TV RGB mod thread

[KPackratt2k]

Not worth it. For component capable consoles, it doesn't offer a tangible improvement. For RGB only consoles, I would just use a retrotink RGB2COMP. The cost of one is low enough that you're time is more valuable.

That depends on how well the TV processes Component YPbPr video compared to RGB, as there are some TVs that still benefit from a RGB mod, even if they already have Component inputs due to how the jungle chip processes that signal (two notable examples are the Sony BA-5 chassis and some Sanyo TVs).

In the case of the Toshiba TVs manufactured by Orion, adjusting the CB DL and CR DL settings in the service menu should improve the Component video input as the default settings for those values are sometimes misaligned.

[vol.2]

That depends on how well the TV processes Component YPbPr video compared to RGB, as there are some TVs that still benefit from a RGB mod, even if they already have Component inputs due to how the jungle chip processes that signal (two notable examples are the Sony BA-5 chassis and some Sanyo TVs).

In the case of the Toshiba TVs manufactured by Orion, adjusting the CB DL and CR DL settings in the service menu should improve the Component video input as the default settings for those values are sometimes misaligned.

I didn't say there's no improvement, just that it's not really worth the trouble. Unless you're just doing numbers go up, you're not going to get enough of a boost to tell the difference sitting down on the couch and playing a game.

[retrozar]

I am trying to mod this japanese tv i have but im not sure where to start. Looking at the service manual, i see the RGB lines have 390ohm resistors, but im not sure which values to replace them with.

Service manual: https://ia801302.us.archive.org/29/item ... MANUAL.pdf

[Delphius]

Where you are seeing the 390ohm resistors is the output of the OSD chip. You need to follow those lines to the right of the page and look at the muxing chip at IC3102. This isn't a jungle chip so it isn't going to follow the standard injection, but you might be able to figure something out if you are able to measure signals right after those 1k resistors and right at the input of that IC.

I am trying to mod this japanese tv i have but im not sure where to start. Looking at the service manual, i see the RGB lines have 390ohm resistors, but im not sure which values to replace them with.

Service manual: https://ia801302.us.archive.org/29/item ... MANUAL.pdf

[MarkOZLAD]

Where you are seeing the 390ohm resistors is the output of the OSD chip. You need to follow those lines to the right of the page and look at the muxing chip at IC3102. This isn't a jungle chip so it isn't going to follow the standard injection, but you might be able to figure something out if you are able to measure signals right after those 1k resistors and right at the input of that IC.

I am trying to mod this japanese tv i have but im not sure where to start. Looking at the service manual, i see the RGB lines have 390ohm resistors, but im not sure which values to replace them with.

Service manual: https://ia801302.us.archive.org/29/item ... MANUAL.pdf

Yep IC3102 is where I’d be looking too but unfortunately I can’t find anything on the web for IZ0081CE.

Looking at the schematic I wouldn’t be surprised if pins 11,12,13,14 were analog RGB/FB but I have nothing to corroborate that, it might be just wishful thinking. If it were my set I might have a crack at them.

[Delphius]

I was wondering the same thing about 11,12,13,14 and I would bet that they are. If that is the case then it almost couldn't be any easier to add RGB if it can be determined how hot of signal and biasing it is expecting.

Where you are seeing the 390ohm resistors is the output of the OSD chip. You need to follow those lines to the right of the page and look at the muxing chip at IC3102. This isn't a jungle chip so it isn't going to follow the standard injection, but you might be able to figure something out if you are able to measure signals right after those 1k resistors and right at the input of that IC.

I am trying to mod this japanese tv i have but im not sure where to start. Looking at the service manual, i see the RGB lines have 390ohm resistors, but im not sure which values to replace them with.

Service manual: https://ia801302.us.archive.org/29/item ... MANUAL.pdf

Yep IC3102 is where I’d be looking too but unfortunately I can’t find anything on the web for IZ0081CE.

Looking at the schematic I wouldn’t be surprised if pins 11,12,13,14 were analog RGB/FB but I have nothing to corroborate that, it might be just wishful thinking. If it were my set I might have a crack at them.

[retrozar]

How would I go about measuring the signals? Can I use a MM or would I need a scope?

What type of signal would indicate analog or digital RGB?

[Delphius]

How would I go about measuring the signals? Can I use a MM or would I need a scope?

What type of signal would indicate analog or digital RGB?

You will probably need a scope for this. It doesn't need to be too fancy, I think I got mine for under $100 and it works just fine for things like this. You will need to measure things like peak-to-peak voltage of the signals and whether there is any bias / steady dc voltage on the signal. If you measure the OSD and the signals peak close to 0.7v on solid colors then you will know that your external RGB needs to also need to peak around the same area. It will most likely be at least 0.5v or 0.7v ptp so you could always try that which you should be able to achieve with a 75ohm resistor to ground right at the inputs of the IC. With the blanking voltage, measure pin 7 of IC3102 when the OSD menu is on and it will show when voltage is used to trigger the switch. From there we can help you figure out a good voltage divider to use to try and match your external 5v blanking voltage. Pins 11,12,13 have a 0v which probably indicates that there is no DC bias so you might want to include a coupling capacitor on each of your external RGB lines. So you could try this
External RGB -> 75ohm to ground -> 220uf capacitor series (positive towards external side) -> Pins 8 9 10
Or severe the trace on pins 11 12 13 and send RGB / blanking there instead. Blanking voltage might be an estimate of like a 4.7k series to 2.2k to ground, but sometimes it is easier to use a potentiometer here so you can adjust it.

