TV RGB mod thread

[Pikkon]

Hi there, I'm new to this whole CRT modding thing, and I'm having a bit of an issue. I have magnavox 20MT1331/17 and after several weeks of research I decided to attempt to mod in component input as outlined in this post: viewtopic.php?f=6&t=56155&p=1440296#p1440296. After many, many checks with a multimeter, I believe I've wired it all up correctly. However, the CVI input option never appears, no matter what value I set in the service menu for OP5. My biggest clue thus far is that while the service manual linked in the post I was following says that a bit value of 8 on OP5 should enable CVI, it actually enables an AV channel labelled FRONT, which the manual says should be on a bit value of 16. And 16 does nothing, even after attaching the blanking pin to 8V with a surface mount 1k resistor, as instructed.

Am I just possibly on a different firmware that doesn't support component and therefore SOL? Or am I missing something? Thanks in advance.

For OP5 try to input 204.

Also you shouldn't need any other voltage at the blanking,think it has voltage by default.

[matt]

Hi there, I'm new to this whole CRT modding thing, and I'm having a bit of an issue. I have magnavox 20MT1331/17 and after several weeks of research I decided to attempt to mod in component input as outlined in this post: viewtopic.php?f=6&t=56155&p=1440296#p1440296. After many, many checks with a multimeter, I believe I've wired it all up correctly. However, the CVI input option never appears, no matter what value I set in the service menu for OP5. My biggest clue thus far is that while the service manual linked in the post I was following says that a bit value of 8 on OP5 should enable CVI, it actually enables an AV channel labelled FRONT, which the manual says should be on a bit value of 16. And 16 does nothing, even after attaching the blanking pin to 8V with a surface mount 1k resistor, as instructed.

Am I just possibly on a different firmware that doesn't support component and therefore SOL? Or am I missing something? Thanks in advance.

What was your original OP5 value?

[RIPConMan]

What was your original OP5 value?

It was 192. I tried 200 as the original post said, as well as 255 just in case any of the settings did anything useful. Neither brought up the CVI input option.

[PompPenguin]

Hello,
I recently found an Orion TVDVD092, a 9" CRT with DVD combo, and decided to try to RGB mod it. I found a similar tv (Toshiba MD13P3) and it's schematic:
https://c.searspartsdirect.com/mmh/lis_ ... 405081.pdf

I was able to get the OSD to stay on with a switch to the blanking pin on the chroma, sending it 5v. I am sending the RGB directly through some jumpers on top of the board. I am syncing with composite using the front input. This is my first mod and I am having weird results with the colors being too bright and the text being illegible. I tried bridging 75ohm resistors to ground, but that made the colors too dark. When using 0.1uf capacitors the image sharpened dramatically and I could read the text, but the colors were either too dark or way off. If anyone knows what I am doing wrong, please let me know.

I marked the images as spoilers

Top of the board before mod:

Spoiler

Chroma chip:

Spoiler

Wire job of direct RGB and blanking to chroma:

Spoiler

Image result from sending RGB directly to those jumpers:
The colors seemed to be too bright and I can't see any of the text at the top
(Mario NES version)

Spoiler

Adjusting each RGB value with inline 2k potentiometers on each line:

Spoiler

colors seem off and text is illegible
(240 test suite, Genesis on Mister via VGA IO board)

Spoiler

[MarkOZLAD]

Hello,
I recently found an Orion TVDVD092, a 9" CRT with DVD combo, and decided to try to RGB mod it. I found a similar tv (Toshiba MD13P3) and it's schematic:

Looks like the RGB input is digital. Colours are either on or off.

[retromaniak]

What values should the resistors have in the case of RGB Mod in such a TV? (Roadstar CTV-1010XKT)


The original diagram is here.

[matt]

What was your original OP5 value?

It was 192. I tried 200 as the original post said, as well as 255 just in case any of the settings did anything useful. Neither brought up the CVI input option.

Hmm, that should work - it did on my 14" Magnavox. Did you unplug the TV for 10 seconds and restart?

Have you tried 196? That normally enables S-Video.

[RIPConMan]

Hmm, that should work - it did on my 14" Magnavox. Did you unplug the TV for 10 seconds and restart?

Have you tried 196? That normally enables S-Video.

I have been unplugging and restarting my TV every time I change settings, yes.

196 doesn't seem to enable any new channels either. I only have AV available on that setting.

I don't know if it's relevant, but I might as well note that it's quite a late model 20MT. October 2006, according to the back of the unit.

[Bryanjc08]

Hi guys not sure exactly where I should post this I have a JVC AV-20420 that i rgb modded with standard 75 ohm termination to ground on the RGB lines and the image is super washed out like almost white and when I turn the switch from composite to the RGB the whole screen goes white does anyone know what I did wrong and how I can fix it.

[Syntax]

Just posting that you modded a JVC AV-20420 doesnt help us help you much.
A model number for the jungle would be much more useful to check see if this is stuck in YUV country or not.
White screen could be that or wrong terminations, remove sync or blanking and see if its still white but rolling black bars.
That service manual sucks.

