JVC TM-H and DT-V thread

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Namingway_PL
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Re: JVC TM-H and DT-V thread

Post by Namingway_PL »

@Tempest_2084 Yes it's safe. Nothing to worry about. It's on the main board. Close to the center. It's the only pot there so You should find it easily.
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Tempest_2084
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Re: JVC TM-H and DT-V thread

Post by Tempest_2084 »

Thanks. What exactly does this do and why does it need adjusting? Just curious.
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matt
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Re: JVC TM-H and DT-V thread

Post by matt »

Tempest_2084 wrote:So it's safe to adjust that pot then? It's not going to cause other problems? Where is it located on the main board?
You can absolutely cause problems by adjusting that pot! It controls the B+ voltage, which is the main power supply for the flyback. Raising it will increase the high voltage to the tube, heater voltage, etc. You really can damage the monitor if you raise it too high.

If you do want to adjust the B+ voltage, check the service manual and make sure it stays within the proper range.
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Tempest_2084
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Re: JVC TM-H and DT-V thread

Post by Tempest_2084 »

matt wrote:
Tempest_2084 wrote:So it's safe to adjust that pot then? It's not going to cause other problems? Where is it located on the main board?
You can absolutely cause problems by adjusting that pot! It controls the B+ voltage, which is the main power supply for the flyback. Raising it will increase the high voltage to the tube, heater voltage, etc. You really can damage the monitor if you raise it too high.

If you do want to adjust the B+ voltage, check the service manual and make sure it stays within the proper range.
That's what I was afraid of. I think I'll leave it alone for now.
Fed
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Re: JVC TM-H and DT-V thread

Post by Fed »

Do the HSTAT and VSTAT pots on the sideboard for a DTV-17 only work with certain video signals ?
These two pots were making a difference when touched on my DTV-1900 in 240p but they are completely irresponsive on my DT-V17.
The Sideboard appears to be correctly connected to the mainboard and to the Yoke so I am really puzzled as to why they are not having any effect.
Namingway_PL
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Re: JVC TM-H and DT-V thread

Post by Namingway_PL »

Tempest_2084 wrote:
matt wrote:
Tempest_2084 wrote:So it's safe to adjust that pot then? It's not going to cause other problems? Where is it located on the main board?
You can absolutely cause problems by adjusting that pot! It controls the B+ voltage, which is the main power supply for the flyback. Raising it will increase the high voltage to the tube, heater voltage, etc. You really can damage the monitor if you raise it too high.

If you do want to adjust the B+ voltage, check the service manual and make sure it stays within the proper range.
That's what I was afraid of. I think I'll leave it alone for now.
Haha! :) I've done this a lot with my monitors and never had any issues. Also never heard of any issues after adjusting it from anyone else.

@Tempest_2084 just do it. There is nothing to worry about.

@matt do You have any proof that adjusting that pot can damage the monitor? Or is it something You heard from someone? :)
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matt
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Re: JVC TM-H and DT-V thread

Post by matt »

Yes, I've seen several cases where people have asked for help because they tweaked the B+ pot too much and blew the deflection circuit. There's a reason why the manufacturers specify a range for the B+ voltage in their service documentation.

I'm not saying don't adjust the B+ - it's fine as long as you're careful and check the voltage to make sure you're staying within the proper range. I have indeed adjusted the B+ pot slightly on my own JVC monitor, but I'm not going to use it as an indiscriminate method of controlling screen size.
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Tempest_2084
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Re: JVC TM-H and DT-V thread

Post by Tempest_2084 »

If I were to adjust it, is it just a very small turn left or right? The monitor right now is really good and I usually don't overscan it much so if I have to adjust it I don't think it would be by very much. Then again I'm not sure it's worth the risk.
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matt
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Re: JVC TM-H and DT-V thread

Post by matt »

It's probably fine, just look up the service manual and confirm the voltage with a meter if you're concerned about it.
Namingway_PL
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Re: JVC TM-H and DT-V thread

Post by Namingway_PL »

matt wrote:Yes, I've seen several cases where people have asked for help because they tweaked the B+ pot too much and blew the deflection circuit. There's a reason why the manufacturers specify a range for the B+ voltage in their service documentation.

