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  #21  
01-10-2022, 09:26 AM
Plubbingworth Plubbingworth is offline
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Finally had a chance to try this after a long holiday break. Unfortunately the replacement power supply for the DVK100 didn't really seem to help.

I've got my entire system unplugged due to the power going up and down... winter is hard on the KUB system apparently.

My next couple of ideas is to replace the UPS with a new one, and then try replacing the PSU in the PC itself. I've been trying to get into electronics and power supply theory so I can understand how to even diagnose that, but I'll probably just swap it with a separate PSU.

Would anyone happen to have any recommendations for specific UPS and PSU models?

Edit: Oh also I've ordered a cheap isolation transformer, doesn't seem to have a ground pin though. As I understand it a lot of isolation transformers have the ground bounded from the input to the output, so I don't really understand if a regular IT would prevent ground loops.
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  #22  
01-10-2022, 10:31 AM
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I wouldn't fart about with UPSs until you've exhausted the basics.

As the noise is evenly spaced and continuously rolling it's most likely mains referred, mathematically anyway as best I can see it on a tiny screen using your sample at the top.

Did you try the supplementary earth bonding to see if that eliminated it? Also are there any coaxial connections in your system?

Also - to add, an isolation transformer with a common earth connection across the windings won't help with the issue you describe. It may help, but not if you're trying to 'lift the earth'.
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  #23  
01-10-2022, 12:53 PM
Plubbingworth Plubbingworth is offline
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So I added the ground wire with some spare wire I had. I'm pretty much a novice, so my idea was to solder that to a ground pin which I then plugged into the power strip (which is connected to the battery side of the UPS). ...Then the resulting image had really bad hum bars, I don't remember if they were there before that. I then plugged a ground pin isolator between the power strip and the UPS, here's the resulting image.

I have some coax *around* the PC, but not connected directly to it.

Yeah, the isolation transformer I purchased has no ground pin.

So I dunno, I still see some kind of noise in the chroma, but the luma looks squeaky clean. Is this the best that I can expect?


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File Type: avi humtest1-SHORT.avi (88.54 MB, 3 downloads)
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  #24  
01-10-2022, 01:26 PM
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Quote:
Originally Posted by Plubbingworth View Post
So I added the ground wire with some spare wire I had. I'm pretty much a novice, so my idea was to solder that to a ground pin which I then plugged into the power strip (which is connected to the battery side of the UPS). ...Then the resulting image had really bad hum bars, I don't remember if they were there before that. I then plugged a ground pin isolator between the power strip and the UPS, here's the resulting image.

I have some coax *around* the PC, but not connected directly to it.

Yeah, the isolation transformer I purchased has no ground pin.

So I dunno, I still see some kind of noise in the chroma, but the luma looks squeaky clean. Is this the best that I can expect?
If doing that is exacerbating it, we can probably say it's mains referred.

There are some things that might be tried, however if you're a novice (and I'm not familiar with US domestic wiring, it's totally alien to the Britbong 'sparky writing this) I'm not going to suggest anything further regarding touching the power side. Await an approriately qualified US response!

Dump the UPS, honestly, they emit more broadband HF 'crap' than just about any other non-RF device, don't add things that do high-power switching into the signal chain at the moment! There are appropriate power-conditioning units, but a cooking model UPS isn't one of them when it comes to video in my opinion.

I've not really followed the thread, but that looks like an S-Video connection, have you tried a different cable? Could just be a basic shielding issue?
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  #25  
01-10-2022, 01:45 PM
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Another monkey wrench is the TVA. I'm betting you're on that grid. I had issues with DataVideo gear, now some 15 years ago. Reports are the this was resolved years ago, and this is the first time it's been possible in ages.

UPS are necessary in USA, our power is too prone to fail and flicker, and you'll lose a pricey item if plugged into a wall outlet directly. Some Europeans swear by using outlet-only power, but I'm dubious. There's really nothing special there, or anywhere. Power spike/fail can easily mean a $2K TBC = instant paperweight. I'm not risking my gear.

I have to try something like this soon, for a problem bass speaker.
https://amzn.to/33m2D9z
Not sure that'll fix it, but here's hoping. If not, Amazon return.

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  #26  
01-10-2022, 02:13 PM
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Originally Posted by lordsmurf View Post
Another monkey wrench is the TVA. I'm betting you're on that grid. I had issues with DataVideo gear, now some 15 years ago. Reports are the this was resolved years ago, and this is the first time it's been possible in ages.

