TV RGB mod thread

[Syntax]

If you put diodes in series on the OSD you need pull ups to compensate the .7v drop right?

After dissecting many sets I'd toyed with this idea with Mark but haven't had a chance to play with it as I've run out of sets.

The idea was to run scart as usual with 75 ohm termination and 100n caps, and connect the OSD to the scart rgb lines via series signal diodes and a triple gang pot for pull up till it looks sweet and then replace with corresponding resistors.
This way there's no division of termination resistors.

[viletim]

If you put diodes in series on the OSD you need pull ups to compensate the .7v drop right?

Usually the OSD signals are 5Vpp or 3.3Vpp. They require series resistors. In the case of the Daewoo TV I just mentioned, the amplitude of the OSD signal (blue) can be calculated as follows.

VCC = 5V (of OSD microcontroller)
R740 = 1200
R541 = 150
R531 = 75
Rsource = 75 (only when something is plugged in)

Vosd = (VCC - 0.7) / (R740 + R541 + (R531 || Rsource)) * (R541 + (R531 || Rsource))

The 0.7 drop is to account for the diode D703.

[evilsim]

Thanks for the advice Tim, I think I'll get rid of these Panasonics and others with TDA chips and wait until better units come along. One of the panasonics has YUV input so that one is still handy. I have a friend at Zeiss who I bumped into today and I now have him on the prowl for good old medical Sony crt's for me, so fingers crossed he finds a few.


I took a screenshot of the image from P65 of the daewoo manual, here it is.
I've added the "OSD RGB >>" bit in so you can see where the OSD joins the RGB in lines.

[Syntax]

With the Sony sets it's more common to have a weaker pull down on the OSD and a larger resistor inline.

Taking a quick.look at a kv series it has 5.6k inline then 680ohm pull down then clamping cap.

Are you suggesting these sets have poor clamping on the OSD due to high series resistance?
Because they don't to my eye.

[viletim]

With the Sony sets it's more common to have a weaker pull down on the OSD and a larger resistor inline.

Taking a quick.look at a kv series it has 5.6k inline then 680ohm pull down then clamping cap.

Are you suggesting these sets have poor clamping on the OSD due to high series resistance?
Because they don't to my eye.

Sony has a reputation for quality products. I doubt they would share an RGB input between the OSD and SCART like this. In this circuit the analog video is clamped, the OSD is not. The OSD has no black or black level (on account of the diode) it is either white (fully on) or not present.

[Syntax]

What stops the OSD signal from being clamped?

What you say about the OSD having no black levels due to the diode has shown to be true for me in practice but
with the scart switching setup on a BnO the RGB signals pass through signal diodes and have pull ups and inlines.
So I'm confused as he'll now

[viletim]

What stops the OSD signal from being clamped?

The clamp is activated by the trailing edge of the sync pulse and is active for about 4us. The OSD is not allowed to be on during this time for this circuit to work correctly. It's off and invisible due to the diode.

What you say about the OSD having no black levels due to the diode has shown to be true for me in practice but
with the scart switching setup on a BnO the RGB signals pass through signal diodes and have pull ups and inlines.
So I'm confused as he'll now :)

You'll have to show me the circuit. My comments so far are specifically about this Daewoo chassis.

[Syntax]

[meleniumshane90]

I'm modding an identical set. Do you have any pictures or a drawing of how you wired yours up? I haven't figured out how to trigger the blanking signal yet. Also, I didn't realise that you were putting the 75ohm to the respective colors ground. Couldn't it just bridge right on the SCART connector, or am I not seeing something? Thanks!

Shane,

I'm the one who told you to mod this set when I saw it on the CRT collective, happy to answer any of your questions

Yes, you should be able to bridge the RGB's to their grounds with 75ohm resistors on the scart connector to perform the 75ohm termination. Another way is to bridge them to the chassis ground via 75 ohm resistors. Your choice.

To trigger the blanking signal you can connect the 5V pin from the closed caption connector to the YS pin of the closed caption connector. If for some reason the 5V is inactive on the closed caption connector you colud find the 5V regulator on the TV chassis and connect it's output (marked with an O) to the YS. Another great option is to use the 3-5V coming in on pin 16 of the scart and connect it to YS.