I'm not saying don't adjust the B+ - it's fine as long as you're careful and check the voltage to make sure you're staying within the proper range. I have indeed adjusted the B+ pot slightly on my own JVC monitor, but I'm not going to use it as an indiscriminate method of controlling screen size.
Well, I can't argue with that. This pot is definitely not meant to controll the screen size, but if the monitor has too much underscan and settings in the menu can't help it, the pot needs to but adjusted.

I had a lot of TM-H units and this is really a common "issue" on those sets. I've made this adjustment many times, and never had any issues afterwards, so from my experience this is safe.

Ofcourse while making adjustments on a CRT, caution is highly advised, but panicking about it is not ;) Adjusting it a bit just to make the image fill up the screen is ok, just don't go all reckless about it and don't spin the shit out of it, and it should be fine.
HoldyourfireImahuman
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Re: JVC TM-H and DT-V thread

Post by HoldyourfireImahuman »

I saw another user recently post about this but I too am curious...

Who else here notices with their tm-h models that the geometry appears to bow outwards in the bottom half of the screen? I've seen it in a number of them and was wondering if it's just due to the tube shape? Some get it worse than others.
Thanks!
Nino Bot
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Re: JVC TM-H and DT-V thread

Post by Nino Bot »

I got a JVC DT-V1700CG with both a BNC component video card and SCART RGB inout card. 480i and above works but 240p connected to either card results in a scrambled screen with out of range message. I tried my RGB-Pi/Pi4 and PS2 + SCART cable.

Anyone know what I can do to fix it?

Also whenever i press the volume up or down button, all the buttons become unresponsive, then the monitor clicks off then on again. ImageImage

Sent from my SM-G955U using Tapatalk
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amontre
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Re: JVC TM-H and DT-V thread

Post by amontre »

Is there a way to replace front panel frame ? I got cracked plastic when i moved to a new place. 3D printed maybe ?
ViraLicious
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Re: JVC TM-H and DT-V thread

Post by ViraLicious »

Hi!

Does anyone here know if there is a cap replacement kit available somewhere for the DT-V1710CG like Savon Pat has for the Sony PVMs? I’m mainly interested in replacing the deflection caps.
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Einzelherz
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Re: JVC TM-H and DT-V thread

Post by Einzelherz »

My guess would be no since the in-the-wild ratio of PVMs to JVCs of any flavor is probably 20:1.
ViraLicious
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Re: JVC TM-H and DT-V thread

Post by ViraLicious »

Yeah that’s true and understandable. If I were more savvy with that stuff I would’ve taken it upon myself to document it all. However, I am still a newbie with electronics etc. For sake of preservation it would be awesome if anyone could compile a list of the various components - for example for the power supply, deflection or whatever else may be necessary to keep the monitor alive and kicking. Feel it’s a shame it’s so hard to find info about PVMs, even if it’s a niche interest. I myself would’ve loved a wiki with all the info or something.
NYI
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Re: JVC TM-H and DT-V thread

Post by NYI »

Hi all,

I have a Ikegami 1700r using a clone RGB card. Hours meter reports 075 x 100, although I know people said you may be able to change that count anyway?

Few issues, maybe related if the tube is just spent?

-Contrast is pretty high, needs to be around 25% or white level is too high - even at 0 the image is very visible.
-Brightness needs to be 75% to show detail! From 0-50 the knob doesn't show much, at 75 brightness appears to be ok, raising from 85-100 is not much effect. 0-50 results in practically no image at all - in fact from 0-40% it's like there's no effect. Interestingly it's not like blacks are even very grey even at the highest brightness.
-Focus, or perhaps convergence, or both, change when contrast is raised, for the worse. Set contrast to 50% and can see red to the right of whites.
-Text/icons look blurry at 720p, fine at 240p.
-Has the 16:9 bezel - but even after adjusting the vsize and hsize to minimum, image appears to be too big for the bezel at 720p?
fernan1234
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Re: JVC TM-H and DT-V thread

Post by fernan1234 »

NYI wrote:I have a Ikegami 1700r using a clone RGB card. Hours meter reports 075 x 100, although I know people said you may be able to change that count anyway?
They can be reset to zero (not changed to a specific number), so most likely the 7500 hours on yours are the actual usage. Not bad at all!
NYI wrote:-Text/icons look blurry at 720p, fine at 240p.
How are you getting a 720p signal into this? I'm assuming the source is digital. HDMI to component or RGBHV? Or SDI? What converter are you using? Any scaling going on during the conversion? Just asking in case this is making a difference. Keep also in mind that each picture mode (240p vs 720p) has its own calibration, including the focus setting, though convergence is adjusted via the rings if I recall correctly and so should be about the same across all the picture modes.
NYI wrote:-Has the 16:9 bezel - but even after adjusting the vsize and hsize to minimum, image appears to be too big for the bezel at 720p?
Try the underscan mode?

