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 Post subject: Sega 32X whining coil, audio and video noise
PostPosted: Mon Aug 29, 2016 10:03 am 


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So I've got a Sega 32X that works, but is kinda unreliable and has other issues. Anytime it is powered on in a Genesis, it emits obnoxiously loud coil whine. This includes when the 32X is not even really being 'used' such as sitting at the Sega CD bios. There's also a buzz in the audio where the pitch seems to change in-sync with the way the coil whining pitch changes. The picture is completely visible, but there's some faint horizontal lines moving all around as interference.

I've tried it with an official AC adapter, newer 9V adapter, multiple Genesis systems, and the behavior is pretty much the same on all of them. Trying to search around about the coin whine, I saw things such as "coils don't go bad. If they're whining that bad that means they're being fed the wrong power levels" paired with suggestions to recap the 32X. I replaced all the capacitors and the behavior is still the same. I have no idea how the 32X power circuit works. I tried to see where the incoming DC from the power brick was going to see when it hits some sort of voltage regulator to drop it down to (I assume) 5V to make sure it is the correct voltage, but I'm having a hard time following it. I also don't know what signal/circuit from the Genesis tells the 32X to power up.
Console5 has some nice schematics of the 32X here https://console5.com/wiki/32X but i'm not knowledgeable enough to follow the power circuit (incoming AC is on the "sub section" schematic).

Anyone have any experience with 32X issues like this, and/or are better than me at reading a schematic to make some knowledgeable suggestions?

EDIT: If nobody has any suggestions, is anyone knowledgeable enough to show my an exact replacement for 32X coil/inductor? Preferably on digikey.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Aug 30, 2016 6:02 pm 



Joined: 06 Oct 2012
Posts: 1201
Check that power supply. The capacitor inside is probably leaking.

I got a Genesis one time that was making terrible buzzing noise in the audio when i turned it on.

I tried a few different things including another power supply. Buzzing went away.

once i opened it up i saw that the power supply that came with that genesis had a badly leaking capacitor. I replaced it and the buzzing was gone.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Aug 30, 2016 8:47 pm 


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cr4zymanz0r wrote:
I've tried it with an official AC adapter, newer 9V adapter, multiple Genesis systems, and the behavior is pretty much the same on all of them.

mvsfan wrote:
Check that power supply. The capacitor inside is probably leaking.

I got a Genesis one time that was making terrible buzzing noise in the audio when i turned it on.

I tried a few different things including another power supply. Buzzing went away.

once i opened it up i saw that the power supply that came with that genesis had a badly leaking capacitor. I replaced it and the buzzing was gone.

:|


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Thu Sep 01, 2016 1:01 pm 



Joined: 07 Aug 2006
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Location: Sydney, Australia
Take a photo of the inductor with a (metric) ruler next to it for scale.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Fri Sep 02, 2016 8:25 am 


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viletim wrote:
Take a photo of the inductor with a (metric) ruler next to it for scale.


Just posted some images here: http://imgur.com/a/O4ngs

Also, I took apart a 32X that's working without issue and it had an inductor that looked to be the same size, but was a different model. It actually had a company and model number on it: Tokin SBC7-301-122-P3
However, googling it got me nowhere.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Sun Sep 04, 2016 7:35 pm 


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Bump?

I'd like to get a replacement inductor/coil ordered with the next round of components I order from digikey.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Sep 13, 2016 8:24 pm 


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Well crap. I took a semi-educated guess and ordered this replacement inductor: http://www.mouser.com/Search/ProductDet ... C8-331-142

Swapped them, similar levels of coil whine and still getting the audio buzzing and video interference. Video interference appears to only be for 32X, as it was fine on the Sega CD bios screen (but still has audio pops and such).

I'm kinda at a loss now. All caps and the inductor have been replaced everything is still the same or possibly marginally improved.
I have another working 32X that gives absolutely no problems at all, so I don't know what's up with this one.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Jun 26, 2018 12:34 am 



Joined: 26 Jun 2016
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I realize this is a rather old thread, but I had this exact same problem and finally managed to fix it today.