This is just an estimate, realistically you will want to prepare for several scenarios or resistor values. But that might be a good place to start if you wanting to do this.

[LeaveItTubeBeaver]

I'm about to start on my sony KV32s42. I normally read as much as humanly possible before these things. I'm comfortable starting this mod except for blanking.
I'm wanting to pull blanking voltage from the TV and have it on a switch because I'll be using an extron matrix switch as well as a few devices that might not give blanking voltage, like a PC.

I tried searching my specific chassis and model here as well as a few others places and some of the guides are dead links now. Just curious if anybody has modded a similar set and can point me in the right direction. Otherwise I suppose I can poke around with a multimeter and find 5v somehwere. But the wiring still throws me off. Every guide I've seen says that you should run the blanking to the scart and if you have issues, go from there.

I also have a 9' RCA on the way that is rgb moddable as well. I might make that my first mod, but I have everything needed to start. I just want to be sure on a few things!

[Delphius]

I'm about to start on my sony KV32s42. I normally read as much as humanly possible before these things. I'm comfortable starting this mod except for blanking.
I'm wanting to pull blanking voltage from the TV and have it on a switch because I'll be using an extron matrix switch as well as a few devices that might not give blanking voltage, like a PC.

I tried searching my specific chassis and model here as well as a few others places and some of the guides are dead links now. Just curious if anybody has modded a similar set and can point me in the right direction. Otherwise I suppose I can poke around with a multimeter and find 5v somehwere. But the wiring still throws me off. Every guide I've seen says that you should run the blanking to the scart and if you have issues, go from there.

I also have a 9' RCA on the way that is rgb moddable as well. I might make that my first mod, but I have everything needed to start. I just want to be sure on a few things!

Most likely the OSD is also going to output a 5v blanking voltage. Take a look at the circuit / schematic and see what it is doing there. There is usually a series resistor and a pull down to ground for creating a voltage divider. The pull down should be on the jungle chip side and will be part of your own fast blanking circuit. Most likely you can use the same series resistor that the OSD uses, but maybe plan to have slightly lower and higher values just in case. You will also want a 1N4148 diode. You can also measure the voltage at the jungle FB when the OSD is active to get the exact voltage needed and do some voltage divider calculations. You might also drop a little voltage through the 1N4148 which is why you want to prepare for a slightly higher value just in case if it is close to the threshold. Or if you want you can even put this on a potentiometer once you know the basic range (probably a 10k pot).

Your circuit will look something like this
5v Tap -> Switch -> Series Resistor -> 1N4148 -> Jungle FB

If you don't want to solder directly to the jungle chip you can also solder to the pull down resistor (not the ground side) or something like that if you want. This should work, even though I am not a huge fan of sending 5v through a switch.

edit: Check for a diode on the OSD line as well. It might not have one or be required, but if you can also sneak a diode in for the OSD that will prevent the 5v from your switch feeding back into OSD blank pin. It will have its series resistor for protection but this is still a nice to have. If you find the schematic for this circuit and share it this might be helpful as well.

[LeaveItTubeBeaver]

I'm about to start on my sony KV32s42. I normally read as much as humanly possible before these things. I'm comfortable starting this mod except for blanking.
I'm wanting to pull blanking voltage from the TV and have it on a switch because I'll be using an extron matrix switch as well as a few devices that might not give blanking voltage, like a PC.

I tried searching my specific chassis and model here as well as a few others places and some of the guides are dead links now. Just curious if anybody has modded a similar set and can point me in the right direction. Otherwise I suppose I can poke around with a multimeter and find 5v somehwere. But the wiring still throws me off. Every guide I've seen says that you should run the blanking to the scart and if you have issues, go from there.

I also have a 9' RCA on the way that is rgb moddable as well. I might make that my first mod, but I have everything needed to start. I just want to be sure on a few things!

Most likely the OSD is also going to output a 5v blanking voltage. Take a look at the circuit / schematic and see what it is doing there. There is usually a series resistor and a pull down to ground for creating a voltage divider. The pull down should be on the jungle chip side and will be part of your own fast blanking circuit. Most likely you can use the same series resistor that the OSD uses, but maybe plan to have slightly lower and higher values just in case. You will also want a 1N4148 diode. You can also measure the voltage at the jungle FB when the OSD is active to get the exact voltage needed and do some voltage divider calculations. You might also drop a little voltage through the 1N4148 which is why you want to prepare for a slightly higher value just in case if it is close to the threshold. Or if you want you can even put this on a potentiometer once you know the basic range (probably a 10k pot).

Your circuit will look something like this
5v Tap -> Switch -> Series Resistor -> 1N4148 -> Jungle FB

If you don't want to solder directly to the jungle chip you can also solder to the pull down resistor (not the ground side) or something like that if you want. This should work, even though I am not a huge fan of sending 5v through a switch.

edit: Check for a diode on the OSD line as well. It might not have one or be required, but if you can also sneak a diode in for the OSD that will prevent the 5v from your switch feeding back into OSD blank pin. It will have its series resistor for protection but this is still a nice to have. If you find the schematic for this circuit and share it this might be helpful as well.

