TV RGB mod thread
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cr4zymanz0r
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Re: TV RGB mod thread
For the people that have had successful mods without interference, how are you doing the internal wiring? Did you just use any regular wire and stuff the excess inside the TV, used shielded wire for the RGB signals, or what?
Re: TV RGB mod thread
Would anyone know if the Jungle IC equivalent M52300BSP from a Mitsubishi TV be a candidate for RGB modding?
Datasheet https://www.digchip.com/datasheets/down ... =M52300BSP
Datasheet https://www.digchip.com/datasheets/down ... =M52300BSP
Re: TV RGB mod thread
See those 3 pins labeled OSD In (R G B) ?
That should be what your looking for.
yeah looks like your tv IS RGB Able.
That should be what your looking for.
yeah looks like your tv IS RGB Able.
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KnuckleheadFlow
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Re: TV RGB mod thread
Probably is good for it, but the thing is, when I looked at the data sheet it didn't say what peak-to-peak voltage those pins take. It's possible it takes TTL RGB which wouldn't be good at all. Can't be sure without seeing the TV's service manual.
I used coax up to the switch with the termination resistors but I don't think that's necessary so long as you keep the wires only as long as needed.cr4zymanz0r wrote:For the people that have had successful mods without interference, how are you doing the internal wiring? Did you just use any regular wire and stuff the excess inside the TV, used shielded wire for the RGB signals, or what?
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cr4zymanz0r
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- Joined: Sat Oct 19, 2013 6:36 am
Re: TV RGB mod thread
Hmmm. I even went back and redid the wiring making it shorter and used shielded wires and it didn't change anything. Here's what it's doing:
1.) When set to the OSD stock circuit on the switch, everything looks normal. The black screen waiting for a signal is completely black.
2.) When set to the RGB modded circuit, black on a no signal screen is mostly good but looks slightly lighter
a.) There's also 2 forms of interference. One is dim scrolling horizontal lines. The other is kinda like random static noise on the screen, but very faint.
b.) When actually giving it a signal on RGB, if the screen is mostly black (maybe just a black screen with a bit of text) then the interference i still noticeable. If it's a overall black screen but has a lot more things/color going on (such as the Sega CD bios screen) then the black interference is usually greatly diminished or not even there as far as I can tell. It's distracting when playing a game and it goes to the "right" kind of black screen and there's the interefence nagging you.
Here's a video showing some of it https://www.youtube.com/watch?v=C2siT-vVIPk
It doesn't pick up nearly as good on camera, but you can see if you look closely. It starts with the switch set to RGB mode and there's the horizontal lines scrolling upward and the faint static. Then it gets switched to OSD and everything looks normal, then back to RGB again.
I'm not sure if other people just aren't having the issue or aren't noticing it since it's somewhat minor, or if I'm just anal and once I see it then it continues to bug me .
any ideas?
EDIT: forgot to mention, even feeding it 5V from a completely separate power supply doesn't change the interference as far as I can tell.
1.) When set to the OSD stock circuit on the switch, everything looks normal. The black screen waiting for a signal is completely black.
2.) When set to the RGB modded circuit, black on a no signal screen is mostly good but looks slightly lighter
a.) There's also 2 forms of interference. One is dim scrolling horizontal lines. The other is kinda like random static noise on the screen, but very faint.
b.) When actually giving it a signal on RGB, if the screen is mostly black (maybe just a black screen with a bit of text) then the interference i still noticeable. If it's a overall black screen but has a lot more things/color going on (such as the Sega CD bios screen) then the black interference is usually greatly diminished or not even there as far as I can tell. It's distracting when playing a game and it goes to the "right" kind of black screen and there's the interefence nagging you.
Here's a video showing some of it https://www.youtube.com/watch?v=C2siT-vVIPk
It doesn't pick up nearly as good on camera, but you can see if you look closely. It starts with the switch set to RGB mode and there's the horizontal lines scrolling upward and the faint static. Then it gets switched to OSD and everything looks normal, then back to RGB again.
I'm not sure if other people just aren't having the issue or aren't noticing it since it's somewhat minor, or if I'm just anal and once I see it then it continues to bug me .
any ideas?
EDIT: forgot to mention, even feeding it 5V from a completely separate power supply doesn't change the interference as far as I can tell.
