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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Wed Jul 25, 2018 1:15 am 



Joined: 02 Jan 2018
Posts: 37
I'll mail it out probably Thursday. Along with the toroid, I'll throw in an SMD part and pretty much an cross to the blue sleeved inductor that was on my 32x -- just from the company I work for.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Wed Jul 25, 2018 2:05 pm 


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did you want me to test all of them, or are the other parts just a fallback if the hand wound toroid doesn't perform as expected?


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Wed Jul 25, 2018 5:44 pm 



Joined: 02 Jan 2018
Posts: 37
Fallbacks.

I had to order cores from a sendust supplier today, so I requested enough toroids to make 4 more custom chokes.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Sat Jul 28, 2018 4:18 pm 



Joined: 02 Jan 2018
Posts: 37
I received my parts from mouser. I didn't notice any difference in AV with the LHL13TB331K. I scoped current, and it looked good -- not saturating.

I also ordered a Bourns 2100LL-331-H-RC (I really want a 2100LL-331-V-RC, but there was no stock). This part uses a sendust, low magnetostriction/low emi core. It seemed to work fine. This might be a good OTS solution as you can convert the -H to a -V easily.

samson7point1 is sending me his "bad" inductor. I'll test it when it arrives.

maxtherabbit, if the parts I sent work, can you send me your bad one?

I also might grab a 47 and 100µH replacement for the AVCC filter inductor from work Monday to replace L6, it really bothers me that the schematic doesn't match the BOM.


Last edited by xwred5 on Sat Jul 28, 2018 4:20 pm, edited 1 time in total.

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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Sat Jul 28, 2018 4:19 pm 


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Posts: 272
xwred5 wrote:
I received my parts from mouser. I didn't notice any difference in AV with the LHL13TB331K. I scoped current, and it looked good -- not saturating.

I also ordered a Bourns 2100LL-331-H-RC (I really want a 2100LL-331-V-RC, but there was no stock). This part uses a sendust, low magnetostriction/low emi core. It seemed to work fine. This might be a good OTS solution as you can convert the -H to a -V easily.

samson7point1 is sending me his "bad" inductor. I'll test it when it arrives.

maxtherabbit, if the parts I sent work, can you send me your bad one?

sure, if you're letting me keep the good one :D


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Sat Jul 28, 2018 4:23 pm 



Joined: 02 Jan 2018
Posts: 37
If it works you can have it.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Thu Aug 02, 2018 8:13 pm 


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ok got the stuff today - the hand wound toroid did eliminate 90% of the audible sound coming from the unit itself, however it unfortunately had no impact on the video disturbance

update: tried the blue one - exact same behavior as OEM inductor, loud whine and video disturbance remained constant

I'm hesitant to spend the time and effort installing the SMD coil unless someone thinks it's going to do something different...


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Thu Aug 02, 2018 11:46 pm 



Joined: 02 Jan 2018
Posts: 37
maxtherabbit wrote:
ok got the stuff today - the hand wound toroid did eliminate 90% of the audible sound coming from the unit itself, however it unfortunately had no impact on the video disturbance

update: tried the blue one - exact same behavior as OEM inductor, loud whine and video disturbance remained constant

I'm hesitant to spend the time and effort installing the SMD coil unless someone thinks it's going to do something different...


It's probably not worth trying the SMD one.

Barrage of items to consider.

What is your input supply? are you using a Sega AC adapter or are you using a 3rd party? Can you try swapping your input AC adapter? The Model 2 wall adapter is a AC-AC 60 Hz transformer (I think), so there should be no real high frequency harmonics.

Has it always done this for the life of the unit (not sure if it's childhood)?

CE14 is a 100µF cap holding up the VCC rail at the input to the video chip. I'd also consider a cap replacement. There are a lot of electrolytics around IC12 -- which is mixing the video.

Also check to see your model Genesis, it looks like there were some changes due to issues with the VClock
https://console5.com/techwiki/images/8/ ... letins.pdf

You don't have to send anything back BTW.

samson7point1 send me his inductor this week -- unfortunatly I am out Sat-Sat to drop my kids off in Upstate NY while I visit customers. I won't be able to look at his bad inductor until the week of the 12th.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Fri Aug 03, 2018 12:34 am 


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I don't have a OEM sega power supply but I have tried multiple known good switchers (i.e. I have checked ripple on a scope) to the same effect

I have tried on both a model 1 VA6 and a model 2 VA3 genesis, no effect on behavior

I don't know the provenance of this unit

I'd also like to reiterate that if I supply regulated 5VDC directly to the 32x power rail from a benchtop supply the thing works perfectly

If sending back any of the parts would be helpful I'd be happy to do so, my plan at this point is to just delete the onboard SMPS and rig it to take 5VDC externally


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Fri Aug 03, 2018 12:48 am 



Joined: 02 Jan 2018
Posts: 37
I’d swap the caps, the buck’s operation changes if the cap can’t hold the load when the switch is off. If you have a regulated 5v supply, your source should to be steady with bad caps.

