TV RGB mod thread

[roush97]

I've been reading about this RGB mod for a couple weeks now. I'm good with electronics and soldering, but have never messed with a CRT. I could use a little guidance. I'm attempting to add RGB to a JVC AV-27230. My Micon and Jungle IC chips seem nearly identical to KnuckleheadFlow's chips.





However, I'm not sure where the blanking signal is. Also, my Micon RGB outs aren't labeled as OSD. Can anyone point me in the right direction? Is this TV not a good candidate? Any help would be greatly appreciated.

Thanks
Mike

[suprcrackers]

Houston, I think we have a problem.

[xga]

Don't tell me that you've RGB modded all of those sets???

[leonk]

I hope he's not in Houston, and I hope that's not open free space behind him! (You know what they say about Texas, open space, and guns!)

[suprcrackers]

A)Houston - No, you are safe, South Dakota.
B)Open Space and Guns - In my neck of the woods, that would be an affirmative.
C)No, only 6 have been RGB modded so far, I'm looking at downsizing. Half of these TV's are going to go bye-bye. The family and I took a trip down to KC this weekend with a trailer and picked up 11 mod ready Trinitrons and one mod ready Panasonic for a grand total of $5. The rest are from when I first started and just picked up whatever CRT I could get my hands on whether it could be modded or not.

[suprcrackers]

I've been reading about this RGB mod for a couple weeks now. I'm good with electronics and soldering, but have never messed with a CRT. I could use a little guidance. I'm attempting to add RGB to a JVC AV-27230. My Micon and Jungle IC chips seem nearly identical to KnuckleheadFlow's chips.





However, I'm not sure where the blanking signal is. Also, my Micon RGB outs aren't labeled as OSD. Can anyone point me in the right direction? Is this TV not a good candidate? Any help would be greatly appreciated.

Thanks
Mike

The blanking pin is #19 on the TB1253AN followed by 20-22 for R, G ,and B respectively. They are just right for RGB at 0.7Vp-p.

[roush97]

Thank you suprcrackers. That was my guess. I'm not sure on a couple of other things. Do I need to disconnect the original blanking signal or just add 5v? I'm going to pull sync from component (cmp_y2, pin 45 Jungle). Will that work? There is a capacitor inline on that input. Does it matter if I tap in before or after the cap? Do I need the 75 ohm resistors inline on my RGB input and 75 ohm resistors from each RGB line to ground? I really appreciate the help.

[knohbody]

Hello everyone,

I'm hoping someone can help me. I'm modding a Sanyo DS-13330 for RGB input.

I've tracked down the service manual, as well as the jungle IC datasheet. The datasheet is somewhat lacking. It has the pinouts, but not what the chip is expecting.

Datasheet: https://www.dropbox.com/s/edrve6bzjwk3a ... y.pdf?dl=0

Service manual: https://www.dropbox.com/s/j5nr6s918bc9h ... 0.pdf?dl=0

So far, I've removed the stock resistors on the chassis, wired in the R, G, and B lines with a 0.1 decoupling capacitor and terminated them with a 75 ohm resistor to ground. I've tied composite video/csync (depending on the system) to the video input on the chip, and wired a switch in to apply 5v to the blanking pin.

Everything works, but the video is very dim on the genesis (Model 1) that I'm using to test, to the point of only being able to see the brightest of colors, and slightly dim, and missing shades of colors on the super famicom I'm using. I have a strong feeling that this is due to the inputs not expecting 0.7 peak to peak voltage on the RGB lines. Page 25 in the service manual shows the RGB out from the chip, but nothing on the input that I can see. Any suggestions?

[suprcrackers]

Sorry it took so long to get back to you. Nothing beats working a 16 hour day.

I always disconnect the blanking signal and put it on a 4 pole double throw switch along with the RGB signals. I've never tried leaving it untouched and just applying 5v. It could work, but am not sure. I always pull luma (y) from the back of the (green) component plug itself or the back of the luma on svideo. It's just easier for me that way plus I'm already there for the left and right audio respectively. You just need 75 ohm resistors from each RGB line to ground not inline. If you have any other questions, let me know. Good luck.

[roush97]

Thank you again suprcrackers, I've got it working now. I just need to clean up the wiring.

[roush97]

knohbody...

I looked at your data sheet and saw a .1 volt for the RGB pins in. I'm not sure what that means, I'm new to this. Mine were at .7. I will say this though, I had problems for 2 days with my first attempt. Problem ended up being a weak ground.

[KnuckleheadFlow]

Houston, I think we have a problem.

Oh that's nice. I'm worried about my own CRT lust leading to hoarding, but I guess I've got nothing on that.