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cr4zymanz0r
- Posts: 356
- Joined: Sat Oct 19, 2013 6:36 am
Re: TV RGB mod thread
Ok, I think I figured out the majority of the issue. I have a good eye for sharpness but not really for correct colors unless they're just obviously wrong. I'd been somewhat thinking the colors might look slightly washed out in RGB mode, but I thought maybe that was just my imagination since I'd never seen RGB on a consumer TV before.
I had the 'crazy' idea to turn the brightness down on the tv, and now colors look more vivid and I can't see the interference on black.
This made me further curious so I went back to the OSD setting and jacked the brightness up, then I was seeing similar (but a little bit cleaner) interference in blacks I was seeing in RGB mode before lowering the brightness.
While this is a nice work around, I'd like to balance it out so I don't have to change the brightness in the menu settings each time I want to switch between RGB and other sources.
What would be the best way to go about this? Currently I'm doing the 'typical' incoming RGB is terminated to ground with 75 ohm resistors, then each RGB signal has a 0.1uF cap inline before getting the Jungle IC. What's the best way to lower the brightness by roughly 15%-ish (just guessing from how much I needed turn down the brightness in the menu). Should I add a small resistor after each 0.1uF cap, use slightly smaller caps, or what?
EDIT: After lowering the brightness on the TV, other sources (component) still seem to look fine. Not dim or dark as far as I can tell. I guess this will work then. I'd be nice to know how to get it completely aligned with the brightness of other signals, but probably not worth the effort at this point as long as I don't notice any other issues
I had the 'crazy' idea to turn the brightness down on the tv, and now colors look more vivid and I can't see the interference on black.
This made me further curious so I went back to the OSD setting and jacked the brightness up, then I was seeing similar (but a little bit cleaner) interference in blacks I was seeing in RGB mode before lowering the brightness.
While this is a nice work around, I'd like to balance it out so I don't have to change the brightness in the menu settings each time I want to switch between RGB and other sources.
What would be the best way to go about this? Currently I'm doing the 'typical' incoming RGB is terminated to ground with 75 ohm resistors, then each RGB signal has a 0.1uF cap inline before getting the Jungle IC. What's the best way to lower the brightness by roughly 15%-ish (just guessing from how much I needed turn down the brightness in the menu). Should I add a small resistor after each 0.1uF cap, use slightly smaller caps, or what?
EDIT: After lowering the brightness on the TV, other sources (component) still seem to look fine. Not dim or dark as far as I can tell. I guess this will work then. I'd be nice to know how to get it completely aligned with the brightness of other signals, but probably not worth the effort at this point as long as I don't notice any other issues
Re: TV RGB mod thread
I finally got around to working on my RGB mod on my 32" sony. Been a crazy past couple weeks at home!
I got the BNC inputs wired to the switch, terminated with 75 ohm resistors, and soldered the 0.1uF caps to the common side of the switch. I figured I'd wait on soldering the wires to the rest of the switch until I know how long the wires need to be (also I have a hunch the wire I'm using is too large to solder to points on the TV's PCB....we will see LOL).
Now I have to wait for the next time my dad comes to visit to help me move the TV out of the arcade cabinet I built. It's very heavy and leaning back about 15 degrees so it's definitely a team lift. If it was a 25" I'd yank it out myself, but it isn't worth risking my back trying it on a 32". As soon as I can get it out of there I'll pop off the rear cover, yank out the PCB, and get cracking on it!
I've been thinking about my situation with my PS1/2 and Saturn using Luma sync....I should just get a sync stripper and install it on the luma pin of my SCART cables to give me csync like everything else. That will solve many headaches I think since I don't think this modded TV will let me use sync-over-luma like my 14" PVM does.
I got the BNC inputs wired to the switch, terminated with 75 ohm resistors, and soldered the 0.1uF caps to the common side of the switch. I figured I'd wait on soldering the wires to the rest of the switch until I know how long the wires need to be (also I have a hunch the wire I'm using is too large to solder to points on the TV's PCB....we will see LOL).
Now I have to wait for the next time my dad comes to visit to help me move the TV out of the arcade cabinet I built. It's very heavy and leaning back about 15 degrees so it's definitely a team lift. If it was a 25" I'd yank it out myself, but it isn't worth risking my back trying it on a 32". As soon as I can get it out of there I'll pop off the rear cover, yank out the PCB, and get cracking on it!
