that would be limited to the XL variants that came after the 1200XL, and would not be inclusive of the XE line of computers.

 

In the case of the 1200XL, its keyboard is structurally robust on its own, and does not need any additional support from a shield.

 

On an XE system, there are plastic posts coming up through holes in the shield towards the rear and there is a molded in edge support in the front part of the case. On those systems the shield not only doesn't have any "rubber blocks", but also was never designed to actually touch the bottom of the keyboard, which it certainly doesn't. So in other words no structural keyboard support via the shield.

 

4 hours ago, _The Doctor__ said:

You want the best video, the best way to keep your Atari keyboard and pcb going for another 30 years? Keep them on.

Let's qualify this statement. Specifically I agree that if you want the best quality "RF Video" that yes you need the shield. For any other kind of video output besides RF this statement would be false.

 

And I'll presume that the pcb you are referring to is the one on the keyboard, which would only apply to the 600/800XL systems because via the shield and the rubber blocks, bending of the keyboard assembly is hopefully being prevented. Only for those specific XL systems could this statement possibly be accurate.

 

4 hours ago, _The Doctor__ said:

Many of my Ham friends have dealt with this kind of topic ad nauseum for a number of what we now call retro electronic devices.

Definition: Ad nauseam is a Latin term for an argument or other discussion that has continued to the point of nausea.^[1][2] For example, "this has been discussed ad nauseam" indicates that the topic has been discussed extensively and those involved have grown sick of it.

 

Yep I would agree that this does get talked about way too much, with all the same talking points constantly being debated. So let me try once again to condense it down to the essence so that we can all move on

 

No Shielding

Cons

• Computer emits sufficient Radio Frequency Interference to affect various nearby communication and receiving devices using aerial antenna for reception (e.g., TV/AM/FM standard broadcast receivers, HAM radio reception over various bands). Also interferes with the Atari computers "own" RF video output.
• On some XL computers (600/800XL) this serves as structural support for the keyboard assembly, thereby preventing any bending and degradation .

Pros

• Unimpeded access to innards of computer for diagnostics, repair, and upgrades.

 

EDIT: I just had to add the following... no matter how much anyone may insist that the shields should be left in place, it reminds me of all the Harley Davidson motorcycles that soon after purchase have the quieter stock exhaust system stripped and replaced with much louder obnoxious and illegal after market pipes. Bottom line a lot of people don't care if they offend their neighbors with the extra noise that this creates. Basic human nature prevails

 

BTW, this is much more disturbing to others than me leaving the shields off my Atari.

[ClausB]

On 1/21/2024 at 11:23 AM, CommodoreDecker said:

Well, 256kb or 1mb can be very, very useful

Hmmm, I struggle to see the usefulness of 1 millibit. Did you mean 1 MB?

[+Stephen]

To really settle this argument, we should consider the alternate interpretation of the title.

 

Star Raiders - do you play with shields on, or off.  Don't get started on the green vs blue argument either!  Simply on or off.

[Overange]

9 minutes ago, ClausB said:

Hmmm, I struggle to see the usefulness of 1 millibit. Did you mean 1 MB?

I'm pretty confident most people understand what's being talked about.
A millibit isn't something you hear much about in tech or data storage talk. Sometimes in specific areas, folks might mention "millibit" to mean one thousandth of a bit, but it's not something everybody knows or agrees on.

 

Like this topic:-

 

[+mytek]

Star Raiders: shields ON always

[Geister]

 

3 hours ago, ClausB said:

Hmmm, I struggle to see the usefulness of 1 millibit. Did you mean 1 MB?

Maybe he meant KIB and MIB.  I don't know from Kibblebits, but I do know Men In Black. 😃

Edited January 25 by Geister

[Beeblebrox]

1 hour ago, Geister said:

 

Maybe he meant KIB and MIB.  I don't know from Kibblebits, but I do know Men In Black. 😃

Ah I can help here, Kibblebits:

 

 

  Sorry, couldn't resist!  😁

[Havok69]

6 hours ago, mytek said:

Star Raiders: shields ON always

You must be a galactic cook...

