The ghosts of all those RF shields you’ve tossed out have had their revenge! ;)

@platypusfrenzy

3 жыл бұрын

I have to say, in re: the title, that "improper grounding due to removed RF shield" is indeed a cause of malfunction in one of Adrian's computers that I'd believe in.. :P

@vasopel

3 жыл бұрын

to be fair..this machine's RF shield was so rusty it HAD to go.

@wimwiddershins

3 жыл бұрын

Fellow RF shield thrower here. Apple shenanigans 😂

@PCEngineGaijin

3 жыл бұрын

It always drives me crazy when he does that. I repair a lot of electronics from the late 80’s to mid 90’s, and quite a few circuit board designs use the rf shield to connect ground planes like this. It’s really not that unusual.

@bitoxic

3 жыл бұрын

Adrian, don't let this experience discourage you to toss out future RF shields!

This feels like nothing but divine retribution for serial RF-shield snubber Adrian.

I love this joke "Just to recap, I recapped the motherboard!!!"

@frankowalker4662

3 жыл бұрын

He Re-capped the Re-cap. :)

@Charlesb88

3 жыл бұрын

@@frankowalker4662 and now you’ve recapped a recap of a recap of recap which I have just recapped. Since this can go on forever I suggest we now put a cap on this conversion.😃

@frankowalker4662

3 жыл бұрын

@@Charlesb88 LOL.

@isaacposselt7089

3 жыл бұрын

This joke will scar me for the rest of my life, JUST TO RECAP. You have to recap right? It's food, I mean for the motherboard; I guess 🤷

When/if you ever open a merch store, the first T-shirts available should say, "It works! It freaking WORKS!" ❤️ when you say that.

@TheSulross

3 жыл бұрын

Right up there with that classic film line, "It's alive, it's ALIVE!" (1931 Frankenstein - for those that don't watch B&W films)

@RayBrooks0

3 жыл бұрын

"Hello, Chip Dippers!" "Welcome back, Cave Dwellers." "Hi, it's Jan Beta." "IT WORKS! IT FREAKING WORKS!" I know who has my favourite catchphrase 😄

Since we're being clickbait-y :) "RF Engineers get revenge on Adrian with this ONE simple trick!"

@BrightSpark

3 жыл бұрын

"The SECRET TRICK that Apple does NOT WANT YOU TO KNOW!"

@BillAnt

3 жыл бұрын

12:49 thank me later. ;D

@bandrej

Жыл бұрын

This simple trick to repair ALL your old hardware the support doesn't want you to know.

As the guy in SimCity 2000 says: "YOU CAN'T CUT BACK ON -FUNDING- RF SHIELDS! YOU WILL REGRET THIS!"

15:30 - Split ground planes are to prevent digital logic ground currents from contaminating the lower level analogue circuitry...

@nickwallette6201

3 жыл бұрын

Commenting to raise this. It’s pretty common to keep analog and digital grounds separated except for some central star ground point. Think of a PC case, for example. The whole case is grounded to the PSU. The motherboard grounds to the case via the screw posts. Drives ground their chassis via metal to metal contact to the case. The Pro Audio Spectrum 16 sound card uses the ISA bracket for its audio ground. (I found this out when I removed the bracket after replacing old corroded jacks with new ones that were slightly shorter.)

@SianaGearz

3 жыл бұрын

@@nickwallette6201 I weep when i see modern ATX enclosure front panels connect audio ground and USB ground together. When you get interference from increased load, no surprise. The mainboards are remarkably careful about star-grounding the audio unit today.

@robiniddon7582

3 ай бұрын

Using the shield as the return path is not very clever though. It creates an enormous loop for the high impedance and noise sensitive audio signals. Audio frequencies are so low that they don't cause a problem for RFI so it's not necessarily a problem to involve the shield in the audio circuit. Until some other RF signal decides it would like to join in 😂

Only stupidly simple problems take so long to diagnose. That’s something I’ve learnt over the decades

@BillAnt

3 жыл бұрын

Just plug in a Zip drive, problem solved. ;D

Hi Adrian, the separation of grounds was indeed for RF shielding but I suggest you solder only one "bridge" to the external ground to avoid "ground looping". You would notice this also by hearing strange noises through the speaker. It probably won't cause any noticeable difference but in the case of any surges a star ground is always a rule of thumb. Cheers and keep up the great vids!