Thanks a ton for the quick reply. I do have 1N4148 diodes as well as SPDT switches. I'm with you on 5v through a switch, it sort of goes against anything I've ever done, that's probably why I'm having a hard time visualizing this part of the mod.

You've given me more than enough information to dive into. I'm going to look over the schematics tomorrow and come up with a gameplan. Might run it by here just to be certain. I won't lie, it's tempting to let the devices provide blanking. I believe the mister will as well as a plethora of my consoles. It's basically a PC running software that is holding me back. I belive the pi can even provide blanking if it has the correct hat.

Sorry, rambling now. Thank you for the great explanation

[Delphius]

I'm about to start on my sony KV32s42. I normally read as much as humanly possible before these things. I'm comfortable starting this mod except for blanking.
I'm wanting to pull blanking voltage from the TV and have it on a switch because I'll be using an extron matrix switch as well as a few devices that might not give blanking voltage, like a PC.

I tried searching my specific chassis and model here as well as a few others places and some of the guides are dead links now. Just curious if anybody has modded a similar set and can point me in the right direction. Otherwise I suppose I can poke around with a multimeter and find 5v somehwere. But the wiring still throws me off. Every guide I've seen says that you should run the blanking to the scart and if you have issues, go from there.

I also have a 9' RCA on the way that is rgb moddable as well. I might make that my first mod, but I have everything needed to start. I just want to be sure on a few things!

Most likely the OSD is also going to output a 5v blanking voltage. Take a look at the circuit / schematic and see what it is doing there. There is usually a series resistor and a pull down to ground for creating a voltage divider. The pull down should be on the jungle chip side and will be part of your own fast blanking circuit. Most likely you can use the same series resistor that the OSD uses, but maybe plan to have slightly lower and higher values just in case. You will also want a 1N4148 diode. You can also measure the voltage at the jungle FB when the OSD is active to get the exact voltage needed and do some voltage divider calculations. You might also drop a little voltage through the 1N4148 which is why you want to prepare for a slightly higher value just in case if it is close to the threshold. Or if you want you can even put this on a potentiometer once you know the basic range (probably a 10k pot).

Your circuit will look something like this
5v Tap -> Switch -> Series Resistor -> 1N4148 -> Jungle FB

If you don't want to solder directly to the jungle chip you can also solder to the pull down resistor (not the ground side) or something like that if you want. This should work, even though I am not a huge fan of sending 5v through a switch.

edit: Check for a diode on the OSD line as well. It might not have one or be required, but if you can also sneak a diode in for the OSD that will prevent the 5v from your switch feeding back into OSD blank pin. It will have its series resistor for protection but this is still a nice to have. If you find the schematic for this circuit and share it this might be helpful as well.

Thanks a ton for the quick reply. I do have 1N4148 diodes as well as SPDT switches. I'm with you on 5v through a switch, it sort of goes against anything I've ever done, that's probably why I'm having a hard time visualizing this part of the mod.

You've given me more than enough information to dive into. I'm going to look over the schematics tomorrow and come up with a gameplan. Might run it by here just to be certain. I won't lie, it's tempting to let the devices provide blanking. I believe the mister will as well as a plethora of my consoles. It's basically a PC running software that is holding me back. I belive the pi can even provide blanking if it has the correct hat.

Sorry, rambling now. Thank you for the great explanation

Using a switch with 5v / FB isn't really that big of a deal. I used it on my last build and I am pretty sure it is standard around here. It is probably better practice to use a mosfet to trigger the 5v and connect to switch to ground, but it will definitely complicate things. But that does give me an idea to do this on a circuit I am planning to build.

I know a lot of people like to use SCART and use 5v from the console, but there are also some that say BNC / phono is superior. I use it because it is much easier to drill. You can get nice switches that are nearly flush as well and they look really nice. It gives you more control like you have already mentioned as well since not everything is going to give you FB from external. Or you could try to do both and allow the switch to be available to force it.

[LeaveItTubeBeaver]

Hey I’m back again. Before I start the Sony rgb mod I wanted to try on an rca that I have. Although the guide is a little confusing. They show some of the work being done for a more DIY approach, and the second half shows a mux board that you can buy. Only difference is resistors used and I believe that’s my issue.

I followed the guide but I used the resistors recommended from sunthars config and not martins. I lifted the 4 resistors near the osd chip and added diodes, stripe facing away from the chip. I wired up the scart cable as shown (it’s ugly and I need to tidy it up but nothing is shorting and I checked the resistors before I installed)
I have the 75 ohm to ground with the recommended values for rgb. The blanking has the resistance from sunthars method with another diode, bar facing away from the scart plug.
Looks like a pretty gnarly sync issue but also heavy on blue. I tried with a SEGA Saturn and a mister fpga.

Sorry to be that new guy, I believe I just used the wrong values but before I keep poking around, I wanted to see what you guys think.

Thanks again

Edit: after searching tx808 here I found some good info. I’m going to use the 180ohm grounding resistors. I’ll change the inline resistors to 820 as mentioned as well.

Hopefully I’m on the right path. I’ll clean up the scart jack as well.