As to your brightness/contrast observations, not sure if that's normal or not, but as long as you can get a correctly displayed picture with some settings it shouldn't be a problem.
NYI
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Re: JVC TM-H and DT-V thread

Post by NYI »

fernan1234 wrote:They can be reset to zero (not changed to a specific number), so most likely the 7500 hours on yours are the actual usage. Not bad at all!
Yeah I was pretty happy to see that! Which is why it's so strange this monitor needs to be basically set to 100% brightness to see the correct level of detail, while the contrast level needs to be set to minimum. I turned sub brightness up to about 11 out of 20, did help somewhat, but still needs to be at 100%. Setting the contrast up even a bit results in visible blooming and when you get to 50% it's way too bright, you start to get convergence issues, and everything is crazy blown out after that.

Here's some comparisons between contrast and lowest and then at 50:

https://i.ibb.co/kM8JqwZ/20220603-225825-Copy.jpg, https://i.ibb.co/JzxnvsZ/20220603-225833-Copy.jpg

https://i.ibb.co/chW3XD2/20220603-225738-Copy.jpg, https://i.ibb.co/KX1Yk0j/20220603-225728-Copy.jpg

It's weird: I've seen tubes where detail is just gone but I've never seen such a mismatch between brightness and contrast level, where contrast needs to be minimum and brightness maximum.



One last one: menu open when in 720p mode. Interesting effect of what looks like red misconvergence that's not really visible in the menu at 240p, and fluctuates with white visible in image/gets a bit worse with more contrast:

https://i.ibb.co/NnzzNb5/20220603-230354-Copy.jpg
fernan1234 wrote:How are you getting a 720p signal into this? I'm assuming the source is digital. HDMI to component or RGBHV? Or SDI? What converter are you using? Any scaling going on during the conversion? Just asking in case this is making a difference. Keep also in mind that each picture mode (240p vs 720p) has its own calibration, including the focus setting, though convergence is adjusted via the rings if I recall correctly and so should be about the same across all the picture modes.
My current setup is RBGHV out from video card --> Crosspoint ---> RGBHV to the monitor. Here's a picture https://i.ibb.co/zNdq8x0/20220603-231423-1-Copy.jpg (splotch effect not visible IRL)- perhaps I just need to assume 720p isn't going to be quite as "sharp" as trying to make a comparison to something else like a PC CRT? Not bad actually, just somewhat blurry but still looks pretty good with video use.
fernan1234 wrote:Try the underscan mode?
This one doesn't allow for that on RGB, unfortunately.
fernan1234
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Re: JVC TM-H and DT-V thread

Post by fernan1234 »

NYI wrote:It's weird: I've seen tubes where detail is just gone but I've never seen such a mismatch between brightness and contrast level, where contrast needs to be minimum and brightness maximum.
Oh yeah this is weird, didn't catch this is what's happening. I would suspect that the brightness/contrast settings in the service menu are mismatching the settings in the "setup menu", the two are tied up so if you set brightness to something in the service menu, whatever you change in the setup menu changes with the former as the basis. Have you checked the service menu?

NYI wrote:This one doesn't allow for that on RGB, unfortunately.
I forgot about this, we haven't been able to figure it out but it looks like underscan is disabled for RGB on some units (the manual also says it's disabled), but works perfectly on others. It works on a couple of 1710s I've had, but not on 1910s. The 1700 and 1900 is slightly older so that may have something to do with it too. We think there's a setting in the service menu that may affect this.

I guess an alternative would be to use YPbPr.
Namingway_PL
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Re: JVC TM-H and DT-V thread

Post by Namingway_PL »

NYI wrote:Hi all,

I have a Ikegami 1700r using a clone RGB card. Hours meter reports 075 x 100, although I know people said you may be able to change that count anyway?

