TV RGB mod thread

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MarkOZLAD
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Re: TV RGB mod thread

Post by MarkOZLAD »

isolenz wrote:Hi All, First time poster, long time reader.

I just picked up a samsung txj2550. It has a TDA8373. I believe I have the proper pins nailed down (Pins 23,24,25 and 26 (blanking)).

The RGB voltage (based on the schematic for my tv) looks to be 3.3V, and I plan on using this primarily for JAMMA based boards which I understand are 0 -> 4V. I may want to use this down the road for SCART voltages in the future too though, which I understand top out at 0.7v.
I also have a PARSEC supergun which seems to output 0.7v RGB through it's BH7236AF IC which is an option for running my JAMMA based boards.

How should I handle this situation? Should I target a common input of 0.7v regardless of the situation and amplify the signal to 3.3v for the TDA8373? Or would I get better quality putting in multiple lines, one for JAMMA and bring it down a smidge, and another for other sources that I would need to amplify up?

Thanks!
https://datasheetspdf.com/pdf-file/325258/NXP/TDA8373/1

TDA8373 accepts 0.7Vp-p RGB via pins 23,24 and 25. (see page 3 of the TDA837x datasheet V23-25 RGB input voltage)

I don't know exactly what the 3.3V that shows on the Samsung schematic against those pins refers to. Some kind of maximum rating or something. See it in other schematics too but have never been sure what it means.

Blanking is 0.9-3.0V on pin 26. (page 31)

Use the supergun to attenuate the Jamma RGB to 0.7Vp-p. You'll be ready for scart voltages then too.
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skum
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Re: TV RGB mod thread

Post by skum »

Pahnda wrote:Hi all,

I just tried to do a RGB mod to my TM-1700PN-K using this guide: https://immerhax.com/?p=336

However my mod is not working so I undid everything.
When thinking about what went wrong ... I noticed that my OSD Menu is all black and not white, like it should be.
It also was like this before I started to do the mod.
I'm quite sure, that that's the reason why my mod is not working.

Image

The blanking voltage on pin 24 is about 0,3 V when OSD is off, when I press the menu-button and the black OSD is shown, it is 0,6 V.
Shouldn't it be about 5 V in the menu?
I tried applying 5V direktly to pin 24 when the OSD is on, but than the picture goes completly black.

Has anyone a hint where to look at? I think I first need to get the OSD menu white again :D.
Any ideas?
So the caps on RGB lines are back again? When you apply 4V+ on blanking, you're blanking the output of the jungle, but since OSD is mixed in *after* the jungle I cannot see why this should make a difference (since when the monitor blanks for OSD, it does exactly this, send 4V+ to blanking so the jungles output is black. This of course all assumes there aren't different versions of the monitor. Can you verify the jungle IC and such?
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DotMatrixMoe
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Re: TV RGB mod thread

Post by DotMatrixMoe »

Can anyone give a quick glance at this and tell me I'm not going to start a fire? :lol: All resistors will be on SCART head.

https://imgur.com/a/7bIRUHn

Also, I was wondering if I should remove blanking's resistor to ground.
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MrW
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Re: TV RGB mod thread

Post by MrW »

Hello all

My quest to RGB my crt to use in my arcade has sent me here

Everything seems a little confusing but hopefully you lovely people can steer me in the right direction

I have tried doing some reading but all it has done has confused me more

I have a teac as per the below service manual

https://www.vintageshifi.com/repertoire ... Manual.pdf

Is this tv possible to rgb mod?
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DotMatrixMoe
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Re: TV RGB mod thread

Post by DotMatrixMoe »

I also can't help but to notice that the OSD looks much brighter and/or saturated after removing the voltage dividing resistors. I'll see if it works later today.
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DotMatrixMoe
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Re: TV RGB mod thread

Post by DotMatrixMoe »

Looked at an older post on my chassis, I'll follow that.
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MarkOZLAD
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Re: TV RGB mod thread

Post by MarkOZLAD »

MrW wrote:Hello all

My quest to RGB my crt to use in my arcade has sent me here

Everything seems a little confusing but hopefully you lovely people can steer me in the right direction

I have tried doing some reading but all it has done has confused me more

I have a teac as per the below service manual

https://www.vintageshifi.com/repertoire ... Manual.pdf

Is this tv possible to rgb mod?
Which chassis is yours?
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MrW
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Re: TV RGB mod thread

Post by MrW »

Looking at the serial number I have the syber chassis
MarkOZLAD
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Re: TV RGB mod thread

Post by MarkOZLAD »

MrW wrote:Looking at the serial number I have the syber chassis
assuming that the RGB inputs on the OM8838 (TDA8842 clone) jungle are enabled...

C901, C903 and C905 are your target entry points for RGB. The legs farthest from the jungle are connected to ground. You will need to disconnect them from ground, possibly by desoldering and lifting the legs farthest from jungle.

These lifted legs can be your entry point for RGB.