The replacement coil I used was this one:
https://www.mouser.com/ProductDetail/81 ... 2C-331MAP3

The whole story if anyone's interested:
http://nowab.blogspot.com/2018/06/32x-squeal-fix.html


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Jun 26, 2018 1:07 am 


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that's awesome that you fixed it, but I'm scratching my head as to how changing the inductor for an equivalently valued one made a difference...


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Jun 26, 2018 1:08 am 



Joined: 26 Jun 2016
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maxtherabbit wrote:
that's awesome that you fixed it, but I'm scratching my head as to how changing the inductor for an equivalently valued one made a difference...


Well, the one I replaced it with is shielded for one thing.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Jun 26, 2018 1:25 am 


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samson7point1 wrote:
maxtherabbit wrote:
that's awesome that you fixed it, but I'm scratching my head as to how changing the inductor for an equivalently valued one made a difference...


Well, the one I replaced it with is shielded for one thing.

according to your blog post the first shielded one you tried didn't fix it


also, can you describe the video noise you were initially having please


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Jun 26, 2018 3:37 am 



Joined: 26 Jun 2016
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maxtherabbit wrote:

according to your blog post the first shielded one you tried didn't fix it


also, can you describe the video noise you were initially having please


The more I think about it, there were a couple of other elements I didn't think were important enough to write down, but in hindsight they may be relevant.

I read that physical vibration is a factor with these. I've seen a few systems, like the Turbo Express where the coils are covered in gray epoxy - presumably to dampen them. The shell of the through-hole coils have a kind of skirt that makes contact with the board in a circle all the way around the coil. When I first tried replacing the coil with the exact same part, I was careful to make sure to get full contact with the surface of the board, but it didn't appear to do much good. With the first shielded coil I tried, the legs were too far apart to fit through the vias for the original coil, so I had to put some right-angle bends in them and when I installed that coil, the skirt of the coil wasn't making contact with the board at all. With the SMD coil, I had to put a little triangle of electrical tape over an exposed ground point that sits under the coil to keep it from shorting to the coil, but otherwise the entire underside of the coil sits flush against the board - it's possible that full contact and possibly the electrical tape is allowing the PCB to absorb the vibration.

The other thing is the inductance variation between the parts. When I measured the original, and the exact replacement, they both registered 0.3mH. It isn't exact, but it's at the low end of tolerance. The first shielded coil I tried measured 0.33mH - exactly as rated, and it _did_ seem to make an improvement. Since my component analyzer doesn't have an easy way to measure SMD parts, I used DMM probes to measure the last coil and got 0.36mH. I assumed the DMM probes were going to introduce a certain amount of inductance by themselves and that might be throwing the reading off. But since you asked the question I went back and measured the original part using the probes and got 0.3mH - meaning that the probe wires weren't throwing the measurement off, and the SMD coil does have a significantly higher inductance value.

The original part has a tolerance of 10%, meaning anything from 297uH to 363uH _should_ technically be acceptable.

So, in addition to being shielded, although the replacement is rated exactly the same, it actually has nearly 20% more inductance than the original, and is almost definitely making better physical contact with the PCB. It's entirely possible one of those two things made the difference.

I have no intention of fussing with that 32X any further now that it's working perfectly, but logically if you wanted to try fixing it without replacing the coil, you could try doing something to fix the coil to the board, like hot-glue, or silicone sealant or something like that first.

Edit: Sorry, you also asked about describing the noise. It was a constant high-pitched whine almost like a whistle, along with scratchy static hiss. The video noise was like a dark flicker that covered mostly the top half of the screen. I apologize that I did not take any video or audio recordings while I was experiencing the problem.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Wed Jun 27, 2018 10:58 am 



Joined: 20 Mar 2017
Posts: 98
Interestingly enough, the model 2 on its own produces a high pitched whine from its sound circuitry, it's most noticeable if you have a Mega Amp installed.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Jul 03, 2018 12:47 am 



Joined: 02 Jan 2018
Posts: 38
I found out about this topic via Bob's weekly roundup.