UPS are necessary in USA, our power is too prone to fail and flicker, and you'll lose a pricey item if plugged into a wall outlet directly. Some Europeans swear by using outlet-only power, but I'm dubious. There's really nothing special there, or anywhere. Power spike/fail can easily mean a $2K TBC = instant paperweight. I'm not risking my gear.
UPS are very electrically noisy, whether that has a bearing on your work is for you to determine and satisfy yourself with, or at least most basic 'interactive' units are, I can't speak for your unit in your application.

Our 'quality and continuity of supply' regs (harmonised across the EU & Britbongland) are pretty draconian and tightly adhered to. In my years of working around sensitive electronic appliances, the total I've seen damaged by 'power spikes' is nil. Like most of Europe we work on a national grid (helpfully in the UK, called the 'National Grid') which probably isn't as practical in the vastness of the US, many of the European grids are linked too which improves continuity.

I can't speak for all areas, but we had a power-cut around two weeks ago in one of my offices for around 30s and that caused quite a stir, power cuts do occur but they're very rare, probably a couple a year and for no more than a few seconds. We don't get a tremendous amount of lightning either, which is obviously climate and terrain dependent. It makes the national news if we get a half-decent thunderstorm; not to mention the nation grinds to a halt on anything deeper than 3mm of snow.

Also, in Britbong land often sockets will have voltages approaching 270V-RMS (@32A, in most cases, that's why we wire our homes differently and fuse our sockets) which is 330V PP which may mean the equipment is less sensitive to transient high voltage by design, possibly, I can convince myself either way on that one.

We need electric kettles due to the millions of cups of tea consumed daily here in Brexistan - we need high socket-power in every room and continuous supply. Speaking of which, my mug is empty.....

Anyway, @Plubbingworth, do you have a multimeter?
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  #27  
01-10-2022, 02:22 PM
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UPS noisy? No. Most actually purify the power, even the switchover types.

My coffee maker is on the PFC in the kitchen. And my mug needs refill as well.

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  #28  
01-10-2022, 02:37 PM
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Quote:
Originally Posted by lordsmurf View Post
UPS noisy? No. Most actually purify the power, even the switchover types.
Ah, I'll leave that there, I fear this may get dragged somewhere else. If you're satisfied it's not having an effect, carry on.

Quote:
My coffee maker is on the PFC in the kitchen. And my mug needs refill as well.
I got nothing there unless you're talking about Power-Factor Correction, in which case I'm excited?! Oh, and I'm a coffee drinker actually, I'm not a full national stereotype. Tea tastes vile to me, but don't tell anybody or ma'am will want my passport back.
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  #29  
01-10-2022, 02:50 PM
Plubbingworth Plubbingworth is offline
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My cables don't appear to be especially shielded, I'm just using some cheapish ones rather than any from like BJC or something. I'm willing to go that route, but I'd prefer to try the less expensive options first? That being said, I did just drop the cash on the product that LS just linked to....

My concern with the UPS is that it's kinda old and I don't think the battery is very good.

I have a good multimeter, yes.
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  #30  
01-10-2022, 02:54 PM
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Originally Posted by Plubbingworth View Post
I have a good multimeter, yes.
Two things you can do:

Firstly, check for resistance value between the outer 'ring' of both ends of the S-Video cable.

Then, (if you feel confident) see if you have an AC voltage between the casing of the machine and earth (ground), however, you get earth in the US, I think your sockets may have it exposed.

That 'thing' looks like a cheap cap & choke in a plug, doesn't mean it doesn't work, but I'd wager there's about 50p worth of components in it. As said above, send it back if it doesn't prove anything.
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  #31  
01-10-2022, 04:26 PM
Plubbingworth Plubbingworth is offline
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Oh well speaking of my UPS, I'm suddenly unable to power anything off of the battery side. So that's encouraging!

I'm glad you had me check my S-video cables, because the one that I had going between my DVK and my purple dongle actually had an open connection on the outer ring. A second cable I have on hand tests at roughly .35 of an Ohm. Unfortunately simply swapping the cables didn't seem to fix anything.

Uh well I have low Ohms between the chassis and the ground pin of the PSU if that's what you mean? Or do you mean to test for voltage between the metal of the chassis and the ground pin of the socket while the PC is on?

And I... also have low Ohms between the ground pin and the open screw holes of the rack that this is racked into, since I have this PC built into a rack case. That seems not ideal.

I feel really foolish for not considering continuity on that path. I'm going to have to take the entire PC out and test all of this isolated from the rack.

Last edited by Plubbingworth; 01-10-2022 at 05:07 PM.
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  #32  
01-10-2022, 05:15 PM
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Originally Posted by Plubbingworth View Post
Oh well speaking of my UPS, I'm suddenly unable to power anything off of the battery side. So that's encouraging!