You should then just need to attach 75 ohm terminated RGB lines to the legs you just lifed.

For blanking I would take a 5v Line, add a 2K ohm resistor and then attach to R916 on leg that goes to jungle. This should give you a blanking voltage about 1.9V. A 1K would be suitable too, giving a voltage arounf 2.7V. M805 is your 5V regulator, could attach to its output pin.
Last edited by MarkOZLAD on Wed Dec 01, 2021 12:09 am, edited 1 time in total.
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MarkOZLAD
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Re: TV RGB mod thread

Post by MarkOZLAD »

DotMatrixMoe wrote:I also can't help but to notice that the OSD looks much brighter and/or saturated after removing the voltage dividing resistors. I'll see if it works later today.
Because it is no longer having its voltage divided.
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"Imagine toggle switch OSD modding a TV in 2019" - maxtherabbit
abispac
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Princes tv

Post by abispac »

I have 3 of this disney princes sets, and they are diferent models, i was going to attempt the mod found on youtube but realize is not the mux mod, so i was wondering if someone is kind enough to tell me where to inject the signal based on the specs. Also, if i would need to replace the 680 ohms resitors or leave them in there?? Thanks for any help provided
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Last edited by abispac on Wed Dec 01, 2021 6:14 am, edited 2 times in total.
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DotMatrixMoe
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Re: TV RGB mod thread

Post by DotMatrixMoe »

MarkOZLAD wrote:
DotMatrixMoe wrote:I also can't help but to notice that the OSD looks much brighter and/or saturated after removing the voltage dividing resistors. I'll see if it works later today.
Because it is no longer having its voltage divided.
Yeah makes sense. A previous post of yours also said to replace the OSD inline resistors with 2.4k, and that made the pixels less... weird on the OSD.

On top of that, I did a diagnosis and found out I'm not getting blanking working correctly... but is this the sync data? Looks cool, but I don't keep it on screen too long.

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DotMatrixMoe
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Re: TV RGB mod thread

Post by DotMatrixMoe »

Oops! Forgot to set sync polarities to positive. No more of whatever was happening, but a little shaky when in composite. I'll see if I can find a switch locally for blanking.
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shikikanzero
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Re: TV RGB mod thread

Post by shikikanzero »

So working on a KV-13M42 BA-4D chassis, did a couple of these already, but I kept losing blanking after being on for a while and after some minor troubleshooting found its because the 5v slowly drops down to like .9v after a while. Time for a recap?
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DotMatrixMoe
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Re: TV RGB mod thread

Post by DotMatrixMoe »

I don't know whether I should use the luma pin on the S video port or keep using composite! To be honest, the luma pin seems a bit more reliable.
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Osirus
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Re: TV RGB mod thread

Post by Osirus »

DotMatrixMoe wrote:I don't know whether I should use the luma pin on the S video port or keep using composite! To be honest, the luma pin seems a bit more reliable.
S-video luma usually has less of a horizontal shift to the picture.
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Re: TV RGB mod thread

Post by Osirus »

shikikanzero wrote:So working on a KV-13M42 BA-4D chassis, did a couple of these already, but I kept losing blanking after being on for a while and after some minor troubleshooting found its because the 5v slowly drops down to like .9v after a while. Time for a recap?
Where are you pulling your 5v from?
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DotMatrixMoe
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Re: TV RGB mod thread

Post by DotMatrixMoe »

Probably my last question, but does anyone know where I can get a good sync/audio ground on a BA-4D chassis? I found a ground by the ports, but they’re shared and might become a problem.
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Re: TV RGB mod thread

Post by shikikanzero »

Osirus wrote:
shikikanzero wrote:So working on a KV-13M42 BA-4D chassis, did a couple of these already, but I kept losing blanking after being on for a while and after some minor troubleshooting found its because the 5v slowly drops down to like .9v after a while. Time for a recap?
Where are you pulling your 5v from?
So at first I was pulling it from the test point TP602, but after measuring the voltage on it I had 5v at standby, but when the set was powered on I lost voltage. So I moved it to the 5v off pin 3 on the RF tuner, but then found that I was slowly losing voltage there too. I havent tried tracing further up the circuit, but I did take a quick look at the 9v line which I think the 5v is coming off of? and it seemed stable. Is it the Q650 for the 5v or the components around there thats possibly bad?
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Re: TV RGB mod thread

Post by shikikanzero »

DotMatrixMoe wrote:Probably my last question, but does anyone know where I can get a good sync/audio ground on a BA-4D chassis? I found a ground by the ports, but they’re shared and might become a problem.
That ground should be good, They all share the same ground if you look at the traces.
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Re: Princes tv