@8BitRetroJournal

3 жыл бұрын

So it helped in shielding? So only circuitry that needed shielding was put on that ground plane? But anything you plug in externally in that SCSCI port undoes that. Very confused on the purpose of dual ground planes. But I was thinking that likely you only needed to bridge it in one place.

@pragmax

3 жыл бұрын

Do you think he would get power supply switching noise and other artifacts? CRTs can generate a ton of noise too. IIRC, early 1990's macs developed a reputation for good quality audio production. I wonder if isolating analog audio ground this way contributed to that?

@UpLateGeek

3 жыл бұрын

@@8BitRetroJournal As pragmax suggests the purpose is to reduce noise from the digital circuitry. Not sure if it's the exact right way of putting it, but the sharp edges of digital signals cause noise that can be picked up by the ground plane (I know, it's an oversimplification of the issue). Having a separate ground for the analogue parts of the circuit means that noise can't cause interference with the audio signals. So yeah, connecting an external device which shorts these two ground planes could also cause the digital noise to to be picked up by the audio circuitry, which may also be the case with Adrian's modifications. However it's a little more complicated than that, since you also need to take into account return current paths, and that's where having a star ground helps. Connecting an external device would also only connect the two ground planes at a single point, similar to a star ground, so that might not be so bad.

@absalomdraconis

3 жыл бұрын

Haven't watched the whole video yet, so not sure if it has anything relevant to this, but: 1) if you're worried about bridging grounds partially via audio connections, bear in mind that sound connections commonly have capacitive isolation, and 2) "shield" grounds commonly have little to no noise on them in the first place because they aren't used for signaling at all.

@absalomdraconis

3 жыл бұрын

Upon watching a bit further, I remembered something about SCSI: it uses bus termination, so there should be little to no noise reaching ground from the SCSI bus itself.

I wonder what Adrian does for a living? He is so knowledgeable and hardly ever seems to get completely stumped.

@MOS6582

3 жыл бұрын

Dunno but pretty sure he’d be the guy that every tech related workplace has who deliberately keeps really quiet about how much he really knows otherwise he’d be swamped with requests to fix shit (on his own time and with no extra duties pay ofc)

@daxx77m

3 жыл бұрын

I got a feeling that he’s an electrical engineer or graphic designer like his dad

@nickwallette6201

3 жыл бұрын

Hasn’t he said before that he’s in IT? He just has really good troubleshooting skills.

@SuperMoleRetro

3 жыл бұрын

Yeah, electrical engineer was my guess.

That’s cool! I designed that back panel and posted it on 68kmla.

"Just for a quick recap I took the board and recapped it" nice, nice.

Having a split ground plane to minimise interference between digital and analogue circuitry is standard practice. Using the RF shield to connect the two was probably just the cheapest/most convenient solution.

Every time you remove an RF shield, I struggle... Like, they actually perform a function (not just using them for grounding and this kind of weirdness), but also, they block RF emissions (which can screw with cell phone, Wi-Fi, and Bluetooth reception, among other things). Like even if it has no RF specific components inside, some of those old CPUs and ASICs can generate radio noise, and noisy power rails can act as antennas. It's part of why they have those RF shields in the first place...

@UnreasonableSteve

3 жыл бұрын

Exactly! His I'll will towards shielding will probably bite back in much more subtle ways than just grounding issues. I guess I have to hope he lives out in the middle of nowhere

@undefinednan7096

3 жыл бұрын

Don't forget the other way around. Noise can screw with circuitry, especially analog circuitry, but by no means is digital circuitry immune.

I have absolutely no knowledge on electronics, apart from the very theoretical basics I learned in High School. Your videos, though, made me learn so much more about retro technology and how it works in practice, that I managed to repair a C64 and a C64C. I still can’t believe it, this channel is a blessing!

That RF shield, and digital/analog ground split was the best way to prevent EMI from exceeding the emission rules of the day. Split grounds also helped keep digital noise from getting into the sound signals. It works if done right. I use split grounds in my microprocessor projects when I use the A/D and D/A in the microcontroller. It keeps the analog signals separate from the digital signals. Apple probably had to work hard to meet the emissions requirements and that was their solution. Great video!! Thank you!!

"You know what I do to RF shields...into the trash!"

