TV RGB mod thread

The place for all discussion on gaming hardware
DemoNight
Posts: 33
Joined: Sat Mar 24, 2018 2:53 am

Re: TV RGB mod thread

Post by DemoNight »

Osirus wrote:
DemoNight wrote:
Thanks for the reply, i'll leave the diodes out since the math is already done for me to not have them. Though, and this is more of a theory question then a question for this project, but I don't understand how a diode will effect resistor values in this case. If I go both resistors, then a diode on the cricut back to the microcontroller how does that affects the resistance on the circuit going to the jungle?

Anyways, my only other question is for sync, do I need to add resistors to that? I plan to solder onto the back side of the composite input to a female scart plug that i'm going to mount in the case. Actually, two more questions come to mind if that's ok. First, I read a few people say the resistors on the RGB input should be resistors to ground, I won't even bother to ask why that makes a difference but with this version of the mod I should ground all 3 signal wires with a 75ohm resistor for each (and to be super clear we are talking the grounds on the scart plug, i'm planning to ground the scart plug itself to the same composite ground), do I still need that 0.01 cap in that circuit I see other people use? Then have the signal wires run to that 330ohm resistor then bring the output of that into the Micro to Jungle chip circuit, do I have that right?

And for that L003 inductor, i'm going to apply 5v to the input side of that inductor with a 470ohm to blank the screen, is that right?
The sync input you apply your sync to should already have its own 750 ohm termination if you apply your sync to the composite input. No need for any resistors there.

The RGB inputs you add need to have 75 ohm resistors to ground. That's standard for analog video signals. It will match the output impedance of the devices you connect to the tv. If you look at the composite, s-video, or component inputs that the tv already has they will also measure 75ohm to ground.

What you said about the 470ohm resistor to the L003 inductor sounds right, without looking.

Thanks, plan to prototype this on a breadboard first, confirm it's working right then hard wire it into the set. I'm in way over my head. I've done some basic mod chip on console installs before but nothing like this. I looked for someone local to do the mod for me but couldn't find anyone, thanks for spending time helping me.
Akuji
Posts: 14
Joined: Tue Oct 04, 2016 7:45 pm

Re: TV RGB mod thread

Post by Akuji »

matt wrote:
Akuji wrote:I recently modded a Sharp 13K-M100 for RGB. However, I'm now getting some retrace lines towards the top of my screen after the mod.
This is probably not due to the mod. What you're describing sounds like vertical foldover, which is cause by a bad pump-up capacitor in the vertical deflection circuit. It is a very common problem. On your TV it is C508 (100uF/35v). Make sure to replace it with a low ESR/high ripple current cap or else the problem will come back sooner or later.
Update, I've replaced the cap but it seems as if nothing changed. Could it be any other issue?

I guess a few things to mention for the heck of it:
- The color in RGB looks a bit purple, very noticeable on the MiSTer's TV static screen. I've maxed out the RGB cutoffs in the service menu because of the brightness for now.
- As the TV heats up, the RGB starts getting horizontal color banding. Very noticeable when watching the red INPUT OSD when the TV is turned on.
- Sometimes the lines and/or the OSD bob up and down, as if something was shaking them. It happens in a very "analog" way where it's clear that it isn't something happening in the signal on screen.
- The picture is slightly tilted but that's probably something I'll deal with later that isn't relevant to this.

EDIT
Oh Jesus. My TV had this option called Blue Screen, and when I turned it on the picture started rapidly shaking up and down, the OSD was flashing on and off, and the TV turned itself off. Something went REALLY bad and I didn't want to power it on again, but I waited a bit, replugged it in, and quickly turned off Blue Screen before shutting off the TV for now.
KPackratt2k
Posts: 211
Joined: Sun Apr 04, 2021 11:02 pm
Location: Seattle, WA, USA

Re: TV RGB mod thread

Post by KPackratt2k »

Shiozaki wrote:I guess the mod failed, i got everything wired up to the best of my ability and buttoned the shell back on for the first post-mod power on.