I've been thinking about my situation with my PS1/2 and Saturn using Luma sync....I should just get a sync stripper and install it on the luma pin of my SCART cables to give me csync like everything else. That will solve many headaches I think since I don't think this modded TV will let me use sync-over-luma like my 14" PVM does.
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KnuckleheadFlow
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Re: TV RGB mod thread
Hey looking good, should be a nice clean install.
Regarding sync, I was thinking once I decide which TV going to replace the Nanao in my NAC, I could just put a sync stripper right on the sync input, never have to worry about what I've got hooked up. In addition to a couple of lm1881s, I got a couple of these:
https://www.digikey.ca/short/39m332
They're not cheap, but seem much more capable.
Regarding sync, I was thinking once I decide which TV going to replace the Nanao in my NAC, I could just put a sync stripper right on the sync input, never have to worry about what I've got hooked up. In addition to a couple of lm1881s, I got a couple of these:
https://www.digikey.ca/short/39m332
They're not cheap, but seem much more capable.
Re: TV RGB mod thread
That's a great idea, I'm already making a cable that goes from BNC to s-video with just the luma and ground pins connected.....I might as well just throw a sync stripper in that and never have to worry about it.
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KnuckleheadFlow
- Posts: 111
- Joined: Tue Jul 26, 2016 1:40 pm
Re: TV RGB mod thread
I now have a 27" Panasonic Gaoo that I'll be modifying later so I've been reading up on this. I haven't found a service manual for my set specifically yet but I have good reason to believe that its OSD RGB will also need 0.5 Vp-p. I'll do more research when I get to it, but for now I think you should look into what's called a T-pad attenuator circuit.frsj8112 wrote:OK that makes sense. But what can I do to make the signal fit the jungle chip?
http://www.electronics-tutorials.ws/att ... uator.html
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FinalBaton
- Posts: 4461
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Re: TV RGB mod thread
How do I know if a TV can be RGB modded?
What should I be looking for in the schematic?
Model I wanna check for is a Sony KV-27TS30 :
http://diagramasde.com/diagramas/televi ... 20P-3A.pdf
What should I be looking for in the schematic?
Model I wanna check for is a Sony KV-27TS30 :
http://diagramasde.com/diagramas/televi ... 20P-3A.pdf
-FM Synth & Black Metal-
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KnuckleheadFlow
- Posts: 111
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Re: TV RGB mod thread
1) A standard def TV that has an on screen display for menus, volume, video input, etc. CRTs that have 480p, EDTV, HDTV are no good.
2) two chips, a microprocessor (AKA "micon", "controller", "tuning") and a jungle IC. These can go by different labels (with terms such as "chroma", "deflection", "IF") but every jungle IC I've seen was the last IC before the neckboard, usually feeding it RGB. That's not the RGB we're looking for though, you want...
3) lines that say OSD R, G and B, along with something like "YS", "BLK", "blank", "fast blank" etc, coming out of the micro and going into the jungle.
4) capacitors before the jungle IC inputs will indicate it's probably analogue RGB. There's also TTL, logic or digital RGB which we don't want. A data sheet for the jungle IC or a waveform of one of the pins will let you know which it has.
5) if the RGB input is listed as taking 0.7 Vp-p (peak to peak voltage. For example, white would be like 2.9 V, black would be 2.2V) you're golden. It'll take terminated RGB from your source straight (with an inline decoupling capacitor, often the ones that are already there work fine). 0.5 Vp-p seems pretty common too. I haven't worked with that yet, but I'm pretty sure it'll be simple to attenuate the source 0.7 to 0.5.
It seems to me most higher end TVs from the early 90s to the early 00s had the first 4 of this setup. Around the early 2000s I start seeing single chip micro/jungle IC which of course have no external RGB inputs.
Looking at your pdf's page 21, I see that your micro seems to output OSD RGB on pins 45 - 47 but it doesn't feed it to the jungle IC and does some weird stuff I haven't seen yet. I don't know if adding your external RGB will work. You can try of course but frankly, given how easy it is to find a TV that's proven to work, and for cheap, I don't know if it's worth trying.
2) two chips, a microprocessor (AKA "micon", "controller", "tuning") and a jungle IC. These can go by different labels (with terms such as "chroma", "deflection", "IF") but every jungle IC I've seen was the last IC before the neckboard, usually feeding it RGB. That's not the RGB we're looking for though, you want...