@Adrian It's interesting to hear you reflecting on these compact Mac's. My SE Superdrive was the computer that got me through university and I remember loading up Netscape & Z-Term and getting it online for the first time. It had a 68000 16Mz accelerator in it but was still unbearably slow. Even Maelstrom was sometimes my game of choice to distract me from the all those papers I wrote on that little Mac. A colour classic would have been my dream setup too, and thanks to your channel I have a Color Classic II on its way to me right now from a Japanese auction website. Who knows if it will work or even survive the journey, but all I know that I need to get it out of my system and find out. If I can eventually coax Maelstrom to work on it then that will bring some nice closure too. :)

@charlesconto3154

Жыл бұрын

Did you get your Color Classic running?

@InitialiseDisk

11 ай бұрын

How did it go?

It was only a matter of time before an RF shield got its revenge on you

"It Freakin, Freakin works", that's one happy Adrian, right there.

@simonbarnes8303

3 жыл бұрын

I think we need a T-shirt with this on

I’m currently restoring my old Color Classic, and I’m looking forward to the day when I can say, “It works! It freaking works!”

Adrian, Apple did not split the analog ground plane from the digital ground plane to reduce EMI. Splitting the ground planes is a standard tactic to reduce noise in the analog circuitry for several reasons(*). When digital circuitry switches, especially CMOS, it will briefly draw a much larger "gulp" of current to switch voltages (needs to charge/discharge various capacitances). Because of ohm's law and the fact that real ground planes have nonzero impedance, this will actually produce a voltage spike on the parts of the ground plane the current flows through, which screws with all circuitry, but especially analog circuitry -- digital circuitry is somewhat protected by noise margins on logic levels. This is mitigated to a certain extent by bypass capacitors, which essentially spread the current spikes over a longer period of time -- the same amount of current will eventually need to flow in order to recharge the bypass caps. However, the current flow from digital circuitry still tends to produce noise on analog circuitry. Splitting the ground planes forces the return currents from the analog and digital circuitry to take completely different paths (**). Usually, the ground planes will be connected on the PCB, perhaps at a "star ground", but using the chassis or RF shielding is not terribly uncommon. * Note that this sort of design gets very complicated and there are disagreements about when to or if one should use split ground planes. However, my goal is to just explain why they were used here, not talk about what should be done for new designs. Please don't take this as advice on how to design PCBs. ** Note: modern sources advocate analyzing return paths instead of blindly splitting planes.

Congratulations on figuring out the sound problem! It's blowing my mind, I'm sure I'd never figure it out if I had to debug this system. The destroyed shield made sure if you assemble the machine it'll never work on it's own.

Ground path through the RF shield was used to avoid ground loops. Ground loops are created when having more than one path towards the ground. Although you might thing this would be good, in electronics, such a configuration creates an antenna. As a result of the loop, the circuit will pic up interference. The frequency of that interference is related to the length of the loop and you can refer to it as the characteristic frequency (or range of frequencies). In case this is within the operating range of your circuit, then you will be picking up noise. I would do what other people already suggested, only connect the two grounds in a single point.

Oh man, Maelstrom. *That* brings back memories.

The RF shield revenge! Very surprise about the main cause of non working internal audio. Excellent serie, great job of restauration/troubleshooting for a wonderful machine at the end. I’m waiting for the next série now lol

Adrian got 0wn3d by RF shield. I love this sweet irony ^^

Thanks for this Color Classic repair series, it was really fun to watch!

So happy you figure this out Adrian !! Nice work !!

That was an excellent bit of troubleshooting Adrian. Great job!

LOL. When you tossed that RF shield (as bad as it was) I was like "uh.. i think you might need that ! It's not just Rf shielding!"

That is one awesome vintage MAC. Awesome job with all of the repairs as well!! The video looks awesome on my late 2009 macbook!

Hi Adrian I really look forward to seeing your work. I have been teaching myself about electronics and the repair of. You are a great instructor and bring all your work down to a understandable level Thanks again.

Adrian, glad to see you finally fix the sound issue. Like others below I had a chortle when it was the RF Shielding :)

That jelly donut shirt cracks me up every time... I only found your channel a few months ago, not big into Macs but I like that people restore these old computers, my elementary school had a few older units knocking around when they got the newer G3's. That startup "bong" always reminds me of sneaking off somewhere during lunch to play the Mac version of SimAnt or something on one of the older color Mac's they had around.

