TV RGB mod thread

[jd213]

Yeah, pretty sure those are the same as the RGBS RCA cables sold on Aliexpress, I don't think any of them have components in them, so their Genesis 2 cable will similarly have blown out brightness.

You might as well return it and get a better cable if you have to go to the trouble of modding it, or return it and get it for $8 or whatever they sell for on Aliexpress.

[Bard_the_Bowman]

Yeah, pretty sure those are the same as the RGBS RCA cables sold on Aliexpress, I don't think any of them have components in them, so their Genesis 2 cable will similarly have blown out brightness.

You might as well return it and get a better cable if you have to go to the trouble of modding it, or return it and get it for $8 or whatever they sell for on Aliexpress.

I'm wayyyyyyyy outside the return window I bought this months ago and my dual RGB/Component mod got delayed due to me inadvertently dropping one of the component inputs on the motherboard, causing a short, causing power to surge up to the jungle chip, resulting in repairs that took me a while to work through lol, had to replace jungle chip and everything.

So I'm going to give modding it a quick go and see what happens, especially since I already have some 220uf caps laying around, if that doesn't work I'll order a different one.

[Bard_the_Bowman]

Yeah, pretty sure those are the same as the RGBS RCA cables sold on Aliexpress, I don't think any of them have components in them, so their Genesis 2 cable will similarly have blown out brightness.

You might as well return it and get a better cable if you have to go to the trouble of modding it, or return it and get it for $8 or whatever they sell for on Aliexpress.

https://imgur.com/gallery/YanXvWh The 220uf caps I had were way oversized but I went ahead and did it anyway and replaced half the cable end casing with hot glue. Cable is cursed af but works.

[gunderwhelmed]

First post! I just completed my first mux mod on my trusty JVC D-Series AV-27D200 from 1999. I ordered Sunthar's mux board kit, which included a curated kit of components for my tv. For reasons unknown to me there were 5 diodes included (one extra based on the instructions given in Sunthar's guide.) I followed along with Sunthar's instructions for the AV-27D201, which it says are the same for my model. I did find differences on the selecter board when wiring up audio and sync, but I doubt this is my issue.

Here's where I'm at: A console connected through component displays perfectly (yay) but now the OSD displays in black. My N64 (rgb modded with Voultar kit and not requiring csync restoration) is connected with a csync SCART cable from retrogamingcables.co.uk and I have no picture, but audio is working. Blanking seems to work since the picture displayed over component is overtaken by the black screen when the SCART console is powered up second.

The RGB image does NOT project through the now black OSD text. Where should I start with troubleshooting?


Update: I was injecting RGB on the wrong side of the inline diodes. Corrected this and now EVERYTHING works!

[JMAN005]

I could use some help modding a Samsung TXK2766 (same as the Akai CFT2490 and Samsung CFT24907X). There's not alot of information about the TXK line or boards that they are used in.

I'm not a electronics expert and I only have a faint understand of all this. I prefer to do the method with Y/PB/PR and a OSD switch since it looks the simplest for me.

Service manual:
https://www.manualslib.com/products/Sam ... 90598.html

Jungle - VDP3112B: https://www.alldatasheet.com/datasheetp ... 3112B.html

MICOM - SDA555XFL: https://datasheet4u.com/datasheetpdf/Mi ... ?id=955214

Where exactly do I tap into the RGB? R223-5 or R264,5 and 7? are these it or I'm I incorrect? Also where exactly do I get the blanking from because that's a bit confusing to me and I know I can't solder a wire directly to the chip.

[Kvazikvark]

Hello everyone! I'm just new on this forum!
Read this topic to make RGB mod for my Panasonic CRT. I have the same TV like amxcs, but slighly small diagonale, and made everything his done for TV. But resulting picture is dark... I have only 3 PP-capacitors (100nf) for R, G and B lines, like he suggested in his post, and no third party resistors. In a more early post he removed all installed capacitors and resistors and picture become ideal. Maybe I should remove PP-capacitors too or trouble may be in elsewere direction?

I made connections for R, G, B and YS lines in this points (see picture).

Spoiler

I would appreciate for any suggestions.

[B3AR_creative]

Why Hello there.
I was wondering if you fine folk might be able to help me along my journey to mod a set that I'm hoping didn't cost me £60 to be a lost cause. It's pretty old, its an ITT Trimline CT2512 and only has an RF input. I've done my due diligence and managed to get hold of the schematics and I believe it does have a PAL Decoder Chip TDA3561. I'd really appreciate a bit of guidance as to next steps, if all just to give me a bit more confidence attempting it. I have gone through some sunthar, 8bit guy and MacroRetros tutorials but I'm getting lost in specifics for this set.