3) lines that say OSD R, G and B, along with something like "YS", "BLK", "blank", "fast blank" etc, coming out of the micro and going into the jungle.
4) capacitors before the jungle IC inputs will indicate it's probably analogue RGB. There's also TTL, logic or digital RGB which we don't want. A data sheet for the jungle IC or a waveform of one of the pins will let you know which it has.
5) if the RGB input is listed as taking 0.7 Vp-p (peak to peak voltage. For example, white would be like 2.9 V, black would be 2.2V) you're golden. It'll take terminated RGB from your source straight (with an inline decoupling capacitor, often the ones that are already there work fine). 0.5 Vp-p seems pretty common too. I haven't worked with that yet, but I'm pretty sure it'll be simple to attenuate the source 0.7 to 0.5.
It seems to me most higher end TVs from the early 90s to the early 00s had the first 4 of this setup. Around the early 2000s I start seeing single chip micro/jungle IC which of course have no external RGB inputs.
Looking at your pdf's page 21, I see that your micro seems to output OSD RGB on pins 45 - 47 but it doesn't feed it to the jungle IC and does some weird stuff I haven't seen yet. I don't know if adding your external RGB will work. You can try of course but frankly, given how easy it is to find a TV that's proven to work, and for cheap, I don't know if it's worth trying.
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FinalBaton
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Re: TV RGB mod thread
ok, thanks a lot for the answer KnuckleheadFlow! This is really appreciated!
Hmmm, I might pick it up anyway for an S-video rig since it's a very good tube (trinitron Microblack). But I won't attempt an RGB mod on it.
Hmmm, I might pick it up anyway for an S-video rig since it's a very good tube (trinitron Microblack). But I won't attempt an RGB mod on it.
-FM Synth & Black Metal-
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KnuckleheadFlow
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Re: TV RGB mod thread
I'd still suggest finding a TV, maybe a small one, and giving it a go. It feels good making it do something it wasn't intended for. Having given the little Toshiba to my brother, it was time to move on to bigger and better things; the JVC AV-32D501 and it turned out great. I'm not sure in what way, but to me it looks better than the Toshiba. Maybe it's just the size.
Anyway, at first I couldn't find a service manual for the D501 online anywhere, even in the 13GB torrent of JVC manuals. I did find one for the D502 and it showed it had the same jungle IC as the Toshiba. Great I thought, maybe it'll be practically the same as the D501. I finally opened it up this weekend and wouldn't you know it, it is practically the same except for the jungle IC! It's got some JVC branded one which I couldn't find a data sheet for, of course. It's probably another manufacturer's but who knows which one. The micro was the same, however. I traced the RGB lines to the jungle IC, before finding a service manual for another TV that uses the exact same chassis but lacks the PiP daughter board that my TV has.
Looking at the schematics, I confirmed that I did indeed have the right pins. What was interesting was that I noticed the RGB going into the jungle IC was labled "mix RGB". It was routed first around an unpopulated header for Guide Plus (a late 90s early 00s thing like the menus you get with a digital cable box) then into and out of the PiP board. Ahhh, so what they're doing is using the same RGB inputs for OSD, Guide Plus and PiP and just muxing one on top of the other.
Testing the RGB input was as easy as pulling the PiP board and plugging the Genesis RGB into the connector, along with 5v off a regulator into the blanking ("YS") line.
Results were a near perfect RGB picture! I took some photos, but I wasn't satisfied with how those turned out TBH. I can try again later if people are interested. There's a purity or convergence issue in the upper right corner that I'll have to address but with no OSD being muxed by the PiP board I couldn't do it with the RGB input... or could I?
Long story short, I should have an LT1675 RGB mux IC Wednesday evening (with 10 more for $25 on the slow boat from Ali Express). It's actually made for things like OSD and PiP. Not only will this let me keep the the OSD overlaid with the RGB input, looking way more like it came like that from the factory, it means the 4PDT switch is no longer needed, since I think I can have the mux IC switch to overlay the OSD with the OSD's blanking signal. The LT1675 from Ali Express costs actually less than half of what I paid for my 4PDT switch too! All that'll be needed is a on/off switch for the 5V blanking.
