AJA computers suddenly start glitching on s-video capture?

[Runrunsparrow]

This is a somewhat complicated puzzle I haven’t been able to solve. I’ve recently switched between digital and analogue capturing with my two stations - AJA Kona Lhi on Windows and Aja Kona Lhe on Mac G5 - to capture SDI video. No problem. S-video, usually no problem. Now switched to analogue input for a batch of VHS.

JVC Super VHS with TBC —-> Datavideo TBC 3000 —-> AJA S-video input.

While inserting two new tapes to be captured I discovered a ripple in the Stand by blue screen in the AJA software monitor ON BOTH stations. Ripple also visible on good material (recorded from tv). Physically disconnected the TBC and wired the VCR’s S-video outputs directly to the AJA S-video input. VCR Stand by blue screen is now jumping and glitching uncontrollably ON BOTH machines.



I’ve tried to approach the problem with the knowledge I have in audio engineering.

Ground loop
Lack of grounding where it there should be one
Differences in electric potential between different power outlets (often causes audio hum at 50, 100, 200 Hz (Europe) and so on in the audio world and I guess hum, of any frequency, would not be good in analogue video transfer either.
Ripple on the mains caused by other connected equipment.

I decided to start with the Windows machine.

Disconnected EVERY power consumer in my basement studio part from the PC, its monitor and one of the VCR:s. Connected them to the same power strip. The PC:s power cord is grounded type. The VCR:s is not. VCR Stand by blue screen is still jumping and glitching in the AJA software. VCR playback jumps for a sec or so but then stabilizes. However audio and video are seconds out of sync. When stopping VCR playback, the audio from AJA software lingers for 1-2 secs. I know it’s not the case, but it’s almost as if there was a TBC on the AJA PCI card doing its best to stabilize the signal.

Wired the JVC VCR to a monitor with S-vhs and RCA audio cables. Blue screen is stable, audio and video is in sync.

Connected a Hi8 cam to the AJA SDI input. (Powered from wall power outlet) The blue Stand by screen is stable in AJA software! Playback also works excellent with audio and video in sync.

Took a 50 m power cord and connected it to an outlet that has no other consumers at all (usually used for a high power drying cabinet). No joy.

Isolated (taped) the grounding tounges for the PC and monitor (very easy to do on Scandinavian type power plugs). No joy.

Tried to force ground the VCR:s circuits by running av wire to on of the ground tongues on the power strip and holding the other end to the one of the VCR’s ground rings on the audio output. No joy.

Re-inserted the TBC. Now the Stand by blue screen is stable, has no ripples and audio video is in sync. This puzzles me and perhaps I should be happy. But it collides with my work ethos and the way I advertise my business to know that without the TBC the signal looks like sh*t to the AJA hardware. And when I reconnect and power up the other equipment, the ripple will likely reoccur.

Thanks in advance for every little bit of help!

[latreche34]

First of all don't worry about blue screen or the menu within it, it is never a standard source to judge your flow based upon, Always check with a tape playing contents. As to when you remove the TBC you get issues, that's normal, most professional capture cards and devices are not designed for noisy consumer sources unless stated otherwise, If the TBC3000 works, keep it in the workflow.

[aramkolt]

Maybe post a video of what you're seeing.

Has the TBC3000 been recapped at any point? All kinds of odd intermittent things can happen if it hasn't been recapped as Datavideo used poor capacitors on some models. I haven't personally used a TBC3000, but my understanding is that typically they will pass a blue screen and make it into 480i, but latreche is correct, blue screens are not a standard NTSC signal - they are something like 270P. Some devices won't pass the blue screen at all, but then work fine once video starts playing. Generally it is a good idea to turn blue screen off if the TBC doesn't like it.

Or if your unit TBC3000 hasn't been recapped, I'd start there.

When you say "both stations had the same issue" are you saying that you were running two separate sources through the TBC3000 since it has two inputs and two outputs? That would actually make more sense that it is the power supply of the TBC3000 as it would feed both TBCs inside it and voltage fluctuations can do that. Not sure why it is intermittent, but could be temperature related. Some people use cold spray on capacitors to see when making individual capacitors cold how the video output changes, and then warming them up with a heat gun on a low setting. That will allow you to confirm the issue, but I'd still probably recap everything if it hasn't been done yet and you're worried about reliability/longevity.

[Runrunsparrow]

Attached is a short clip on how what it looks like without the TBC.

So okay, a glitchy blue screen is not a measurement on how the VCR:s signal quality. But I still have fact that both the playback from all 3 VCR:s (which have built in TBC:s on line level) is impossible for AJA to capture. While the blue screen and playback from the Hi8 camera is flawless.

[aramkolt]

Blue screens themselves definitely aren't standard either, so I'm not too surprised that maybe the Hi8 cameras have blue screens that the cards can lock to and the VCRs don't. Usually the fix is to turn the blue screen off in settings, so it'll show static as the background. Menu should still be overlayed so you can see what you're doing. Have you tried that? Hi8 I don't know if you can always turn off blue screen, but every VCR I've seen you can turn it off. Could be called "blue back" as well.

What would be odd is if your TBC3000 used to work with those same blue screens from those same VCRs and now it doesn't.