Yes, it looks promising. From the datasheet:

"13, 15, 17. Inputs for external RGB signalsThe external signals must be a.c.-coupled to the inputs viaa coupling capacitor of about 100 nF. Source impedanceshould not exceed 150Ω. The input signal required fora 5 V peak-to-peak output signal is 1 V peak-to-peak.At the RGB outputs the black level of the inserted signal isidentical to that of normal RGB signals. When these inputsare not used the coupling capacitors have to be connectedto the negative supply."

So one would assume that it would just take inserting the RGB signal into those pins with an series 100nf ceramic capacitor, and probable a 75ohm resistor to ground for termination.

The IC is from 1982, so I would doubt there is any concern about an EEPROM to set the input. My first attempt would probably just to do what the datasheet for the jungle IC says and see what happens. You will need to feed it composite sync or composite video as sync through the luminance input signal most likely, so in order to do that you need to look at the schematic and figure out where exactly the output of the IF section of the RF input is.
You need to do it this way because there are various sections of the circuit like the contrast and possibly automatic brightness or whatever that also need the sync signal to work, so you can't just bypass all that junk and stick luma into the jungle IC. There will be a point somewhere in the circuit that the whole RF circuit outputs luma and that will get split off to everything else. You need to cut the circuit off at that point and wire you composite video directly into the circuit, effectively removing the RF from the story

If you wanted to keep the RF, you'd have to mux it with a small circuit or put it on a switch.

It looks like the Luma comes in from the RF/IF section on that thick black line that says "Composite Colour Signal" and is then broken off for sync purposes, etc.

There appears to be a pin to select the external RGB input pins. Pin 9.

"9. Video-data switchingThe insertion circuit is activated by means of this input byan input pulse between 1 V and 2 V. In that condition, theinternal RGB signals are switched off and the insertedsignals are supplied to the output amplifiers. If only normaloperation is wanted this pin should be connected to thenegative supply. The switching times are very short(< 20 ns) to avoid coloured edges of the inserted signalson the screen"

I don't have any updates just yet as not had the opportunity to attempt this, but just wanted to say thank you for your reply. Super helpful!

[Kvazikvark]

Okay, I removed capacitors from RGB lines and picture become ideal... But only for a limited time, the more picture in a static position than darker it become. It gets as dark as it was with the capacitors installed.
Any suggestions?

[Kvazikvark]

Found another attempt to mod MX-3 chassis with no success... What a mystery TV, why someone can modify it and another one cannot?
Maybe this set need to be setting up RGB cutoff/gain in service menu?

[vol.2]

Okay, I removed capacitors from RGB lines and picture become ideal... But only for a limited time, the more picture in a static position than darker it become. It gets as dark as it was with the capacitors installed.
Any suggestions?

Ok. I don't know how to fix it, but I have a guess as to explain the weird behavior.

I think perhaps that the pedestal level (black level) for the RGB signals and/or the luma is too high, and the set may have an AKB circuit that is trying to correct it. If that was the case, then removing the capacitors wouldn't necessarily solve the problem, it would just push the overall brightness up, making the brightest video information closer to the correct level in comparison to the darkest. Following that, if the set has an AKB (Auto Kine Brightness) circuit, then the reason it gets darker is because the set is trying to autocorrect for the high pedestal (which isn't lowered by removing the capacitors).

This is just a guess mind you, but I think it could explain what you are seeing maybe. Although it wouldn't explain why two identical mods didn't both work. If that's true, then maybe there's a messed up connection somewhere, or the sets are not as identical as you think. Sometimes manufacturers can make small changes to the circuits in the middle of the PCB run, or for different territories (actually quite common), so some of these sets might have AKB (or some other form of automatic gain control) and some don't.

[Kvazikvark]

Okay, I removed capacitors from RGB lines and picture become ideal... But only for a limited time, the more picture in a static position than darker it become. It gets as dark as it was with the capacitors installed.
Any suggestions?

Ok. I don't know how to fix it, but I have a guess as to explain the weird behavior.