Post by MarkOZLAD »

abispac wrote:I have 3 of this disney princes sets, and they are diferent models, i was going to attempt the mod found on youtube but realize is not the mux mod, so i was wondering if someone is kind enough to tell me where to inject the signal based on the specs. Also, if i would need to replace the 680 ohms resitors or leave them in there?? Thanks for any help provided
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R102, R103 and R104 are the "grounding" resistors that you will want to remove. The empty pads left behind can be the RGB injection point. Check the spreadsheet for mux resistor value. OSD factory inlines are 4.7K ohm....
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DotMatrixMoe
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Re: TV RGB mod thread

Post by DotMatrixMoe »

Woot woot, everything is up and running EXCEPT just blanking. You can see the injected signal through the OSD.
It was a problem on my side with sync, turns out I had to disable and re-enable Csync on CRT Emudriver. No more coupling resistors, just send the H-Sync VGA pin to pin 20 on SCART and enable Csync. Love Emudriver 2.0!
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Peeakbo from Microsoft Explorer, it came to haunt us all!
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DotMatrixMoe
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Re: TV RGB mod thread

Post by DotMatrixMoe »

I forgot the most important part, mounting the SCART connector!
I just need to know, do I need both screws and nuts or just screws.

Oh and fellas, stay mature. :lol:
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abispac
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Re: Princes tv

Post by abispac »

MarkOZLAD wrote:
abispac wrote:I have 3 of this disney princes sets, and they are diferent models, i was going to attempt the mod found on youtube but realize is not the mux mod, so i was wondering if someone is kind enough to tell me where to inject the signal based on the specs. Also, if i would need to replace the 680 ohms resitors or leave them in there?? Thanks for any help provided
Spoiler
Image
Image
R102, R103 and R104 are the "grounding" resistors that you will want to remove. The empty pads left behind can be the RGB injection point. Check the spreadsheet for mux resistor value. OSD factory inlines are 4.7K ohm....
understood, thank you kind
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DotMatrixMoe
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Re: TV RGB mod thread

Post by DotMatrixMoe »

Hey, just finishing the mod... and of course I had to have a least ONE caveat. Despite pulling 5V from the chassis along with a 1k resistor to the OSD’s inline resistor (R028) it still didn’t blank the whole screen. And well, the video speaks for itself: https://youtu.be/NHqeStBmE3g

Any ideas?
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shikikanzero
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Re: TV RGB mod thread

Post by shikikanzero »

DotMatrixMoe wrote:Hey, just finishing the mod... and of course I had to have a least ONE caveat. Despite pulling 5V from the chassis along with a 1k resistor to the OSD’s inline resistor (R028) it still didn’t blank the whole screen. And well, the video speaks for itself: https://youtu.be/NHqeStBmE3g

Any ideas?
Whats the actual voltage youre getting at your switch? Try removing that resistor. Also, its actually not that apparant whats going on in that video. Is the image too dim or something? Or is the windows image not the proper image over the blanking?
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DotMatrixMoe
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Re: TV RGB mod thread

Post by DotMatrixMoe »

shikikanzero wrote:
DotMatrixMoe wrote:Hey, just finishing the mod... and of course I had to have a least ONE caveat. Despite pulling 5V from the chassis along with a 1k resistor to the OSD’s inline resistor (R028) it still didn’t blank the whole screen. And well, the video speaks for itself: https://youtu.be/NHqeStBmE3g

Any ideas?
Whats the actual voltage youre getting at your switch? Try removing that resistor. Also, its actually not that apparant whats going on in that video. Is the image too dim or something? Or is the windows image not the proper image over the blanking?
The image is alright, just not blanking as expected. Inputs can still display. I’ll try removing the resistor and measuring the voltage with me.multi,enter.
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DotMatrixMoe
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Re: TV RGB mod thread

Post by DotMatrixMoe »

Removing the 1k resistor I put inline to the chassis 5V worked! RGB is a bit dim, but I think the 910ohm resistors are a bit too high after changing the osd's inline resistors to 2.4k

Edit: I should've looked deeper into the thread, because someone had the same problem as me and solved it by removing the 1k resistor, too. Other than that, just gotta change the RGB inline resistors, make the termination of the RGB permanent, and install a switch!
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Re: TV RGB mod thread

Post by shikikanzero »

DotMatrixMoe wrote:Removing the 1k resistor I put inline to the chassis 5V worked! RGB is a bit dim, but I think the 910ohm resistors are a bit too high after changing the osd's inline resistors to 2.4k

Edit: I should've looked deeper into the thread, because someone had the same problem as me and solved it by removing the 1k resistor, too. Other than that, just gotta change the RGB inline resistors, make the termination of the RGB permanent, and install a switch!
sorry, didnt actually catch what chassis youre working on, sounds like a BA4D? If you got the 910ohm resistors from the chart, that was meant for if you were leaving the original 5.6k resistors in there. If you changed existing to 2.4k like some of the older examples youd need something closer to 400ohms.
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DotMatrixMoe
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Re: TV RGB mod thread

Post by DotMatrixMoe »

Yeah, figured... I was actually soldering now. Changing the OSD in-line resistors did wonders anyways because now it looks better. I’m kind of mixing both the modern and past guide.
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