[Delphius]

Overall your install looks good to me. What are you using for sync? I assume you are using composite for sync but just want to check since you didn't specify but mentioned a sync issue.
edit: of course if you are using SCART then you should be getting sync through composite there. But maybe something isn't connected correctly. Sunthar's diagram doesn't really show it connecting to anywhere on the TV circuit board, so you will want to tie that directly into the composite line at least to start.

I don't think the resistors are going to change anything since the values used in Martin's guide is nearly the same ratio as Sunthar's. There might be a slight variation of brightness between the two, but the voltage division should be similar enough that I don't think it would cause the issue you are describing. If it is mostly the blue signal then I would definitely start there and just make sure each of the points are correct. You could maybe try removing the inline diodes on the RGB from the OSD, though it would just be as a sanity check. I am actually not certain what qualifies the need for diodes on the RGB lines and every time I had experimented with using them I have had poor results. Also, my experience with soldering things directly to a SCART connector has always given me poor results. Making sure all the ground connections are correct and not shorting anything is a pain in the ass. I sort of recommend getting a phono block to use for testing phase because it is so much easier to visualize and make changes while you are figuring things out. I use something like this
https://www.amazon.com/dp/B07PDYL17M?re ... in_title_1
although of course it will require you to use phono cable outputs on your consoles. Once you know it is working then you can switch the config to SCART and it will help you identify if it is an installation problem or not.

Hey I’m back again. Before I start the Sony rgb mod I wanted to try on an rca that I have. Although the guide is a little confusing. They show some of the work being done for a more DIY approach, and the second half shows a mux board that you can buy. Only difference is resistors used and I believe that’s my issue.

I followed the guide but I used the resistors recommended from sunthars config and not martins. I lifted the 4 resistors near the osd chip and added diodes, stripe facing away from the chip. I wired up the scart cable as shown (it’s ugly and I need to tidy it up but nothing is shorting and I checked the resistors before I installed)
I have the 75 ohm to ground with the recommended values for rgb. The blanking has the resistance from sunthars method with another diode, bar facing away from the scart plug.
Looks like a pretty gnarly sync issue but also heavy on blue. I tried with a SEGA Saturn and a mister fpga.

Sorry to be that new guy, I believe I just used the wrong values but before I keep poking around, I wanted to see what you guys think.

Thanks again

Edit: after searching tx808 here I found some good info. I’m going to use the 180ohm grounding resistors. I’ll change the inline resistors to 820 as mentioned as well.

Hopefully I’m on the right path. I’ll clean up the scart jack as well.

[LeaveItTubeBeaver]

Yeah I’m using composite for sync. Fairly certain that I have it landed in the correct spot, however I only used a single ground for the scart connector, taken near the composite location. I’m also wondering if I need to separate grounds a bit. Might not matter.

The guide shows the diodes right after the osd chip, on the schematic mock up, they show the blanking having one right at the osd but the other 3 are further downstream, but I also don’t see them used often online with rgb.
Also, I have that diode at the scart plug for blanking, is this solely to protect whatever is hooked up? Not sure if feedback can occur there.

I like the phono block idea. I’m going to order some.

So I’ll remove the diodes from rgb, double check ground and try to figure out if it’s best to have a few ground sources

Overall your install looks good to me. What are you using for sync? I assume you are using composite for sync but just want to check since you didn't specify but mentioned a sync issue.
edit: of course if you are using SCART then you should be getting sync through composite there. But maybe something isn't connected correctly. Sunthar's diagram doesn't really show it connecting to anywhere on the TV circuit board, so you will want to tie that directly into the composite line at least to start.

I don't think the resistors are going to change anything since the values used in Martin's guide is nearly the same ratio as Sunthar's. There might be a slight variation of brightness between the two, but the voltage division should be similar enough that I don't think it would cause the issue you are describing. If it is mostly the blue signal then I would definitely start there and just make sure each of the points are correct. You could maybe try removing the inline diodes on the RGB from the OSD, though it would just be as a sanity check. I am actually not certain what qualifies the need for diodes on the RGB lines and every time I had experimented with using them I have had poor results. Also, my experience with soldering things directly to a SCART connector has always given me poor results. Making sure all the ground connections are correct and not shorting anything is a pain in the ass. I sort of recommend getting a phono block to use for testing phase because it is so much easier to visualize and make changes while you are figuring things out. I use something like this
https://www.amazon.com/dp/B07PDYL17M?re ... in_title_1
although of course it will require you to use phono cable outputs on your consoles. Once you know it is working then you can switch the config to SCART and it will help you identify if it is an installation problem or not.

Hey I’m back again. Before I start the Sony rgb mod I wanted to try on an rca that I have. Although the guide is a little confusing. They show some of the work being done for a more DIY approach, and the second half shows a mux board that you can buy. Only difference is resistors used and I believe that’s my issue.

I followed the guide but I used the resistors recommended from sunthars config and not martins. I lifted the 4 resistors near the osd chip and added diodes, stripe facing away from the chip. I wired up the scart cable as shown (it’s ugly and I need to tidy it up but nothing is shorting and I checked the resistors before I installed)
I have the 75 ohm to ground with the recommended values for rgb. The blanking has the resistance from sunthars method with another diode, bar facing away from the scart plug.
Looks like a pretty gnarly sync issue but also heavy on blue. I tried with a SEGA Saturn and a mister fpga.