PS - With this bigger set, I now see that my HDG non-TMSS Genesis does indeed have the dreaded jailbars. I thought I'd gotten lucky. I couldn't see them with the Toshiba and they're not that bad really, but now I can't unsee them of course. I'll have to take care of them when I re-cap it.
Anyway, at first I couldn't find a service manual for the D501 online anywhere, even in the 13GB torrent of JVC manuals. I did find one for the D502 and it showed it had the same jungle IC as the Toshiba. Great I thought, maybe it'll be practically the same as the D501. I finally opened it up this weekend and wouldn't you know it, it is practically the same except for the jungle IC! It's got some JVC branded one which I couldn't find a data sheet for, of course. It's probably another manufacturer's but who knows which one. The micro was the same, however. I traced the RGB lines to the jungle IC, before finding a service manual for another TV that uses the exact same chassis but lacks the PiP daughter board that my TV has.
Looking at the schematics, I confirmed that I did indeed have the right pins. What was interesting was that I noticed the RGB going into the jungle IC was labled "mix RGB". It was routed first around an unpopulated header for Guide Plus (a late 90s early 00s thing like the menus you get with a digital cable box) then into and out of the PiP board. Ahhh, so what they're doing is using the same RGB inputs for OSD, Guide Plus and PiP and just muxing one on top of the other.
Testing the RGB input was as easy as pulling the PiP board and plugging the Genesis RGB into the connector, along with 5v off a regulator into the blanking ("YS") line.
Results were a near perfect RGB picture! I took some photos, but I wasn't satisfied with how those turned out TBH. I can try again later if people are interested. There's a purity or convergence issue in the upper right corner that I'll have to address but with no OSD being muxed by the PiP board I couldn't do it with the RGB input... or could I?
Long story short, I should have an LT1675 RGB mux IC Wednesday evening (with 10 more for $25 on the slow boat from Ali Express). It's actually made for things like OSD and PiP. Not only will this let me keep the the OSD overlaid with the RGB input, looking way more like it came like that from the factory, it means the 4PDT switch is no longer needed, since I think I can have the mux IC switch to overlay the OSD with the OSD's blanking signal. The LT1675 from Ali Express costs actually less than half of what I paid for my 4PDT switch too! All that'll be needed is a on/off switch for the 5V blanking.
PS - With this bigger set, I now see that my HDG non-TMSS Genesis does indeed have the dreaded jailbars. I thought I'd gotten lucky. I couldn't see them with the Toshiba and they're not that bad really, but now I can't unsee them of course. I'll have to take care of them when I re-cap it.
Last edited by KnuckleheadFlow on Tue Oct 11, 2016 5:32 pm, edited 1 time in total.
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FinalBaton
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Re: TV RGB mod thread
I was actually also considering a JVC D-series set!
There are a couple near me (AV-27D200, AV-27D201, AV-27D500, AV-27D501) which are rated at 700 TVL, which is damn sharp for 27 inch consumer tv
There are a couple near me (AV-27D200, AV-27D201, AV-27D500, AV-27D501) which are rated at 700 TVL, which is damn sharp for 27 inch consumer tv
-FM Synth & Black Metal-
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KnuckleheadFlow
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- Joined: Tue Jul 26, 2016 1:40 pm
Re: TV RGB mod thread
Do it. I'll check if I have the manual when I get home. Hopefully it'll be as easy as that D501.
E: The difference between the D200s and the D500s is just the PiP I think.
E: The difference between the D200s and the D500s is just the PiP I think.
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FinalBaton
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Re: TV RGB mod thread
have you compared how the RGB modded set's picture looks compared to using a top quality RGB-to-component transcoder on the stock component input?
-FM Synth & Black Metal-
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KnuckleheadFlow
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Re: TV RGB mod thread
I have not. Theoretically, I know any difference should be imperceptible with a good transcoder. But part of the reason I did this was to learn more about electronics as a hobby, part of it was the DIY aspect of it (“The Man didn’t give us consumer RGB options so we’ll make our own”) and part of it was (and this is going to sound really stupid) more philosophical; the consoles generated RGB and RGB is the raw, simple, pure way of generating analogue video.
So for all this, I don’t really care for the obviously easier and more practical solutions to get great 240p.
So for all this, I don’t really care for the obviously easier and more practical solutions to get great 240p.
