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Plubbingworth 12-13-2021 06:42 PM

How to remove this video interference?
 
So I've got my AG1980 connected to my TBC(ish) ES15+DVK100 and from there to my ATI AIW 7500.

Currently I've just got video going to the purple dongle, and I recorded a short sample of the blue DVK100 picture, which has some pretty obvious rolling lines... that I don't remember the name or the possible cause of. Some audio is getting into the video despite me recording this without any RCA L+R going to the purple dongle, all I have is the audio from the ATI AIW 7500 to the AUX of my Turtle Beach Santa Cruz.

Here's a short HuffYUV video with 500 frames.

https://drive.google.com/file/d/1RNH...ew?usp=sharing

Any ideas what I can do about this? I'm guessing it's electrical interference.

latreche34 12-13-2021 07:37 PM

I don't quite understand your issue, can you post a usefull video with objects in it rather than a green screen?

Plubbingworth 12-13-2021 08:15 PM

1 Attachment(s)
Sorry, I figured it would be easier to see with a solid color. I'll grab another capture tomorrow.

I will mention that I am referring to the diagonal lines scrolling across the video. I think it's EMI, but I'm not sure, and I don't really know what to do about it if so.

-- merged --

Today I took the time to rewire my entire video chain and power it all off of one power strip / surge protector, and that has removed the diagonal lines. I guess it was a ground loop?

There's still some noise, particularly noticeable when I use ExtractU or ExtractV in Avisynth. Not yet sure if that's something that I'll just have to live with or if I should get some professional S-video cables. The ones I have *look* shielded but I'm not sure.

-- merged --

I switched the power strip / surge protector for a Cyberpower UPS that I had. It's... alright? I don't really notice much change. I used an SVHS capture that I got from TGrantPhoto as a test record, I'll try to get a sample uploaded later.

-- merged --

Here's a new sample. Beware, file is 600 or so megabytes.

https://drive.google.com/file/d/1spr...ew?usp=sharing

My main concern now is that audio at the beginning.

Edit: Here's a short audio sample.

Plubbingworth 12-16-2021 09:41 AM

2 Attachment(s)
What finally got rid of that pulsing was removing the damn CD audio cable from between the AIW7500 and the TBSC's AUX port. But that was my audio source, so this solution isn't exactly ideal.

When I got the cable from ebay I did have to rewire it. I also had it tied into a loop with a twist tie. Perhaps I screwed something up?

I also have a second AIW7500 that I can try.

Edit: Nevermind, when I connected my Monoprice RCA cables to the line-in port with an adapter the noise comes back. So I have no clue.

Edit edit: Oh but the noise is not nearly as bad as it was in the above sample. So it's improved.

-- merged --

Here's a sample of the line input and the aux input. At the end of the line input record I remove the cable entirely to hear what it sounds like with no connection.

Edit: Aaaahhh, it's even quieter from the line input when I switch the VCR to input 1 rather than input 2.

Edit edit: Okay, so it looks like I should keep my AG1980 on input 1 (back) when dubbing, because for some reason when it is set to input 2 (front) it is introducing some noise. No change when I change the inputs on my ES15. Also the AUX input is really noisy for some reason, so while I am going to leave it internally connected I am going to use the RCA outputs on my AG1980 and go straight to the line input on the TBSC via an adapter.

latreche34 12-16-2021 03:41 PM

I disconnected all my VCR's front input connections ribbon cables from the main board inside the VCR, They serve nothing but add interference, Always capture from the back connections since they are soldered right on the board.

Plubbingworth 12-16-2021 09:05 PM

I was surprised to learn that it would add noise even if I had nothing connected to the front panel input, while switched to it. Maybe sometime I'll try disconnecting them internally, but I'd probably only do that if I thought they were adding noise even when not switched to them.

I found a new AUX cable (with a Y split that I may later snip off) in my storage today, that I didn't even have to rewire. It's got cleaner audio than the AUX cable that I was using, but still not as clean as the line input.

lordsmurf 12-16-2021 09:32 PM

On some systems, AUX cable is just a noise vector. So you have to route RCA audio direct from VCR to capture card via quality RCA>mini cable. I like AUX, cleaner wiring. But some AIW models, some VCRs, some systems, it's a no-go. I have a system like that myself.

But interesting about disconnecting ribbons. I never thought of that. I need to open some decks.

@latreche, which exact models have you done this on?

timtape 12-16-2021 10:10 PM

Quote:

Originally Posted by Plubbingworth (Post 81172)
Today I took the time to rewire my entire video chain and power it all off of one power strip / surge protector, and that has removed the diagonal lines. I guess it was a ground loop?

Probably yes. Running equipment from different power outlets and then connecting them to each other is a recipe for ground loops. As is leaving connections to the VCR inputs. For tape capture it's safer to use only the video out and the audio line outs.

I also noticed that the clip you uploaded seems to be in mono. That's unusual.

latreche34 12-17-2021 01:18 AM

Quote:

Originally Posted by lordsmurf (Post 81231)
@latreche, which exact models have you done this on?