Sorry to be that new guy, I believe I just used the wrong values but before I keep poking around, I wanted to see what you guys think.

Thanks again

Edit: after searching tx808 here I found some good info. I’m going to use the 180ohm grounding resistors. I’ll change the inline resistors to 820 as mentioned as well.

Hopefully I’m on the right path. I’ll clean up the scart jack as well.

[LeaveItTubeBeaver]

So far I have done everything mentioned here except for removing ri532,528 and 525. Might be getting somewhere, plus remove rgb diodes

Another progress update. After putting the EEPROM idea on ice, I looked for a place to do the sync. TV_IN was not working; the sync seemed to be at the wrong level, so a test composite input was flickering and rolling. It also seemed to confuse the whole system in terms of whether a channel was tuned, presumably because it wasn't detecting a sync lock.

So what I did was hook up a VCR to the tuner and put it on a still frame, then compared the Vpp at different areas to see what the level should look like with a good signal; the issue was the the sync was too low as-is and needed to be amplified by a transistor slightly upstream before it entered TV_IN.

See this hideously-marked-up graphic for what I did:


Basically by removing RI532, RI528, and CI525, it isolates the tuner circuit's CVBS output. Then into the center leg of TI21 we can insert composite here and, voila, every "channel" in TV tuner mode is now that composite input. Similarly you can input composite sync on its own here, and it works in RGB mode too. Without this extra amplification step I was unable to get sync working properly.

So now that we have a good sync input I turned to doing the OSD mux stuff. I used your spreadsheet, MarkOZLAD. The factory in-line resistors on the TX808 series are 3.3k. By the math on the sheet (no diodes) I came to a value of 470 for the new mux resistors. I removed the grounding resistors as instructed, added the 470's and 75's for grounding, and it worked! We have RGB, and the OSD works! But it is pretty dim. I am wondering if possibly the suggestion of "Existing TV capacitors may need to be replaced with 100nF" applies here. The existing caps are 22nF. Would that cause dimming?

For reference here is the area of interest where the RGB tapping is occurring. I have marked up just one of the lines to show you how my resistors are set up.


Before modification, the inline resistors (3.3k) and the grounding resistors (820) were creating a voltage divider from 5V->1V into the jungle. Could it be this jungle chip wants to see 1V on the RGB input lines, and we're overdoing it shooting for 0.7 Vpp?

[Delphius]

Ok if you have composite injected correctly then your sync should be fine. Is it rolling hard or just slightly?

If I understand the SCART connection correctly, non of the ground pins are connected to each other by default. So in this example are all of your 75ohm pull down / termination resistors connected to that same point of ground? If not, then you will need to connect the pin that is connected to the circuit ground to all of those pins which is why I found it to be a pain. Much easier to manage this with a circuit board. From the looks of it you seem to have this correct by linking the ground legs of each of those resistors to that same ground point. But it might also be that you need to connect any other floating ground pin on the SCART connector to that same ground point. The console and the TV needs to have a clean ground return path between each other and this might also affect things like the composite sync.

With that RCA block I showed you the ground sleeve of each phono jack are already connected to each other so it only requires one ground wire to get things working.

As far as the diodes go I would imagine that Sunthar's guide to adding the diodes inline on the RGB is probably correct. I am just curious as to why the chart you posted that shows that Martin's guide says that the inline diodes are not required. I wonder why they differ.
The diode is especially important on the fast blanking because it keeps voltage back feeding through the SCART connector to the console. This is important since the OSD will produce it's own voltage on that line when active and you don't want that going to anything external. However, whenever I have tried adding 1N4148 diodes on RGB lines the signal would not even pass through. It does for a moment, but then slowly fades to nothing. So I just haven't had a situation yet that needed them or understood how they work in that type of circuit. But I have seen plenty of guides say to use them so I am sure there is logic behind it.

Yeah I’m using composite for sync. Fairly certain that I have it landed in the correct spot, however I only used a single ground for the scart connector, taken near the composite location. I’m also wondering if I need to separate grounds a bit. Might not matter.

The guide shows the diodes right after the osd chip, on the schematic mock up, they show the blanking having one right at the osd but the other 3 are further downstream, but I also don’t see them used often online with rgb.
Also, I have that diode at the scart plug for blanking, is this solely to protect whatever is hooked up? Not sure if feedback can occur there.

I like the phono block idea. I’m going to order some.

So I’ll remove the diodes from rgb, double check ground and try to figure out if it’s best to have a few ground sources

Overall your install looks good to me. What are you using for sync? I assume you are using composite for sync but just want to check since you didn't specify but mentioned a sync issue.
edit: of course if you are using SCART then you should be getting sync through composite there. But maybe something isn't connected correctly. Sunthar's diagram doesn't really show it connecting to anywhere on the TV circuit board, so you will want to tie that directly into the composite line at least to start.

