RCA to BNC plugs on PVM outputs makes it brighter??

[Plazmunky]

Long time lurker, first time poster. I'm still somewhat new to doing the whole RGB thing. I already have a 1CHIP SNES with a SCART cable connected to my PVM and a normal Model 1 Genesis SCART hookup as well. It all looks amazing. My goal is to learn as much as possible about getting the best image out of all of my hardware. Particularly in retro gaming and in the future arcade machines. Ultimately want to pursue a career in engineering.

I own two Sony PVM 14-L5 monitors. Image is pretty good on one of them, colors are very washed out on the other. In general however, it would be nice if the contrast was better on both of them. They've both seen a lot of usage.

Getting to the point, I was just messing around with my preferred 14-L5 and had recently picked up some RCA to BNC adapters so I wouldn't have to purchase more BNC cables and opt to use the tons of RCA cables I have laying around. Link to what I purchased: http://www.amazon.com/gp/product/B005B4 ... ge_o02_s00

I hadn't ever tried using the output on the back of my PVM before, so I was just giving it a go because I was bored. I already had the 240p test suite displayed running off of my Wii via component running in 240p mode. As soon as I put one on each output, my image's contrast immediately increased significantly. To my surprise after putting one on each output, the image was way more vivid than before. It's very nice! I had to drop my contrast from 80 to 50 and drop the brightness a bit to compensate. It wasn't too vivid or anything, nothing that seemed dangerous for the screen. The overall quality had seen an incredible boost. I was pretty floored. I tried the same thing on my other 14-L5 and the same thing occurred. It didn't fix the washed out colors on my second one, but the contrast jumped up quite a bit. However whenever I would insert an RCA cable into one of the respective plugs, the corresponding color would drop to what it used to be. No doubt reacting to the signal being split and sent through the RCA cable. Removing the cable would immediately bring me back to that high quality image.

So my theory was that the RCA to BNC adapters were acting as a sort of terminator, even though they weren't terminators. I'm aware that BVM models require terminators for their outputs. However the 14-L5 service manual states that there's a built in terminator on the particular inputs that I was using whenever I'm not using the outputs. I opted to order some actual 75ohm bnc terminators online, the ones that I ordered are these: http://www.amazon.com/gp/product/B00TDM ... ge_o01_s00

They arrived today and I tried them out instead of the previous adapters. Nothing. The image didn't change at all when I inserted BNC terminators on all of the outputs. I left them in there a while and still no difference. Putting the RCA to BNC adapters back in makes the image jump in quality again. I'm completely baffled now and decided it was time to finally post on this forum and ask those who know better than me to maybe provide some input as to why in the world this is working because clearly I'm missing something here. If you want some picture comparisons, I can provide them.

[Ed Oscuro]

I had to drop my contrast from 80 to 50 and drop the brightness a bit to compensate.

I wouldn't mind this - you want to run these settings at lower levels to prolong tube life anyway.

If anything, this suggests the cables that do not put out such a nice picture are faulty.

We'd be able to give more comments if you share more details about what exact cables and connections you're using which give the nice / not so nice pictures. I also think it's possible that you're seeing the results of different settings for RGB/component/other signals in your L5 series.

[Plazmunky]

Thanks for the response!

I'm normally using this cable: http://www.amazon.com/gp/product/B000VG ... ge_o00_s00

That connects to a Shinybow Distribution Amplifier here: http://www.amazon.com/1x5-Component-Com ... +component

The amplifier sends the signal to my Micomsoft X-Capture 1, my PVM, an additional display if need be, with an audio breakout that I use with some headphones for direct game audio.

I connect my PS2, Wii, anything that uses component to the inputs on the amplifier as well. I've tried many different sets of nicely shielded, gold plated component cables. There's never been a different result. I've also taken the amplifier out of the question and connected the console directly, no different. Over the course of owning my PVM for the past half year or so, I've gotten the white balance, through lots of rigorous practice and reading/comparing to my Sony KV-27FV310, to a point where it's as good as it can get basing the colors off of the D65 standard and adjusting the GAIN/BIAS from there. That's all old news however. I've only recently tried using the same techniques to adjust the image on my secondary L5 I picked up not long ago, but there's only so much I can do for it no matter how much I tweak the balance.