i tested to make sure the tv worked before modding it of course.

after the mod i turn it on and see the blue screen, good, the osd and menu are working, good, but the tv just powers off after a few seconds...

no ideal what i did to cause that... i opened it back up to make sure nothing looked like i was grounding it out and it all seems fine...

if anyone have any ideas im open to suggestions, im considering returning it to pre-mod status and see if it works, but that would be a lot of work.
When I was modding an RCA E13309 TV with the exact same chassis (TX808A), I was experiencing the same problem (although there was smearing on my OSD). As it turned out, replacing the 680 ohm terminating resistors with 470 ohm resistors caused the OSD chip to not draw enough power, resulting in it overloading the CRT, causing the set to power off. What I ended up doing was using the 680 ohm resistors in tandem with the 470 ohm resistors which fixed the issue for me. Alternatively, you could theoretically use 1150 ohm resistors as your "mux" resistors.

I don't know if you still have this TV in your possession (or if you even still visit this forum), but hopefully this helps you or anyone trying to mod an RCA/GE TV with the TX808 chassis.
camtron47
Posts: 6
Joined: Wed Jun 09, 2021 4:42 am

Re: TV RGB mod thread

Post by camtron47 »

I'd like to mod a Sony KV-XA21M30 which has a BG-3R (BG3R) chassis (similar to BG-3S / BG3S). MarkOZLAD has advised me I can do an OSD mux via the teletext port, so I have looked at the schematic and I think I have worked out most of the resistor values. But I'm quite unsure about the blanking arrangement, so I have some questions.
Firstly here is my drawing of what the RGB lines will look like before and after the mod. The changes are:
  • - Remove the 330 ohm resistors that go to ground.
    - Add the diodes between the 2.2k resistors / 10pF caps and the injection point. (How necessary is this? I think it will require cutting the traces, given the resistors and caps are surface mount, so that would kind of suck.)
    - Stick 390 ohm resistors in the R, G and B holes in the teletext header, and then 75 ohm resistors from the other end of the 390's to ground. My R, G and B signals go in between those 2 resistors.
    - Swap the 0.01uF caps for 0.1uF caps (how necessary is this?)
So how does this look?
Spoiler
Image
Next up is the blanking circuit which looks different to the examples I've seen for other chassis because there is a transistor in the middle. My electronics is quite rusty, but I'm guessing the transistor is being used like a switch here, and when the YS signal is sent from the controller, it allows the 5V to pass through the transistor. Then 5V will be applied across the 470 ohm resistor and go through the 100 ohm resistor to the YS/YM pin on the jungle.
So, do I simply apply 5V to the teletext header's BLK port and it will have the same effect? Or do I need to add/remove a resistor somewhere here as well?
Spoiler
Image
Thanks.
DemoNight
Posts: 33
Joined: Sat Mar 24, 2018 2:53 am

Re: TV RGB mod thread

Post by DemoNight »

Can anyone check my plan for my KV-32V36?

I'm supposed to remove R1123, R1128, and R133, the resistors I highlighted are the correct resistors right? Also a dumb question, do I bridge the pads after I remove them or do I just remove them? If I just remove them what am I taking out of circuit?


Image

I was planning to tie in on R064, R065, and R066

Image

If I got it right, I can leave this resistor in place, and just solder on the leg that's going to the jungle chip, right? Picking here to tie in for ease of soldering. And I'd be putting a 330 ohm resistor plus a 75 ohm resistor that i'm gonna put on the back of the RGB input. Do I have that right?
User avatar
Osirus
Posts: 214
Joined: Tue Jun 16, 2020 8:51 pm

Re: TV RGB mod thread

Post by Osirus »

The resistors you remove from the OSD lines are where your RGB gets injected, in between 75 ohm to ground and whatever your calculated resistor value is going back into the OSD circuit.
DemoNight
Posts: 33
Joined: Sat Mar 24, 2018 2:53 am

Re: TV RGB mod thread

Post by DemoNight »

Osirus wrote:The resistors you remove from the OSD lines are where your RGB gets injected, in between 75 ohm to ground and whatever your calculated resistor value is going back into the OSD circuit.

