JVC DT-V1910CG /1710CG Unstable Image (Wobble)

[Namingway_PL]

Hello!

I know that there is a JVC DT-V&TM-H thread here, but I think this deserves a separete thread as it is easily overlooked.

The JVC DT-V1910CG & DT-V1710CG are great monitors, but like many other multiformat CRT's they have a fair share of quirks and wierd behavior.

One of these quirks is this so called "wobble" where the image is slightly unstable and a bit "shaky" both in RGBS and Component sources, mostly noticable in 240p resolution. A common solution for this with RGBS sources is to use an Extron RGB interface or a Sync Strike to seperate the sync signal to RGBHV (this helps with some sync issues as well). For Component, there is a setting in the menu called "Aperture Controll" which needs to be set to "off".

Both of these solutions help to reduce the effect to the point where it's almost unnoticeable, but it's still there when You look very closely.

Some time ago I got the MiSTer FPGA, and thought that if it has a RGBHV (DB-15) output it might produce a "better" signal and in resoult have a rock solid image. Unfortunately it was the same as my PS1 going through a Sync Strike...

I made a short video showing this effect in closeup (through a magnifying glass). This is the MiSTer FPGA running the Neo Geo Core with the analog (DB-15) output on the DT-V1910CG.

https://youtu.be/v4vvxSWz4zk

As You can see, the dots at the edges of the letters seem to flicker a bit. It's the most prominent with like a PS1/PS2 hooked up directly with RGBS. With the Sync Strike it's much better, and looks just like on the MiSTer video. The best resoults I get with component inputs with the aperture control set to off, and with a MiSTer in direct video mode, through a HDFURY3 converter where the effect is only noticable with a magnifying glass.

I'm trying to figure this out for years now, and at this point I'm out of ideas. I tried many diffrent things, like diffrent cables, switchers, converters, RGB interfaces, sync strike, and even bought a power conditioner. Unfortunately it's always there no matter what I do...

To sum everything up also have a few things to share:

I owned about 12 diffrent units of the DT-V1710CG, and also one DT-V1910CG and the all behaved exactly the same. Most of them were in near mint condition ranging with 1K to 3K hours of use, and two of them had 20K hours. So this is not an issue with only one particular unit but with all of them. It's the same on my friends DT-V1910CG, any many other DT-V owners also from this forum, reported the same behavior on their units.

With HD resolutions like 720p/1080i the image is rock solid and looks perfect.

Also the DT-V1900CG seem to not to have this issue. I can't confirm that for sure as I never owned one, but I talked to a few owners of these units, and they said that they do not see this on their monitors.


Ofcourse, using a Sync Strike/Extron or Component is ok and looks fairly good, and I could just ignore it, but this issue bugs me a greatly, and I would like to get to the bottom of this and try to "fix" it. I'm running out of ideas, and recently started suspecting that it might be an some what a design flaw. It's most noticable in 240p, but this is not a proper TV standard so I suspect that this might have sliped unnoticed when the monitors came out of the factory, but that's just a theory which I'm not able to confirm. Also I'm no technician, and don't know much about electronics (just an amateur who loves CRT's).


Posting this in hopes that someone might have a, solution or any type of info about this matter, or any idea on why these monitors are doing this.

Thanks for reading!
Cheers!

[fernan1234]

I know you're confident that this is a general issue with all units since you've seen this in so many of them, but I would still wonder if it's something in your setup/chain, especially if you tested all those units in the same place with some variables held constant.

I say this because, while I've had contact with less units than you, I did not find this to be an issue on them, including my current unit. And yes, I did get my nose up very close to the screen. I'll try to take a zoomed video later.

If this is correct the good news would be that you may just need to find the culprit in your setup. BTW, I never use sync strikes or Extron interfaces with stuff I connect, whether it's MiSTer's RGBHV from the IO board, stuff converted from HDMI to RGBHV, or plain old RGBS console sources with custom D-Sub cables. Everything just goes though my Extron VGA Ars switch, which does raise any video level sync to TTL, for what that's worth. Also all my stuff is NTSC and not PAL (I've heard that any issues can be more common with PAL).