I actually design magnetics (transformers and inductors) for a living, and have been doing it for 15 or so years. Believe it or not, that is a real job.

I suspect the coil is coming in and out of saturation. The schematic on console5 shows that this is a buck inductor running ~50kHz taking the ~10V and dropping it to 5V, and it's using a saturating pnp switch (fig 13b form the on spec) , which would indicate that it has peak currents near or above the IC's spec .. which is on the high end for this choke.

Schematic: https://console5.com/techwiki/images/6/ ... ection.png
IC Spec (from one vendor): http://www.onsemi.com/pub/Collateral/MC34063A-D.PDF

I just ordered a bunch of stuff, including an o-scope to check this out. I plan on trying to resurrect a dead ebay 32x. Once working, I will remove the coil and replace it with essentially two test points where I can clip some alligator leads to it and swap the coil. I'll also add a 0.10Ω ± 1% non-inductive shunt resistor in series, so I can look at the current waveform. This should only drop the efficiency of the circuit a bit, I think I calculated about 0.20Ω added resistance to the coils section of the buck. The 32x service manual says it's nominal power usage is 4W, which would mean the coil should see around 0.8Arms of current (4W/5V).. so that's like around 0.200-0.125W of added loss.

If the stock choke is saturating, the input current waveform (s/b sawtooth) will have a non linear component, as energy storage of an inductor is 1/2 L*I^2. As L decreases from saturation, current goes up exponentially to maintain energy storage.

I went ahead and tuned a 330µH choke to the min spec (296µH actually) and I also brought home some 390µH coils. The coils I am going to use have a ferrite with a higher saturation flux density than was was avalible in the 90's. The lower the inductance, the higher the peak current will be.

Also I'll dissect the stock inductor and calculate the flux density.

This project will take a few weeks, maybe a month, as I'll have to work it inbetween family stuff and work travel.

This stuff is my jam, hopefully I can help solve an issue.

BTW I have no clue why this would actually show up outside the power circuit, unless power is dropping out in the audio circuit.

BTW #2: don't mess with power stuff unless you kind of know what you are doing. This is rather safe as it's a class 2 linear transformer going into the 32x providing me safety from mains. If you are using a $5 SMPS from China, it's less safe.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Jul 03, 2018 4:27 pm 


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cool, good luck on the experiments!


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Jul 03, 2018 4:56 pm 


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I don't have much to add except also express my interest in your findings, xwred5. I can at least relate that a dot of hot glue or silicone will mitigate coil hissing from personal experience.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Fri Jul 20, 2018 8:52 pm 



Joined: 02 Jan 2018
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I have my test setup. I need to RTFM on the o-scope, I can't get a good image of the current waveform. I am also going to order a 1 ohm shunt to try... which should give me a ~1V peak signal to look at instead of a 100mV signal.

I discovered something while taking apart the 32x and I have a new theory. However, considering how wrong I think I was, let me try to get data first... and some new inductors.. and new resistors...


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Jul 24, 2018 12:46 am 



Joined: 02 Jan 2018
Posts: 38
I have results I'd like to share.

The TLDR; is

A) The 32x uses a SMPS to drop the ~12V DC unregulated input to 5V regulated. This uses a Buck inductor, L7, 330µH.
B) The core used is a ferrite core.
C) The core used has an open construction (i.e. radiates Flux like a bar magnet)
D) There is a nasty occasional 20kHz ripple current. This is in the audible range.
E) The RF Shield is Ferrous.

The noise is likely, coming from two places.

1) Vibration of the inductor from Magnetostriction from the ripple current.
2) Vibration of the electro plated steel RF shield when the inductor becomes magnetized.

The coil is operating fine, if you can’t hear the noise or it doesn’t bother you, it’s probably best to ignore it.