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FinalBaton
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Re: TV RGB mod thread
One of these days, I'm going to have to try this with the 27" JVC D-Series sitting in the basement. The mod doesn't look to difficult to perform compared to some other sets.
Re: TV RGB mod thread
I have an av36s33. it has the inputs for pip but doesnt have the pip board. I had kinda picked up that you might be able to feed RGB in where the pip goes but i didnt think the jungle ic supported rgb because the main inputs are component and s-video. I guess i might have been wrong.
Ill take a look at that jungle ic again and look for mix inputs.
Ill take a look at that jungle ic again and look for mix inputs.
Re: TV RGB mod thread
The unit I have in the basement is an AV-27D503. Looking at the service manual, they completely redesigned the circuit. . Looks like the only inputs on the jungle I/C are component. RGB from the PIP board is converted by a Toshiba TA1287F before entering the chip.
Re: TV RGB mod thread
yeah thats kinda what i got the first time i looked at it. Its component only.
Not that it needs anything done to it. It has great video quality as is. my snes and nes look awesome on this set.
Not that it needs anything done to it. It has great video quality as is. my snes and nes look awesome on this set.
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KnuckleheadFlow
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Re: TV RGB mod thread
mvsfan wrote:av36s33
From a cursory glance at the schematics, unfortunately it would appear that neither of those sets can be easily modified using this method.NJRoadfan wrote:AV-27D503
However, that D503 looks interesting since its PiP IC has RGB inputs and seems to have decoupling caps on them (C4316, C4317 and C4318) but the lines are going to ground. I'd be very interested in seeing if the pins are still active. If you were to remove R4315, disconnect the grounding on that PiP board connector's pins 2, 3, 4 and 5 and fed your RGB and 5V blanking in there, I wouldn't be surprised if it worked. Sure, the Toshiba TA1287F would convert it to YUV before going to the jungle, but that'd probably not mess things up too much, I'm guessing.
I'd try it if I could; if it doesn't work, just connect those lines back to ground and your TV is the same as before.
Re: TV RGB mod thread
Hey knuckle, have you worked anything on this yet?KnuckleheadFlow wrote:I now have a 27" Panasonic Gaoo that I'll be modifying later so I've been reading up on this. I haven't found a service manual for my set specifically yet but I have good reason to believe that its OSD RGB will also need 0.5 Vp-p. I'll do more research when I get to it, but for now I think you should look into what's called a T-pad attenuator circuit.frsj8112 wrote:OK that makes sense. But what can I do to make the signal fit the jungle chip?
http://www.electronics-tutorials.ws/att ... uator.html
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KnuckleheadFlow
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Re: TV RGB mod thread
I have not. But I did work out the values for a T pad attenuation circuit that should get the levels from 0.7 Vpp to 0.5 Vpp. I first did it myself after reading that link I posted earlier, then confirmed it on a couple of website calculators. The math is right, but whether or not this is the right circuit to use remains to be seen. I'm pretty sure a pi pad attenuator would also work and a simpler L pad might be sufficient. When I get to it, I'll do some testing with my oscilloscope to make sure.
Note that this is all rather new to me and it could be very wrong, but I'm trying to figure it out.
First we need to find the attenuation we need in dB. The formula for a gain or loss in Volts peak-to-peak is dB = 20*log10(Vout/Vin). Vin is 0.7, Vout is 0.5 and this worked out to -2.9225. That negative means a loss (attenuation) of 2.923 dB. Using the formula in that link (the value for the dB is given as positive since attenuation is presumed), I worked out the following values for the T pad circuit. Confirmed it here too. You would connect this on each RGB input, before the usual 75 Ω termination to ground, I think. I'm also not sure where the decoupling caps should go because I can see them needing to be before R1, but I can see it also not mattering. Again, I'll have to do testing. Or you can, of course!
With SMD resistors, I found it more economical to buy smaller values to use in series. For R1 and R2, a 2.5 Ω in series with a 10 Ω, and for R3, 169 Ω in series with 50 Ω, worked out to be significantly less than actual 12.5 Ω and 219 Ω resistors.
Along the same lines, here's how a pi attenuator would look.
Note that this is all rather new to me and it could be very wrong, but I'm trying to figure it out.