Happy modding!

Cheers,

Mark

Cool, thanks. I'm about to re-do what I messed up on Friday. Hopefully what I'm working out in my head works out in practice so I can get this done.

I was able to wire everything up, but I hit a bit of a wall here.

The composite video & stereo audio work, but the RGB doesn't. I have the 5V lead on a switch and wired to the YS pin. When I throw the switch, the video signal blanks & "Video 1" disappears, but no video displays.

I have the red, green, and blue lines individually wired 75Ω to common ground & to the "104" capacitors, then into the respective R, G, & B inputs on the board. I've tested everything I can think of, but still no video signal. What could I be doing wrong? What can I test? Thanks!

Edit: It's a Sony 20TS29 & I'm wiring into the CC Port via the desoldered CC card, if anyone missed the original post.

[viletim]

Syntax,

This works differently. In this TV the diode is biased on by the transistor when the input is active. The diode is always biased no matter the state of the input signal - black, white, not present. Notice there is a coupling cap on the input and output of the diode switch.

In the case of the Daewoo the diode is biased off when the signal is 'black' and on when it is white.

[fandangos]

The size of the coupling capacitor (usually 1u, 100n, 10n) is decided by the properties of the IC (the input bias current and clamp current). Find the best value form another RGB input, the datasheet, or another schematic that uses the same IC.

From your description it sounds like the RGB input you are using either doesn't have a clamp circuit (digital only) or the clamp circuit has been switched off by the microcontroller (the LA76818 has such a clamp off feature for example).

Thanks for the reply, Tim.
I often search for similar European TVs with the same IC, I'm actually trying to trouble shoot 2 TVs, a widescreen CRT Philips and a Gradiente 29" brazilian tv.

Do you mind trying to answer this to me:

1. Does the source matter? I'm using the Teletext/OSD RGB input here. From the IC that generates the teletext/menu it goes trough a 22n cap and a 100 ohm resistor, that's it. But I have no idea what's the VPP that's generated on that IC.
So should I use a 22n? I'm using a 0.1uF right now.

2. Just to be sure, when I read 22n on the service manual, that means nanofarads, right? Here the stores sell it like 22k picoFarads, so 22k pF = 22n, right?

3. If there's no 75 ohm terminated resistor on the original input schematics, should I use it?

4. Does ceramic and polyester caps makes any differences? On a similar european tv it's specified as 22n/67v, isn't that too much just for R G B? Does it make any difference using such high voltage capacitors?

[MarkOZLAD]

I was able to wire everything up, but I hit a bit of a wall here.

The composite video & stereo audio work, but the RGB doesn't. I have the 5V lead on a switch and wired to the YS pin. When I throw the switch, the video signal blanks & "Video 1" disappears, but no video displays.

I have the red, green, and blue lines individually wired 75Ω to common ground & to the "104" capacitors, then into the respective R, G, & B inputs on the board. I've tested everything I can think of, but still no video signal. What could I be doing wrong? What can I test? Thanks!

Edit: It's a Sony 20TS29 & I'm wiring into the CC Port via the desoldered CC card, if anyone missed the original post.

Just some quick thoughts.

1) Have you confirmed, visually and with the multimeter, that there is continuity from the R,G and B ports to the jungle?
2) The fact that it is blanking is very positive. It is possible the jungle on this chip requires a voltage in a certain range for RGB insertion. Try wiring a 10k pot as a variable resistor on your 5V line and alter the voltage.
3) Did this TV have a closed caption board in it from the factory? If not we might have to try and find a way to turn on in the Service menu.

I'll have a quick look now at the schematics and see what I can find out.

EDIT: Checked the datasheet for the CXA1465AS, Ym just needs something greater than 1V blank. Still wouldn't hurt to try the pot.

Are you able to get into this menu?

