TV RGB mod thread

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Osirus
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Re: TV RGB mod thread

Post by Osirus »

Did it up with a schematic tool.

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vol.2
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Re: TV RGB mod thread

Post by vol.2 »

Osirus wrote:Did it up with a schematic tool.
Hey! Looking good. 8)
Xpander
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Re: TV RGB mod thread

Post by Xpander »

OK. So I've tried my stock 2 chip snes using a Csync retro gaming scart cable. I've tried sending pin 20 to y and c of s-video input 1. I've also tried futher in on that board on the y and c. I've also tried it on the y in on the junglechip. I've tried these with and without an s-video plugged in.i get an image or white screen
When I get a image it's rolling. Is the rolling image only usually caused by sync issues? Any ideas what I'm doing wrong here?
Last edited by Xpander on Tue Nov 24, 2020 5:27 am, edited 1 time in total.
Xpander
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Re: TV RGB mod thread

Post by Xpander »

Is it OK to be using a Csync scart cable for the snes wired to Luma pin on s-video or should I be using a sync on Luma cable like the one for the ones I've seen for the n64?
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matt
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Re: TV RGB mod thread

Post by matt »

I've found that some TVs have a hard time with Csync from consoles. Composite video or luma is more likely to work.

Also, if your SNES cable is wired for TTL sync you'll need to add a resistor to bring the voltage down. Most TVs won't accept it and it could cause damage over time.
immaburr
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Re: TV RGB mod thread

Post by immaburr »

I've been looking into this mod both in this thread and in some archived FB Group chats. Not much of an electronics expert but feel like after the CRT discharge there isn't much more difficulty to the previous GBS8200 mods I've done.

I own a KV-20M42 but from what I've read the KV-27S42 is nearly the same chassis. This doesn't seem correct when I compare manual model numbers so I wanted to get some confirmation.

Manual for my model:
https://www.manualslib.com/manual/69960 ... e=1#manual

In preparation for the mod I had also been studying this album:https://imgur.com/a/TVU4Qe2 (For the life of me can't find OP.)

@Osiris also had these suggestions in another thread:
I would start by trying the unused RGB inputs on 26/27/28. There's a good chance they are disabled in software, but to check you can grab 1V and put in on Ys on pin 25 and switch your TV to the 'TV' input (static). If the screen goes black when 1V is applied, the inputs are available.

If they are disabled, you can do the standard OSD mix method by pulling R087, R088, and R089 and injecting there. Can discuss further in the RGB mod thread.
With that, I'm trying to get my ducks in a row:

1. I know I should firstly dismantle and discharge the CRT to clean everything up. In the manual (Page 13) it says not to use a grounded Flat-Head screwdriver. Is something like a discharge pen for this: https://www.amazon.com/dp/B07ZYVVYJF/?c ... _lig_dp_it I have visions in my head of doing this and the tube popping like a large lightbulb :shock:

2. To the option of pulling the unused inputs from the Jungle chip I'm pretty sure this is disabled in the software. If this was previously just home used is it safe to assume this? (This is also still not having the set opened.) I don't believe there is currently a way to unlock this via a hardware/software modification is this also correct? This does appear to be the best option but given my limited experience I feel if I'm not able to easily test I'm afraid of messing something up functionality-wise.

3. Also not sure where/how to identify and calculate the resistors/diodes needed.

4. If BNC can be done can the Factory Video and Audio RCA's be modified and replaced BNC bulkhead connectors (Sync, Audio) and then use a BNC to RCA adapter in case the normal RCA Audio and Video want to be used? If this is too much trouble I'm perfectly fine doing Female Scart.

I've dug through this thread a few times to try to identify what I need so apologies if there is something I glazed over or if something is staring at me directly in the face...

Thanks for any help!
qjkxbmwvz
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Re: TV RGB mod thread

Post by qjkxbmwvz »

immaburr wrote:I don't believe there is currently a way to unlock this via a hardware/software modification is this also correct?
Try changing some zeros to ones in the ID options in the service menu.
PitViper75
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Re: TV RGB mod thread

Post by PitViper75 »

qjkxbmwvz wrote:
PitViper75 wrote:All set - needed to plug something into the s-vid jack for it to work. Also moved the video sync ground (though wasn’t the problem).
I recently did a similar set. The S-video connector has a detection pin that connects to ground when the port is in use. I put a short wire between that and the ground pin, which makes S-video always on on Video 1, disabling composite. There's a similar pin in the right audio connector that disconnects it from the left when in use so that you don't get mono when you have the right plugged in - I desoldered that pin, which disabled mono on that input, giving me proper stereo. For the future, I'm planning on rewiring to the unused front input (Video 2). Just need to get a few resistors and caps.
Awesome, thank you! When I redo my setup i'm going to do a breakout box on my "test" shelf for connections to s-vid, composite, and component on multiple CRTs- so those ports will always be plugged in even when not in use.
PitViper75
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Re: TV RGB mod thread

Post by PitViper75 »

Any tips for a Trini AA-1A chassis? I recently snagged a KV-27XBR45 that I want to RGB mod to a SCART connector on back. Can I just tap into the RGB from the closed captioning circuit? Blanking still 5v on this one? THX!!
immaburr
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Re: TV RGB mod thread

Post by immaburr »

Try changing some zeros to ones in the ID options in the service menu.
Oh wow, I didn't know this was a thing! I will look into this more.
PitViper75
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Re: TV RGB mod thread

Post by PitViper75 »

AA-1A chassis (KV-27XBR45)

I'm not going to use the CC circuit, so what's the best way to tackle this? I'm assuming I can tap into where CC IC pins 5,6,7 connect to the PCB or somewhere around there?