You could also try scoping your 5v rail.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Fri Aug 03, 2018 1:53 am 


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xwred5 wrote:
I’d swap the caps, the buck’s operation changes if the cap can’t hold the load when the switch is off. If you have a regulated 5v supply, your source should to be steady with bad caps.

You could also try scoping your 5v rail.

just put the OEM coil back in there and scoped the 5v rail - it looks like a damn sine wave lol (about 175mVpp)

which caps you think? CE17-19? including the low ESR one (CE18)?


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Fri Aug 03, 2018 3:30 am 



Joined: 02 Jan 2018
Posts: 37
Here is my 5V rail measured from the output of the inductor (side towards the caps and the other inductor) and the - terminal of CE16 (ground). My polarity is flipped, but I am at 5.12V

Sorry for a pic with my phone, I don't have a thumb drive on me.

https://i.imgur.com/RlTTVIE.jpg

I'd just get a console5 cap kit and do them all. https://console5.com/store/sega-32x-cap-kit.html

Edit: FYI I have a bourns 2100LL-331-H-RC in as my buck inductor.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Fri Aug 03, 2018 12:35 pm 


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that looks pretty flat, but you might want to try to zoom in to 100 or 50mV/div to sniff out any low amplitude HF

I really, really, super hate indiscriminately replacing components, but I actually do have almost all the electrolytics in stock to do a full recap except the 1 mircofarad one I think and I don't have an OS-CON

I'm thinking pull the 470uF on the power rail next to the OS-CON and check it...


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Fri Aug 03, 2018 7:00 pm 


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I dont have an ESR meter, but I pulled CE17, CE18 and CE19 off the board and they tested 479, 106 and 96 mike, respectively

so I think they are ok at least

debating whether to pull CE16 as well or just give up on the on board PSU already


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Sat Aug 04, 2018 4:14 pm 



Joined: 02 Jan 2018
Posts: 37
It all depends if you want to get to the route cause of your noise.

Keep in mind that the smps is turned on with the genesis, so if you externally supply it, you should probably duplicate that behavior.

If I had a 32x with these issues I would.

1) recap the whole board
2) try an official gen 2 ac adapter

These are the “low hanging fruit” in the problem.

Past that, literally on the power supply the only 2 things left are the switching ic and the saturating bjt switch. The switching ic is available, but the bjt is packaged with a diode and looks like a pain to source.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Sat Aug 04, 2018 5:54 pm 


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xwred5 wrote:
It all depends if you want to get to the route cause of your noise.

Keep in mind that the smps is turned on with the genesis, so if you externally supply it, you should probably duplicate that behavior.

If I had a 32x with these issues I would.

1) recap the whole board
2) try an official gen 2 ac adapter

These are the “low hanging fruit” in the problem.

Past that, literally on the power supply the only 2 things left are the switching ic and the saturating bjt switch. The switching ic is available, but the bjt is packaged with a diode and looks like a pain to source.



The only reason I was even still pursuing this is the possibility of helping others who may have the same problem, I would have been content to pull the plug on it for personal use long ago

Not sure I mentioned it before, but I have tried a 9v linear supply before and it made no difference

Based on what I've tried and measured so far, I doubt that a full recap nor purchasing an OEM supply would accomplish anything and frankly I'm not willing to waste the time or money

If anyone else would like to try out the hand wound toroid, I'll be happy to pay it forward


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Sat Aug 04, 2018 6:00 pm 



Joined: 02 Jan 2018
Posts: 37
I'd def replace CE14 and CE13 are key for AV, they are holding up VCC on IC12.

I'm going to see if I can get ahold of a 32x with AV noise....

I can say for certain, the coil, in all cases, has the potential to make audible noise. I'd be good to get a larger sample size, the coil might just be getting blammed because it has the potential to make audible noise.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Sat Aug 04, 2018 6:09 pm 


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xwred5 wrote:
I'd def replace CE14 and CE13 are key for AV, they are holding up VCC on IC12.

I'm going to see if I can get ahold of a 32x with AV noise....

I can say for certain, the coil, in all cases, has the potential to make audible noise. I'd be good to get a larger sample size, the coil might just be getting blammed because it has the potential to make audible noise.

My thinking is that if the bypass caps for the video chip were bad, the video noise would still be present when driving the 5v rail with the external switcher I've been using for testing

Furthermore, none of the caps have visible leakage of any kind (the bottoms are visible) and the few I've pulled so far show no evidence of aging out


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Mon Aug 06, 2018 4:35 pm 



Joined: 26 Jun 2016
Posts: 34
maxtherabbit wrote:
xwred5 wrote:
I'd def replace CE14 and CE13 are key for AV, they are holding up VCC on IC12.