Here's a crude mspaint of my setup:

http://imgur.com/tUfpSOE

So on the back of my PVM I have a set of RGB/Component BNC inputs and outputs. Connecting the signal to the input provides the picture I was normally used to. Putting the small RCA to BNC adapters on the outputs BEFORE connecting any cables to them seemed to somehow significantly increase the picture quality. Leaving only one on the green, or the blue respectively would enhance the quality of that color. If I connect an RCA cable to the output, the quality drops to what it used to be again. Using 75ohm terminators did not yield the same results. I'm trying to figure out why in the world connecting those adapters is enhancing my image at all. I might upload a video of the effect in action.

[Ed Oscuro]

First, take a look at this helpful reply from earlier this year:
http://shmups.system11.org/viewtopic.php?f=6&t=53060

For my part, I'm still confused. To simplify this problem for diagnosis you should take everything out of the equation but the source, system cable, BNC-RCA, and monitor. What you describe in the second half of your post, and what seems to be the source of the problem, doesn't seem related to the diagram with wiring through the amplifier anyway, but I remain just a bit unsure. For my part, I only use system->SCART into SCART->BNC cables, as well as regular system RGBs or component cables -> RCA to BNC adapters, and I certainly don't get this kind of operation with the L5 series. The cables you posted look pretty neat, but I'm not ready to run out and buy some to play with, since I don't need them (as I'm not using a distribution amplifier...yet).

One thing that I immediately notice is that you used terminators on a PVM L5 series. These monitors are set up to auto-terminate signals, so you shouldn't use them. (I'm also not sure what you mean by saying that using terminators didn't give a different result - different to what? The high or low brightness image?)

If this doesn't immediately fix the problem, well: It doesn't strike me as normal operation that you'd get lowered image brightness when using the PVM's pass-through function, and it sounds like normally you don't use it at all. Can this be ruled out? It also doesn't strike me as normal that simply plugging BNC-RCA adapters onto the inputs would confuse the set's internals on setting brightness, or when plugging in while the monitor is on or off. However, I believe that these results could be possible, perhaps the result of something being faulty or failing.

[Einzelherz]

On my 14L5 if I put adapters on the OUT side of a line, but no connection to another device, the brightness changes. Only attach things to the OUT side if you're actually using it.

[Plazmunky]

On my 14L5 if I put adapters on the OUT side of a line, but no connection to another device, the brightness changes. Only attach things to the OUT side if you're actually using it.

You seem to be getting the same effect that I am. Personally, the picture is much better when I leave adapters on and I'd rather keep it that way. I'd rather not do any potential damage to my display however. Is there any reason why I shouldn't just leave them on even if I'm not using the outputs for anything?

[Plazmunky]

For my part, I'm still confused. To simplify this problem for diagnosis you should take everything out of the equation but the source, system cable, BNC-RCA, and monitor. What you describe in the second half of your post, and what seems to be the source of the problem, doesn't seem related to the diagram with wiring through the amplifier anyway, but I remain just a bit unsure. For my part, I only use system->SCART into SCART->BNC cables, as well as regular system RGBs or component cables -> RCA to BNC adapters, and I certainly don't get this kind of operation with the L5 series.

Okay, I have done this after switching from component to RGB mode. I have a SCART to BNC breakout that I connect to a Super Nintendo SCART CSYNC cable to my 1CHIP SNES. The image is pretty stellar, but even better when I connect the RCA -> BNC adapters onto the PVM outputs. So the effect is occurring here as well.

One thing that I immediately notice is that you used terminators on a PVM L5 series. These monitors are set up to auto-terminate signals, so you shouldn't use them.

Yeah, I mentioned in my first post that the manual stated that I didn't need to use terminators. I just assumed that terminators may produce the same result. It was just a shot dark to see if it would have any sort of improved effect.

(I'm also not sure what you mean by saying that using terminators didn't give a different result - different to what? The high or low brightness image?)

Yes, using the 75ohm BNC terminators did not give me a different result than what I was used to looking at before I connected the RCA -> BNC adapters to the PVM outputs. The image was just as bright as I was used to seeing before I ever connected the adapters.

If this doesn't immediately fix the problem, well: It doesn't strike me as normal operation that you'd get lowered image brightness when using the PVM's pass-through function, and it sounds like normally you don't use it at all. Can this be ruled out?

Sorry, I may not have worded what I was asking/saying very well. My PVM's overall contrast isn't the best whenever I have it hooked up normally, but it's good enough for use. The contrast increases to a point that I was unable to achieve previously when I connect the RCA -> BNC adapters to the PVM's outputs. I like the image I'm getting much better this way. When I connect RCA cables to the adapters, the quality just goes back to what it was before; the way I'm used to looking at it. What I'm wondering is if I can safely keep the RCA -> BNC adapters on without connecting any RCA cables to keep that better image that it produces without doing any unwanted damage to the PVM. I'm just wondering if it's safe to do that or not. I'm also wondering why this even works in the first place.