Test Setup:
32x with Inductor removed
O-Scope is a Rigol DS1054Z
3x 1.0Ω ± 5% resistors in series as a shunt. (My current is the voltage/~3 with a 5% error, I didn't measure the complete resistance, and it’s moot to the experiment).

https://imgur.com/yu6pS9G


Measurements
I initially thought that the inductor was saturating. In a SMPSs running well above audible (which they should), when the core saturates, it loses its magnetism and this can happen in a period that is audible.

To check for saturation, I wanted to look at the linearity of the inductor current waveform. As an inductor saturates, power is maintained through 1/2 L*I^2, so current becomes exponential to maintain power.

Stock Inductor ~0.73A peak.
https://imgur.com/2Zo6jpY

Note the inconsistencies in the waveform frequency are, I believe normal, when the IC is in Quiescent operation.... which is part of the problem.

Stock Inductor, Linearity at Peak.
https://imgur.com/V5n2Z80

When I tore apart my 32x... with a magnetic tip screwdriver... I noted that the screwdriver stuck to the RF shielding i.e. it is ferrous. There is also a little cut out for the inductor in the shielding.

(I stole this picture)
https://imgur.com/Tz4CT9f

Because hearing sucks, I used the RF Shield to amplify the noise. In some cases, I couldn’t hear any noise from the inductor alone. NOTE: These cores are NON conductive. I know this because I design with these components daily. I don't recommend placing parts on metal carelessly.

Stock Inductor:
https://www.youtube.com/watch?v=4gVR0B7gd4E

SMD Shielded Inductor, Similar to Blog Post:
https://www.youtube.com/watch?v=F9_6fo5NU9o

So when the core becomes magnetized, in addition to vibrating itself (which varied among the inductors), it can also interact and vibrate the RF shield. In some cases, I could not hear the inductor when not placed on the shield.

Solution:

I am not a power supply designer, but you could re-design the power supply to get away from having ripple current in the audible range.

Since I strongly suspect it’s a combination of Magnetostriction and the vibration of the RF shielding, I quickly designed a coil that is shielded and uses a core with no Magnetostriction (Sendust) https://en.wikipedia.org/wiki/Sendust

I had a designer kit of a new high frequency sendust cores at my desk, probably the old stuff would work fine, but I didn't want to wait a week for cores to arrive to wind a part to test.

Core: 3x Micrometals SH-050125-2, stacked. https://www.micrometalsarnoldpowdercore ... aSheet.pdf
Winding: 52 turns of #23 magnet wire, in 2 layers. https://en.wikipedia.org/wiki/Magnet_wire
Other: Polyolefin heat shrink, cores taped together with 1mil yellow polyester tape.

I measured ~420µH @ 0Adc and ~320µH @1Adc ~0.16Ω

Waveform:
https://imgur.com/XqJveSJ

Noise.. or lack there of -- (P.S. that Pfffff noise isn't from the 32x, not sure what I picked up)
https://www.youtube.com/watch?v=DcSz5QtmQ4k

Since making your own custom inductor for your 32x isn't really possible for everyone, I am looking for an off the shelf solution. I have one in mind that I will try to duplicate and test later this week. You might have to cut your RF shield…

To be continued…

For fun, below are all the parts I tested… sorry about the kerning

https://imgur.com/MtJMylJ


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Jul 24, 2018 12:13 pm 



Joined: 26 Jun 2016
Posts: 35
xwred5 - thanks for sharing your findings!

It seems like you focused on noise coming from the inductor itself rather than noise/interference polluting the audio/video. Maybe you're seeing both but didn't mention the other? I just want to make sure we're talking about a solution to the same problem. Is the coil's interaction with the ferrous RF shield causing the interference to leak in through the ground plane and mess with the A/V out?

The inductor with blue plastic insulation you pictured is, anecdotally speaking, the "good" one. Of my two 32X units, the one with the blue variant of the part was the one I mentioned in my blog post as functioning perfectly with no noticeable interference in the A/V output. I've found (thought can't seem to find now) at least one other report of someone having the exact same experience - the stock black inductor has a whine and video interference and the stock blue one does not. The black one is the exact part you can still buy from Digikey.