[takeshi385]

After success with other tv i have decided to mod a Sony KV-27FS100. I pulled pin 40 the ys2/ym pin and tied it to pin 44vcc. I also pulled pins 41-43 and soldered my rgb lines to them and finally I fed sync to pin 64. After all this I am not getting a picture.
The tv uses a cxa2154as. I'm not sure if pin 44 is 5v or 9v and like the post above i might need to feed it over 5v to blank. Since this is a well known model i was hoping someone knows what i am doing wrong.

[Syntax]

STOP PULLING BLANKING PINS DAMN IT PEOPLE!!!
There is seriously no need. Your making your life harder.

[MarkOZLAD]

....like the post above i might need to feed it over 5v to blank. Since this is a well known model i was hoping someone knows what i am doing wrong.

That was a Typo on my part. I meant over 1V.

Sorry.

[MarkOZLAD]

STOP PULLING BLANKING PINS DAMN IT PEOPLE!!!
There is seriously no need. Your making your life harder.

The original post tells everyone that you need to pull pins to RGB mod. It needs to be made clear that Mike's original mod that he posted about is just one method for modding. There are many more.

ONLY SNIP OSD AND PULL PINS IF THERE IS NO ALTERNATIVE!!!

Please research your schematic and datasheets first. inspect your TV's chassis. Very often there are far easier ways to mode than the "OSD Snip" method.

As far as I'm concerned the OSD snip method is just one rung above the neckboard method, which is the last resort.

[takeshi385]

Alright i don't know if it was the right move, but since syntax has helped me before i trust his or her's guidance. I bent the blanking pin (pin40) back down and soldered it to the board. I am certain it will break if I have to pull it again. If this happens i will have to bust out the dremel and reveal more of the pin on the chip.

[Syntax]

I can semi understand people lifting r g b pins if there is no through hole capacitor near them or they suck at smd soldering but there is absofuckingloutly no reason to pull blanking.

It usually has a 100 ohm current limiting resistor as a bare minimum and people are pulling it out of circuit and feeding it anywhere up to 9v directly...

The original post should be modified to show how to build a voltage divider from 2 resistors to initiate blanking.

9 times out of 10 you will find the blanking line already has dividers.

PS, I'm a he, and if I ever found a female modder there would be little screen heads all over the place.

[evilsim]

there would be little screen heads all over the place.

LoL

[takeshi385]

I can semi understand people lifting r g b pins if there is no through hole capacitor near them or they suck at smd soldering but there is absofuckingloutly no reason to pull blanking.

It usually has a 100 ohm current limiting resistor as a bare minimum and people are pulling it out of circuit and feeding it anywhere up to 9v directly...

The original post should be modified to show how to build a voltage divider from 2 resistors to initiate blanking.

9 times out of 10 you will find the blanking line already has dividers.

PS, I'm a he, and if I ever found a female modder there would be little screen heads all over the place.

I hate to break to this to you, but you're gonna have to fight me first. Cage match and no help from the vicious Australian Wildlife. I've seen those bold kangaroos y'all have. Those things will gut someone with their toe claws. Also you guys have cute possums, whilst our opossums are like crack fiends.

[Syntax]

I have to wear the helmet and no pants and your not allowed to bite.

[meleniumshane90]

I was able to wire everything up, but I hit a bit of a wall here.

The composite video & stereo audio work, but the RGB doesn't. I have the 5V lead on a switch and wired to the YS pin. When I throw the switch, the video signal blanks & "Video 1" disappears, but no video displays.

I have the red, green, and blue lines individually wired 75Ω to common ground & to the "104" capacitors, then into the respective R, G, & B inputs on the board. I've tested everything I can think of, but still no video signal. What could I be doing wrong? What can I test? Thanks!

Edit: It's a Sony 20TS29 & I'm wiring into the CC Port via the desoldered CC card, if anyone missed the original post.

Just some quick thoughts.

1) Have you confirmed, visually and with the multimeter, that there is continuity from the R,G and B ports to the jungle?
2) The fact that it is blanking is very positive. It is possible the jungle on this chip requires a voltage in a certain range for RGB insertion. Try wiring a 10k pot as a variable resistor on your 5V line and alter the voltage.
3) Did this TV have a closed caption board in it from the factory? If not we might have to try and find a way to turn on in the Service menu.