Also for YS on the jungle, best way to inject the 5v?

Thanks!!

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Osirus
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Re: TV RGB mod thread

Post by Osirus »

For Ys I use a voltage divider between Vcc and GND for whatever blanking voltage is needed.

Why aren't you using the CC circuit? I don't see any other way. The OSD lines look to be Digital RGB.
PitViper75
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Re: TV RGB mod thread

Post by PitViper75 »

Osirus wrote:For Ys I use a voltage divider between Vcc and GND for whatever blanking voltage is needed.

Why aren't you using the CC circuit? I don't see any other way. The OSD lines look to be Digital RGB.
Hi, thank you for the reply!

Using the CC circuit but don't care if the actual CC works after - was trying to figure out the best place to inject without having to lift pins on the jungle (if possible).
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Osirus
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Re: TV RGB mod thread

Post by Osirus »

PitViper75 wrote:
Osirus wrote:For Ys I use a voltage divider between Vcc and GND for whatever blanking voltage is needed.

Why aren't you using the CC circuit? I don't see any other way. The OSD lines look to be Digital RGB.
Hi, thank you for the reply!

Using the CC circuit but don't care if the actual CC works after - was trying to figure out the best place to inject without having to lift pins on the jungle (if possible).
Should be the same as doing an OSD mux, only you use the CC lines instead. I think removing R101, R103, and R105 and injecting there following MarkOZLAD's chart should be the plan.

https://klovimg.com/images/2018/07/17/O ... uit-v2.png
PitViper75
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Re: TV RGB mod thread

Post by PitViper75 »

Osirus wrote:
PitViper75 wrote:
Osirus wrote:For Ys I use a voltage divider between Vcc and GND for whatever blanking voltage is needed.

Why aren't you using the CC circuit? I don't see any other way. The OSD lines look to be Digital RGB.
Hi, thank you for the reply!

Using the CC circuit but don't care if the actual CC works after - was trying to figure out the best place to inject without having to lift pins on the jungle (if possible).
Should be the same as doing an OSD mux, only you use the CC lines instead. I think removing R101, R103, and R105 and injecting there following MarkOZLAD's chart should be the plan.

https://klovimg.com/images/2018/07/17/O ... uit-v2.png
Thanks! I'm not going to mux it since I don't care about CC working after. I lifted the RGB pins on the CC chip and wired/injecting to the PCB there.

Think 5V will work for blanking? It does on my other moded trinis but none of them are as complicated as this thing. ugg.

This thing is such a nightmare the way the boards are stacked - I can't even get at the IC or input boards to test/tweak while it's together.
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Osirus
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Re: TV RGB mod thread

Post by Osirus »

I couldn't find a datasheet for that Jungle IC so I don't know how blanking for the CC RGB inputs is activated.

You should remove the inline and grounding resistors from the CC lines to inject in order to get the correct 75 ohm terminations for your inputs.
PitViper75
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Re: TV RGB mod thread

Post by PitViper75 »

Osirus wrote:I couldn't find a datasheet for that Jungle IC so I don't know how blanking for the CC RGB inputs is activated.

You should remove the inline and grounding resistors from the CC lines to inject in order to get the correct 75 ohm terminations for your inputs.
Welp, making progress! my rigged 5v blanking switch -> resistor -> Diode -> PIN 10 (YS) of jungle chip is working! Stereo audio good, sync good.

Picture is dark and a little ghosty. I haven't addressed those factory inline 5.6k/ground resistors yet - Think that's the issue?

Thanks for your help! This TV was a little intimidating at first.
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Osirus
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Re: TV RGB mod thread

Post by Osirus »

PitViper75 wrote:
Picture is dark and a little ghosty. I haven't addressed those factory inline 5.6k/ground resistors yet - Think that's the issue?
Probably. The RGB inputs for your mod need to be 75 ohm terminated, those factory grounding resistors are 680 ohm.
PitViper75
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Re: TV RGB mod thread

Post by PitViper75 »

I’m going to pull it out and take another look - was thinking about adding 75ohm surface mounts in place of the factory ground resistors, and removing/bridging the inline ones but the jungle and microcontroller chips are shielded leaving me a tiny alley to work in. May be easier to just move my injecting lines to the jungle pins.