[mrpvmsouthafrica]

I can confirm that the OPs experience is a known thing and it is valid. I own a DTV1710cg and it exhibits the same behavior. I will post what I found solved it soon as I'm busy now, but the solution isn't for everyone and certainly isnt simple, and won't fix the issue with standalone consoles.

[Namingway_PL]

@fernan Well ofcourse I tried to eleminate anything I could within my setup that could cause this. Tried hooking up everything directly to the monitor, used diffrent Extron Crosspoint and VGA switchers, diffrent cables, consoles and such. I tried like everything I could to find out why is this happening.

And it was not at the same place as I moved to another apartment (like I said, I'm trying to figure this out for years). Also, I know from other DT-V owners (some from this forum) that they experience the same thing on their monitors too, and my friend confirmed that on his DT-V1910CG it's exactly the same. If it was only me who see this I would asume that I'm just crazy and it would be the end of that

And I also own a bunch of all types of diffrent CRT monitors, like Sony PVM/BVM, JVC TM-H, Barco etc. And only the DT-V's do this.


So yeah, I'm pretty sure this is a "DT-V thing" and I quite confident about it. If would check my posts in the JVC thread, I would see that I mentioned this way back, like about 4 years ago.


And Yes, I live in PAL territory, and my systems are PAL or have a region mod. But I don't think this would matter in case of the MiSTer.

And I forgot to mention that when I turn on the OSD while playing the game, the OSD is rock solid, but You can see that the game is "shaky".

That's why I posting this here, because at this point I truly ran out of ideas on what could I try next and I truly don't know what's what could case this wierd behavior...

Just have in mind that this is quite hard to notice, and You have to have a very trained eye for CRT's (which I don't doubt that You don't have). Probably 90% of people wouldn't notice that at all.


@mrpvmsouthafrica Hi! Yeah I remember that we talk about it a long time ago! Thanks for joining in! Looking forward to Your next post!

[fernan1234]

I can also add that I have actually noticed this exact kind of "wobble" on other high-end AG monitors I owned, in particular a D24 BVM and a D20 where it was the most obvious. I also owned an A24 where in the same setup it was 100% not present (edit: actually, the D20 times may have been with a SCART setup).

Which leads me to think that this could also be a thing that tends to develop over time after all these years on high resolution aperture grille tubes, including these. And yet somehow I may have gotten lucky with the DT-Vs I've had access to.

What's more, that experience with the D20, one of my first pro monitors, actually made me sensitive to this kind of wobble and made me look for it whenever I got a different monitor. Besides never seeing it on the ~6 DT-Vs I've used, it was also not on any of the 14L5 PVMs I had.

[Namingway_PL]

@fernan Not sure about the D20, as I never had one, or seen any in person so can't say nothing about this model. Only I heard that sometimes they can be a bit problematic too.

As for the DT-V, there is no way that this is an issue that devoleped through out the years. The effect is exactly the same on all of them. Same on a monitor that was mint with 1K hours, and exactly the same on a diffrent one with 24K. It would be pretty much impossible that all these monitors (all 13 of mine, and some other of my friends) would develop exactly the same issue. I owned too many aperture grill monitors through out the years, and never experienced anything similar.

To be honest I just think Yours has this too, but You just don't notice this. If You can, please take a magnifying glass and try to make a similar video to mine. If for some reason, this don't occure on Your DT-V it will definitely be a supprise, and it will be a huge help and the next logical step for me would be to get a NTSC console and try it out on my monitor.

As You see, the purpose of this thread is to give an idea what could be causing this, and try to find out how to fix this. I don't want to argue about the fact if this is a thing or not.

[fernan1234]

To be honest I just think Yours has this too, but You just don't notice this.

I don't think you can make this assumption reasonably, especially after I've easily noticed this kind of thing on other monitors. But you said you don't want to argue about this happening in all units or not, so we can leave it at that. But yeah, I do plan to take a video as that would be helpful for all.

What I'm also thinking is that some of these monitors, due to their highly resolving capabilities, are actually displaying analogue noise in the form of this "wobble". After all noise can easily creep into analogue chains from the environment. I'm also wondering if being on a 200V area versus 100V can make a difference in noise sensitivity.