[Paul Westphal]

On 1/22/2024 at 2:31 PM, mytek said:

Ok so I just completed a series of tests with a 65XE, and here are my results...

1. STRUCTURAL TEST: No discernible difference with or without shield (removed bottom and top shield). Also had zero influence on keyboard strength since the shield makes zero contact with the underside of the keyboard (it rests on the inside front area of the case and two plastics posts that stick up in the rear).
2. RF OUTPUT INTERFERENCE: Unfortunately my camera ran out of juice to take a picture, but I definitely could see some herringbone patterns traveling across the screen without the shielding in place. Mileage may vary depending upon the TV being used.
3. NON-RF VIDEO and AUDIO INTERFERENCE: No additional noise was seen or heard.
4. ELECTRICAL MASS: The PCB Ground Plane has an extremely low resistance over distance, being on the order of .004 ohms as measured from one side of the PCB over to opposite side with no shield in place (based on these results I saw no need to test with the shield).

I used my Lab Quality HP3466A MultiMeter in it's mili-ohm mode to obtain readings...

 

10 ohm Reference with 1% Tolerance Metal Film Resistor

Zero Point Test (shows how much resistance the test leads add)

Across the Board Test

 

In conclusion here's what leaving in the shield adds...

When RF Output (TV Channel 3 or 4) is desired, it is definitely required to minimize screen noise. And if you don't want to cause interference with someone close by listening to either weak AM or FM radio transmissions over an aerial, the shield should be retained (however now days this concern is probably negligible, and should be dealt with on a case to case basis).

 

Making a Case for Leaving out the Shield...

At least where an Atari XE is concerned, it does not add any significant and/or observable structural strength to the overall case, or to the keyboard. It does not cause any interference to the Composite or S-Video output, and it does not add any additional background noise to the audio. The added metal mass of the shield does not appear to add to the integrity of the ground plane on the PCB (not really sure how it could based upon what my mili-ohm tests showed).

 

As for structural aspects where an XL is concerned, my feeling is that the XE would be most prone to being weak as compared to the XL systems due in large part to the thinner plastic and fewer screws holding the case halves together. Also in the XL, the keyboard is attached with screws to the underside of the case top and doesn't appear to rest on the shield, and it also has a metal backing plate. So I doubt there would be any structural side effects of leaving the shield out of an XL as well.

 

The Atari design employees considerable RF/ESD filtering networks that I've never seen an externally generated RF noise source cause any hiccups with the computer's operation.

 

Bottom line, leaving out the shield makes it infinitely easier to add upgrades to the Atari, and/or diagnose problems.

 

It would be nice to put a lot of the folklore about whether to shield or not finally to rest. Of course as per usual there will be those that disagree with my assessment - so be it, at least I tried to apply a scientific method

Thanks for all that work! I have always removed the top shield unless the customer wants it OG. I sometimes leave the bottom shield on for weight... it kinda feels empty without it

[+mytek]

On 1/27/2024 at 1:52 PM, Paul Westphal said:

Thanks for all that work! I have always removed the top shield unless the customer wants it OG. I sometimes leave the bottom shield on for weight... it kinda feels empty without it

You're very welcome Paul.

 

As an aside, it was implied in an earlier post that the shield might factor into the electrical integrity of the Atari, or in other words something that would be required to allow full and proper operation. As for our Atari systems this isn't the case, but I did come across a video talking about the Color MAC Classic where the shield was absolutely required to have all aspects working properly.

 

 

[_The Doctor__]

For example, using a cartridge based storage device like the Atarimax MyIDE+Flash1m... many carry on and operate inconsistently without shields and work fine with the shields on. This isn't the only device that is flaky without shields but I bet you, someone else has encountered it on the forums.

 

I am glad highlighting the Apple emi/rf shield and the reasons why they did theirs the way they did made the forum.