I’ve done v42, s42, and s45 trinis but this thing is another beast lol. It’s basically a cube of PCBs with the ones I need being the last ones to come out of the stack. Can’t de-solder anything because the pads come up even on the lowest setting applying almost no heat, IC pins break just looking at them. Can’t believe how fragile this thing is for a top of the line set (albeit 25 years old).
PitViper75
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Re: TV RGB mod thread

Post by PitViper75 »

Osirus wrote:
PitViper75 wrote:
Probably. The RGB inputs for your mod need to be 75 ohm terminated, those factory grounding resistors are 680 ohm.
OK, injecting RGB directly into the jungle chip - got an odd ghosting issue. You can see like a faint drop shadow on everything... but the crazy part is it goes away while the OSD text is on the screen, then comes back when OSD is exited. anyone run across this? Don't mind the crappy pics - TV hasn't been calibrated yet and lighting off in garage. You can see the shadows in first pic.

Image

Image
tongshadow
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Re: TV RGB mod thread

Post by tongshadow »

That's just a poor grounding point I believe.
PitViper75
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Re: TV RGB mod thread

Post by PitViper75 »

tongshadow wrote:That's just a poor grounding point I believe.
Hmm, i'll double check the grounds in the AM. I'm using luma on the svid for sync, so the video ground is coming from the luma ground pin. Common ground I'm pulling from the ground pin on the closed caption IC.

I wonder if there is some processing going on in there that doesn't play nice with RGB? Odd that it goes away when the OSD text is up. TV didn't have a remote so I cant get to the settings or service menus just yet (one is on the way).
PitViper75
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Re: TV RGB mod thread

Post by PitViper75 »

tongshadow wrote:That's just a poor grounding point I believe.
Grounds appear to be good. I can trace video ground from SCART pin all the way through to the luma ground in the svid jack.

I also tried swapping the main ground to the RF shielding inside the TV but it didn't make a difference. Actually, I had both of the grounds disconnected completely at one point and it didn't seem to change the picture.
Issac Zachary
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Re: TV RGB mod thread

Post by Issac Zachary »

PitViper75 wrote:Actually, I had both of the grounds disconnected completely at one point and it didn't seem to change the picture.
Maybe something is not grounded well on the other end??
PitViper75
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Re: TV RGB mod thread

Post by PitViper75 »

Issac Zachary wrote:
PitViper75 wrote:Actually, I had both of the grounds disconnected completely at one point and it didn't seem to change the picture.
Maybe something is not grounded well on the other end??
Testing with both PS1 and Sega Saturn using RGC SCART cables. Both consoles/cables work great on my 2 other RGB modded trinitrons (27v42, 27s42). I’m baffled as to why the picture looks right when the OSD text is on the screen.
PitViper75
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Re: TV RGB mod thread

Post by PitViper75 »

FIXED!!!!!!!

Found a universal remote that would at least get me into the settings. Turned OFF velocity modulation and the shadows went away!!

Thank you all for your help!!
Issac Zachary
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Re: TV RGB mod thread

Post by Issac Zachary »

PitViper75 wrote:FIXED!!!!!!!

Found a universal remote that would at least get me into the settings. Turned OFF velocity modulation and the shadows went away!!

Thank you all for your help!!
Awesome!

One of these days I'm going to get around to modding my Trinitron.
PitViper75
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Re: TV RGB mod thread

Post by PitViper75 »

Issac Zachary wrote:
Awesome!

One of these days I'm going to get around to modding my Trinitron.
Go for it!! The 27v42 and 27s42 I did weren't that bad - I'm happy with the XBR but not in a rush to work on another one lol
Mrmatt3465
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Re: TV RGB mod thread

Post by Mrmatt3465 »

I have an interesting one.

I have a Sharp 21G-SF1 which is a 21” Sharp CRT with a built in Super Famicom. I have been toying with the idea of modding it to accept RGB as the game input instead of S-Video that it’s currently set up for. I don’t care about being able to use the external inputs or the TV RF functions but I would desire OSD.

A few hurdles: I cannot find any data sheets for the ICs on the board. When I search them I get zero information (probably because the TV itself is pretty rare and the ICs are probably exclusive to this TV). So I don’t have anyway to determine what pins are potentially OSD RGB inputs other than maybe looking at other Sharp TV circuits and trying to find similar components in line (a header area with 3 or 4 inputs with certain resistors in line maybe? Or maybe pulling resistors and seeing if a color drops from OSD?)

The SFC board has an AV out on it and I was planning on grabbing the RGB and CSYNC signals straight from there. If I decided that I don’t actually care about OSD, how can I take the RGB signals from the AV out and interface them potentially just straight to the CRT? Is this even a possibility? From what I understand, the neck board has voltage to the color specifically and a transistor that attenuates the signal based on information from the jungle IC. Would this be where I would drive the signal to if I wanted to tackle this in a simpler matter?

Thanks for your help.

Matt
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vol.2
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Re: TV RGB mod thread

Post by vol.2 »

Mrmatt3465 wrote: I cannot find any data sheets for the ICs on the board.
There's only two ways to do it. Either find the datasheet or use logic probes and a scope to reverse engineer the chip. You'll most likely need a schematic for the actual set as well and that may contain enough details and even a pinout of the chip.

You might be able to get a clue about the ICs by finding similar chips with a different sheet. Often ICs are in a "family" of ICs, and they may even been made by more than one company over time.
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