JVC's, I never bothered to do it on Betamax, Too much stuff in the way and I'm sure Sony has coaxials running not like JVC running a strip of ribbon cables from the front left all the way to the back center with no shielding what so ever.

timtape 12-17-2021 04:10 AM

Quote:

Originally Posted by latreche34 (Post 81217)
I disconnected all my VCR's front input connections ribbon cables from the main board inside the VCR, They serve nothing but add interference,

I dont understand this. Normally in play mode, arent all video and audio input signals electronically disconnected or muted from appearing at the outputs?


Quote:

Originally Posted by latreche34 (Post 81217)
Always capture from the back connections since they are soldered right on the board.

I dont understand this either. Are there VCR's with video and audio output sockets at the front?

latreche34 12-17-2021 04:54 AM

It's not about the video signal itself, the ground side is shared. Anything extends is a target for interference and acts as an antenna, I even though about removing the TV tuner box, just wasn't sure how the system control would react afterwards and may give an error code.

RobustReviews 12-17-2021 01:26 PM

Quote:

Originally Posted by latreche34 (Post 81237)
It's not about the video signal itself, the ground side is shared. Anything extends is a target for interference and acts as an antenna, I even though about removing the TV tuner box, just wasn't sure how the system control would react afterwards and may give an error code.

There's nothing inherently 'wrong' with the shared ground/earth (or 0V proper) - it's how these devices work ultimately, check out any schematic and you'll find the same unless I've misunderstood your point and you're saying it's not the problem that they're shared - I'll grant you that if I've misunderstood.

We always 'terminate off' any unused terminals on our machines (as would generally be done in broadcast) as a matched termination will curtail a good deal of interference. I know enough about electrical noise to know I don't know enough about it. There are libraries stuffed with volumes detailing methodologies for minimising electrical noise and still lots to discover.

Mismatched impedances are a nightmare, and like you say tend to become very effective aerials (antennas) with cable runs etc. I'm (to my genuine shame) a ham so this is a deeply complex topic I'm not really qualified to give advice on beyond general advice. Sometimes knowing 'a bit' highlights how little you know under scrutiny, but these are interesting experiments and something I might look at myself over my long awaited break over Chritsmas.

Plubbingworth 12-19-2021 01:00 PM

I guess later on I'm going to try bypassing parts of my video chain to see if the noise that appears is caused by something specific. It kinda looks like hum bars to me, but I'm not sure.

-- merged --

I'm thinking it might be the DVK-100. In isolation it seems to be the noisiest device, with rolling bars. Anybody have any advice on how to ground this thing? It has the back nut thingy for doing so, but I don't... know how, electrically speaking.

lordsmurf 12-20-2021 12:02 PM

Odd. Never seen that with a DVK. It has to be local power issue.

RobustReviews 12-20-2021 12:41 PM

Quote:

Originally Posted by Plubbingworth (Post 81270)
I guess later on I'm going to try bypassing parts of my video chain to see if the noise that appears is caused by something specific. It kinda looks like hum bars to me, but I'm not sure.

-- merged --

I'm thinking it might be the DVK-100. In isolation it seems to be the noisiest device, with rolling bars. Anybody have any advice on how to ground this thing? It has the back nut thingy for doing so, but I don't... know how, electrically speaking.

If you are the UK, I would suggest connecting directly the terminal to mains earth - however I am not qualified to give advice for any other domestic wiring system. As you used the term ground rather than earth I guess you're not in the commonwealth nations?

Does the device use an external PSU or does it just connect directly to the mains?

Plubbingworth 12-20-2021 03:56 PM

3 Attachment(s)
I'm from the USA. I kinda swap between the terms. :)

I'll have to find a means of connecting it to ground. The DVK has a tiny SMPS I think, that plugs into a Cyberpower UPS.

Here's a sample of the DVK, the ES15, and the AG190, all with a signal generator with SMPTE bars going in and a direct record out. I think I'm hitting placebo territory, because I am not sure if I can easily see the difference. I think the AG1980 might be cleaner though.

lordsmurf 12-20-2021 04:13 PM

Go simpler. Your power grid may hate that power supply. And that's easy to fix.

Plubbingworth 12-20-2021 05:56 PM

Well I'm already pretty simple (i.e. stupid), so I have to ask, what do you mean by that?

I realized that I had the Cyberpower UPS plugged into a rack and I hadn't considered our facility's UPS, so I moved it to a plug that I know is not on the facility UPS. Still analyzing a test capture now.

lordsmurf 12-20-2021 06:09 PM

The AC adapter that came with unit.

It came with a standard 12V 3A, but 2A works fine, even up to 5A. The amps don't matter as much, but I'd floor it at 2A. Standard 12V center-positive, 2.1/2.5 tip. If you want to buy a new one for under $10, APD (good brand), I can point you in the right direction. Or perhaps some other devices near you already uses this rating, such as an external 3.5" powered hard drive.

Also realize that UPS can leak if other devices on the UPS leak badly.

Plubbingworth 12-20-2021 06:25 PM

Aaaahhh. Yes please, I'd like to give that a try.


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