I'm really confused now, I thought I was removing them 3 surface mount resistors to take "something" out of circuit, then I could go to another more easier place to solder to inject RGB. I'm trying to do the OSD MUX style and not the switching or whatever the other style is called. I'm not sure if I have the soldering skill to get a wire on something as small as the pads for them surface mount resistors. If I have to get one them pads, the post i'm following says I gotta use the ungrounded pad, and I know this is a stupid question but what pad is the ungrounded pad?
User avatar
Osirus
Posts: 214
Joined: Tue Jun 16, 2020 8:51 pm

Re: TV RGB mod thread

Post by Osirus »

DemoNight wrote:
Osirus wrote:The resistors you remove from the OSD lines are where your RGB gets injected, in between 75 ohm to ground and whatever your calculated resistor value is going back into the OSD circuit.

I'm really confused now, I thought I was removing them 3 surface mount resistors to take "something" out of circuit, then I could go to another more easier place to solder to inject RGB.
Oh, you absolutely can of course. That's normal. The original grounding resistors are removed and replaced with the injected RGB that doubles as a ground for the original OSD RGB, but they do not have to use the same pads, etc.
DemoNight
Posts: 33
Joined: Sat Mar 24, 2018 2:53 am

Re: TV RGB mod thread

Post by DemoNight »

Osirus wrote:
DemoNight wrote:
Osirus wrote:The resistors you remove from the OSD lines are where your RGB gets injected, in between 75 ohm to ground and whatever your calculated resistor value is going back into the OSD circuit.

I'm really confused now, I thought I was removing them 3 surface mount resistors to take "something" out of circuit, then I could go to another more easier place to solder to inject RGB.
Oh, you absolutely can of course. That's normal. The original grounding resistors are removed and replaced with the injected RGB that doubles as a ground for the original OSD RGB, but they do not have to use the same pads, etc.

If i'm gonna attempt to solder onto the pad once I remove the surface mount resistor, what side am I injecting RGB into? I'm not bridging the two pads right? Would you be willing to look at a diagram and maybe point out where might be the easiest place to solder? I MIGHT be able to get a wire on them pads but I don't wanna risk it
User avatar
Osirus
Posts: 214
Joined: Tue Jun 16, 2020 8:51 pm

Re: TV RGB mod thread

Post by Osirus »

Ok AA-2D is very common. You can't inject into R064,65,66. Those resistors are on the digital side of the OSD circuit, injecting analog into that point won't work. You have to inject into the same node where you removed R133, etc. Either into those pads or on R1355, R1356, R1357 on the side farthest from the jungle IC.

This is an often linked to post where I modded a Trinitron with the same chassis: viewtopic.php?p=1429634#p1429634

If yours has CN1801 and CN1802 those are perfect points for doing the RGB injection and blanking switch, but not all AA-2Ds sets have them.
DemoNight
Posts: 33
Joined: Sat Mar 24, 2018 2:53 am

Re: TV RGB mod thread

Post by DemoNight »

Osirus wrote:Ok AA-2D is very common. You can't inject into R064,65,66. Those resistors are on the digital side of the OSD circuit, injecting analog into that point won't work. You have to inject into the same node where you removed R133, etc. Either into those pads or on R1355, R1356, R1357 on the side farthest from the jungle IC.

This is an often linked to post where I modded a Trinitron with the same chassis: viewtopic.php?p=1429634#p1429634

If yours has CN1801 and CN1802 those are perfect points for doing the RGB injection and blanking switch, but not all AA-2Ds sets have them.