A way to go about testing for noise would be to connect the same inputs to an OSSC or RT5X with optimal timings and phase adjustment to see if the noise manifests there in the same way/rate as the wobble on the CRT.

[Namingway_PL]

Sorry, didn't want to be rude or anything. It's just that I never seen a DT-V that didn't had this.

To be honest I kind of hope that You are right and that this is not a thing on Your monitors. That would mean that a sulution is possible so it would be good news So I'm looking forward to that video!

And if I'm right that this is a design flaw, that would be much worse...

[fernan1234]

Here's the video: https://youtu.be/BrRl1G9BSuc

Do you think it's the same? Don't have a micro lens so max zoom up close is the best I could do. If I then zoom in on the already zoomed in video, maybe I can see a hint of flicker at the edge of bright scan lines? But to the naked eye from any distance I really don't see any flicker or wobble, unlike those that I could see on some of the monitors I mentioned before.

Oh also, when testing for noise using an ADC it would be necessary to turn off LPF or anything else that could be cleaning up the noise from the digital output. At the same time, there's also the possibility that some particular component in some units (not the tube itself, so not related to how many hours are on it) may become more sensitive to noise under certain circumstances.

[MKL]

viewtopic.php?f=6&t=69191

See my two posts in there, one of which is a reply to a post that claims "the JVC TM sets all do this". I haven't seen the schematics of the DT series but I wouldn't be surprised if they shared this feature with the TM series.

[kitty666cats]

Tried sync on green? I've heard Fudoh (I think it was him) mention that it is useful on these monitors when your source signal is unstable

[Wise123]

I have a DT-V1710CG and it has a manufacturing date of October 2005. It currently has 1200 hours of use according to the hour meter in the service menu and had sub 1000 hours when I first got it. This hasn't been reseted (bought it from a very reliable source) so it was very mint.

With that said let me first start by saying that I don't have a solution, but I did notice something while playing my Nintendo Wii with original component cables. When I first got the monitor I chose to try Super Metroid (originally downloaded from the old Wii Virtual Console store) and the screen was changed to 240p (as it should I guess?) and the "wobble effect" would kick in right away. I went away for a short while (like 10 min) and when I came back the wobble effect was greatly reduced. After around 25 min you had to be like 1 inch from the screen to actually notice anything at all.

I came to the conclusion that since component (atleast to my knowledge) uses sync on the green line I wanted to try it out with other consoles as well. So I got myself an Extron RGB 192 and a scart to VGA-cable and converted all my signals to sync on green. And it actually worked (same way as on the Wii - it slowly and gradually went away over a span of like 20-25 min). I have no idea how it actually works, I just know that this is currently my solution to this problem and I'm happy with it.

I am in no way an expert, just want to help out as much as I can solving this issue as it seems to be and issue for a lot of people.

[Namingway_PL]

@fernan Ok, but as You could see on my video, the object (letter) is on a all black background, and only the dots on the far left and right edges of the displayed object are flickering. The dot next to the flickering dot are not lit so it's easy to see the effect.

On Your video the background is all green, meaning all the dots are lit, so it's pretty much impossible to see the effect. But that tiny bit of flicker that You noticed (I also see it on Your video) gives me a hint that it might be the thing that I'm talking about.

To see it clearly, You would need to make a video of an object on all black background, and look closely on the edges of the displayed object. Or You could hook up something with component like a ps2, and try changing the "aperture control" setting and check if You see any diffirance between high, low and off. It might give You an idea what I'm talking about. Like I said, this is not that easy to notice, and this can be easily overlooked . But when You see it, You won't be able to unsee it.

Also I would like mantion that I posted this also on FB and recived a few messages from DT-V owners where they confirmed that they see it too.

I totaly get Your point about the noise, but first I would like to determine if Your monitor does this too or not, and then move on.

@MKL yeah I've seen that thread, and I can confirm that I experienced this micro jitter on the Sony BVM and JVC TM-H too, so definitely this is also a thing. But the "thing" on the DT-V is a bit diffrent

@kitty666cats as You mention it, Yes I did try it some time ago, but unfortunately couldn't get it working. I tried to convert the sync using the Extron RGB interface, but it seems that the SoG dip switch is for the input and not for the output. If You have any tips on how to properly convert RGBHV or RGBS to RGsB it would be great.