Few issues, maybe related if the tube is just spent?

-Contrast is pretty high, needs to be around 25% or white level is too high - even at 0 the image is very visible.
-Brightness needs to be 75% to show detail! From 0-50 the knob doesn't show much, at 75 brightness appears to be ok, raising from 85-100 is not much effect. 0-50 results in practically no image at all - in fact from 0-40% it's like there's no effect. Interestingly it's not like blacks are even very grey even at the highest brightness.
-Focus, or perhaps convergence, or both, change when contrast is raised, for the worse. Set contrast to 50% and can see red to the right of whites.
-Text/icons look blurry at 720p, fine at 240p.
-Has the 16:9 bezel - but even after adjusting the vsize and hsize to minimum, image appears to be too big for the bezel at 720p?
Hey, did You try to factory reset the unit? Seems that someone must've mess with the settings, and this can happen.

After a proper reset it should be fine. Try setting all the knobs to neutral position (in the middle) and reset all settings in the service menu.

Not sure if that will help, but it's worth a try.
Pinkbulletstorm
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Re: JVC TM-H and DT-V thread

Post by Pinkbulletstorm »

Hi all, I'm just wondering if anyone would have any tips to help me narrow down a problem I'm having. I've got a JVC TM-H140PN here that's being troublesome. Basically it will turn on, but turn off straight away like it's protecting itself. When I do turn it on, the front power led will show briefly, but then once it shuts off, it's completely dead until plugged out for a few moments, at which point if I try power it up it just shuts off again.

So far I've replaced the PTC, the main voltage regulator, and a few of the large caps near the voltage Reg (they all loon visually fine). At this point I'm lost in terms of how to proceed with troubleshooting.
NYI
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Re: JVC TM-H and DT-V thread

Post by NYI »

fernan1234 wrote:
NYI wrote:It's weird: I've seen tubes where detail is just gone but I've never seen such a mismatch between brightness and contrast level, where contrast needs to be minimum and brightness maximum.
Oh yeah this is weird, didn't catch this is what's happening. I would suspect that the brightness/contrast settings in the service menu are mismatching the settings in the "setup menu", the two are tied up so if you set brightness to something in the service menu, whatever you change in the setup menu changes with the former as the basis. Have you checked the service menu?
Good call, I hadn't checked the service menu. I lowered the contrast and increased the brightness there and I have a better range now, thanks. If I set the service menu to the "default" level for brightness from the Panasonic service manual for the BT-H1700 it's way too high. Couldn't find the Ikegami service manual though so maybe their values were a bit different or this unit just needs lower settings.

Now I just have to find a way to dial in the focus on 720p - I tried tweaking some of the focus settings in the service menu that are supposed to apply to 720p and I believe even the common inputs submenu but I didn't see any effect. Wonder if this is something that can't be done through service menu on the Ikegami model?

fernan1234 wrote:
NYI wrote:This one doesn't allow for that on RGB, unfortunately.
I forgot about this, we haven't been able to figure it out but it looks like underscan is disabled for RGB on some units (the manual also says it's disabled), but works perfectly on others. It works on a couple of 1710s I've had, but not on 1910s. The 1700 and 1900 is slightly older so that may have something to do with it too. We think there's a setting in the service menu that may affect this.

I guess an alternative would be to use YPbPr.
Yeah, as a workaround I changed the size in the service menu to be smaller for now.
Namingway_PL wrote:Hey, did You try to factory reset the unit? Seems that someone must've mess with the settings, and this can happen.

After a proper reset it should be fine. Try setting all the knobs to neutral position (in the middle) and reset all settings in the service menu.

Not sure if that will help, but it's worth a try.
I haven't tried that yet, but if I think I'll need to, I'll give it a shot, thanks.
LewieP
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Re: JVC TM-H and DT-V thread

Post by LewieP »

Looking into doing the power button replacement on a JVC TM-A170G. I've never done anything like that before, never opened a CRT. Does anyone have a link to a comprehensive guide that would help me through the process? Earlier discussion was useful, but I don't want to make any mistakes.