Original blanking signal

If there's diodes behind the point where you add the 5v, they'll keep the electricity from flowing back that way. I had diodes, so I left the original blanking signal intact. It lets a faint ghost of the osd show so I can at least see the volume, input, etc. without having to switch back. It certainly doesn't hurt to disconnect the blanking line though.

...wired in the R, G, and B lines with a 0.1 decoupling capacitor and terminated them with a 75 ohm resistor to ground.

Are those terminating resistors before the capacitors? That is this:

Code: Select all

Console RGB out}--------[TV plug]------| C |-----{RGB jungle ic in
                                    |
                                 75 ohm
                                    |
                                   gnd

Maybe it's just the way you wrote it, but it sounded like you put the termination after the cap and before the ic rgb pins. If so, I don't know if that'd cause your problems though, but it's something to try.

[knohbody]

knohbody...

I looked at your data sheet and saw a .1 volt for the RGB pins in. I'm not sure what that means, I'm new to this. Mine were at .7. I will say this though, I had problems for 2 days with my first attempt. Problem ended up being a weak ground.

In the data sheet or the service manual? I don't see anything like that in the data sheet, but maybe there's something in the service manual I missed. Fairly certain my ground is good, I'll give it another check when I get home. I appreciate the second set of eyes.

KnuckleheadFlow, I do indeed have the resistors before the decoupling caps like in your diagram. My wording may have been a bit off.

[BONKERS]

Houston, I think we have a problem.

Dear lord. What do you plan on doing with these when you are done with them?

[KnuckleheadFlow]

KnuckleheadFlow, I do indeed have the resistors before the decoupling caps like in your diagram. My wording may have been a bit off.

Dang, I was hoping it'd be something simple like that.

I noticed that the datasheet sheet shows decoupling caps on the RGB in pins, whereas the service manual doesn't have them. Then I noticed the part numbers are slightly different (TV has LA76834NMP) and they're different form factors. The voltages roush97 mentioned are on page 26 of the service manual, they show the RGB pins as taking 0.1v.
I couldn't find a manual for the MP version specifically, but I think those RGB lines are digital. If that's the case, then unfortunately this TV is a no-go. Unless the pins can be set to analogue over i2c or something, but I don't know anything about that.

Hopefully it won't be too hard to find a better candidate.

[knohbody]

Bah! Just found the voltages you guys were talking about. It does seem that this set takes digital inputs. Quite disappointing. Thanks for the help roush97 and knuckleheadflow! I'll see if I can pick up a better set to mod.

[KnuckleheadFlow]

Come to think of it, I think OP or someone else had described the same video issues as you at some point and it turned out to be because the expected RGB input was digital.

If you look for models in specific series that were modded in this thread, you'll probably get a good outcome. I can speak for the Toshiba 20AF41C and JVC AV-32D501/2 and 301/2 (same jungle IC as the Toshiba). And the right Trinitrons would rock, it goes without saying. Of course I haven't modded one myself yet.

[roush97]

I am actually having a couple issues. Everything works great except the picture is a little dim. It also seems shifted to the left and up a little bit. I am syncing with the component y input. Can anyone tell if there is a better sync option for me? I typed in directly at the component input plugs, and I know it goes through at least one capacitor, will that make a difference? Should I tap in at the jungle IC instead? Should I play with adding a resistor in line with my sync signal? As far as it being dim, should I play around with different resistors and caps? On my schematics, the RGB pins are showing a 2.1 voltage. On the data sheet is says those pins are .7 volt. That is confusing me a little bit.

[roush97]

Also, my RGB lines from OSD have 4.7 k resistors inline and 1.5 k resistors to ground. Would setting up my RGB input similar to this help?

I forgot to mention, I'm using an ntsc SNES with a scart connector for testing. I have tried that with and without the 220uf caps.

[texaspowtapa]

any hope about getting rgb out of this set?

http://www.electronica-pt.com/esquema/f ... down/1623/

[knohbody]

Also, my RGB lines from OSD have 4.7 k resistors inline and 1.5 k resistors to ground. Would setting up my RGB input similar to this help?

I forgot to mention, I'm using an ntsc SNES with a scart connector for testing. I have tried that with and without the 220uf caps.

Roush97, did you isolate your inputs from the resistors that are already on the OSD? If not, that's probably why your picture is dim.

[roush97]

Knohbody, yes, I did. The .1uf caps were the last thing inline to my jungle IC on the RGB lines. I desoldered those, replaced with 6 wires (3 in from OSD and 3 out to jungle IC. On the 4PDT switch, I soldered .1uf caps inline on each RGB to jungle IC. That way my OSD and my RGB input can both utilize the caps. I have 75 ohm terminations on my RGB lines (terminated to ground on my SCART connector). I also switched my original fast blanking signal (ys) and 5v with the 4PDT switch. It works great except that it is a little dim and shifted to the left a little. Hopefully someone can tell me how to fix it.

