TV RGB mod thread

[DotMatrixMoe]

I guess you can call me a fellow muxxer! Or... muxee? Whatever! I had a lot more problems to fix, such as sync interference and RGB interference. Firstly, I gave the RGB signals their own original voltage dividing ground so interference is prevented. Secondly, I made all my wires shorter and now I experience NO interference at all!

Spoiler

[realm]

Hello, this is my first post here. I have an RCA F19430 Chassis CN-001N that I want to mod using the OSD RGB Mux mod method developed by Syntax and MarkOZLAD and had a few questions about the mod.

I found the service manual for this particular chassis and have traced the OSD RGB and Blanking circuit to the input of the Jungle chip.

Each OSD RGB out line has a 100p grounded capacitor along with two 1k resistors, one inline and one grounding, and a 0.1U inline capacitor before entering the Jungle chip.
The OSD Fast Blanking line also has two 1k resistors, one inline and one grounding before entering the Jungle chip.

I'm trying to figure out what I need to do with this circuit.

Following what the OSD Mux mod requires I have to...
1) Remove the 1k grounding resistors from OSD RGB lines coming from the Micro Computer
2) Using the chart for the OSD Mux mod I need to add a 91 ohm inline resistor to each of my injected RGB lines along with 75 ohm grounding resistors.
3) Injected Fast Blanking line needs a 1k inline resistor with a 75 ohm grounding resistor.

My questions is do I need to remove the 100p grounded capacitors on the OSD RGB lines or leave them? Also do I remove the 0.1U inline capacitors on the OSD RGB lines?

Thanks to everyone that contributed to this thread and I would also like to thank Syntax and MarkOZLAD for the OSD Mux mod.

[notsonic]

I did the mod with external blanking and rgb mux on my tv.

Testing with my genesis looked fine at first, but after like 30 seconds the RGB input gets dim and the osd starts to blow out. I also had it on for a while diagnosing my mixed up RGB and Blanking lines (I had blanking and one of the colors connected) and didn't notice the picture get dim during that and it was on for a while.

Composite video looks fine. It does not get dim over time like RGB.

I followed the rgb mux circuit. (https://klovimg.com/images/2018/07/17/O ... uit-v2.png)

RGB, Sync, and Blanking are all connected to ground via 75ohm resistors.

I removed 1.8K resistors that tied the OSD to ground.
I added 1n4148 diodes in series after the existing 6.8k inline resistors.
OSD RGB still has 470pf caps to ground near the osd chip.
RGB has the stock 0.1uf coupling caps to the jungle chip.

I removed a 2.7k resistor that tied the OSD blanking to ground. I did not install a diode for blanking.
OSD Blanking still has a 470pf cap to ground near the osd chip and a 6.8k resistor inline.

I calculated a 1.3k resistor for the input RGB, 2.7k for Blanking.

Does it have to do with the jungle chip coupling caps? Maybe the grounding caps near the osd chip? Maybe I blew something by accidentally tying blanking and blue together?


Audio is not hooked up.

Also I tried my SNES and it doesn't seem to output a high enough voltage to enable blanking. It's only showing 1.46v across the 75ohm termination resistor. In comparison the genesis is only outputting a little more at 1.48v but that seems to be enough. Should I just give up on the external blanking and add a switch?

[Syntax]

Find a 5v source from inside the TV and blank via that with a switch, its way less headaches.
I think your on the money with the coupling caps. Upgrade them from 1n to 100n and see if it helps.

[notsonic]

Find a 5v source from inside the TV and blank via that with a switch, its way less headaches.
I think your on the money with the coupling caps. Upgrade them from 1n to 100n and see if it helps.

Isn't 0.1uf equal to 100nf?

But yeah, I think my next step will be to hard wire blanking to remove it as a potential part of the problem.

[notsonic]

I added a diode inline with the blanking signal from the osd chip and put the grounding resistor back in. Then I just found a 5v source and made a button to toggle it. Everything looks pretty great now. The blanking voltage must affect the brightness of the RGB input, and it was in an inbetween state or something.

Anyway, the picture is actually a little too bright now, so I've gotta try adding more reistance inline on the RGB lines.

Here's some pics:

Spoiler

[Syntax]

If you have a sub brightness pot try lower it a touch.

The diode drops .7v off the 5v line.

Without an inline resistor before the grounding one there's no divider and you are feeding 4.3ish volts into the jungle.

It really should have a current limiting resistor or a divider to lower it a touch but it should be fine as its a 5v tolerant chip anyway.

The state it was in before is called Half-Tone Blanking. Its used primarily for OSD.

[notsonic]

I couldn't find a sub brightness pot on the board and nothing in the service menu did anything so I just lowered the screen pot. Composite is still plenty bright so no harm done.