I think perhaps that the pedestal level (black level) for the RGB signals and/or the luma is too high, and the set may have an AKB circuit that is trying to correct it. If that was the case, then removing the capacitors wouldn't necessarily solve the problem, it would just push the overall brightness up, making the brightest video information closer to the correct level in comparison to the darkest. Following that, if the set has an AKB (Auto Kine Brightness) circuit, then the reason it gets darker is because the set is trying to autocorrect for the high pedestal (which isn't lowered by removing the capacitors).

This is just a guess mind you, but I think it could explain what you are seeing maybe. Although it wouldn't explain why two identical mods didn't both work. If that's true, then maybe there's a messed up connection somewhere, or the sets are not as identical as you think. Sometimes manufacturers can make small changes to the circuits in the middle of the PCB run, or for different territories (actually quite common), so some of these sets might have AKB (or some other form of automatic gain control) and some don't.

Just in case, I want to test this TV with another SCART cable (without 220uF capacitors for PS2).
When I tested this TV with PS1 and PS2 - restarting the TV, unplugging and plugging it from power, and unplugging and plugging the SCART cable did not make the picture bright again like when I just started the console and I can't explain this behavior.

[vol.2]

Just in case, I want to test this TV with another SCART cable (without 220uF capacitors for PS2).
When I tested this TV with PS1 and PS2 - restarting the TV, unplugging and plugging it from power, and unplugging and plugging the SCART cable did not make the picture bright again like when I just started the console and I can't explain this behavior.

I think that might point to a bad (or intermittently bad) component or a poor connection somewhere. But it's honestly hard to say. I gave you a guess that could explain what's happening, but only if everything else is equal and the set it in perfect condition electrically.

[Kvazikvark]

Just in case, I want to test this TV with another SCART cable (without 220uF capacitors for PS2).
When I tested this TV with PS1 and PS2 - restarting the TV, unplugging and plugging it from power, and unplugging and plugging the SCART cable did not make the picture bright again like when I just started the console and I can't explain this behavior.

I think that might point to a bad (or intermittently bad) component or a poor connection somewhere. But it's honestly hard to say. I gave you a guess that could explain what's happening, but only if everything else is equal and the set it in perfect condition electrically.

Okay, I tried another one SCART-cable without 220uF capacitors.
PS1 - just white screen.
PS2 - the same behaviour like with previous SCART, picture gradually get more and more darker to some point.

Well, I will give back 0.1 PP-capacitors to RGB lines and want to play with termination resistors (I din't setup them, because amsxs said they make picture very dark), start with default 75 ohm and then 100 or 120 ohm.

I'll report back about results.

ps
Found this article about dark RGB and methods to make it great again.

[Kvazikvark]

Well, I have some progress.
Tried 75 ohm termination resistors - dark picture.
Than tried 180 ohm resistors - well, dark picture aswell, but I notice some slightly changes in bright (maybe).
Than I put 1 kOhm resistors - picture become noticebly brighter!

I need some adjustable resistors to adjust bright.
This is legit way?

[vol.2]

I need some adjustable resistors to adjust bright.
This is legit way?

I can't say yes or no because I don't understand why you're seeing differing levels of brightness. If it has something to do with an automatic level control system, then it could possibly readjust itself to the same level as you had it before. Increasing the resistance of the termination will impede the signal to ground and increase the voltage level at the input. Also, I would expect this to have a bad effect on the video signal integrity because the video is supposed to be 75ohm to match the cable impedance. The point of it is to effectively control the signal reflections in the cable itself and prevent ghosting and smearing. Altering the termination resistor value could have unexpected consequences.

If it was me, I'd read the datasheet of the IC and figure out what the exact voltage levels it's expecting on those RGB and Luma or sync pins are, and then I would look at the schematic for the TV itself and see what DCV values there are on those inputs and try to make my input look like their input.

[Kvazikvark]

I can't say yes or no because I don't understand why you're seeing differing levels of brightness. If it has something to do with an automatic level control system, then it could possibly readjust itself to the same level as you had it before. Increasing the resistance of the termination will impede the signal to ground and increase the voltage level at the input. Also, I would expect this to have a bad effect on the video signal integrity because the video is supposed to be 75ohm to match the cable impedance. The point of it is to effectively control the signal reflections in the cable itself and prevent ghosting and smearing. Altering the termination resistor value could have unexpected consequences.

If it was me, I'd read the datasheet of the IC and figure out what the exact voltage levels it's expecting on those RGB and Luma or sync pins are, and then I would look at the schematic for the TV itself and see what DCV values there are on those inputs and try to make my input look like their input.