[+mytek]

8 hours ago, _The Doctor__ said:

I am glad highlighting the Apple emi/rf shield and the reasons why they did theirs the way they did made the forum.

in the Apple Color MAC Classic it was totally unnecessary to do it that way. Think about it for a moment... why was only the internal speaker circuit GND tied into the shield and required it to be there in order to work. Think about all the other aspects going on in that PCB that also required a ground and got it without needing the shield to be installed. Personally I think it was an oversight and not a designed in feature. The same can be said for the missing Chroma connection on the XL systems - pure oversight, since there was absolutely no cost or design advantage to leave it out.

 

Oh and the split ground plane for analog vs. digital on the Apple wasn't dependent upon the shield being there in order to have it's intended noise isolation advantages. However it's always a good design strategy to isolate analog and digital ground paths whenever feasible. Which is something that 4-layer boards with their internal power planes are a godsend in this regard, giving you massive unbroken shield planes, as well as greatly minimizing ground bounce due to the low resistance paths that this provides. But 4-layer boards in the 80's were very expensive, hence the reason that so many 8-bit motherboards were only 2-layer.

 

Let's face it, Apple just like every other personal computer developer in the 70's-80's wasn't perfect, and did make their share of mistakes. Commodore and Atari also made a bunch of mistakes as well, especially when it came to video noise (e.g., jail bars). Although I gotta say that this wasn't entirely their fault, because at the time CRTs were very prevalent, and LCDs were in their infancy, with the later really showing off the video noise issues. It's too bad that they didn't have LCDs from the get go. Of course there are ways to redesign the video circuits to overcome these problems, something that I like to do, and I think do very well at

 

8 hours ago, _The Doctor__ said:

For example, using a cartridge based storage device like the Atarimax MyIDE+Flash1m... many carry on and operate inconsistently without shields and work fine with the shields on.

Never heard of that with any of those products. Can you show actual examples or forum posts highlighting this?

[_The Doctor__]

@Marius might remember such experiences with MyIDE / MyIDE 1 / MyIDE 1+ Flash and shielding way back when.

and I believe @flashjazzcat may as well. My grey matter remembers snippets of conversation about this subject, I also believe Hias may have ventured into that conversation and it worked out to making sure the timing was good (74f08 on atari and ls series in the MyIDE), the power supply being solid, noise minimal, and shields being on. The shielding tipped the balance to the devices working as expected. This was the case for a few other PBI / Cartridge Devices from those segments in time.

There is always more than one way to skin the cat if you want to make things more expensive and add isolation/buffering/ caps and resistors etc but most of the older devices were simple, effective, and relied on solid foundations to work.

In any event, I know longer recall in exact detail that which might be insisted apon down to the exact density of the electrons flowing through materials but maybe I'll find my engineering books and refresh on it one day. I might start with something simple like a search.

https://duckduckgo.com/?kl=us-en&q=electrical+mass+noise+shield+caps&t=seamonkey&ia=web

might find some things to read or lead to more on the subject.

My heart isn't into the endless back and forth as happens from time to time. I have spent many years sharing and honestly don't beat myself to death over this stuff anymore. I find it comforting that a good deal of the forums have new blood looking into and reading the old texts and becoming fascinated with how and why things used to work. I still have equipment that runs using capacitive power supplies. Imagine explaining why they must be double insulated to someone today. I simply explain it's dangerous not to, and a serious shock might result etc. If it becomes a can of worms because someone can't fathom capacitors used to take mains voltage and turn it to DC- I tire and expect them to search it out for themselves. As stating things to them wont be enough... maybe the texts will be considered 'credible' - I might even mutter something about galvanic isolation or lack thereof in hopes that sparks some interest and leads them to know why. Pretty soon I won't remember my own name, chances are I'll still remember some of this stuff, now where is the flux capacitor? -Doc Brown

Edited January 30 by _The Doctor__

[Badwolf]

I don't get why people don't just leave it on. It doesn't hurt anything to keep it intact. If I have to do work on my motherboard I just pull the top off. No big deal.

[Beeblebrox]

1 hour ago, Badwolf said:

I don't get why people don't just leave it on. It doesn't hurt anything to keep it intact. If I have to do work on my motherboard I just pull the top off. No big deal.