I'm going to see if I can get ahold of a 32x with AV noise....

I can say for certain, the coil, in all cases, has the potential to make audible noise. I'd be good to get a larger sample size, the coil might just be getting blammed because it has the potential to make audible noise.

My thinking is that if the bypass caps for the video chip were bad, the video noise would still be present when driving the 5v rail with the external switcher I've been using for testing

Furthermore, none of the caps have visible leakage of any kind (the bottoms are visible) and the few I've pulled so far show no evidence of aging out


FWIW, prior to replacing the coil, I completely recapped my noisy 32x and it made 0 difference. Further I tested the caps I removed and all of them were within tolerance and none had gone high-ESR. Also I have two OEM power supplies as well as a regulated and switched unit. Switching between these made 0 difference as well. That SMD coil was the smoking gun for me. I realize xwred is the expert here, but honestly I think it's worth trying the SMD coil. It's not that difficult to install - just lay down some electrical tape, or kapton tape to make sure the feet don't make contact with those vias in the middle of the circle.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Mon Aug 06, 2018 5:44 pm 



Joined: 02 Jan 2018
Posts: 37
The smd part has a higher saturation current than the toroid. So it *could* fix it, but if that’s the case the boost converter on your 32x is operating differently than mine.

I’ll test your inductor ASAP when I get back home.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Mon Aug 06, 2018 6:11 pm 



Joined: 02 Jan 2018
Posts: 37
Was thinking about this:

What game are you testing with? Actual cart or everdrive?

I only have Star Wars and an X7 everdrive.

We should standardized our testing. I can buy another cart.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Mon Aug 06, 2018 7:58 pm 


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I've been using virtua fighter, I also own star wars


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Mon Aug 06, 2018 11:03 pm 



Joined: 02 Jan 2018
Posts: 37
I just grabbed VF-when I test the inductor I’ll scope the audio out with the inductor current.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Fri Aug 10, 2018 1:45 am 


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xwred5 wrote:
The smd part has a higher saturation current than the toroid. So it *could* fix it, but if that’s the case the boost converter on your 32x is operating differently than mine.

I’ll test your inductor ASAP when I get back home.

would it be beneficial to you for me to test the SMD part then? I'm over it for personal use, but I'd still like to help the overall effort


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Fri Aug 10, 2018 3:19 am 



Joined: 02 Jan 2018
Posts: 37
Let me test the noisy inductor when I get home... sundayish


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Mon Aug 13, 2018 11:10 pm 



Joined: 02 Jan 2018
Posts: 37
Virtual fighter is a great test game because the noise is on the big white intro screen. MUCH better than Star Wars.

My "test" 32x, with the wires hanging out has noise, bad. I tested on my composite and RGB through OSSC. I had video noise regardless of the inductor installed.

I'd like to think it was fine before my testing, but frankly it would wrong to disregard the possibility that it was always bad. I was focused on inductor noise, which this unit had, and I probably played star wars for about 30 mins prior to this investigation. The noise is only on 32x added graphics.

My Model 2 and other 32x look fine. I tried the "bad" 32x with 2 different AC adapters and on two differnt model 1 systems -- one is a "High definition graphics" version. I also tried the Everdrive on this system and had the same problem.

I am thinking that either
1) I am blind and I've had this problem on my test unit all along.
2) I broke something/another component failed

Just for fun, what model 32x do you have? I have a MK-84000 (Made in Japan) in my main setup that is GOOD. The one making noise is MK-84000A (Made in Taiwan)

I'll need a free weekend to look at this some more -- won't be this weekend as the wife is out of town.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Aug 14, 2018 2:00 pm 


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xwred5 wrote:
Just for fun, what model 32x do you have? I have a MK-84000 (Made in Japan) in my main setup that is GOOD. The one making noise is MK-84000A (Made in Taiwan)


same here - 84000A has the audible whine and video noise in 32x games, 84000 is fine

I'm going to guess you had the problem all along and just didn't notice it on star wars because it's so dark


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Aug 14, 2018 4:47 pm 



Joined: 02 Jan 2018
Posts: 37
I'm going to re-cap it "asap"

I just noticed this on Console5:
Does your 32X make a buzzing/sizzling sound? Is the image unstable? We have a prototype repair kit for the power regulation section and are looking for good "loud" candidate 32X units for testing. Please contact us for options!

I'll e-mail him -- looks like he is on vacation for about a week though.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Tue Aug 14, 2018 7:54 pm 



Joined: 02 Jan 2018
Posts: 37
Luke @ Console5 is sending me a new coil and voltage regulator IC to test.


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 Post subject: Re: Sega 32X whining coil, audio and video noise
PostPosted: Wed Aug 15, 2018 12:00 am 


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xwred5 wrote:
Luke @ Console5 is sending me a new coil and voltage regulator IC to test.

the mc34063am? I've been assuming that was the root cause since we started lol


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