Okay, here is the datasheet.
I can not correctly find needed parameter about external RGB voltage lines for IC. This is it? (see screenshot)

Spoiler

I can measure current voltage on RGB lines for knowledge.
But from tomorrow start my working week for 3 days, until that (25 feb) we can only speculate about. I have ordered 3 potentiometer (10 kOhm), they arrived around that date aswell.

RGB lines on board must be fully isolated from any other paths? I did just like amxcs - cut js602-605 lines (see photo few posts above), but I found another electric paths through some voltage drop to OSD IC.

[vol.2]

This is it? (see screenshot)

That's 2-3Vpk. Way too high for a regular video signal. No wonder it's not working. You would have to build a level shifter circuit for your video input that was 75ohm terminated and then bumped everything up. But you would also need some fine control over the pedestal and the contrast.

Non-trivial. Out of scope for this thread unless you want to build it come back here and show everyone.

[Kvazikvark]

This is it? (see screenshot)

That's 2-3Vpk. Way too high for a regular video signal. No wonder it's not working. You would have to build a level shifter circuit for your video input that was 75ohm terminated and then bumped everything up. But you would also need some fine control over the pedestal and the contrast.

Non-trivial. Out of scope for this thread unless you want to build it come back here and show everyone.

I've been thinking about your words during a day.
Well, I definitely have enthusiasm to dig in, but may have lack of knowledge.

Some googling and reading give me an idea about simple level shifter. Maybe I can use op-amp LM321 for this purpose? Just some reference voltage with potentiometer and we have nice fine tune for voltage range. But what about pedestal and contrast? With solution above we only raising signal voltage with saving waveform.

Nevertheless I still want to give a try adjusting termination resitance. This method can distort image, but may have any other consequences like burning anything (eg PS1)?

[vol.2]

Some googling and reading give me an idea about simple level shifter. Maybe I can use op-amp LM321 for this purpose? Just some reference voltage with potentiometer and we have nice fine tune for voltage range. But what about pedestal and contrast? With solution above we only raising signal voltage with saving waveform.

I read the relevant part of your datasheet and the RGB input is intended for an OSD signal generated from an OSD IC, which is why it wants such a high voltage level. It's a TTL level video signal.

Looking at the datasheet, it gives a couple of useful bits of info. First, the screenshot you took is just the "dynamic range" of the signal. That means the difference in voltage between the darkest dark and the brightest bright. It needs a minimum of 2V pkpk for the signal.

The pedestal voltage for the RGB inputs is a nominal 2.3V, but this is the output pedestal, not the input pedestal, which I would estimate at around 0V for the RGB inputs.

NTSC video is about 0.7Vpkpk and the pedestal is at 0.054V.

You would have to build a circuit that could not only translate the brightness values of a typical NTSC video signal to what the IC is expecting on those inputs, but also make sure that those values map with the same weight at any given level. It would also most likely be necessary to give yourself some room for fine adjustments, especially at the ends.

I would give up. There's nothing you can do. Go back in this thread and you can see that people aren't really trying to work on TTL ICs.

Regardless, it's out of scope for this thread unless you want to go solve the problem by designing and building the circuit and coming back here and presenting it as a new option. It would be a very advanced project.

[reminiz]

Hi all, first time posting long time… reader?

I just wanted to check if the following set can be RGB modded. I think it can but I’m no expert just using info gathered over the last 6 months..

Unit: Sharp CX36NF3 14” CRT

here’s the service manual: IC801 jungle chip??

https://jmp.sh/s/wCcaVy1MbhZu3MYlciEb

My guess is the R2/G2/B2/BLK2 IN are the ones to use? They look spare?

[Lowlife]

I'm looking for help with either an rgb or svideo mod for this philips pr0930x. I've done a few rgb mods on trinitrons following guides but I could use some help with this one.

Thanks

Service manual page 63 I think
https://archive.org/details/philips-19- ... 1340-b-101

[k6lcm]

I'm planning on modding a Sharp 13G-M60. It has a IX2573CE for the jungle chip.

Pin 14 Blanking
Pin 15 R
Pin 16 G
Pin 17 B

My problem is that this tv only has an RF input, so I have to do something for sync. Pin 39 is marked as Ext Video In, so I think it's safe to assume composite/sync can go there. But how do I tell the tv to switch to it? Block diagrams for similar Sharp jungle chips show a switch between Pin 37 and Pin 39 but not what controls the switch.