Sure, where possible people can of course. But as mentioned in my earlier replies it's not always possible because very often with an A8 ful of U1MB, Stereo, and video upgrades, (VBXE, Sophia2, UGV, etc), the sheilding simply won't fit back on. Certainly this is the case for the tight fitting clamshell like 600XL one piece shielding I've encountered with every single PAL 600XL I've worked on. 

 

Check it out, took these the other day on a 600XL PAL I was upgrading to U1MB, (where incidentally this also highlights another reason for my often not reinstalling the 600XL shielding - razor sharp rusty metal - (time to update my Tetanus shot heh heh!)) 😁:

 

 

 

 

 

 

 

Edited January 30 by Beeblebrox

[+mytek]

7 hours ago, _The Doctor__ said:

@Marius might remember such experiences with MyIDE / MyIDE 1 / MyIDE 1+ Flash and shielding way back when.

and I believe @flashjazzcat may as well. My grey matter remembers snippets of conversation about this subject, I also believe Hias may have ventured into that conversation and it worked out to making sure the timing was good (74f08 on atari and ls series in the MyIDE), the power supply being solid, noise minimal, and shields being on. The shielding tipped the balance to the devices working as expected. This was the case for a few other PBI / Cartridge Devices from those segments in time.

There is always more than one way to skin the cat if you want to make things more expensive and add isolation/buffering/ caps and resistors etc but most of the older devices were simple, effective, and relied on solid foundations to work.

In any event, I know longer recall in exact detail that which might be insisted apon down to the exact density of the electrons flowing through materials but maybe I'll find my engineering books and refresh on it one day. I might start with something simple like a search.

https://duckduckgo.com/?kl=us-en&q=electrical+mass+noise+shield+caps&t=seamonkey&ia=web

might find some things to read or lead to more on the subject.

Thank you Doc. I find this stuff very interesting and will likely be doing some searches of my own.

 

7 hours ago, _The Doctor__ said:

My heart isn't into the endless back and forth as happens from time to time. I have spent many years sharing and honestly don't beat myself to death over this stuff anymore.

Well I tend to find such discussions to be very educational myself, and I certainly hope you aren't looking at this as some kind of battle which it's not. I'm self taught in almost all the endeavors I'm involved in, and learned a long time ago that the best way to do this was to always ask questions and never just accept someone else's viewpoint simply because they said it was so. A good example of this is in what I now do for my 'real' job where I develop multi-refrigerant autocascade chillers that get down to as low as -120 C for 3rd party companies. I first learned how to do this by shadowing the owners of a previous company I worked for that made systems based upon similar technology that got used for many things, including preventing water vapor in a vacuum coating chamber from contaminating silicon wafers for integrated circuit fabrication. As I grew more knowledgeable, I began to go down my own path and found myself questioning some of what I had previously been taught, and this led to new innovation and eventually to me creating my own consulting and development company revolving around a new approach to autocascade chiller design.

 

2 hours ago, Badwolf said:

I don't get why people don't just leave it on. It doesn't hurt anything to keep it intact. If I have to do work on my motherboard I just pull the top off. No big deal.

Well when it comes to cramming some of the newest and greatest upgrades into the cramped confines of our 8-bits, it's just much easier to do so without the top shield in place. In many cases like this, it would require getting out the tin snips to cut clearance holes for some of those upgrades. So this discussion is kinda about "where is leaving out the shield permissible", and what are the pros and cons of doing so. If you like having the shields, and wanna keep them, by all means do so if that works for you

[Badwolf]

Yeah that makes sense. I have on 800XL with a RAM upgrade and whoever had it had to snip some of the top plate to accommodate some wiring going to the PIA chip. It's got the thick Type 4 keyboard too so it's very solid.  You are right, though, that if you had additional modifications raised above the PCB there might not be enough clearance for the top plate unless you modified it, or removed it.  Amazing what Atari could fit into these small chassis. Of course the original power supply is about half the size of the entire 800XL ! 😄

[+remowilliams]

1 hour ago, Beeblebrox said:

Yep, that made my hands cringe in fear 😄