What ohms value for potentiometer for ES15 brightness limiting?

[lordsmurf]

I look forward to seeing how this works.

Those ES10/15 type units are not TBCs, with multiple undesirable affects on video, so the ability to nuke one of the problems will be a win.

[Hushpower]

I'm now going to put a S-video socket on each end of the box. Could somebody please tell me which wires hold the luma signal?

SVideo panel socket.jpg

https://www.jaycar.com.au/4-pin-mini...ocket/p/PS0376

Thanks!

Edit: Found it. https://www.leadsdirect.co.uk/techni...-video-wiring/

[lollo2]

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A question: what are your thoughts on the overall higher level/shape of the trimpot histogram verses the GV procamp histogram? Better or worse?

I do not think that higher levels means better. The "quality" is more related to the distribution and absence of holes.

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For example, the GV histo has that huge spike right at the end but is much flatter in the middle.

That can be a problem, if the GV-USB is clipping the whites before the signal reaches the internal procamp, and then are lost and you cannot do anything. But the capture range of the GV-USB is close to 252, so there should be no loss in principle. BTW, you should allow the card to capture up to its higher limit, and not limit the range to 235.

I share your impression that the trimpot methodology is somehow "better". Waiting also comments fro Bogilein and hodgey, they are familiar with the ES-10/ES-15 levels

[Hushpower]

Made up my combo Composite/S-Video trim pot box. I'm glad I don't solder S-video sockets for a living! Took me hours. The 100ohm pot works well, with lots of rotational movement for small amounts of signal reduction. Certainly easier to set the contrast than using the proc amps of the capture sticks.

I'll do some interference tests next. Watching the AGC in my GV-USB2 working is fascinating. It really fights when the signal is strong but eventually gives up as I reduce the signal.

20220707_211659.jpg

[hodgey]

The Panasonic AGC boosting but then giving up below some level is what I've noted as well, and that's been notet on those german forums too. You don't want to lower it too much either though of course so need to locate the sweet spot where it's lowered enough to avoid clipping but not so much that the panasonic gets issues with signal locking.

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Originally Posted by lollo2

That can be a problem, if the GV-USB is clipping the whites before the signal reaches the internal procamp, and then are lost and you cannot do anything.

You sure this isn't the ES15 clipping? It is how it's looked like when I've gotten clipping on the ES10 and EH57 and used the analog outputs atleast (With HDMI out from the EH57 it goes up to 255 but image content can go above and clip without level limiting on the input of some sort). Or does lowering the GV-USB procamp even more help?

[RobustReviews]

Looks like a smart little project. It should really use coax (goes back to tedious impedance control discussions) but if this works, it works brother.

I haven't the schematic to hand for the Panasonic AGC but I can well imagine it could be something as simple as Zener-clamped, meaning if the level drops below the VZ it could well just bypass the AGC for stability reasons.

I don't have the circuit in front of me though, but you're right if you run the level too low you could well cause various nagging issues with stability.

I'm looking at a tiny picture, but I guess you've got the Y signal of the S-Video bypassing everything in the box?

Well done on building it though, the soldering from what I can make out looks absolutely fine. If you wanted a bit of a extra credit you could have gone for some heat-shrink etc (or a dab of dielectric grease even) on the open solder joints but that's only finesse stuff, this still looks like a rather neat little project.

I'm very much in the 'biggest tip, smallest solder' camp for things like this, if you're fighting the soldering switching to a nice chisel tip and 0.6mm might make things a bit easier. It's a personal thing though, there are no one-size-fits-all answers to how people choose to solder hobby projects. Also, I don't know if you used it, but some good old fashioned rosin flux really makes connections of things like wires to tabs much easier.

[lollo2]

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You sure this isn't the ES15 clipping?

No, just my guess; I trust more your experience

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Or does lowering the GV-USB procamp even more help?

Maybe HushPower can experiment that

[Hushpower]

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I'm looking at a tiny picture, but I guess you've got the Y signal of the S-Video bypassing everything in the box?

Yes, straight from In to Out across the top.

I did consider buying S-Video splitter cables so only the Luma would be in the box going through the trimpot (like that PCB on the Gleitz forum) but that was going to cost me $60 Aussie! Better to spend 6 hours of fiddling...

The main hassle, apart from the stiffish wiring I used (probably a bit too high-gauged, with hindsight) was actually seeing everything. I need a pair of magnifying glasses (those ones on FB are a WOFTAM, BTW).

Re the levels, when doing some more tests with a different tape today, I couldn't get the contrast to bounce as much, either direct to the GV or via the ES-15. Maybe it was that awful tape or used initially.