TV RGB mod thread

[metrodigital]

Hi Guys,

I have the opportunity to buy a Sony Trinitron KV-XA25M30A CRT TV, and I want to RGB mod it for use in an arcade.
Would it be a good model to mod?
I'm very new to how this all works, but don't want to miss the opportunity of picking up a good TV that is also the right size for my use.

Here is the link to the TV Service Manual:
https://we.tl/t-KlEZldumJZ

Thanks

[goldendark007]

Imagine toggle switch OSD modding a TV in 2019

That actually made me laugh pretty hard. This topic was actually the last thing I found while looking up info on if RGB modding a consumer CRT was possible. I watched countless videos in different languages and tried to reverse engineer what I was seeing. Good to know it's in the realm of being a working method.

goldendark007

Your TV is an excellent candidate for an OSD/External RGB Mux method. Please don't mutilate your set with an OSD snip method. It's obsolete, inelegant and actually harder to implement.

R803, R804, R805 are the existing OSD termination resistors that you will want to remove. Unfortunately they are surface mount so we can't cheat with the twisting resistor methods I like to use. You will likely need to build a little circuit board or be good at soldering at the scart port.

Resistors R2024, R2025 and R2026 are the factory OSD inline resistors. They are 6800R. If you look at the table in my signature you will see that means we want to use 1100R as our new external RGB inline resistors.

If you want to use scart to blank, follow the diagram. You will just want to use 3300R on your external blanking line. If you want to rig up a switch, find an internal 5V line, run it to a switch input leg, on the output leg connect a 6800R and connect it to the leg of R2027 that is farthest from the Microcontroller (IC2001)

Please check out the diagram in my signature. Your diagram correctly identifies the parts, compare the patterns.

Just for the record, your diagram does an excellent job of showing an OSD Snip method, it is just that the OSD snip method is obsolete.

Also, with the OSD/Ext RGB mux method you won't need to add caps. We will go through the factory ones.

Ok, so I see the new edits - what is the easiest way for me to deal with the surface mount resistors? I will make whatever I need or do whatever I need to at the SCART port, I just need some clarification. As for the rest, I can follow the block diagram to locate the resistors you mention? I will try to locate them on the actual PCB and post some pics later today.

[maxtherabbit]

The SMDs on 90s CRTs have a tendency to be fairly large like 1206, so they are usually pretty easy to work with

[goldendark007]

The SMDs on 90s CRTs have a tendency to be fairly large like 1206, so they are usually pretty easy to work with

Surface Mount Diodes? I am sure I can handle it, just need the clarification on what I am doing hah. My basic understanding up to this point can be summed up by this image:

Edit: there should be a 6800R resistor coming off the blanking out.

[maxtherabbit]

No mate the joke was that the switch is obsolete. You want to wire it up like this:


This allows the OSD to overlay the external RGB signal for a factory like experience with no manual switching

[goldendark007]

No mate the joke was that the switch is obsolete. You want to wire it up like this:


This allows the OSD to overlay the external RGB signal for a factory like experience with no manual switching

Okay - I am tracking now. Pardon my ignorance, but where do I tie in my external lines? Is there a specific location from the MC to the Jungle that I tie my wires into? My guess is right after the MC inline resistors.

Edit - alright, I get why it was important to note that the inline resistors are surface mounts. I need to tie my external line in the outgoing leg of the inline resistor from the MC, correct? Can I still do that with a SMD?

Thanks in advance- this seems like a much easier job than anticipated.

[MarkOZLAD]

Okay - I am tracking now. Pardon my ignorance, but where do I tie in my external lines? Is there a specific location from the MC to the Jungle that I tie my wires into? My guess is right after the MC inline resistors.

Edit - alright, I get why it was important to note that the inline resistors are surface mounts. I need to tie my external line in the outgoing leg of the inline resistor from the MC, correct? Can I still do that with a SMD?

Thanks in advance- this seems like a much easier job than anticipated.