Or maybe it's better to just get it serviced by someone who knows what they're doing, and ask them to install the button...
mccall
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Re: JVC TM-H and DT-V thread

Post by mccall »

have a dt-v1710cg from japan that i imported recently for a decent price and expected it to be broken but turned it on and seems to work fine as far as i can tell. problem being that im missing the sync type setting option in the menu and can't seem to get a picture displaying with my ps2. i did try and reset the settings in one of the menus but i'm not sure it was the service menu or not. gone through the service manual and no settings in the service menu seem to effect what i'm experiencing. any thoughts? can take pics of each menu i think i'm missing aperture as well. believe it only has the hd sdi card installed, only has one at least so have just been trying to feed it composite from cables i know work with others.
1040STF
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Re: JVC TM-H and DT-V thread

Post by 1040STF »

Hi there!

I own a JVC DT-V1910cg and I'm very happy about it.. except I feel the picture could pop a little more in its brightness intensity, like CRTs are capable of.

I have turned the contrast front toggle to the max.
I have turned the contrast up to the max both in the main (+20) and service menu (+63) to get good colors.
If I turn the brightness up in the main menu, I feel like it turns the screen brightness a little (which is cool) but the picture brightness too which impact the black levels. So I've set it to +10 (it can go up to +20)
If I turn the brightness up in the service menu, I feel like it affects only the picture brightness, which I don't want. So I've kept it to 0.

The result is quiet nice but hurts a liiiitle the black levels. I feel it could be even better.

On my Sony PVM 2130QM, there's is a pot in the back that allows to enhance the screen brightness and the result is amazing. Is there an equivalent on that JVC DTV ?

Another question : what are the CPU Block settings in the Service Menu ? It's not featured in the Service Manual...
Namingway_PL
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Re: JVC TM-H and DT-V thread

Post by Namingway_PL »

@1040STF Yes, You will find the same pot on the DT-V as on the PVM. it's labeled "screen" and it's located on the flyback. But You don't need to take off the hood to access it.

On the back of the monitor, in the bottom right corner, You will find three holes lined up vertically. They are there to easily access the pots. The top one is for the pot You are looking for. The two other are for Focus.


As for the CPU block, just don't touch it. It's not featured for reason :)
1040STF
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Re: JVC TM-H and DT-V thread

Post by 1040STF »

Namingway_PL wrote:@1040STF Yes, You will find the same pot on the DT-V as on the PVM. it's labeled "screen" and it's located on the flyback. But You don't need to take off the hood to access it.

On the back of the monitor, in the bottom right corner, You will find three holes lined up vertically. They are there to easily access the pots. The top one is for the pot You are looking for. The two other are for Focus.


As for the CPU block, just don't touch it. It's not featured for reason :)
Thanks a lot for your (quick!) answer!
I've never noticed the three holes before, wow.
I've tried the top one... and it was the focus haha. The one about the screen intensity is the bottom one.

Though it didn't helped me much. Because if I turned it a little up, I was creating some colors bleeding in the picture. The more I turned, the more the colors bled, turning more and more into a light green color. Strange, no? Would you know what it means?
Namingway_PL
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Re: JVC TM-H and DT-V thread

Post by Namingway_PL »

@1040STF Did You try to reset everything? I don't remember the exact procedure and I don't want to mess something up like with those pots as I'm writing from memory,so You better check the manual before You do that. Not sure if You will have to reset each setting one by one or is there a general reset function like the "factory reset" in Sony monitors, but there is definitely a way to do that. Just be sure to set the knobs to neutral position before You reset anything.

Worth a try.
fernan1234
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Re: JVC TM-H and DT-V thread

Post by fernan1234 »

I'd suggest not messing with the SCREEN pot on the flyback, that's really only meant for factory calibration or very minor adjustments to adapt to tube aging, within a small margin.

@1040STF Does your DT-V still have the anti-glare filter on the tube? It does a fantastic job at keeping blacks black and almost eliminating all reflections in a bright room, and it's neutral density so color accuracy is preserved, but at a small tradeoff with slightly less "pop" than CRTs with absolutely no filters, like almost all BVMs and many PVMs for example. That may be the difference you're noticing, and IMO it's a very worthy tradeoff. Slightly increasing contrast and brightness may be fine, though as you can see it's not good to take it too far. The tube is already being overdriven in a way at stock values since it has to compensate for the anti-glare filter which is 1 stop (50% brightness cut). The overall difference should be slight, if not hard to notice, unless the tube has seen a lot of work. How many hours on your unit?
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