[Bryanjc08]

So the jungle chip is ta1242 so I have 3 volts going to blanking and my RGB lines are only terminated to ground with a 75 ohm resistor. I was reading through a guide for the muxing method and from that it looks like I may also need an inline resistor on the RGB lines and their value should be based on the resistors that are coming out of the chroma chip witch are 4.7k resistors so according to the muxing method I would need a 750 ohm inline resistor on the RGB lines as well. Can someone confirm if this is correct. Thanks!

[MarkOZLAD]

So the jungle chip is ta1242 so I have 3 volts going to blanking and my RGB lines are only terminated to ground with a 75 ohm resistor. I was reading through a guide for the muxing method and from that it looks like I may also need an inline resistor on the RGB lines and their value should be based on the resistors that are coming out of the chroma chip witch are 4.7k resistors so according to the muxing method I would need a 750 ohm inline resistor on the RGB lines as well. Can someone confirm if this is correct. Thanks!

Can you tell us more about how you modded it?

There is a similar mod underway being documented here..

viewtopic.php?f=6&t=69727

You might be able to find some useful info there.

[Bryanjc08]

So for the mod I wired up the scart connector and the only leads that are terminated 75ohm to ground is the RGB lines. I pulled the jumpers for the r,g,b,ys lines and wire straight into the board the and they go to a 2 way 4 pole switch the goes from stock osd signal to the scart input I used 9 volts with a voltage splitting circuit to bring it down to 3 volts. Other than that I know oh my scart connections are wired properly and I'm getting an image it's just super washed out. From the maxing method I'm assuming I just need to add in my resistors to the RGB lines going to try that in the next couple days and hopefully that fixes the problem I'll post an update if it works.

[MarkOZLAD]

If you’ve done a switch mod you won’t need mux resistors.

[Bryanjc08]

So then what could be causing my image to be so washed out?

[Slammer661]

I did an rgb mod with a Sony trinitron through the closed caption chip. I got sync through video 1,ground through “e” pin and both L and r sounds all through the broad. The rgb signals and the ys with the 5v was taken from the closed caption slot.plus I bridge all the grounds to the “e” pin on the board. I got the capacitors to resistors to ground. I also have a 3 pin switch which is wire to the cc slot to the ys and 5v. Which does nothing when on and off. Everything works, video and sound. Now I have a yoke issue but I don’t think it can fix it through there. I’ve the service menu but I can’t get the tilt counter clockwise, only up and down/ left to right.

[MarkOZLAD]

So then what could be causing my image to be so washed out?

Pretty hard to tell from the other side of the planet.

Perhaps it’s worth adjusting the screen control on the flyback.

[poponon]

Hey all - just thought I'd ask in this thread for recommendations on understanding fundamentals of CRT driver board circuitry / testing. I have been interested in modification of consumer CRTs for some time now and want to take the plunge to really start understanding this stuff and hopefully start working on my own solution or joining in other people's projects.

[MarkOZLAD]

Hey all - just thought I'd ask in this thread for recommendations on understanding fundamentals of CRT driver board circuitry / testing. I have been interested in modification of consumer CRTs for some time now and want to take the plunge to really start understanding this stuff and hopefully start working on my own solution or joining in other people's projects.

Randy Fromm has a bunch of YouTube videos.

[poponon]

Thank you - just checked these out quickly - lots to catch up on here. Thanks man. any books or or texts or anything too , really trying to get my basics down. background in EEng / compsci for idea of where I'm jumping off from

[poponon]

Just finished listening to his CRT Workshop #1 video - this is just the sort of thing I've been looking for! An old great mind sharing the secrets of the trade we would not have been able to hear otherwise. Thanks so much for sharing

[ClassicsRisingEnt]

Hello everyone. Recently picked up some PVM's dirt cheap, but they're S video and composite only. Chip is a TA8801AN . Here's the PDF.

https://www.alldatasheet.com/datasheet- ... 801AN.html

These may all be stupid questions.

Where should I tie in? The RGB outputs (pins 13-15) or inputs (pins 16-18)?
To which pin does sync need to connect?
To which pin do I connect the blanking switch?
What kind of components need to be inbetween the RGB connections on the outside of the monitor and the connection to the chip?

Thanks for putting up with my lack of experience. I look forward to your answers.

[PlanesWalker308]

Hello everyone, I am new to the realm of RGB modding crts and was wondering if I could get a little help with this JVC AV-36D501 that I recently picked up.

From the few videos I've watched and research I've done, I understand the concept of RGB modding pretty well, and I definitely have the solder skills to do it, I just want to make sure I don't mess up this amazing machine and get it right the first time. Here is a snapshot of the schematic for my set. If my understanding is correct, I need to wire in my RGBs signal between IC701 and IC201, do I simply inject the RGB signal directly into the RGBs legs of the 201 chip?



Thanks in advance for any help!

[Osirus]

Hello everyone. Recently picked up some PVM's dirt cheap, but they're S video and composite only. Chip is a TA8801AN . Here's the PDF.

https://www.alldatasheet.com/datasheet- ... 801AN.html

These may all be stupid questions.