The factory OSD termination resistors R803, R804, R805 will be removed. You could try and solder your external RGB lines to the pads left behind, the ones that have connectivity to the jungle. It might be easier to solder to the legs of resistors R2024, R2025 and R2026 that are on the jungle side. Perhaps connect your 1100R resistors to those legs and the run wires from them to the scart port. At the scart port put in your 75R terminations to ground.

[goldendark007]

Okay - I am tracking now. Pardon my ignorance, but where do I tie in my external lines? Is there a specific location from the MC to the Jungle that I tie my wires into? My guess is right after the MC inline resistors.

Edit - alright, I get why it was important to note that the inline resistors are surface mounts. I need to tie my external line in the outgoing leg of the inline resistor from the MC, correct? Can I still do that with a SMD?

Thanks in advance- this seems like a much easier job than anticipated.

The factory OSD termination resistors R803, R804, R805 will be removed. You could try and solder your external RGB lines to the pads left behind, the ones that have connectivity to the jungle. It might be easier to solder to the legs of resistors R2024, R2025 and R2026 that are on the jungle side. Perhaps connect your 1100R resistors to those legs and the run wires from them to the scart port. At the scart port put in your 75R terminations to ground.

Just to be clear: I need to remove the three resistors you mentioned earlier and solder the 1100R resistors to jumpers from the SCART port to the pads on the Jungle side? When I remove R803, R804, and R805, the OSD is still connected to the Jungle? Or am I removing any functionality? If it is easier for me to connect the R2024, R2025, and R2026 just let me know.

When I wire up the SCART port, can I just ground the channels to each of the pins next to them? I was planning to use an audio breakout, so I wanted to leave the audio disconnected as well. I also ground everything that isn't connected to TV, right? I am also still a little unclear as to how the SYNC is wired in. Do I just run a wire from the Y-in on the Jungle chip or am I, again here, missing something?

Thanks for all the help. Ordering everything I need right now.

[MarkOZLAD]

> Just to be clear: I need to remove the three resistors you mentioned earlier

Yes


> and solder the 1100R resistors to jumpers from the SCART port to the pads on the Jungle side?

Yes

> When I remove R803, R804, and R805, the OSD is still connected to the Jungle?

It will remain connected but the voltage will not be being divided by the R803/804/805 because they are gone. If you don't understand voltage division it's worth looking up because it is the principle being used. The 1100R and 75R we will be adding will become our new "R2" of our voltage divider on the OSD RGB circuit. The R1 of the voltage dividers are the R2024, R2025, and R2026 factory OSD inlines.

> Or am I removing any functionality?

The aim of the OSD/Ext RGB mux is to maintain the OSD, mixed in with the external RGB rather than having to switch between them.

> If it is easier for me to connect the R2024, R2025, and R2026 just let me know.

That's an implementation decision for you to decide. The pads of the removed resistors that lead to the jungle and the legs of the R2024, R2025, and R2026 that are on the jungle side are identical as far as the circuit goes.

> When I wire up the SCART port, can I just ground the channels to each of the pins next to them?

I assume you mean connect pins 15 to 13, 11 to 9 and 7 to 5, each with 75R...Yes. A good idea to connect 13, 9 and 7 to the TV's chassis ground too. It is not mentioned in my diagram....Hmmmm.

These will act as your 75R termination on the RGB video.

> I was planning to use an audio breakout, so I wanted to leave the audio disconnected as well.

My diagram shows you how you can achieve this if you want to break it out from the scart port.

> I also ground everything that isn't connected to TV, right?

My diagram tells you which pins to ground to the TV chassis ground

> I am also still a little unclear as to how the SYNC is wired in. Do I just run a wire from the Y-in on the Jungle chip or am I, again here, missing something?

Connect it to the AV port Video in. You can break it out to an RCA and plug it in or you can wire it underneath. This is also shown on my diagram, you likely won't need the mono mix though

> Thanks for all the help. Ordering everything I need right now.