I never owned a Macintosh classic until a few years ago (now have Classic, Classic 2, and SE/30). Really love the compactness and the HANDLE! First time seeing the Color Classic 2 in action; while I'm not a fan of the case changes, the colors do make a tremendous difference. Nice job on the restoration, glad you stuck it out until the end!

I loved this series very much. Thank you. 😀

Hello from the future. This was a great fix of a great looking mac. Thanks

WARNING: Do never ever remove a RF shield from a motherboard. Sometimes it's sounds bad. ;-) Thank you for this another amazing video.

I can only imagine the reaction from your local retro buddies when they watch this video and see the RF shield karma! haha

Good show. Nice print job on that cover too. Thanks.

I forgot all about Maelstrom. I loved that game, mostly because of the awesome graphics, very impressive sprite control.

Awesome series and I loved it. Our first computer was a black and white mac around 1991

I freakin' love this channel. Period.

I've done many designs where single point grounding was used on a PCB (star point) especially when using high speed ADCs, but it seems like bad design to rely on external mechanical ground connections for a circuit to work. Perhaps this was the only way to get the board to pass FCC testing - sometimes when a product fails a test you get desperate!

@z80dad61

3 жыл бұрын

Bad design practice / 90s + apple engineering seem to go hand in hand

Very well done Adrian!!

Well done in finding why the sound would not work and sound advice for anyone else having the same problem. 👍

Congrats on figuring out the sound issue!

thanks for all the video,s adrian superb work as always .

Cool video adrian, excellent troubleshooting - you have a new subscriber :) i have a bunch of old macs - mine are all PowerPC machines but I love seeing these older classic macintoshes, i hope to get some soon.

We had an old Mac when I was in elementary school. It eventually got raffled off, and I lost. I was devastated. The "rich kid" got it. I would have loved getting it, but I hope Ben got some good use out of it. Love your videos. Thanks for the updates.

I liked this series! Great to see it working now imo

Adore your tenacity. I would have given up on this long ago😁

I fully enjoyed your fault finding solution in the sound. So funny finding out the shielding was the problem. In the future removing the shielding may be the problem why things don't work . Lesson learned. Great watching look forward to future videos.

Great repair job!

Just FYI - when you were looking at the scope trace of the audio signal, it was jumping up and down when you plugged in the external speakers. I have a theory on what caused that. Audio circuits are AC coupled, at least usually. It’s always nice when you have +/- voltage rails so the AC can be centered around 0V, but quite often it’s using a 5V DC supply. This means you have to center the AC waveform around some DC bias voltage to make sure the negative swing of the signal can go below the reference point. You would then use a capacitor to remove the DC bias and re-center the waveform around 0V. Hence, AC coupled. (Even if you have a -5V rail, you still need to AC couple to make sure you don’t have a ground potential difference. Moreover, in many cases the -5V rail is only used for amplification and the D/A is still DC biased. I haven’t looked at the Mac schematics though.) The “outside” or jack side leg of that cap needs to have a ground reference, since there’s no DC flow through the cap. Usually, the input stage of whatever you’re plugging into (like a powered speaker or a mixer, etc.) will have a resistor to ground. This sets the input impedance to something between 1K and 100K, often around 10-47K. Instrument and mic level inputs are higher (maybe 1M), balanced pro audio is 600R, but you get the idea. That R to ground pulls the AC coupled signal to ground, but isn’t strong enough to short the output, so you get a voltage swing around Gnd. So what you may have been seeing on the scope when you plugged in the audio cable is the external ground being applied to the AC coupled waveform, bringing the bias point down. Particularly if the ground reference was missing on the internal speaker circuit path.

Nice Adrian. I’m addicted to every one of your videos. I need to get an oscilloscope and learn how to read them from a signal standpoint.

I was amazed at the quality of the picture which wasn't what I was expecting at all, I thought it would look much more basic. We had some of these Macs in the school lab although I don't know exactly which model but definitely didn't have much ram and had the black and white screens which I think is why I was so impressed to see such a detailed image as I just think of the basic mono graphics the ones I used had,

Woah! Maelstrom! I completely forgot about that game. We used to play in middle school.

Hi Adrian, love your channel. You mention different parts for your videos at the beginning. KZread does a great job of suggesting the parts in order if it's part of the title. Something to consider if you can do that. I know you're probably bouncing around projects and other things so might be hard to keep track which part you're on :)

keep up the great work Adrian 🕹

Awesome troubleshooting.