Where should I tie in? The RGB outputs (pins 13-15) or inputs (pins 16-18)?
To which pin does sync need to connect?
To which pin do I connect the blanking switch?
What kind of components need to be inbetween the RGB connections on the outside of the monitor and the connection to the chip?

Thanks for putting up with my lack of experience. I look forward to your answers.

Unfortunately it uses digital RGB inputs.

[ClassicsRisingEnt]

Hello everyone. Recently picked up some PVM's dirt cheap, but they're S video and composite only. Chip is a TA8801AN . Here's the PDF.

https://www.alldatasheet.com/datasheet- ... 801AN.html

These may all be stupid questions.

Where should I tie in? The RGB outputs (pins 13-15) or inputs (pins 16-18)?
To which pin does sync need to connect?
To which pin do I connect the blanking switch?
What kind of components need to be inbetween the RGB connections on the outside of the monitor and the connection to the chip?

Thanks for putting up with my lack of experience. I look forward to your answers.

Unfortunately it uses digital RGB inputs.

I unfortunately came to the same conclusion right after making that post. I am now looking into doing the neckboard mod.

[matt]

Hmm, that should work - it did on my 14" Magnavox. Did you unplug the TV for 10 seconds and restart?

Have you tried 196? That normally enables S-Video.

I have been unplugging and restarting my TV every time I change settings, yes.

196 doesn't seem to enable any new channels either. I only have AV available on that setting.

I don't know if it's relevant, but I might as well note that it's quite a late model 20MT. October 2006, according to the back of the unit.

I remembered a few days ago that I did in fact have a 20MT1331/17 in storage that someone gave to me a while ago. So, I pulled it out and had the same results as you did. No SVHS or CVI input, just "front". I think we might be SOL on this one.

My 20MT is from July 2005. Meanwhile, the 14MS (that does work with the component mod) is from May 2006.

I did notice that the firmware ID was listed as L03UM1 on the 20MT, and L03UN1 on the 14MS. According to the service manual, there are different firmware versions for mono and stereo TV. I'd guess that some features are missing from this model vs the 14MS2331 and 20MS2332.

[mgerety]

EDIT -- Previous post was a configuration issue.

I've modded a KV-27S42, and I really want to push the sync through the SVideo, but I can't get it to detect the sync through the luma pin. Does anyone know how I can force the TV to think the SVideo cable is plugged in?

[ClassicsRisingEnt]

Here's a fun question. For all of these monitors that do not have analog RGB inputs on the jungle chip, would it be possible to use a jungle chip that does have analog RGB inputs, hook up the 5V (or whatever voltage it needs) and GND, run your SCART connection into that, and tie it in past the RGB outputs on the original jungle chip? If so, does any one have a part number for a jungle chip that there might be a lot of NOS of?

[Dreamcazman]

Hey all, hoping someone can check the mod I recently did to my Sony KV-XJ29M31 (BG3R chassis) & clarify that I've done it correctly.

I followed this guys video https://www.youtube.com/watch?v=nntNJcyqhbE who in turn got his info from here, but instead of using a bit of vero board, I did things a little differently.

To summarise, I removed the teletext board, reused the connector & soldered the RGB lines with a 560ohm resister to each. I desoldered the 470ohm grounding resistors on the underside of the board (R063, R064 & R065) & replaced them with 75ohm resistors. The blanking line has a 470ohm resistor in line & tapped 5v from IC100 (as seen in pic).







For the most part, the mod works great, however the RGB picture does seem to be a little dull when compared to the OG Xbox via component. If I adjust the brightness, the blacks end up rather grey & look washed out. Is this normal?

Any suggestions.

PS. I also found a good spot for a push switch, where an S-video port would go

[Cliggster]

So, I'm having quite a peculiar issue with my newly RGB modded KV-27S42 and I'm hoping someone here has had the same issue and figured out a solution. I have successfully RGB (SCART) modded the aforementioned set (chassis BA-4D), plugging sync into luma on s-video through an s-video pigtail wired directly to the back of the female SCART head, and all of my consoles WORK accept for ONE which no longer syncs with the TV for some odd reason.

So, what happened? Well, the short version is that I went down in my basement and fired up the TV and my Pi, played games for a couple hours, went to bed, woke up the next day, fired everything up again, and the TV would not sync.

Notes:
*I have ruled out the RGB-PI setup as being at fault, as it works fine if I pipe sync into the Composite IN on the affected TV (albeit with horizontal shifting), and also works fine on my RGB modded Wega (also wired to pipe sync into luma on S-Video) and my PVM.
*All of my consoles connect to the TV the same way, through SCART.

What I have tried while using the Pi:
*Rubbing sync lines together while checking for any sign of connection. TV acts like I'm not even connecting sync at all, but I know sync line is hot because if I connect it to composite in the TV syncs.
*Connected various value resistors inline with sync. No change.
*Tried terminating sync line with 75-ohm resistor, just for shits. No change.
*Tried connecting various value capacitors inline with sync. Same outcome. TV acts like no sync is connected.

My issue seems to be weirdly limited to the using the PI with the S42, as I only have issues with either device when using them together.

Anyway, my goal is to figure out why my TV suddenly stopped accepting c-sync into s-video for ONE console. Thanks in advance.