[goldendark007]

Ok, last dumb question before I start taking parts out of the tv.. does the voltage or tolerance of my resistors matter? I am about to order off Amazon and just want to make sure I am getting what I need.

As for voltage division, I have a vague idea of how it works but I will definitely read into it. Thanks for all the help thus far!!!

[maxtherabbit]

Ok, last dumb question before I start taking parts out of the tv.. does the voltage or tolerance of my resistors matter? I am about to order off Amazon and just want to make sure I am getting what I need.

As for voltage division, I have a vague idea of how it works but I will definitely read into it. Thanks for all the help thus far!!!

1/8th watt are fine

tolerance does kinda matter, get 1% or better they are cheap enough to not bother with anything less

[goldendark007]

Ok.. really my last dumb question: can I use something like this in case I need to open TV later and take back off? https://www.amazon.com/RGBZONE-20Pairs- ... B075K6N7DF


If you know of something better please do not hesitate to let me know.

Thanks again!!!

[maxtherabbit]

Ok.. really my last dumb question: can I use something like this in case I need to open TV later and take back off? https://www.amazon.com/RGBZONE-20Pairs- ... B075K6N7DF


If you know of something better please do not hesitate to let me know.

Thanks again!!!

sure, just try to keep your wires short and routed away from the HV systems

700mVpp analog RGB signals are not very resilient with respect to reactive coupling

[goldendark007]

Ok.. really my last dumb question: can I use something like this in case I need to open TV later and take back off? https://www.amazon.com/RGBZONE-20Pairs- ... B075K6N7DF


If you know of something better please do not hesitate to let me know.

Thanks again!!!

sure, just try to keep your wires short and routed away from the HV systems

700mVpp analog RGB signals are not very resilient with respect to reactive coupling

Would i be better off with no coupling then?

[maxtherabbit]

Would i be better off with no coupling then?

if you are referring to mechanical coupling i.e. using the pins and socket, then no that won't really make a difference either way

[goldendark007]

Then I must admit I am confused by what is meant by reactive coupling. Is there a better coupler I could get? I wanted one with 6 pins (R, G, B, Sync, Blank, Chassis Ground) and was thinking of something like this: https://www.amazon.com/gp/product/B07G9 ... C3WD&psc=1

If this does not suffice.. or if you have any better suggestions then I will take it! I am looking to order everything by tonight/tomorrow so I can get to it when I am back this weekend.

[maxtherabbit]

Then I must admit I am confused by what is meant by reactive coupling. Is there a better coupler I could get? I wanted one with 6 pins (R, G, B, Sync, Blank, Chassis Ground) and was thinking of something like this: https://www.amazon.com/gp/product/B07G9 ... C3WD&psc=1

If this does not suffice.. or if you have any better suggestions then I will take it! I am looking to order everything by tonight/tomorrow so I can get to it when I am back this weekend.

https://en.wikipedia.org/wiki/Inductive_coupling

https://en.wikipedia.org/wiki/Capacitive_coupling

"coupling" in this context refers to the interplay of electric fields, nothing to do with a physical coupler

[MikeIronFist]

Hey y'all, I've got a KV-27S42 so I hoped you guys might have a good idea of how to properly do the OSD Mux-via-resistors mod.
I've already done the switch-based mod on this set with 75 ohm termination and the end result was great. I didn't have to lift the legs on any of the chips, I just removed C316, C317 and C318 (the caps connecting the jungle to the OSD) and I put 0.1 uf caps on new wires to the jungle IC's RGB and BLK inputs.

I stripped and soldered some Du Pont wires for every connection so I could easily reverse or change the new setup. So, once I know exactly what I need, I can basically just make drop-in replacement wires to connect to the board and SCART socket. The one thing that's tripping me up is what to do with the OSD blanking. Seems like it merges with the O-YM line and goes into a 10k ohm resistor (R004) to chassis ground.