Thanks for being patient with me.

[cfx]

.

[Einzelherz]

On my 14L5 if I put adapters on the OUT side of a line, but no connection to another device, the brightness changes. Only attach things to the OUT side if you're actually using it.

You seem to be getting the same effect that I am. Personally, the picture is much better when I leave adapters on and I'd rather keep it that way. I'd rather not do any potential damage to my display however. Is there any reason why I shouldn't just leave them on even if I'm not using the outputs for anything?

I don't recall there being a difference in picture quality on mine. I took them off because it seemed unnecessary.

[Guspaz]

I was doing some lag testing with my pvm (14L2) last night and plugged an LCMs monitor into the PVM's composite output. I saw the same behaviour, as soon as I attached the BNC to RCA adapter, even with no cable, a massive increase in brightness occurred. This also applies to the RGB outputs, but then only one of the channels is affected, unless the adapters are put on all three. If I was using the outputs, I'd need to turn down the monitor's contrast a lot.

It may be useful in the future if the monitor's brightness drops as it ages, but for now I removed the adapters.

[andy251203]

There seems to be a lot of confusion in this thread, so let me clear some things up for you.

There's a reason you are getting a brighter picture when you plug in RCA to BNC adapters onto the output lines, and that reason is you are un-terminating the line.

Let me explain how termination works for you. On the older cubic style PVM models such as the 2030, there were manual termination switches above the video inputs. You could choose 75ohms termination, which is what you use if you are not using the corresponding video output. Otherwise you would choose "High Z" or high impedance (basically no termination) if you were running the video output to another monitor.

If you switched to High Z mode without running your output to another monitor (and then terminating the signal at that monitor) then you will notice your brightness has increased significantly. This is bad! You are not properly terminating your video signal.

On newer PVMs, if you look closely at the center of the BNC connectors on the back, you will notice that the input BNC connectors look slightly different in the center than the output connectors. This is because the output connectors have a built-in termination switch! (The inputs don't need such a switch) Basically, when something is inserted into an output connector, the pin pushes on a little switch that disables termination. You say your brightness increases whenever you put a RCA to BNC adapter on the output? That because you just disabled termination. Notice how the brightness did not increase when you put a 75 ohm terminator on the output connector? That's because even though you disabled the internal termination, your 75 ohm terminator is still properly terminating the signal. In fact, I have had monitors in the past where the internal termination switch fails, so I have to place a 75 ohm terminator on the back. BVM monitors do not have any built in termination and require the use of 75 ohm terminators on the outputs.

In short, that brighter picture you think is better is actually not. It's so bright because it's not properly terminated. Unfortunately your monitor tube may be on it's way out if a properly terminated signal is too dark for you.

[Guspaz]

In my case the brighter image was not better. It was too bright, and the bright parts of the image on the screen were sort of blooming, which is just what you'd expect if you cranked the contrast way too high. I presume it won't do any harm to the monitor to have it unterminated for a minute or two until the output cable has been attached, as it would be annoying to have to turn the monitor off every time an output is attached. Considering that my PVM is 11 years old and still bright enough without even maxing out the service menu contrast setting or the contrast dial on the front, I think I'd have quite a long time to go before the monitor is not by itself bright enough. If years in the future it's not bright enough, what would the harm be in trying to get a few more years out of it by leaving the lines un-terminated? Even if the monitor were on its last legs, it'd be better than tossing it.

[Plazmunky]

There seems to be a lot of confusion in this thread, so let me clear some things up for you.

There's a reason you are getting a brighter picture when you plug in RCA to BNC adapters onto the output lines, and that reason is you are un-terminating the line.

Let me explain how termination works for you. On the older cubic style PVM models such as the 2030, there were manual termination switches above the video inputs. You could choose 75ohms termination, which is what you use if you are not using the corresponding video output. Otherwise you would choose "High Z" or high impedance (basically no termination) if you were running the video output to another monitor.

If you switched to High Z mode without running your output to another monitor (and then terminating the signal at that monitor) then you will notice your brightness has increased significantly. This is bad! You are not properly terminating your video signal.