[Edit]

Just recived another message on FB from another DT-V user. He confirmed that the thing I'm talking about exists, and suggested to try SoG just as @kitty666cats said. He even sent me some videos to proove it, and it seems promising He wanted to post it here, but unfortunately his post needs to approved by there moderator.

[fernan1234]

@Namingway_PL I checked with black text on an all black background and it's the same, the tiniest of flicker on the very last fine grille at the edge of the scan line when seen zoomed in 2x, but not visible to the naked eye at any distance. So if what you see is visible to the naked eye, it is on a different level of severity (like the ones I could also see on other models).

If the SoG trick makes a difference, it may be for the same reason why my setup also alleviates or sufficiently minimizes this phenomenon to the point that it's not visible without a micro lens or camera zoom. Because the Extron boxes and such that output SoG are elevating the sync levels to TTL, just like my VGA matrix does, so that really may be all that's needed here.

[Namingway_PL]

@fernan I understand. It seems, that what You see is the wobble effect reduced to minimum, and that won't be visible to the naked eye, only in close up. Like I said it's the same on my monitor with the MiSTer in direct video mode, and with Component with systems like the Nintendo Wii or PS2.

From what I can see, the effect is most prominent with the PS1 hooked to the monitor directly with RGBS. The wobble is clearly visible from normal gaming distance, and it's pretty annoying. The sync strike or extron will help, but the resoults are not as good as the Mister or component, and still visible to the naked eye if You look closely.

I have the same Extron SW VGA Ars switch that I use along with my Crosspoint, but they make no differance if the signal is already comming from the RGB interface or sync strike. I also think that the SoG "trick" will give a similar effect, to all other options mentioned before. Meaning it will reduce it to minimum.

I talked to many DT-V users through out the years about this matter, and everyone confirmed the same exact behavior on their monitors, so I'm quite sure that this is a thing with all of them. It can be reduced to the point where is not noticable by eye in normal conditions. But the thing is, that it's always there to variable extent depending on the system, connection or equipment used. This not the same thing as the micro jitter mentioned by MKL, and it's very consistent through out the whole screen.

I don't know any other pro monitor that has the same behavior, and my goal is to find out why the DT-V is doing this and if possible, find a solution. Ofcourse I can ignore the fact that it is there, and just use my MiSTer in direct video mode, and my other systems with connection that work best. But that's not a solution to the problem, it just covers it up a bit. Many DT-V users are strugguling with this, as it's ruins the experience of using this monitor.

Ofcourse I could always get a, different monitor with similar spec, but I like the DT-V and I would like to have a chance to finally see a rock solid 240p image on the thing. It might not be a big deal for some people, but it is for me, and I know many DT-V users that feel the same.

[fernan1234]

From what I can see, the effect is most prominent with the PS1 hooked to the monitor directly with RGBS.

I actually got a video of PS1 RGBS. I do recall that when I got my custom D-sub cables by Retro-Access they added a sync stripper in particular for PS1 and PS2 cables, so that may be a factor too.

https://youtu.be/VAd2kmbtfrw

You can see in this zoomed video especially where white meets black that there is a small flicker from a single grille gap, but again this is not visible to the naked eye even when getting very close to the screen (and luckily I still haven't developed any presbyopia so my eyesight is clear up close).

So even with PS1 it is not a lost cause. DT-Vs are my absolute favorite monitors even only for 240p so I agree with wanting to enjoy them to the fullest without any issues. To me it looks like it's possible!

edit: now I'm also wondering if (sub)brightness and (sub)contrast/calibration settings may be a factor too in making this more or less noticeable. This unit is pretty well calibrated.

[Namingway_PL]

You are right! It looks solid to me. I don't see any signs of the wobble at all on Your video. That Retro-Access cable might be it. Yesterday a fellow DT-V1910CG user contacted me on FB. He had exactly the same issues as I did and struggled with them for a long time. He finally got a cable from HD Retrovision that has a transcoder built in and that pretty much solved the problem. He shared a video with a PS1 on his monitor, and just like on Your video the image was solid.