Here's an image of the OSD chip and Jungle taken straight from the service manual. OSD blanking line is highlighted in orange:

Spoiler

So if I understand the resistor table correctly, I need at least 837 ohms of resistance on each of the RGB lines since the in-line OSD resistors are 5.6k. But what am I doing with the OSD blanking line in terms of resistors? Am I adding a 10k resistor to the external blanking? Am I also removing the 10k resistor that connects the original line to chassis ground? I'm just a little uncertain if I'm following the diagram correctly and want to be sure.

[digitron]

Anyone have instructions on RGB modding a Toshiba 24AF45 by chance? I have a vague understanding of the idea but if someone could hold my hand, I'd greatly appreciate it. I am very experienced at soldering but my electronics skills are low. I can follow directions but I'm a little slower than most of you.

The TV has component but I'm trying to get Groovymame running through my Extron 109 hence the need for an RGB TV.

From the service manual:




Is this the Welcome to the Jungle chip?

[MarkOZLAD]

The Toshiba 24AF45 will be able to be modded using an OSD/External RGB Mux method. I’ve only had a quick look but it appears you will want to remove the OSD RGB grounding resistors R141, R142 and R143.

The factory OSD inline resistors are R127, R128 and R129. They are 3300R so would use 470R as your mixing resistors.

IC101 is the micro controller. IC601 is the jungle....baby!

[digitron]

The Toshiba 24AF45 will be able to be modded using an OSD/External RGB Mux method. I’ve only had a quick look but it appears you will want to remove the OSD RGB grounding resistors R141, R142 and R143.

The factory OSD inline resistors are R127, R128 and R129. They are 3300R so would use 470R as your mixing resistors.

IC101 is the micro controller. IC601 is the jungle....baby!

I sincerely thank you for reply MarkOZLAD.

1 - De-solder grounding resistors R141, R142, and R143.
2 - Where exactly am I soldering the wires from the Jungle (IC601)? From the leading resistor pads R127, R128, and R129?
3 - Do I need to run any wiring between the OSD chip and the Jungle?
4 - RGB/RCA jacks - can I use instead of SCART?
5 - What does the blanking line do and where do I get my Sync from?
6 - Are 1/4W 0.25W resistors ok to use?
7 - Do I need to do anything with the "existing TV Capacitors"?
8 - Use 470R resistors inline to the R,G,B connectors and 75ohm resistors going to their ground. (External)
9 - For BL (R145, 2.2kR in the schematic below) What do I do here?

How far off am I here, lol..

[MarkOZLAD]

> I sincerely thank you for reply MarkOZLAD.

No worries.

> 1 - De-solder grounding resistors R141, R142, and R143.

Yep

> 2 - Where exactly am I soldering the wires from the Jungle (IC601)? From the leading resistor pads R127, R128, and R129?

That will depend on where you find it easiest. Looks like everything's surface mount parts so it will be a bit finicky. There a three main options....The "legs" of R127, R128, and R129 that are farthest from the micro controller, the pads from the desoldered R127, R128, and R129 that aren't grounded or the legs of C136, C137 and C138 that are farthest from the jungle.

> 3 - Do I need to run any wiring between the OSD chip and the Jungle?

Nope. With the mux method we are "crossing the streams"

> 4 - RGB/RCA jacks - can I use instead of SCART?

Definitely can. That's what the 8 Bit Guy did in his mod. If you haven't seen his video it's worth a look.

> 5 - What does the blanking line do and where do I get my Sync from?

You will put your sync straight into the AV port.

...Blanking, I will get to that in a second.

> 6 - Are 1/4W 0.25W resistors ok to use?

Yes

> 7 - Do I need to do anything with the "existing TV Capacitors"?

No

> 8 - Use 470R resistors inline to the R,G,B connectors and 75ohm resistors going to their ground. (External)

Yep. Kinda like...

External R comes in to the RCA port in the signal part. The RCA signal part has a 75R resistor that connects it to the ground. The signal also goes through a 470R and then into the chassis. The RCA ground shield gets connected to the ground on the TV.

> 9 - For BL (R145, 2.2kR in the schematic below) What do I do here?

see below

> How far off am I here, lol..