I'll have a quick look now at the schematics and see what I can find out.

EDIT: Checked the datasheet for the CXA1465AS, Ym just needs something greater than 1V blank. Still wouldn't hurt to try the pot.

Are you able to get into this menu?

1. It's pretty cramped inside the chassis for that, but I'll see if I can do that. Edit: aside from the ohm setting, anything I'm supposed to read?
2. I don't have a 10k pot, otherwise I would do that. Are you saying that it might be blanking the RGB signal?
3. It did. I originally wired the RGB signal (and nothing else) up directly to that without desoldering anything, but then I realized that's not what the other guy did when modded his, so I stripped everything off that CC board, tested it with a meter, and soldered directly onto that. I tested each pin to make sure nothing was connected to anything else.
4. Yes, I can still access that menu. I did cycle through the options, but it didn't do anything.

[MarkOZLAD]

1. It's pretty cramped inside the chassis for that, but I'll see if I can do that. Edit: aside from the ohm setting, anything I'm supposed to read?
2. I don't have a 10k pot, otherwise I would do that. Are you saying that it might be blanking the RGB signal?
3. It did. I originally wired the RGB signal (and nothing else) up directly to that without desoldering anything, but then I realized that's not what the other guy did when modded his, so I stripped everything off that CC board, tested it with a meter, and soldered directly onto that. I tested each pin to make sure nothing was connected to anything else.
4. Yes, I can still access that menu. I did cycle through the options, but it didn't do anything.

> 1. It's pretty cramped inside the chassis for that, but I'll see if I can do that. Edit: aside from the ohm setting, anything I'm supposed to read?

If the TV came factory with a Closed Caption board there should be no issue with either continuity of the RGB lines to the jungle OR the service menu (chip settings)....they should be right.

What I was suggesting was putting the multimeter in diode mode (DC resistance mode would work too), put the prongs on the different parts of the circuit and make sure it shows 0 ohms or closer (if there is no resistor). You won't be able to get a reading through a capacitor. You should get a reading from the caps you put in to the Jungle pins.

> Are you saying that it might be blanking the RGB signal??

Yeah, that's what I was thinking. I didn't read the CXA1465AS datasheet cover to cover but I didn't see anything to confirm this jungle blanks at a certain voltage.

Have you got any 1K resistors? Try adding one at a time to the 5V line and see what happens.

....I admit that I don't know what is going on at this stage.

Have you confirmed the console/external device is outputting RGB? (long shot but worth mentioning)

Did you remove the Closed Caption board or just desolder stuff from the board and leave it in place?

[meleniumshane90]

1. It's pretty cramped inside the chassis for that, but I'll see if I can do that. Edit: aside from the ohm setting, anything I'm supposed to read?
2. I don't have a 10k pot, otherwise I would do that. Are you saying that it might be blanking the RGB signal?
3. It did. I originally wired the RGB signal (and nothing else) up directly to that without desoldering anything, but then I realized that's not what the other guy did when modded his, so I stripped everything off that CC board, tested it with a meter, and soldered directly onto that. I tested each pin to make sure nothing was connected to anything else.
4. Yes, I can still access that menu. I did cycle through the options, but it didn't do anything.

> 1. It's pretty cramped inside the chassis for that, but I'll see if I can do that. Edit: aside from the ohm setting, anything I'm supposed to read?

If the TV came factory with a Closed Caption board there should be no issue with either continuity of the RGB lines to the jungle OR the service menu (chip settings)....they should be right.

What I was suggesting was putting the multimeter in diode mode (DC resistance mode would work too), put the prongs on the different parts of the circuit and make sure it shows 0 ohms or closer (if there is no resistor). You won't be able to get a reading through a capacitor. You should get a reading from the caps you put in to the Jungle pins.

> Are you saying that it might be blanking the RGB signal??

Yeah, that's what I was thinking. I didn't read the CXA1465AS datasheet cover to cover but I didn't see anything to confirm this jungle blanks at a certain voltage.