It seems my PCB does not have CN1801 and CN1802. Looks like I'm gonna have to try and get a wire on R133, etc. Could you just confirm, i'm NOT bridging them resistors and what side i'm trying to get a wire on. I really appreciate your help so far
User avatar
Osirus
Posts: 214
Joined: Tue Jun 16, 2020 8:51 pm

Re: TV RGB mod thread

Post by Osirus »

Ok, if you can inject into where R133 and the other 2 are, you will put your calculated resistor (whatever it was) on the pad connected to the rest of the circuit, your 75 ohm resistor on the pad connected to ground, and your R/G/B signals injected in between.
DemoNight
Posts: 33
Joined: Sat Mar 24, 2018 2:53 am

Re: TV RGB mod thread

Post by DemoNight »

Osirus wrote:Ok, if you can inject into where R133 and the other 2 are, you will put your calculated resistor (whatever it was) on the pad connected to the rest of the circuit, your 75 ohm resistor on the pad connected to ground, and your R/G/B signals injected in between.
Does it have to be grounded on the pad from the resistor or can I ground the rgb lines to another more easier place to solder too? I want to minimize the amount of soldering I gotta do in that small area, I'm not super great at it.
camtron47
Posts: 6
Joined: Wed Jun 09, 2021 4:42 am

Re: TV RGB mod thread

Post by camtron47 »

DemoNight wrote:Could you just confirm, i'm NOT bridging them resistors and what side i'm trying to get a wire on. I really appreciate your help so far
If you mean the termination resistors that go to ground which you are removing, don't bridge those resistor pads - that would ground and therefore disable the OSD RGB signals and would also give an unintended path to ground for you injected RGB signals.

When grounding resistors, you can use any ground point in the circuit - it shouldn't matter whether its the original ground or an easier to solder ground point somewhere nearby. To reduce the amount of soldering you need to do, you can twist the ground legs on the termination resistors together and then solder a since piece of wire onto those twisted legs. Then solder to other end of the wire into a ground point such as a through hole on an empty connector header.
User avatar
Osirus
Posts: 214
Joined: Tue Jun 16, 2020 8:51 pm

Re: TV RGB mod thread

Post by Osirus »

^ Yes any grounding point will do, as long as it's not on the hot side of the chassis.
DemoNight
Posts: 33
Joined: Sat Mar 24, 2018 2:53 am

Re: TV RGB mod thread

Post by DemoNight »

Image

I think the hard part is over, got my RGB and Ground lines hooked up. Not the best soldering ever done but after probing around with my multimeter I'm fairly sure i'm not shorted out and have good contact with the pads. Hope this is the hardest part, now i'm gonna go look around for a place to do my blanking circuit
DemoNight
Posts: 33
Joined: Sat Mar 24, 2018 2:53 am

Re: TV RGB mod thread

Post by DemoNight »

About to sit down and finish up my mod, have a question about how to solder the back of the female scart I'm using. So for the 75 ohm to ground, am I just doing that to the ground that's in the plug? To say another way, I got the ground wire I soldered to the main board or the crt, thats gonna get the back of of the 330 ohm resistors I'm using on the rgb line then the rgb line itself, that goes to the rgb pins on the scart plug. For the rgb ground in the female scart cable is what I'm asking about. Do I put a 75 ohm resistor between the color input and the ground? I dont have to connect the ground from the crt mother board up to the back of the scart plug, right?
User avatar
Osirus
Posts: 214
Joined: Tue Jun 16, 2020 8:51 pm

Re: TV RGB mod thread

Post by Osirus »

You should connect ground on your scart plug to ground on the chassis. The R/G/B lines need to have 75 ohm connections to ground whether you do it on your connector or on the chassis is up to you. I've done it both ways on different mods.
DemoNight
Posts: 33
Joined: Sat Mar 24, 2018 2:53 am

Re: TV RGB mod thread

Post by DemoNight »

Image
Success! As you can see I have RGB from my SNES to my TV. Happy days are here. I have 2 issues, first the image is shifted left, right now I have sync rigged up going into a composite plug I'm plugging into the back of the set. As I understand it if I tie sync to the S Video sync it will fix the picture shift. If I take pin 20 of my female scart and tie it to Pin 3 of the S Video input, that should fix the shift? Should I also tie Pin 18 of the scart to pin 1 on the S Video for ground? Second question, I think I messed something up with my resistors, the picture looks a little too bright. I'm using 330 ohm and 75 ohm resistors wired up like in the pictures bellow. I would drawl a diagram but I really don't know how, hope these pictures tell the story.