Spoiler

I too would like to mod my RF-only Sharp 13G-M60. I really don't need RGB as much as just composite input. Wondering if anyone has been successful with this model. Is it a hot chassis? Does anyone have a schematic/service manual for this model or experience to know which pins where I tap into?

[Kvazikvark]

Regardless, it's out of scope for this thread unless you want to go solve the problem by designing and building the circuit and coming back here and presenting it as a new option. It would be a very advanced project.

Just want to remind about myself, I don't gave up about project. At current time I am study subjects to construct op-amp circuit for analog RGB. Read up many articles and found many useful and interesting information. For example, some people already solved the problem about connection regular RGB-signal to TTL-RGB displays, they just used circuit to level-shift RGB-signal to TTL level and everything works without any additional tunes, except shift voltage. Well, let's deal with problems one by one.
ps
I've decided to change op-amp IC from LM321 to TPH2501, because LM321 too weak for processing video.

[vol.2]

they just used circuit to level-shift RGB-signal to TTL level and everything works without any additional tunes, except shift voltage.

Just doing a linear voltage shift isn't enough, in order to get correct white balance, you must map the voltage shift from one domain to the other.

For example, if you test on the extremes (typically 20 IRE and 100 IRE), and you are able to dial in the brightness and contrast values (white and black levels) at each extreme, then you are likely to have a problem at 50 IRE.

Any level shifting must be able to take that into account.

After you do your shift, get a colorimeter and use HCFR to measure the tracking and see how close it stays to the center.

[Kvazikvark]

they just used circuit to level-shift RGB-signal to TTL level and everything works without any additional tunes, except shift voltage.

Just doing a linear voltage shift isn't enough, in order to get correct white balance, you must map the voltage shift from one domain to the other.

Maybe we can make some signal amplification, but I'll think about it after shifting level.
Meanwhile, can you recommend any way to test CRT(IRE test and etc), I have not any Nintendo or Sega consoles, just PS1 and PS2 working at current time, PS3 on repair.

[vol.2]

Maybe we can make some signal amplification, but I'll think about it after shifting level.

The problem is the (non)linearity of the shift, it's not a matter of amplification.

Consider this. The original signal range is between 0.054V and 0.71V. The OSD is looking for a signal between 0V and 3V.

But it's not as simple as stretching the original signal out into the new range because the gamma ramp is non-linear. You will have to map the weighted luma information to the new values.

Meanwhile, can you recommend any way to test CRT(IRE test and etc), I have not any Nintendo or Sega consoles, just PS1 and PS2 working at current time, PS3 on repair.

Absolutely. You can run HCFR in Windows and select "DVD" as the source. This will allow you to measure an external video source with a connected colorimeter. I would recommend an XRite i1 Display Pro for this purpose. Anything older will be too old and the sensor will have drifted and is not reliable, and anything newer isn't really designed to work with CRTs.

[Kvazikvark]

The problem is the (non)linearity of the shift, it's not a matter of amplification.
Consider this. The original signal range is between 0.054V and 0.71V. The OSD is looking for a signal between 0V and 3V.
But it's not as simple as stretching the original signal out into the new range because the gamma ramp is non-linear. You will have to map the weighted luma information to the new values.

I'll think about it.

Absolutely. You can run HCFR in Windows and select "DVD" as the source. This will allow you to measure an external video source with a connected colorimeter. I would recommend an XRite i1 Display Pro for this purpose. Anything older will be too old and the sensor will have drifted and is not reliable, and anything newer isn't really designed to work with CRTs.

Looks expensive, see what we can do.
I want to buy an oscilloscope, the prices are comparable =)

[vol.2]

Looks expensive, see what we can do.

Ok. Well this is already far too off topic for this thread, so if you want to keep posting about this, start a different one.

[Anonygoose]

Hey guys

Is this a simple direct injection mod? Isolate the pins and directly inject RGB? Also which pin is blanking here?

Panasonic TC-29gf30r

https://imgur.com/gallery/Gg5pytf

[vol.2]

Hey guys

Is this a simple direct injection mod? Isolate the pins and directly inject RGB? Also which pin is blanking here?

Panasonic TC-29gf30r

https://imgur.com/gallery/Gg5pytf

The Toshiba TA8880xx series jungle ICs are controlled by an I^2C bus from an EEPROM. Further, the video signal input levels are all over the place (0.4V pkpk for RGB) so I think it's a no-go.

Not going to say it's impossible, but it's extremely complicated and out of scope for this thread. If you decide to pursue it on your own, make a new thread for your project.