Have you taken measurements with one of those installed? If not, I'd be happy to send you my original inductor to you for analysis.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Jul 24, 2018 2:25 pm 



Joined: 02 Jan 2018
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I have two 32x's

1) Given to me by my buddy last Christmas to complete my tower of power. I have no AV noise, but I have mild audible coil noise.
2) I bought one on ebay that was broken, it has the same coil as my previous unit. I fixed it (loose ribbon) and I have no coil noise.. that I can hear.

I don't have any av noise to diagnose, so my focuses has been on the inductor

I went ahead and bought the part you listed from mouser, and a potential off the shelf solution. If you want to send me your original, I'll PM you my address.

I'll update when I test these parts, not sure how long until I'll receive them.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Jul 24, 2018 2:39 pm 


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my current operating theory is that all 32x a/v quality degradation stems from the onboard SMPS

I've yet to find a unit that has any interference issues after you bypass the power section and inject externally regulated 5VDC to the power rail

perhaps the underlying cause of both issues is failure of a different component, and the unstable power supply then exacerbates the coil noise


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Jul 24, 2018 4:36 pm 



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Posts: 38
maxtherabbit wrote:
my current operating theory is that all 32x a/v quality degradation stems from the onboard SMPS

I've yet to find a unit that has any interference issues after you bypass the power section and inject externally regulated 5VDC to the power rail

perhaps the underlying cause of both issues is failure of a different component, and the unstable power supply then exacerbates the coil noise


Let me test the other inductor samson7point1 mentioned, and see if I can get AV noise. For everyone's reference, I am hooked up via some cheap Component cables I bought on Amazon, my main setup uses an RGB/OSSC.. which I can also test on.

Pretty much all SMPS (with exception to the newer quasi resonant and resonant topologies) make a ton of noise. The name of the game is keeping the frequency of the noise outside of the are of interest--- which I am not sure that the MC34063 does well. Also that inductor is like a flux cannon, the field is going to radiate well around the inductor.. which I suspect was rattling the RF shield of my one 32x.

I have a cap kit from Console5 that I'll install after I look at the other two inductors to see if the waveform changes. From my experience, unless you burn up your driver IC or FET (or BJT in this case), capacitors are the most likely to fail.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Jul 24, 2018 5:27 pm 


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xwred5 wrote:
maxtherabbit wrote:
my current operating theory is that all 32x a/v quality degradation stems from the onboard SMPS

I've yet to find a unit that has any interference issues after you bypass the power section and inject externally regulated 5VDC to the power rail

perhaps the underlying cause of both issues is failure of a different component, and the unstable power supply then exacerbates the coil noise


Let me test the other inductor samson7point1 mentioned, and see if I can get AV noise. For everyone's reference, I am hooked up via some cheap Component cables I bought on Amazon, my main setup uses an RGB/OSSC.. which I can also test on.

Pretty much all SMPS (with exception to the newer quasi resonant and resonant topologies) make a ton of noise. The name of the game is keeping the frequency of the noise outside of the are of interest--- which I am not sure that the MC34063 does well. Also that inductor is like a flux cannon, the field is going to radiate well around the inductor.. which I suspect was rattling the RF shield of my one 32x.

I have a cap kit from Console5 that I'll install after I look at the other two inductors to see if the waveform changes. From my experience, unless you burn up your driver IC or FET (or BJT in this case), capacitors are the most likely to fail.


the 32x I have that makes an audible whine did not change its sound meaningfully when I removed the shield

personally, my interest is in eliminating the audio and video noise on the outputs of the unit (which is visible on CVBS as well as RGB) - the audible noise from the console itself doesn't really concern me


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Jul 24, 2018 6:39 pm 



Joined: 02 Jan 2018
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Do you want me to send you an inductor to try? I can send you the toroid I wound yesterday, or one of the parts I bought from mouser as an OTS replacement.