You are getting there.



Ok, for blanking...

If you are looking to use RCA, I assume you will just want a switch to force RGB. We should be able to do something really simple.

We will want to find a 5V source, I will let you work that out. We will then want to feed this into the blanking circuit in a way that mimics the Micro controller's existing blanking circuit, but this TV has a weird blanking circuit...

The datasheet for the M61283FP says that external RGB is output when pin 24 is at 4.0-5.0V.

What I would try is to tie a 5V line to one leg of a SPDT switch and the output of the switch would then be connected to the leg of the factory diode D105 that is farthest from the micro controller. Of course you only need a switch if you want to be able to disable the external RGB input, you can hardwire it if you want a dedicated RGB monitor.

This should give us 5V at pin 24 when the switch is on and the factory Diode D105 will prevent us connecting the blanking leg of the micro controller directly to 5V.

[digitron]

Thanks again Mark, I ordered up the parts I need to attempt this project. I'll followup in a week or two, take care.

[MarkOZLAD]

Thanks again Mark, I ordered up the parts I need to attempt this project. I'll followup in a week or two, take care.

Looks like there's a fella, u/ottguy74, on Reddit/crtgaming group that has already mux modded the same chassis.

https://www.reddit.com/r/crtgaming/comm ... f44_14_tv/

Unfortunately his image gallery is dead.

Good news for you though, seems it will work.

Perhaps you could join the group and ask him how exactly he did it. I'm thousands of miles away and have never even seen one of these sets!

[digitron]

Thanks again Mark, I ordered up the parts I need to attempt this project. I'll followup in a week or two, take care.

Looks like there's a fella, u/ottguy74, on Reddit/crtgaming group that has already mux modded the same chassis.

https://www.reddit.com/r/crtgaming/comm ... f44_14_tv/

Unfortunately his image gallery is dead.

Good news for you though, seems it will work.

Perhaps you could join the group and ask him how exactly he did it. I'm thousands of miles away and have never even seen one of these sets!

Appreciate it, I sent him a message.

Regarding the diodes, I have some t4148 diodes, can/should I use them? Since I won't be running any wires between the micro controller and the jungle, do I even need them?

[MarkOZLAD]

Regarding the diodes, I have some t4148 diodes, can/should I use them? Since I won't be running any wires between the micro controller and the jungle, do I even need them?

I don't use diodes on my mods anymore. You can if you want but I think they're superfluous. It would likely be difficult to find a place to install them on your chassis anyway.

[digitron]

Regarding the diodes, I have some t4148 diodes, can/should I use them? Since I won't be running any wires between the micro controller and the jungle, do I even need them?

I don't use diodes on my mods anymore. You can if you want but I think they're superfluous. It would likely be difficult to find a place to install them on your chassis anyway.

So far, so good

Grounding resistors removed, R, G, B, and Blanking wires in:

>
> 8 - Use 470R resistors inline to the R,G,B connectors and 75ohm resistors going to their ground. (External)

Yep. Kinda like...

External R comes in to the RCA port in the signal part. The RCA signal part has a 75R resistor that connects it to the ground. The signal also goes through a 470R and then into the chassis. The RCA ground shield gets connected to the ground on the TV.

Just to confirm - On the RCA, the signal (center nipple) goes to the 470R, then the ground (shield) goes to the 75R, then to chassis, correct?

For the 5v to the switch, I pulled from W812 (Tuner) +5V:

[MarkOZLAD]

Can run one ground wire to all three RCA port grounds, daisy chained if you like.

[digitron]

Can run one ground wire to all three RCA port grounds, daisy chained if you like.

You rock Mark!! Thanks for helping me through this, whether I get it to work or not, can't thank you enough. Now to hurry up and wait for the mailman to bring me my resistors.

I would've never guessed you could put a resistor between the signal and ground like that!

[MarkOZLAD]

I would've never guessed you could put a resistor between the signal and ground like that!

It definitely is a concept people struggle with at first, me included. That's the "75 Ohm Termination".