So it seems that there is a solution for this wierd wobble, and I'm very happy to hear that Now I will need to equip myself with some cables from them and give them a try. I hope there is a way to get them shipped to Europe. And Yeah, the DT-V is my favorite monitor too, but this wobble issue is really a thing and many people have problems with it. I spent quite a lot of money on different cables and all kinds equipment trying to figure this out, with disappointing resoults, and I'm not the only one with this experience :/

But still it doesn't explain why the DT-V are doing this, and all other solutions like sync strike or extron RGB interfaces don't work as good as the HD Retrovision and Retro-Access Cables seem. Are the DT-V really that sensitive, and need the best possible cables to work correctly? I hope some day we will figure this out...

[fernan1234]

Are the DT-V really that sensitive, and need the best possible cables to work correctly? I hope some day we will figure this out...

I do have a couple of ideas about this.

One, DT-Vs are essentially a high resolution PC/VGA CRT in the chassis/circuitry of a broadcast monitor with 15khz support. This may make them more sensitive to analogue weirdness than many others. Fun fact that not many people know about DT-Vs is that, like you'd expect of PC CRTs, they can actually display a range of refresh rates, rather than only specific scan rates like pretty much all other multiformat monitors.

And two, DT-Vs use an excellent anti-glare film (I'd say better than pretty much any other film you typically find on most PC CRTs, and this is IMO the main advantage unique to DT-Vs, when it's not damaged at least), a neutral density 1 stop film that halves the brightness, and yet DT-Vs are factory calibrated to be as bright as 15khz tubes with no films. This may mean that in some way the tubes are "overdriven" by default. I wonder if contrast/brightness or even screen pot adjustments on the flyback could make a difference in this regard (just as a test, they should be around the default values if the AG film is present).

[MikeS11]

Just in case anyone runs into this issue, I fixed mine by using direct video with a rankie HDMI to VGA adapter on the MiSTer.

At least from the sample of cores I had issues with before

[famiac]

solution is in the first post. I compared the h-sync circuits for the JVC DT-V1710 and Panasonic BT-H1700 and noticed that the H-sync on the 1710 is double-amped and missing the clamping diodes, which help set the duty cycle for the M52346SP sync processor chip.

remove these components from the signal PWB, then solder two wires and two signal diodes (marked in purple). replace capacitor C103 with a non-polar 4.7uF capacitor.


The mod should make the h-sync circuit identical to the 1900CG and maintains the INT/EXT sync switch functionality.
no wobble anymore with RGBHV output from the extron 203rxi

[fernan1234]

Very awesome finding and mod, famiac!

After temporarily not having access to my old setup of clean sync cables and Extron switch, I became very familiar with the wobble troubles that these monitors can have in particular with console cables that originally use composite video sync. As an external solution, I found that a combination of an external sync separator + an Extron RGB interface re-combining the sync was able to get rid of the wobble for both 240p and 480i inputs (using only a sync separator/cleaner or an Extron unit alone can help to fix wobble on 240p but adds it on 480i, or vice versa), which is especially convenient for those PlayStation 1, Saturn, N64 and such system games that can use both resolutions in the same games.

The MiSTer is more of a unique case as results can vary depending on the specific core that you use (the Amiga core in particular seems to be stubborn using the same solutions that get rid of wobble for pretty much all other cores). If using direct video rather than analogue from an IO board, results may also depend on the particular DAC used.

In any case, that mod is a great alternative to bulky solutions based on external adapter chains. It would be good to test it further not just with RGBHV inputs but also RGBS both with c-sync as well as sync on composite video, TTL sync and video level sync, RGsB, component, etc. noting results as well for 240p and 480i.

[famiac]

internal sync (RGsB) produces a stable image without any mods but for some reason the display will have a green tint. i remember coming across some posts that mentioned the effect but i can't seem to find them now.

the mod should only change the behavior of RGBS and RGBHV. did not compare TTL vs 75 ohm. it may not matter since the input card amplifies all the input signals.

[Namingway_PL]

solution is in the first post. I compared the h-sync circuits for the JVC DT-V1710 and Panasonic BT-H1700 and noticed that the H-sync on the 1710 is double-amped and missing the clamping diodes, which help set the duty cycle for the M52346SP sync processor chip.

remove these components from the signal PWB, then solder two wires and two signal diodes (marked in purple). replace capacitor C103 with a non-polar 4.7uF capacitor.