I don't think the resistors are going to change anything since the values used in Martin's guide is nearly the same ratio as Sunthar's. There might be a slight variation of brightness between the two, but the voltage division should be similar enough that I don't think it would cause the issue you are describing. If it is mostly the blue signal then I would definitely start there and just make sure each of the points are correct. You could maybe try removing the inline diodes on the RGB from the OSD, though it would just be as a sanity check. I am actually not certain what qualifies the need for diodes on the RGB lines and every time I had experimented with using them I have had poor results. Also, my experience with soldering things directly to a SCART connector has always given me poor results. Making sure all the ground connections are correct and not shorting anything is a pain in the ass. I sort of recommend getting a phono block to use for testing phase because it is so much easier to visualize and make changes while you are figuring things out. I use something like this
https://www.amazon.com/dp/B07PDYL17M?re ... in_title_1
although of course it will require you to use phono cable outputs on your consoles. Once you know it is working then you can switch the config to SCART and it will help you identify if it is an installation problem or not.

Hey I’m back again. Before I start the Sony rgb mod I wanted to try on an rca that I have. Although the guide is a little confusing. They show some of the work being done for a more DIY approach, and the second half shows a mux board that you can buy. Only difference is resistors used and I believe that’s my issue.

I followed the guide but I used the resistors recommended from sunthars config and not martins. I lifted the 4 resistors near the osd chip and added diodes, stripe facing away from the chip. I wired up the scart cable as shown (it’s ugly and I need to tidy it up but nothing is shorting and I checked the resistors before I installed)
I have the 75 ohm to ground with the recommended values for rgb. The blanking has the resistance from sunthars method with another diode, bar facing away from the scart plug.
Looks like a pretty gnarly sync issue but also heavy on blue. I tried with a SEGA Saturn and a mister fpga.

Sorry to be that new guy, I believe I just used the wrong values but before I keep poking around, I wanted to see what you guys think.

Thanks again

Edit: after searching tx808 here I found some good info. I’m going to use the 180ohm grounding resistors. I’ll change the inline resistors to 820 as mentioned as well.

Hopefully I’m on the right path. I’ll clean up the scart jack as well.

[Delphius]

Ok I will look this over in more detail, but so far it seems like it might be related. The only thing that is interesting to me is that you should be able to plug a normal composite cable from the console directly into the composite input of the TV for sync. So in my mind if you tap the scart composite to the pin of the composite input of the TV then you should be good to go. If you are trying to tap it further down the line or directly to the jungle chip then you might have issues with incorrect voltages.

There can be benefits for tapping closer to the jungle chip for getting a purer sync signal and bypassing the sync stripper which is normally delayed, but I think that would be better to do as a next step after the initial signal is working.

So far I have done everything mentioned here except for removing ri532,528 and 525. Might be getting somewhere, plus remove rgb diodes

Another progress update. After putting the EEPROM idea on ice, I looked for a place to do the sync. TV_IN was not working; the sync seemed to be at the wrong level, so a test composite input was flickering and rolling. It also seemed to confuse the whole system in terms of whether a channel was tuned, presumably because it wasn't detecting a sync lock.

So what I did was hook up a VCR to the tuner and put it on a still frame, then compared the Vpp at different areas to see what the level should look like with a good signal; the issue was the the sync was too low as-is and needed to be amplified by a transistor slightly upstream before it entered TV_IN.

See this hideously-marked-up graphic for what I did:


Basically by removing RI532, RI528, and CI525, it isolates the tuner circuit's CVBS output. Then into the center leg of TI21 we can insert composite here and, voila, every "channel" in TV tuner mode is now that composite input. Similarly you can input composite sync on its own here, and it works in RGB mode too. Without this extra amplification step I was unable to get sync working properly.

So now that we have a good sync input I turned to doing the OSD mux stuff. I used your spreadsheet, MarkOZLAD. The factory in-line resistors on the TX808 series are 3.3k. By the math on the sheet (no diodes) I came to a value of 470 for the new mux resistors. I removed the grounding resistors as instructed, added the 470's and 75's for grounding, and it worked! We have RGB, and the OSD works! But it is pretty dim. I am wondering if possibly the suggestion of "Existing TV capacitors may need to be replaced with 100nF" applies here. The existing caps are 22nF. Would that cause dimming?

For reference here is the area of interest where the RGB tapping is occurring. I have marked up just one of the lines to show you how my resistors are set up.


Before modification, the inline resistors (3.3k) and the grounding resistors (820) were creating a voltage divider from 5V->1V into the jungle. Could it be this jungle chip wants to see 1V on the RGB input lines, and we're overdoing it shooting for 0.7 Vpp?

[Delphius]

Overall this guide it seems you have been using looks good. If you have good ground connections that you should be fine. Making sure every ground pin on the SCART connector might be overkill, but I just am not certain. But if blue is over exposed then looking at ground on that signal would be the first place I would look. I would keep it simple for now and just make sure everything is connected as described in the guide. Even the composite connection point looks correct so you should be good in general. But just knowing how confusing SCART can be I would just make sure all the points are correct and that there is a good ground connection with the TV circuit board.

https://sector.sunthar.com/guides/crt-r ... d-blanking

I don't want to confuse you especially not knowing this TV or mod all that well. The solution is probably more simple than worrying about removing the inline diodes.