Have you got any 1K resistors? Try adding one at a time to the 5V line and see what happens.

....I admit that I don't know what is going on at this stage.

Have you confirmed the console/external device is outputting RGB? (long shot but worth mentioning)

Did you remove the Closed Caption board or just desolder stuff from the board and leave it in place?

Replying on Facebook

[takeshi385]

I got in contact with pikkon who told me to feed csync through the green component lead. Now i am getting a picture, but it is messed up. I'm thinking i fried the chips logic by connecting it's blanking pin to pin 44. I believe that may be 9v. I ordered a backup jungle chip off ebay. Here is the picture I am getting.

Spoiler

UPDATE: I changed the wiring I was using and it is now fixed. My only issue now is the picture isn't aligned properly. Does anyone have experience with this issue and the kv-27fs100?

Spoiler

Thanks in advance.

[evilsim]

the picture isn't aligned properly

service menu should let you adjust that. with the remote press: (then the tv is turned off, in standby mode)
Display, 5, volume up, power. You should now see the service menu. Lookup your service manual for what to adjust for your specific model TV

some of the sony remotes ive used, it doesnt literally say "display" but there is a button which is the display button. try a few buttons and you should get it.

[Pikkon]

I got in contact with pikkon who told me to feed csync through the green component lead. Now i am getting a picture, but it is messed up. I'm thinking i fried the chips logic by connecting it's blanking pin to pin 44. I believe that may be 9v. I ordered a backup jungle chip off ebay. Here is the picture I am getting.

Spoiler

UPDATE: I changed the wiring I was using and it is now fixed. My only issue now is the picture isn't aligned properly. Does anyone have experience with this issue and the kv-27fs100?

Spoiler

Thanks in advance.

Cool you got it working and as for alignment I never had that problem,did you mess with the service menu before?

[takeshi385]

I haven’t messed with the service menu at all. I was able to restore it to defaults without seeing the menu since zero and enter will do that. However that didn’t fix it and to do more I will have to install the switch. I generally don’t install a switch until everything is perfect, but I guess I need to to move forward.

[cargo]

Thanks Tim. BTW I bought one of your SMSFM boards a while ago and I am loving it. So cool to be able to play my old Master System with FM sound.

About what you said regarding where to place a switch: I've been trying to figure out where to insert my signal. The only place I could find with easy access was a series of resistors placed right after the OSD chip's RGB OUT pins. The OSD chip is under a rusty metal shield protector:




I was thinking desoldering one of the ends from each resistor and move it out of the way without breaking them and use those places as my entry point. Devise a small switching circuit to go there.

EDIT: At first I thought R066 was for red, but after looking at the diagram again I realized I had it wrong. Red RGB out for the OSD uses R012, which is underneath the board:



Anyway it's already been suggested I should try elsewhere but if anyone has any suggestions let me know.

To those like me living in the US: Happy Thanksgiving!

Hi guys:

I have a KV27s22 triniton and was wondering if it could be modded for RGB. It's a 27 incher with composite inputs. According to the service manual this is a simpler version of more expensive models that carried s-video ports. The s-video traces are on the main board but it's missing 3 or 4 tiny ceramic capacitors placed on seriously cramped spaces underneath the board.

The kv27s22 uses the cxa2025as jungle chip (click for bigger image):

The RGB input is being used for the OSD. You can disconnect this or use a mechanical swich between your new RGB input and the OSD. If you use a switch, place it between the series coupling capacitors and the rest of the circuit, not between the IC and the capacitors. The R, G, B, inputs are labelled, th YS is fast blanking. Between 1V and 3V to enable. You can use a resistor divider of 4.7k and 1k to make 1.6V from the 9V power supply for the YS. Add termination resistors and you're done.

[Syntax]

Make sure the OSD still has it's termination resistors, I couldn't see them on that end of the picture.

Really you should be pulling the leg of the .01caps which is furthest from the jungle, as Tim has already suggested to you..
That way you include everything upstream. Cutting at the OSD chip is a nightmare waiting to happen.