The mod should make the h-sync circuit identical to the 1900CG and maintains the INT/EXT sync switch functionality.
no wobble anymore with RGBHV output from the extron 203rxi

Whoa! This is an amaizing find! Great job!

If this works as described, it will be a true life saver for many DT-V users! I was loosing hope and was thinking about selling my units, but now they will definetely stay with me! You should make a tutorial and post it somewhere


@fernan I'm glad that now You are aware that this issue is a thing and that I'm not seeing things! Like I said before in one of my posts, that when You see it, You won't be able to unsee it. I knew this must be some kind of a design flaw, so I'm very happy that finally we have a solution! No more buying useless gear in hopes on fixing this wobble.

Now I need to test this out on my DT-V1710CG before I will try it on my 1910CG.

Thank You @famiac!

[fernan1234]

@fernan I'm glad that now You are aware that this issue is a thing and that I'm not seeing things! Like I said before in one of my posts, that when You see it, You won't be able to unsee it. I knew this must be some kind of a design flaw, so I'm very happy that finally we have a solution! No more buying useless gear in hopes on fixing this wobble.

I never doubted you I just knew it had to be setup dependent since the wobble can be eliminated with the right sync processing combos, so not all gear is useless.

What I learned is that the right sync stripper + TTL will get rid of the wobble for everything. Separating S sync into H+V sync will fix it for 240p, but introduce it for 480i. You can also get clone input cards from China that basically do the same with a sync processing button, which gives perfect wobble-free 240p but introduce it for 480i. The most difficult part is getting a chain that fixes it for everything without having to change anything, but it can be done and should remain an alternative for people who can't do solder mod work on the signal PWB.

Will look forward to other people's results when they try this mod. BTW, in my experience RGsB without further processing can still have wobble, in addition to the weird green tint problem that famiac mentioned.

[famiac]

i will try those low resolutions and report back.
It's interesting you mention that the behavior is different depending on the display format.

The DT-V uses the M52346SP to separate the sync signals.
the timing for the sync clamp pulse is set by a resistor and a capacitor on pin 20 of that chip.

EDIT: the clamp pulse only matters for composite video.

@Namingway: what would you like to see in the tutorial?

[Namingway_PL]

@fernan Yeah, You're right. Not all gear is useless. But with all that I tried, it never removed the issue completely. Ofcource it was reduced to the point where it was not visible in normal viewing distance, but no matter what I used, I still could see it a bit with my nose at there screen. So I have high hopes with this mod Like I said in one of my earlier posts, that I wanted to try to get to the bottom of this issue, and find the reason why the DT-V was doing this in the first place, and it seems that we did


@famiac Not sure really. The mod seems pretty simple and streight forward, but when the posts in this thread start piling up it might be hard to find. You could make a short guide with a bit more detail, and maybe post it in a separate thread, or edit it to the first post in this one, so it will be easier to find it

[fernan1234]

We may have to ask famiac to also put his nose against the screen, just in case the result from the mod may be the same as what some external sync processing seems to be able to do. JVC, Sony, and Ikegami were really ambitious with their multiformat CRTs, no wonder some rough edges ended up yielding quirks like this one.

In any case an easier to find guide with a bit more detail will be a huge help to current and future DT-V users!

[famiac]

i use the OSD to check how much jitter there is. the DT-V probably generates its own sync for it so the menu is always stable.
find a screen where one of the letters on the OSD lines up with a color boundary in the background and you can essentially measure how many pixels the screen is wobbling left and right.

i'll write a guide after i do more testing to verify that the issue is fully solved.

[Namingway_PL]

@famiac Yeah, You're right. The menu is always rock solid, so this is a very good method to determine if it's still there or not. I do that too

This looks really promising! I'm super hyped about it, and can't wait for the guide to try this mod on my units!

[famiac]

after testing i can see that the mod (replacing the amp for h-sync with a clamp) eliminated the wobble at 480p but made it slightly worse in 240p.
swapping the M52346SP with an M52036SP didn't seem to noticeably change behavior.

maybe the UPC1884 is the source of our troubles. I'm going to keep working on this problem.