I remember my older brother playing Maelstrom on his Mac, and I think he even talked to the developer of it about Mac programming in general. It's also available in many Linux repos.

Amazing video, very informative!

Adrian's channel is what convinced me to just enjoy retro computers vicariously - I bought one (Tandy Model 200) and it works, but it will be the one and only. Otherwise will stick with modern neo-retro computer recreations, FPGA MiSTer, and the like.

Hi Adrian, I greatly enjoy all of your videos. I'd love to see you build and MSX2 Omega kit.

Lol, those kind of ground failures can drive you completely crazy. And then the feeling after hours of searching when you solve the riddle and to find out how ridiculous this is. 😅. Well done and very entertaining video. thx.

Grounding through the RF shield? That's one of the craziest things I've seen them do. Back in those days Apple literally had an A team and a B team for hardware. I suspect the A team was busy working on Quadras or something when the Color Classic was imagined and handed to the B team. This was Performa-level shenanigans.

I sold a MAC SE/30 for a lowly low price because I could not get the sound working except from the headphone jack! I tried everything, including replacing the capacitors, checking all connections, resoldering in case of cold joints... to no avail. Finally I have the possible answer to the mystery.

RF shields are important. Example; my C128's RF shield doubles as on large heat sink! They are very important in Apple Color Classics. Concerning that Apple didn't use a ground cable!! Great video Adrian!

Conclusion: RF shields may be useful! LOL! Love your content Adrian, thank you for the videos!

wonderful work.. thank you so much for the video...

Love those beautiful machines.

The delay in opening the jpeg isn't because of the image compression, it's primarily the reduction to 256 colours. That is really processor intensive.

Some DLP projectors also use the shielding as an electrical connector on the power board. A loose screw would keep it from powering up. Specifically all the Viewsonic PJD models.

"Just for a quick recap.." Funny :D

@adriansdigitalbasement

3 жыл бұрын

Very punny :-)

@mikesilva3868

3 жыл бұрын

@@adriansdigitalbasement 🤯

It's kinda interesting that the Mac's comeback after Apple's mid 90s company woes also was itself, also a compact, all in one form factor Mac with a screen, a drive below the screen, and a handle on the top. While obviously not quite as compact as the classic compact Macs, I definitely look at the iMac as the continuation of the small form factor appliance computer that these were more or less also intended to be.

Yes, we did enjoy your videos

Reason I _think_ Apple did this would be: Perfect grounding design on any electronic would be full "star configuration" which means in perfect world that from every ground-point is only one path up to "central grounding point" . That design will make its part ensuring least possible amounts of electrical noise will travel to any other component. From the video it looks that shielding, being perfectly valid grounding plane or "conductor" too, was designed to carry external connectors grounding directly to "grounding central point", which will in theory be best possible way to carry spikes to ground as direct as possible when fiddling with external devices, while grounding within, say, SCSI-pins is considered "digital side" and thus connected to "digital side" of grounding.

Using the RFI shield as the audio ground would probably have been done to help stop radiated emissions from a cable plugged into the audio jack. If the audio ground were connected to digital ground, any noise on the digital ground would be able to radiate from the ground conductor of the cable plugged into the audio jack.

(13:49) It is quite common to have two separate grounds, an analogue ground and a digital ground. Typically these grounds would be joined together at a single common point (ie. Star Ground) in this case the RF shielding. I have repaired many switch mode power supplies that have an isolated ground, and yes, you must connect them together when the supply is on the bench, under test, or it will not work.

"This was the last mac in this form factor" -- well, except for the Color Classic II (aka Performa 275), yeah? 😅 thanks for this video series! So much nostalgia, really fun to see the internals and some classic software. We had a Color Classic when I was growing up for maybe 6 years or so, and even though it was so slow me and my brother played _so_ many games on it... Had an external harddrive and CD player and everything, gravis joystick, etc. I remember playing Doom on it being... not fun at all 😅 you had to play in a literally post stamp sized window for it to have a tolerable framerate! (Our next machine was a 5200, so if you have any like that one around I'd LOVE to see it ;D also I have a LOT of mac retro hardware from that era if there's every some more weird parts you need...)

The animated mouse pointer of JPEGView really brought back memories. Wow.