Image
Image


While I think I know the answer I'm gonna ask anyways, my 5v source is a standby 5v, as in the jungle would be getting 5v even with the TV off. This is probably not good for the Jungle long term right? I should find a 5v source that is switched with the TV turning on and off, right? Also, I read somewhere (but cant find it now) that I should put a 470 ohm resistor in-between the 5v and the jungle, is that true? Right now I have it hooked up directly? Could that be causing my overly bright picture? I didn't use any 0.1 capacitors, I see almost every other mod use them. Should I be using them someplace in my circuit, is that causing the over brightness?


Once again I just want to say THANK YOU for dragging my super under qualified ass through this process,
User avatar
Osirus
Posts: 214
Joined: Tue Jun 16, 2020 8:51 pm

Re: TV RGB mod thread

Post by Osirus »

You can just adjust for the left shift in the service menu. Using S-video for sync can make it more complicated as you'll have to rig up a switch to activate S-video sense on whatever input it's sharing composite with, and in the end you'll probably have a left-shift anyway.

You injected RGB into the OSD lines which already have capacitors on the jungle inputs which is why you didn't need to add any.
DemoNight
Posts: 33
Joined: Sat Mar 24, 2018 2:53 am

Re: TV RGB mod thread

Post by DemoNight »

Osirus wrote:You can just adjust for the left shift in the service menu. Using S-video for sync can make it more complicated as you'll have to rig up a switch to activate S-video sense on whatever input it's sharing composite with, and in the end you'll probably have a left-shift anyway.

You injected RGB into the OSD lines which already have capacitors on the jungle inputs which is why you didn't need to add any.
Have any thoughts about the resistor on the 5v line to the jungle? Or why my picture might be to bright? I'm not even sure if it's too bright or if I'm used to a darker image via S Video.
User avatar
Osirus
Posts: 214
Joined: Tue Jun 16, 2020 8:51 pm

Re: TV RGB mod thread

Post by Osirus »

The resistor probably wouldn't hurt. I think I usually end up using about 3v for blanking. I don't see how that would effect brightness though.
DemoNight
Posts: 33
Joined: Sat Mar 24, 2018 2:53 am

Re: TV RGB mod thread

Post by DemoNight »

Osirus wrote:The resistor probably wouldn't hurt. I think I usually end up using about 3v for blanking. I don't see how that would effect brightness though.
I'll put that resistor in and test before I button up the back. I'm not even sure if the RGB is too hot or not. Is there a way to check with a meter? Looking at my pictures, I do have the resistors in circuit correctly, right?
User avatar
Osirus
Posts: 214
Joined: Tue Jun 16, 2020 8:51 pm

Re: TV RGB mod thread

Post by Osirus »

You'd need an oscilloscope to actually measure the RGB signal voltage.

The 75 ohm resistors on the breadboard for the RGB inputs look correct. What are the resistors on the scart connector grounds for?
DemoNight
Posts: 33
Joined: Sat Mar 24, 2018 2:53 am

Re: TV RGB mod thread

Post by DemoNight »

Osirus wrote:You'd need an oscilloscope to actually measure the RGB signal voltage.

The 75 ohm resistors on the breadboard for the RGB inputs look correct. What are the resistors on the scart connector grounds for?