On newer PVMs, if you look closely at the center of the BNC connectors on the back, you will notice that the input BNC connectors look slightly different in the center than the output connectors. This is because the output connectors have a built-in termination switch! (The inputs don't need such a switch) Basically, when something is inserted into an output connector, the pin pushes on a little switch that disables termination. You say your brightness increases whenever you put a RCA to BNC adapter on the output? That because you just disabled termination. Notice how the brightness did not increase when you put a 75 ohm terminator on the output connector? That's because even though you disabled the internal termination, your 75 ohm terminator is still properly terminating the signal. In fact, I have had monitors in the past where the internal termination switch fails, so I have to place a 75 ohm terminator on the back. BVM monitors do not have any built in termination and require the use of 75 ohm terminators on the outputs.

In short, that brighter picture you think is better is actually not. It's so bright because it's not properly terminated. Unfortunately your monitor tube may be on it's way out if a properly terminated signal is too dark for you.

Thanks a lot for your explanation, this is exactly the info I was looking for. Why, if I may ask, is it bad to leave the signal unterminated? Is it doing any harm to the tube or longevity of my display?

[Ed Oscuro]

You know, I read through the entire OP without realizing you were putting the adapters on the outputs (I see it now in the thread title and there was a subtle clue in the text too). Be more explicit when asking questions like this, it makes a huge difference.

Terminators will stop signal reflections which should stop some quirky image problems, though you didn't report any. I'd say you should also expect some blurriness, and of course you're seeing that extra brightness in the image.

But, in short, there's absolutely no reason why you should bypass the internal termination like this. If you're using the pass-through function, then the adapters are useful; otherwise, take the plugs out.

With the PVM L5 series, there should be two ways to fiddle with brightness and contrast - from the front knobs and also from the menu. I'm not sure what happens when you alter these from the menu while leaving the knobs, but I think they should roughly match up (I can't remember if the default neutral position, where the knob rests in the "up" detent, is 50 or 100 in the menu). You might want to check that.

[Guspaz]

Speaking for the L2, the menu contrast control changes the neutral point on the physical dial, and the physical dial is always an offset of the menu option. So there's no matching them up. Whatever you set the menu version to, you can use the dial to go above or below that value.

Even if you set the contrast to the maximum in the menu, the physical dial will still increase the contrast beyond that if you turn it clockwise. Personally, I set the menu contrast for what looks right to me, and then I can use the dial to increase it or decrease it if I have a need for something other than that: like if a scene in a game is too dark, I can temporarily turn it up with the dial.

This is true for the brightness dial as well, and it's probably true for the chroma and phase dials, but those are disabled on the RGB input anyhow, and many PVMs have the auto-calibration feature for chroma and phase, where you throw up an SMPTE test pattern and the TV will use that to self calibrate.

[Ed Oscuro]

Personally, I set the menu contrast for what looks right to me, and then I can use the dial to increase it or decrease it if I have a need for something other than that: like if a scene in a game is too dark, I can temporarily turn it up with the dial.

This is true, and my point was mainly centered around the probably academic question of trying to figure out if the neutral (for example, factory default) settings are still acceptable before tweaking, which would be a rough estimate of what shape the tube is still in. If you can tweak it to get an acceptable image still, it probably doesn't matter to test this.

BTW, in terms of "matching," I of course don't mean that the menu and dial settings are locked, but rather that one finds both initial neutral settings (which, again, I can't remember for the menu setting, but might be 50 or something). Good to have my suspicions about the additive settings confirmed, thanks!

[Guspaz]

50 is the default on my monitor. I can actually increase it a whole bunch without getting the blooming (if I use the RCA adapters to boost it even higher, then I start getting the blooming), but I ultimately decided that the default contrast was actually pretty good.

I did tweak the brightness, though, using an SMPTE colour bar. Boosted it a bit on all the inputs (although different adjustments were required on different inputs). Conveniently, I have the cables to connect my SNES to any input on the PVM, although it's unfortunate that the NES can't output SMPTE colour bars so that I could calibrate against what I normally connect to the composite input.

[andy251203]

Don't touch your outputs unless you plan on doing this:

[Guspaz]

Are the outputs active even when the monitor has shut off? I've been considering running the output of the PVM to my projector so that I can get my consoles on there when I want something on the big screen.

[Gered]

All my RGB capable consoles are connected like so:

Consoles -> SCART Switch -> PVM -> XRGB Mini -> HDTV

Using the output connectors on my PVM to go to the Framemeister of course. Whether or not the PVM is on, the signal reaches the Framemeister just fine.

[Ed Oscuro]

It's just a passive pass-through, not a powered splitter; the termination clicks into action when the outputs are empty.