Or, would you be willing to send me your noisy 32x or trade?

Let me know. It's hard for me to look at the AV when I am not having problems.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Jul 24, 2018 8:40 pm 


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xwred5 wrote:
Do you want me to send you an inductor to try? I can send you the toroid I wound yesterday, or one of the parts I bought from mouser as an OTS replacement.

Or, would you be willing to send me your noisy 32x or trade?

Let me know. It's hard for me to look at the AV when I am not having problems.

I'd be willing to try a new inductor and report back, but the video noise is *severe*

I'd be very surprised if the inductor fixes it, but can't hurt to try


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Jul 24, 2018 9:32 pm 


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this is not my thread, but the sega-16 member seanami posted a thread years ago with the exact same video disturbance I am experiencing

http://www.sega-16.com/forum/showthread.php?24760-Sega-32x-Buzzing

and here are his pics of the interference - mine looks exactly the same
http://imgur.com/a/Hby21#0


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Jul 24, 2018 11:00 pm 



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maxtherabbit wrote:
this is not my thread, but the sega-16 member seanami posted a thread years ago with the exact same video disturbance I am experiencing

http://www.sega-16.com/forum/showthread.php?24760-Sega-32x-Buzzing

and here are his pics of the interference - mine looks exactly the same
http://imgur.com/a/Hby21#0


I only have one 32x game, I guess I see horizontal lines on the polygons, not really sprites.

Looking at the schematic, there is an extra inductor (L6) and cap (CE19) after the VCC to AVCC. This powers the sound IC11, IC4A, IC1.

The inductor, LC is a cheap little epoxy coated wirewound guy. On the BOM it states 12µH, on the schematic 100µH.... according to the color code on the banding, it's 12µH installed... going up to 100µH seems quite high....


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Jul 24, 2018 11:30 pm 


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xwred5 wrote:
maxtherabbit wrote:
this is not my thread, but the sega-16 member seanami posted a thread years ago with the exact same video disturbance I am experiencing

http://www.sega-16.com/forum/showthread.php?24760-Sega-32x-Buzzing

and here are his pics of the interference - mine looks exactly the same
http://imgur.com/a/Hby21#0


I only have one 32x game, I guess I see horizontal lines on the polygons, not really sprites.

Looking at the schematic, there is an extra inductor (L6) and cap (CE19) after the VCC to AVCC. This powers the sound IC11, IC4A, IC1.

The inductor, LC is a cheap little epoxy coated wirewound guy. On the BOM it states 12µH, on the schematic 100µH.... according to the color code on the banding, it's 12µH installed... going up to 100µH seems quite high....

keep in mind the VDP of the genesis still renders some of the assets on screen - backgrounds, text, etc. - only the stuff rendered by the 32x itself is affected in my experience (so only noticeable in 32x games)


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Wed Jul 25, 2018 12:56 am 



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maxtherabbit wrote:
this is not my thread, but the sega-16 member seanami posted a thread years ago with the exact same video disturbance I am experiencing

http://www.sega-16.com/forum/showthread.php?24760-Sega-32x-Buzzing

and here are his pics of the interference - mine looks exactly the same
http://imgur.com/a/Hby21#0


That's the thread I was trying to find earlier! Yes, this is the exact problem I have with the old inductor. Cleared up 100% after replacing it with the SMD inductor I mentioned in my first post on this thread.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Wed Jul 25, 2018 12:59 am 


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samson7point1 wrote:
maxtherabbit wrote:
this is not my thread, but the sega-16 member seanami posted a thread years ago with the exact same video disturbance I am experiencing

http://www.sega-16.com/forum/showthread.php?24760-Sega-32x-Buzzing

and here are his pics of the interference - mine looks exactly the same
http://imgur.com/a/Hby21#0


That's the thread I was trying to find earlier! Yes, this is the exact problem I have with the old inductor. Cleared up 100% after replacing it with the SMD inductor I mentioned in my first post on this thread.

!!!

Much excite to try that new inductor xwred5 is sending all of a sudden


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