Notes from Claude AI on the subject

For an RGB SCART installation, connecting all ground pins is generally recommended for best results, though you can get away with less in some situations.
Here's the practical breakdown:
Critical grounds to connect:

Pin 17 (composite video ground)
Pin 18 (RGB ground - shared for R, G, B signals)
Pin 21 (ground for blanking/switching signal)

These are the ones directly associated with the signals you're actively using, and they're essential for proper operation.
Why connecting additional grounds helps:

Better shielding - More ground connections provide better electromagnetic shielding and reduce interference/noise in your video signals
Lower impedance ground return path - Multiple ground connections reduce overall ground resistance and help maintain a clean reference voltage
Reduced crosstalk - Particularly important for the separate RGB channels, which can interfere with each other if ground isn't solid

When you might get away with fewer grounds:
If you're doing a simple modification with short cable runs inside the TV and clean signals, connecting just the signal-specific grounds (17, 18, 21) often works fine. Many people do this successfully.
Best practice:
Connect all available ground pins (4, 5, 9, 13, 17, 18, 21) to chassis ground. It's not much extra work and gives you the cleanest possible signal with minimal risk of video noise, hum bars, or interference. The cable shield should also be grounded.
If you're troubleshooting noise or interference issues, systematically adding more ground connections is often an effective fix.

[LeaveItTubeBeaver]

Yeah that’s the guide. The two grounds near composite confuse me slightly, and then the guide goes right into the premade mux board

I also found this which seems pretty straightforward but a different csync area

Overall this guide it seems you have been using looks good. If you have good ground connections that you should be fine. Making sure every ground pin on the SCART connector might be overkill, but I just am not certain. But if blue is over exposed then looking at ground on that signal would be the first place I would look. I would keep it simple for now and just make sure everything is connected as described in the guide. Even the composite connection point looks correct so you should be good in general. But just knowing how confusing SCART can be I would just make sure all the points are correct and that there is a good ground connection with the TV circuit board.

https://sector.sunthar.com/guides/crt-r ... d-blanking

I don't want to confuse you especially not knowing this TV or mod all that well. The solution is probably more simple than worrying about removing the inline diodes.

Notes from Claude AI on the subject

For an RGB SCART installation, connecting all ground pins is generally recommended for best results, though you can get away with less in some situations.
Here's the practical breakdown:
Critical grounds to connect:

Pin 17 (composite video ground)
Pin 18 (RGB ground - shared for R, G, B signals)
Pin 21 (ground for blanking/switching signal)

These are the ones directly associated with the signals you're actively using, and they're essential for proper operation.
Why connecting additional grounds helps:

Better shielding - More ground connections provide better electromagnetic shielding and reduce interference/noise in your video signals
Lower impedance ground return path - Multiple ground connections reduce overall ground resistance and help maintain a clean reference voltage
Reduced crosstalk - Particularly important for the separate RGB channels, which can interfere with each other if ground isn't solid

When you might get away with fewer grounds:
If you're doing a simple modification with short cable runs inside the TV and clean signals, connecting just the signal-specific grounds (17, 18, 21) often works fine. Many people do this successfully.
Best practice:
Connect all available ground pins (4, 5, 9, 13, 17, 18, 21) to chassis ground. It's not much extra work and gives you the cleanest possible signal with minimal risk of video noise, hum bars, or interference. The cable shield should also be grounded.
If you're troubleshooting noise or interference issues, systematically adding more ground connections is often an effective fix.

[LeaveItTubeBeaver]

I think my plan for tomorrow morning, or tonight if i'm feeling froggy, is to move my RGB and Blanking to the top of the board. I'd like to change the values according to some of the posts i've seen here, as well as keep the inline resistor closer to the chip, possibly the 75ohm resistor as well, just to have a cleaner scart plug. still unsure about this though.
Also, get rid of the diodes for RGB


At that point I may power it on to see if I have a more stable picture, but I fell like i'm already having sync issues and from the posts i've seen, people weren't having luck until they removed 2 resistors and a capacitor near the jungle chip and injected Csync there.


I may keep audio the same but i'm going to ground RGBS separately than LR audio in order to have a simpler SCART connection.

Because they will be ground together, I'm unsure if I should do the 75ohm nearest to the board or at the scart connection.
Probably doesn't matter, but I'll hopefully have a better outcome and understanding of this all!

[LeaveItTubeBeaver]

Okay, progress! Probably won’t get back to this until tomorrow but I figured I’d describe what I’ve done and what issues I have to see if I’m on the right path.

The good: it’s working
The bad: slightly dim and audio issues
The ugly: I still have no idea what I’m doing with blanking lol

So blanking still confuses me. I wired everything up according to this

I started the tv with what I thought was the “off” position, meaning that OSD would work as normal and no voltage was being directed at the OSD chip. To my surprise, my SEGA Saturn was displayed! No blanking wire was run to the scart plug, I had found 5v on the pcb. I’m guessing that my idea of off is actually sending the voltage, otherwise I’m not sure how I would have a picture.

The bad isn’t really all that bad. The schematic I just posted is what I went off of. It’s pretty dim, but that may be fixed with either grounding resistors or inline. I believe I still used 75ohm for grounding and 820ohm inline. I’m now seeing that I should have used 180ohm grounding.

As for audio, I still tried to use audio input near the back. I haven’t tried this yet

I’m hopeful that will fix audio.

I’m getting somewhere. Maybe with some resistance changes and a new spot to send audio through. I’ll be all set!

[Delphius]

Okay, progress! Probably won’t get back to this until tomorrow but I figured I’d describe what I’ve done and what issues I have to see if I’m on the right path.