I'm glad you had me check my S-video cables, because the one that I had going between my DVK and my purple dongle actually had an open connection on the outer ring. A second cable I have on hand tests at roughly .35 of an Ohm. Unfortunately simply swapping the cables didn't seem to fix anything.
Yes, it's very common with some lowly cables for them to be unshielded. Shielding is a whole other complex topic, but fundamentally it's quite important for this and 0.350Ω is effectively a 'dead short' for the purposes of this conversation; you can't measure resistances in that range with conventional technique anyway, just a heads-up if you're new to this. Either way, it's fine.

Quote:
Uh well I have low Ohms between the chassis and the ground pin of the PSU if that's what you mean? Or do you mean to test for voltage between the metal of the chassis and the ground pin of the socket while the PC is on?

And I... also have low Ohms between the ground pin and the open screw holes of the rack that this is racked into, since I have this PC built into a rack case. That seems not ideal.
Like I mentioned above, it's AC voltage you're looking for between any earth point on the device and your mains earth - if you have an AC voltage of any appreciable amount (you'll have a few mV due to technique and instrument) that means your equipment is 'above' earth. Anything more than a Volt or two probably needs investigating.

It's one of a range of things you could examine, but it's the only one I'd suggest. Obviously only do this if you understand what you're measuring and how to do it safely.

Otherwise, we're looking at power analysis and politely, if you're asking these questions, I'd suggest it's probably not for you yet.

Well done on getting this far if you're new to this sort of thing, a decent multimeter is still one of the most useful tools in any tool kit if you play with anything connected to electronics in my opinion.
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  #33  
01-11-2022, 05:01 PM
Plubbingworth Plubbingworth is offline
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So today I disconnected the PC from the rack, and set it on a stool. I powered the PC, the monitor, and the DVK100 from one power strip. I tried it connected to ground and I also tried it without ground. I've tried a different power supply in the PC.

The noise is still present regardless of these changes. This is getting immensely frustrating.

I've also tested for AC voltage on the ground connections... there's nothing there that I can see.

I should try and find a different test pattern generator than directly from the DVK100. But if neither the isolation transformer nor the hum remove device works, I'm tempted to look into replacing caps on the motherboard.
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  #34  
01-12-2022, 10:46 AM
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Quote:
Originally Posted by Plubbingworth View Post
So today I disconnected the PC from the rack, and set it on a stool. I powered the PC, the monitor, and the DVK100 from one power strip. I tried it connected to ground and I also tried it without ground. I've tried a different power supply in the PC.

The noise is still present regardless of these changes. This is getting immensely frustrating.

I've also tested for AC voltage on the ground connections... there's nothing there that I can see.

I should try and find a different test pattern generator than directly from the DVK100. But if neither the isolation transformer nor the hum remove device works, I'm tempted to look into replacing caps on the motherboard.
The trouble with replacing capacitors is that the 'scatter gun' approach may just shift the problem elsewhere -or not resolve it after considerable time and expense.

This isn't mains referred in the sense that it's caused by 'unclean power' (how I hate that term) by how you describe it but by your fundamental mains frequency encroaching on to your picture signal, doubly so if you've added a device in to reject common-mode and harmonic 'crap' and still getting the same results. We've lifted the earth to no benefit too, and proven there's no potential between device and earth.

I would now say this is a device issue, but without seeing the device and having test equipment handy it'll be difficult to determine. S-Video is fairly noise immune if you're using a reasonable quality cable due to various design features (gross common mode noise will be rejected at the input on the device, and it's a differential pair) so it's unlikely to be coupling in - not impossible, but unlikely.

A catastrophic impedance mismatch is unlikely with quality commercial products too.

I can't really offer much more without having the equipment in front of me and on a bench, but there are a few EEs here who may be able to chip in.

I can't quite make out from the thread, have you just tried another video signal source?
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  #35  
01-12-2022, 12:25 PM
latreche34 latreche34 is offline
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I skimmed over this thread and I don't see the OP is using a process of elimination method, That's the only way to figure out the problem or he will be posting here for the next ten pages or so.

First identify the faulty component by removing other components, like:
- VCR playing good tape to TV
- Stable video source to VCR to TV
- Stable video source to capture card
- Stable video source to TBC to TV ....etc. you got the idea.

Once the component is identified, then breakdown the area where it happens, like:

- Does it happen on composite?
- Does it happen on S-Video ? If so try turning chroma to zero, is the problem still there
- Does it matter if other components are too close?

This is just an example of the basic troubleshooting, Keeping all the component together and try to identify the problem by just buying and adding more stuff is not going to get you anywhere.
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  #36  
01-12-2022, 05:00 PM
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Quote:
Originally Posted by latreche34 View Post
I skimmed over this thread and I don't see the OP is using a process of elimination method,
Good catch.
I just assumed this had been done already. Perhaps not.
Start over, step 1.

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