Unless I goofed the resistors on the bread board should be 330 ohm, since I removed 390 ohm resistors off the crt circuit board, I had to add more resistance to the grounds of the rgb input. The resistors on the back of the scart are 75 ohm to ground. Did I do that wrong?
User avatar
Osirus
Posts: 214
Joined: Tue Jun 16, 2020 8:51 pm

Re: TV RGB mod thread

Post by Osirus »

If the resistors on the breadboard are connected to ground that's wrong. You have your RGB inputs with 405 ohm terminations if that's the case, not 75 (330 + 75). The 330 ohm resistors should be between the RGB inputs and the OSD circuit of the chassis.

https://klovimg.com/images/2018/07/17/O ... uit-v2.png

Except in your case instead of 1K ohm resistors for RGB you have 330.

Basically, if you have a multimeter, resistance between the RGB input pins on your scart plug and ground should be 75 ohm, resistance between the RGB input pins and the point on the chassis you injected into the OSD lines should be ~330 ohm.
DemoNight
Posts: 33
Joined: Sat Mar 24, 2018 2:53 am

Re: TV RGB mod thread

Post by DemoNight »

Osirus wrote:If the resistors on the breadboard are connected to ground that's wrong. You have your RGB inputs with 405 ohm terminations if that's the case, not 75 (330 + 75). The 330 ohm resistors should be between the RGB inputs and the OSD circuit of the chassis.

https://klovimg.com/images/2018/07/17/O ... uit-v2.png

Except in your case instead of 1K ohm resistors for RGB you have 330.

Basically, if you have a multimeter, resistance between the RGB input pins on your scart plug and ground should be 75 ohm, resistance between the RGB input pins and the point on the chassis you injected into the OSD lines should be ~330 ohm.

Yeah, I did that that wrong. When I get home from work I'll try putting the 330 ohm resistors in the rgb line instead of too grounin and see how that works for me. On a side note, do I have to add any resistors to the sync? I figure since I'm gonna solder to the back of the factory jack that any resistance it needs will be already in circuit
User avatar
Osirus
Posts: 214
Joined: Tue Jun 16, 2020 8:51 pm

Re: TV RGB mod thread

Post by Osirus »

Nope, nothing added to sync. The composite input you're using should be 75ohm terminated already.
DemoNight
Posts: 33
Joined: Sat Mar 24, 2018 2:53 am

Re: TV RGB mod thread

Post by DemoNight »

Osirus wrote:Nope, nothing added to sync. The composite input you're using should be 75ohm terminated already.

Image

So I just wired it up like this, with the 330 ohm resistors on the RGB inputs. While it did bring down the overall brightness, the colors are not right. Looks really washed out. Compared it to the S Video input and the Svideo input is bright and vibrant next to the washed out RGB input. I'm stumped, I can't think of anything it could be. Any ideas on what to check next?

EDIT i'm sitting here racking my brain over this, at this point 1 of 2 things can be wrong. The resistors on the RGB line going to the jungle (like 4 people in this thread have said it's 330 ohm so I don't think that's it) or I wired up the female scart plug wrong. I THINK the issue may be resistor placement on that female scart plug. Right now, on the back of the scart plug I have 75 ohm resistors on the ground pin of each color input, then wired to chassis ground. I'm thinking I should have that resistor on the color "hot" line pulling it to the ground pin, then have both be wired to chassis ground.
DemoNight
Posts: 33
Joined: Sat Mar 24, 2018 2:53 am

Re: TV RGB mod thread

Post by DemoNight »

Image

Finally got it looking the way it should! It really was just how I had the resistors hooked up. Once I had the 330 ohm resistors on the RGB line going to the jungle chip, and have the 75 ohm resistors bringing RGB to ground on the backside of the scart cable, it looked perfect! I knew I had it the second the rare logo popped up on my screen. Also notice how bright and clear the OSD is, to my eye it's perfectly mixed with the RGB. Prototyping on the bread board really helped with changing stuff around while I figured it out. Now that I have the RGB dialed in, I might try and see if I can get sync on the S Video line just to see if that fixes the left shift but I dunno if I'll even bother since the service menu will surely fix the issue.
Post Reply