First we need to find the attenuation we need in dB. The formula for a gain or loss in Volts peak-to-peak is dB = 20*log10(Vout/Vin). Vin is 0.7, Vout is 0.5 and this worked out to -2.9225. That negative means a loss (attenuation) of 2.923 dB. Using the formula in that link (the value for the dB is given as positive since attenuation is presumed), I worked out the following values for the T pad circuit. Confirmed it here too. You would connect this on each RGB input, before the usual 75 Ω termination to ground, I think. I'm also not sure where the decoupling caps should go because I can see them needing to be before R1, but I can see it also not mattering. Again, I'll have to do testing. Or you can, of course!
Code: Select all
RGB source ---[R1 12.5 Ω]-- --[R2 12.5 Ω]-- --- RGB in
| |
| |
[R3 219 Ω] [R4 75 Ω]???
| |
-----[GND]-----
Along the same lines, here's how a pi attenuator would look.
Code: Select all
RGB source -- --[R1 26 Ω]---- --------- --- RGB in
| | |
| | |
[R2 450 Ω] [R3 450 Ω] [R4 75 Ω]???
| | |
-----[GND]----- ---------
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suprcrackers
- Posts: 55
- Joined: Fri Apr 15, 2016 9:31 pm
Re: TV RGB mod thread
Hey I would like to thank Voultar for setting the host of the Retrorgb podcast straight when it comes to RGB modified CRT's vs BVM/PVM's. I completely share his opinion that yes a BVM is of better quality. But why would I want to pay upwards of $300 to play on a 20" BVM when I can for $5 play on a 27"-36" modified CRT with close to the same results? I have been listening to the host rag on modified RGB CRT's for too long.
Good work my friend!
Good work my friend!
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mikejmoffitt
- Posts: 629
- Joined: Fri Jan 08, 2016 7:26 am
- Location: Tokyo, Japan
Re: TV RGB mod thread
The D-series was the first one I ever did, and those work very well:NJRoadfan wrote:One of these days, I'm going to have to try this with the 27" JVC D-Series sitting in the basement. The mod doesn't look to difficult to perform compared to some other sets.
http://mikejmoffitt.com/articles/0032-tvrgb.html
Last edited by mikejmoffitt on Mon Feb 13, 2017 8:20 pm, edited 1 time in total.
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KnuckleheadFlow
- Posts: 111
- Joined: Tue Jul 26, 2016 1:40 pm
Re: TV RGB mod thread
The retrorgb guy rags on modified TVs with regularity? With BS reasons? I'd like to hear this actually, when was this one?suprcrackers wrote:Hey I would like to thank Voultar for setting the host of the Retrorgb podcast straight when it comes to RGB modified CRT's vs BVM/PVM's. I completely share his opinion that yes a BVM is of better quality. But why would I want to pay upwards of $300 to play on a 20" BVM when I can for $5 play on a 27"-36" modified CRT with close to the same results? I have been listening to the host rag on modified RGB CRT's for too long.
Good work my friend!
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suprcrackers
- Posts: 55
- Joined: Fri Apr 15, 2016 9:31 pm
Re: TV RGB mod thread
Maybe rag is too strong of a term. He has mentioned on 2-3 podcasts that I can remember on how the sony PVM/BVM is superior to a RGB modified CRT.
The thing is I don't have a BVM or a PVM to compare it because
a)I live in a rural area. So when the whole craze started I had no access to them.
b) Now that the craze has been going for a many years now, I can not buy them economically. I am not going to drop close to $300 on a 20" BVM so I can feel smug in knowing I have the absolute crispest picture for my games. I would much rather pick up a nice 27-36 inch Trinitron for free, spend a couple dollars in caps, wiring, a switch, a socket, and enjoy gaming on a very close proximity when it comes to clarity. But the also have the added bonus of playing on a much much larger screen.
It just annoys me, that's all.
The thing is I don't have a BVM or a PVM to compare it because
a)I live in a rural area. So when the whole craze started I had no access to them.
b) Now that the craze has been going for a many years now, I can not buy them economically. I am not going to drop close to $300 on a 20" BVM so I can feel smug in knowing I have the absolute crispest picture for my games. I would much rather pick up a nice 27-36 inch Trinitron for free, spend a couple dollars in caps, wiring, a switch, a socket, and enjoy gaming on a very close proximity when it comes to clarity. But the also have the added bonus of playing on a much much larger screen.
It just annoys me, that's all.