The original Xbox also uses the RF shield to distribute ground.

Great video

You can actually browse the web in a relatively modern way even on a classic mac like this. The trick is to get around the encryption which can be quite easily by connecting through a squid proxy that essentially performs a MITM attack and just strips the encryption. I spent a ... reasonable amount of time figuring it out, but I'm sure most of the people that would ever care to try wouldn't have much trouble with it.

I've made that torte recipe, it's actually REALLY good. I highly recommend it.

@katho8472

3 жыл бұрын

So quickly?

@ToTheGAMES

3 жыл бұрын

@@katho8472 As if the site appeared at the same time as this video... LOL

@katho8472

3 жыл бұрын

@@ToTheGAMES Haha of course it existed longer but I supposed that "shadow" got aware of it through this video, as did I, being just a German noob :P

@shadowtheimpure

3 жыл бұрын

@@katho8472 Nah, I found that site years ago crawling the web with Netscape navigator back in the early 00s.

Hi Adrian, long time viewer, I especially enjoy your troubleshooting and repair videos. In part #3 you 3D printed a new rear panel for your custom Color Classic. What brand is the 3D printer and would you recommend it ?

Called it at the first mention of audio not working through speaker, but does work in headphone jack. Bad connection in the internal jack. There is a mechanical 'switch' that turns off the speakers when you insert a headphone jack. Most common issue with that kind of hardware. Troubleshooting 101: Follow Olcums Razor.

Great vid.. Glad to see that Color Classic happy again... Personally, I think just for nostalgia reasons, the Color Classic isn't in my top tier. I like my Classic Macs in B/W. ;-) But great to see it running and with Ethernet! And that 040 was smoking for that era!!

I *had* Maelstrom on my Quadra 610! It was one of my favorites.

Another example of a split ground relying on an RF shield for connectivity is the cartridge port on a ColecoVision game console. Pin 13 of the cartridge port replies on a mechanical connection to the lower RF shield to be electrically connected to the central ground.

:) Best time of the week ADB :)

I'm no RF expert, but have some experience. It was probably a cost reduction discovered when optimizing the overall unit for production. Someone noticed that the shield was conductive, and at ELV voltages. Not expecting people to remove the RF shielding (which would be an FCC requirement), they saved a few cents per unit in the form of reduced board space, better routing, or even something as simple as a via that could be removed. Just about anything that isn't strictly speaking "necessary" while still having the required performance, as well as meeting the necessary specifications goes in high-volume consumer products. It's an entire profession.

I think Dave on Eevblog discusses the split planes approache in one of his latest pcb review videos.

Great video. If you are looking for a game that will run on the classic mac color, There is one I had called "Happy Weed" Its a pac man type game were you run around eating marijuana leaves, cops are the ghosts that chase you and you smoke a doobie to freeze the cops so you can put them in jail. I realize that you might not be in to this type of game but It is funny to play. You run around the maze and collect doobies and can use them when ever you want. The game was well programed and has over 1000 levels. Anyway for the later macs it might not play very well as it does not check for CPU speed and plays way too fast even on the slowest speeds.

Wow, that brings back memories. Even though I knew the answer of the shield grounding, I had completely forgotten about it. Yes, I was a Mac technician back before the Genius Bar killed most of the independent Apple Authorized shops off. P.S. They aren't board-level comprehensive, but if you want I still have a copy of the Apple Tech Disc, it goes all the way up to 2005 so it not only covers all models of Mac, but also iPods and Newtons as well. Somewhere in my collection I also have the older Tech Disc that has the Apple // files. Let me know.

To improve apps on older apple hardware running os 7/8/9 try assigning plenty of ram per-application (select executable icon, get info, memory, typically u double the minimum recommended size); if you really have a plenty of RAM installed in the logic board you can create a ram-disk, reboot, copy the slow app into ram disk, assign it plenty memory and try again; great detective job on the ground plane issue!

Welldone!!

well on most motherboards from pc's , at leasy pentium 2-4 era audio was also insolated grom digital ground they had only connections made by single 0 ohm resistor and had it's own power rail filtration caps all that was made to stop digital noise interference to analog aution which would produce high pitch noise hiss , but also audio interfering with bass sounds pulling ground up and making digital errors on the other side i belive in this case shield worked as low resistance resistor link that would stop crosstalk along with rf interference interesting bug non the less