I tried sound but I just got static. I'm gonna try inserting it further along the audio circuit and see if that helps.

I also noticed a dark band down the right side about an inch in width. It goes away when I rotate or wiggle around the RGB or sync lines so I think it's picking up some interference. I might redo it with shielded wire since I've just been using ribbon cable.

The only other problem is a brighter horizontal line is scrolling up the screen slowly. Is this some kind of power interference? I've got the tv plugged into an isolation transformer and emi filter.

[MrW]

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.

Thanks for the info

This is so helpful

I am pretty new at this stuff but will give it a shot

Do you guys have a basic diagram showing the process in case I am visualising this wrong?

[DotMatrixMoe]

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.

Thanks for the info

This is so helpful

I am pretty new at this stuff but will give it a shot

Do you guys have a basic diagram showing the process in case I am visualising this wrong?

While it's not a one size fits all, I suggest looking at the mux diagram at MarkOZLAD's signature.

[MrW]

Thanks guys

I think I might have the general idea

Next problem….

What do you do if i cannot find where Mark has sent me?

I’m struggling to find R916?

What pin on the jungle do I need to send 5v so I can trace it?

[MrW]

Hey guys

I can’t seem to post a picture but I have attempted the mod and it hasn’t ended well

I have ended up with a black screen with just a thin colourful line through the middle

Any ideas?

[Syntax]

Its called vertical collapse, you have forgotten to plug in an earth or knocked a component around on the chassis.

[DotMatrixMoe]

Its called vertical collapse, you have forgotten to plug in an earth or knocked a component around on the chassis.

Yeah... yikes! Better call Shango.

[MrW]

Awesome

Thanks

I wasn’t too confident on my earth so I reckon that would be it

I’ll reassess and hopefully that helps

[DotMatrixMoe]

Good luck. 0_07

[MrW]

Does it matter where I connect my earth from the Jamma?

Is any earth on the chassis fine?

[Syntax]

That has nothing to do with your vertical collapse issue. Fix the TV before you continue.

[maxtherabbit]

Make sure you plugged the deflection coil back in

[RetroGuy818]

Not hard, just the issues that various other configurations gave were a bit misleading to me

Got the focus really nice in the center of the tube:

Hello, Im planning to do this mod on the exact tv. do you have guide or video how you did it, thanks in advanced.

[MarkOZLAD]

Make sure you plugged the deflection coil back in

Would be missing horizontal deflection as well if that were the case.

Likely blown Vertical IC.

[MrW]

All good guys

It was one of the connections from neck board loose

I’m back to a working tv, ow I just need help with the mod

The original manual I directed mark towards was correct but they have the 2 chassis around the wrong way

Mine is the first chassis not the second if anyone can assist?

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

[shikikanzero]

o 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? At first I was measuring the voltage at TP602, 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. Ive swapped out Q650 and it still does it.

[Daripa]

Good day. Could anyone help me please. I want to RGB mod my ctv-1498 it's a small TV branded for a bank. Im struggling to understand the schematic (hopefully the correct one). I'd also like to remove the auto mute feature it's rather annoying. https://ibb.co/vmFMBL2
https://ibb.co/vPmYnBs https://ibb.co/JRYbpLX https://ibb.co/mzXKQQ0

[maxtherabbit]

Make sure you plugged the deflection coil back in

Would be missing horizontal deflection as well if that were the case.

Likely blown Vertical IC.

Not always. Sometimes there are different connectors for H and V drive

[DotMatrixMoe]

All good guys

It was one of the connections from neck board loose

I’m back to a working tv, ow I just need help with the mod

The original manual I directed mark towards was correct but they have the 2 chassis around the wrong way

Mine is the first chassis not the second if anyone can assist?

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

You scared me!
I might be onto something when I say the IC accepts both RGB and YUV but might have to enable RGB in the service menu.
Other than that; pins 45, 46, 47, and 48 seems cozy. (Blanking and RGB <-- Order of pins mentioned). Voltage dividers are R920, R921, and R922.

Edit: Oh and the voltage dividers are 82 ohms.

[realm]

Hello, I have an RCA F19430 Daewoo Chassis CN-001N. I attempted the RGB mux mod and the results are a failure. I'm not sure what I am doing wrong. I had some long wiring because I used plugs to make it easier to detach the wires coming from my BNC connectors.