The good: it’s working
The bad: slightly dim and audio issues
The ugly: I still have no idea what I’m doing with blanking lol

Nice work!

So blanking still confuses me. I wired everything up according to this

I started the tv with what I thought was the “off” position, meaning that OSD would work as normal and no voltage was being directed at the OSD chip. To my surprise, my SEGA Saturn was displayed! No blanking wire was run to the scart plug, I had found 5v on the pcb. I’m guessing that my idea of off is actually sending the voltage, otherwise I’m not sure how I would have a picture.

Either your switch is wired incorrectly, or the blanking actually works on the opposite. On that schematic it shows the jungle blanking as 0v, so maybe it triggers OSD with ground.

The bad isn’t really all that bad. The schematic I just posted is what I went off of. It’s pretty dim, but that may be fixed with either grounding resistors or inline. I believe I still used 75ohm for grounding and 820ohm inline. I’m now seeing that I should have used 180ohm grounding.

I think you are on the right track here, the 180ohm grounding will probably fix it. Or you can use the other combination of resistors that uses the 75ohm to ground if you want more standard termination. Overall it probably doesn't matter, it should work when you have the right voltage divider.

As for audio, I still tried to use audio input near the back. I haven’t tried this yet

I’m hopeful that will fix audio.

I’m getting somewhere. Maybe with some resistance changes and a new spot to send audio through. I’ll be all set!

I think you are about wrapping it up. Are you planning to use phono or SCART for this mode when you finalize?

[LeaveItTubeBeaver]

I adjusted the rgb grounding resistor to 180ohm and added a grounding resistor to composite.
Unfortunately audio isn’t working with either option I’ve tried. Apparently flashing the EEPROM would give me an “easy” solution as it would give me the option to use the rear composite/audio hookups that were left out of my model.

I’d prefer to find a simpler solution but I’m running out of other examples to go off of.

[LeaveItTubeBeaver]

Oh wow, I was posting an update as you responded! The blanking switch confusion was just me working late and hallucinating. Switch is fine I’m just crazy.

Also my formatting is terrible. Sorry about the quote mess!

I think you are about wrapping it up. Are you planning to use phono or SCART for this mode when you finalize?

I plan on using scart, this set doesn’t have rca jacks but I still may be confused my scart working. Right now I have a 1k resistor on the single mono that runs to the jungle chip. After the 1k it splits to pin 2 and pin 6 with pin 4 grounded with the rest of the scart plug

[Delphius]

I adjusted the rgb grounding resistor to 180ohm and added a grounding resistor to composite.
Unfortunately audio isn’t working with either option I’ve tried. Apparently flashing the EEPROM would give me an “easy” solution as it would give me the option to use the rear composite/audio hookups that were left out of my model.

I’d prefer to find a simpler solution but I’m running out of other examples to go off of.

Looks great! What a nice little TV. The colors and geometry look great on it.

Not sure what to tell you about the sound. I have a programmer on hand so flashing the EEPROM wouldn't be out of the question. Just make sure you grab a backup of what is currently on there so you can flash again if something goes wrong. If you find an injection point for audio at the tuner, you might need to throw a 10uf electrolytic cap on it. Audio circuits are generally very sensitive to DC. Check to see if the audio runs through an opamp or transistor or something like that. Even at the jungle chip I suspect it will need the 1k -> 10uf coupling cap to be safe. But if you are using an audio pin that is disabled in EEPROM it might not work without the flashing.

[Delphius]

I plan on using scart, this set doesn’t have rca jacks but I still may be confused my scart working. Right now I have a 1k resistor on the single mono that runs to the jungle chip. After the 1k it splits to pin 2 and pin 6 with pin 4 grounded with the rest of the scart plug

Of course SCART is totally fine. I like to use these phono connectors with a nut for things like this. Mostly because of how easier it is to drill holes than cut out a perfect shape.
https://www.aliexpress.us/item/32568082 ... pt=glo2usa

Or you could probably find BNCs with the chassis nut as well.

[Delphius]

Oh wow, I was posting an update as you responded! The blanking switch confusion was just me working late and hallucinating. Switch is fine I’m just crazy.

Also my formatting is terrible. Sorry about the quote mess!

Is this you or purely just coincidence? lol

https://www.youtube.com/watch?v=8E9_OeUMhgI

[LeaveItTubeBeaver]

Oh wow, I was posting an update as you responded! The blanking switch confusion was just me working late and hallucinating. Switch is fine I’m just crazy.

Also my formatting is terrible. Sorry about the quote mess!

Is this you or purely just coincidence? lol

https://www.youtube.com/watch?v=8E9_OeUMhgI

Lol that's crazy but it's not. Not the most popular choice so it is interesting. Maybe a fan of shmups or just coincidence!

I am happy to report that audio has been figured out. After following guides found here and reposted by me, I had no idea why it wasn't working. It was my mister FPGA which is crazy.
i'll post a video later, it's beautiful

Edit: https://imgur.com/a/G9vflAS#HaYtFzz

[Anonygoose]

Hey guys. Got this Samsung 36 inch monster I'm trying to Mux mod.

Can someone confirm if I did the calculations correctly for the inline resistors and where to inject the signals?

Link with diagram and schematics: https://imgur.com/gallery/OUtdfW0

TDA8375 Jungle
Chassis Sct55a

Thank you