I have the service manual for this chassis. Here is a link to the schematics of the micro controller and the jungle chip https://www.manualslib.com/manual/47092 ... =20#manual

On my first attempt I removed the 1k terminating resistors from the OSD lines coming from the micro controller to the jungle chip. I then used the chart to select my inline resistor values. Since I was not using diodes on the OSD lines I determined the values to be 91R since the terminating resistors I removed were 1k and 1k for my blanking line. I installed a switch for the OSD blanking and used a 5V leg from the RF Module. I inserted my RGB and blanking lines where I removed the terminating resistors I de-soldered a the composite/L/R Audio connector at the back of the set and used the composite input as my c-sync. My result was a squished black and white image of bars and you can see the OSD is there but almost impossible to make out with the way the picture is displayed.

I removed all of the long wires and I plan on building the mux circuit on a breadboard this time, I just want to make sure I have the resistor values correct. I'm hoping someone could look at the schematic and point me in the right direction.

Thanks

[DotMatrixMoe]

Hello, I have an RCA F19430 Daewoo Chassis CN-001N. I attempted the RGB mux mod and the results are a failure. I'm not sure what I am doing wrong. I had some long wiring because I used plugs to make it easier to detach the wires coming from my BNC connectors.

I have the service manual for this chassis. Here is a link to the schematics of the micro controller and the jungle chip https://www.manualslib.com/manual/47092 ... =20#manual

On my first attempt I removed the 1k terminating resistors from the OSD lines coming from the micro controller to the jungle chip. I then used the chart to select my inline resistor values. Since I was not using diodes on the OSD lines I determined the values to be 91R since the terminating resistors I removed were 1k and 1k for my blanking line. I installed a switch for the OSD blanking and used a 5V leg from the RF Module. I inserted my RGB and blanking lines where I removed the terminating resistors I de-soldered a the composite/L/R Audio connector at the back of the set and used the composite input as my c-sync. My result was a squished black and white image of bars and you can see the OSD is there but almost impossible to make out with the way the picture is displayed.

I removed all of the long wires and I plan on building the mux circuit on a breadboard this time, I just want to make sure I have the resistor values correct. I'm hoping someone could look at the schematic and point me in the right direction.

Thanks

Picture of the symptom?

[realm]

Hello, I have an RCA F19430 Daewoo Chassis CN-001N. I attempted the RGB mux mod and the results are a failure. I'm not sure what I am doing wrong. I had some long wiring because I used plugs to make it easier to detach the wires coming from my BNC connectors.

I have the service manual for this chassis. Here is a link to the schematics of the micro controller and the jungle chip https://www.manualslib.com/manual/47092 ... =20#manual

On my first attempt I removed the 1k terminating resistors from the OSD lines coming from the micro controller to the jungle chip. I then used the chart to select my inline resistor values. Since I was not using diodes on the OSD lines I determined the values to be 91R since the terminating resistors I removed were 1k and 1k for my blanking line. I installed a switch for the OSD blanking and used a 5V leg from the RF Module. I inserted my RGB and blanking lines where I removed the terminating resistors I de-soldered a the composite/L/R Audio connector at the back of the set and used the composite input as my c-sync. My result was a squished black and white image of bars and you can see the OSD is there but almost impossible to make out with the way the picture is displayed.

I removed all of the long wires and I plan on building the mux circuit on a breadboard this time, I just want to make sure I have the resistor values correct. I'm hoping someone could look at the schematic and point me in the right direction.

Thanks

Picture of the symptom?

I have pictures but I don't see and option to upload them here. Is there somewhere to upload files on the site?

[DotMatrixMoe]

Hello, I have an RCA F19430 Daewoo Chassis CN-001N. I attempted the RGB mux mod and the results are a failure. I'm not sure what I am doing wrong. I had some long wiring because I used plugs to make it easier to detach the wires coming from my BNC connectors.

I have the service manual for this chassis. Here is a link to the schematics of the micro controller and the jungle chip https://www.manualslib.com/manual/47092 ... =20#manual

On my first attempt I removed the 1k terminating resistors from the OSD lines coming from the micro controller to the jungle chip. I then used the chart to select my inline resistor values. Since I was not using diodes on the OSD lines I determined the values to be 91R since the terminating resistors I removed were 1k and 1k for my blanking line. I installed a switch for the OSD blanking and used a 5V leg from the RF Module. I inserted my RGB and blanking lines where I removed the terminating resistors I de-soldered a the composite/L/R Audio connector at the back of the set and used the composite input as my c-sync. My result was a squished black and white image of bars and you can see the OSD is there but almost impossible to make out with the way the picture is displayed.

I removed all of the long wires and I plan on building the mux circuit on a breadboard this time, I just want to make sure I have the resistor values correct. I'm hoping someone could look at the schematic and point me in the right direction.

Thanks

Picture of the symptom?

I have pictures but I don't see and option to upload them here. Is there somewhere to upload files on the site?

You can use external sites like Imgur and link them here.