[KnuckleheadFlow]

any hope about getting rgb out of this set?

http://www.electronica-pt.com/esquema/f ... down/1623/

Man that's an annoying service manual to read. On PDF pages 28 and 29 I see pins 61, 62 and 63 on the microprocessor, labeled IC101, sending RGB to 10, 11 and 12 on IC301, which I presume is the jungle IC, on PDF page 13. I don't see any capacitors though and the voltages on those input pins, 0.1v, unfortunately has meant digital RGB in the cases I've seen so far.

[knohbody]

Knohbody, yes, I did. The .1uf caps were the last thing inline to my jungle IC on the RGB lines. I desoldered those, replaced with 6 wires (3 in from OSD and 3 out to jungle IC. On the 4PDT switch, I soldered .1uf caps inline on each RGB to jungle IC. That way my OSD and my RGB input can both utilize the caps. I have 75 ohm terminations on my RGB lines (terminated to ground on my SCART connector). I also switched my original fast blanking signal (ys) and 5v with the 4PDT switch. It works great except that it is a little dim and shifted to the left a little. Hopefully someone can tell me how to fix it.

So, looked at the user manual for that tv ( http://pdfstream.manualsonline.com/3/3f ... cbe32b.pdf ) and saw that there's an option for switching one of the inputs from component to composite.
Might give that a shot and see if it's been changed to component. Also on the spec page for this tv on the jvc site, it says there's a game mode. Some older sets referred to the AV inputs up front as game, but it could also be similar to the newer models where it disables signal post processing. Might try digging through the menus to see if one of those clears up the shift to the left. As for the dimness, maybe a small rgb amp is in order? I'm not sure, just throwing that out there.

I was able to find another small tv for my project that had a more suitable jungle ic. SNES, ps1 and 2 look great. Genesis and master system look horrible, but I think my cable is to blame. Tv is a 13 inch Orion tv1331.

[roush97]

Knohbody, yes, I did. The .1uf caps were the last thing inline to my jungle IC on the RGB lines. I desoldered those, replaced with 6 wires (3 in from OSD and 3 out to jungle IC. On the 4PDT switch, I soldered .1uf caps inline on each RGB to jungle IC. That way my OSD and my RGB input can both utilize the caps. I have 75 ohm terminations on my RGB lines (terminated to ground on my SCART connector). I also switched my original fast blanking signal (ys) and 5v with the 4PDT switch. It works great except that it is a little dim and shifted to the left a little. Hopefully someone can tell me how to fix it.

So, looked at the user manual for that tv ( http://pdfstream.manualsonline.com/3/3f ... cbe32b.pdf ) and saw that there's an option for switching one of the inputs from component to composite.
Might give that a shot and see if it's been changed to component. Also on the spec page for this tv on the jvc site, it says there's a game mode. Some older sets referred to the AV inputs up front as game, but it could also be similar to the newer models where it disables signal post processing. Might try digging through the menus to see if one of those clears up the shift to the left. As for the dimness, maybe a small rgb amp is in order? I'm not sure, just throwing that out there.

I was able to find another small tv for my project that had a more suitable jungle ic. SNES, ps1 and 2 look great. Genesis and master system look horrible, but I think my cable is to blame. Tv is a 13 inch Orion tv1331.

Knohbody, I did try switching the component input, but will have to look into game mode. I was also thinking I may need an RGB amp. I have also read about putting a potentiometer on the H AFC input of the Jungle IC to adjust the shift to the left. I will have to play with it some more. Thank you for all your help.

[KnuckleheadFlow]

.I was also thinking I may need an RGB amp.

You have the same jungle IC as both my Toshiba and JVC, you most likely do not need an RGB amp. From what I gather, it's needless and only over-complicates the setup, at best.
The OP had a similar issue with a dim picture I think. Re-read his exchanges with Voultar again. FYI, his JVC most likely also had the same jungle IC.

[knohbody]

IIRC, the OP's issue with the dim image was due to him not isolating the input from the osd input, which roush97 has done. I would think he wouldn't need an amp if his chip is the same as yours, but it seems to be expecting 1v peak to peak instead of 0.7v. Perhaps it's set up differently on this model?

Roush97, couple of dumb questions that may not have any bearing on anything...
Are you using ceramic or electrolytic caps?
Is the osd dimmer than it was before the mod?

Edit: sorry 2.1v according to the schematic on the rgb lines into the jungle ic.

[roush97]

Knohbody, I am using ceramic caps. Also, my OSD seems perfect. I actually thought it looked ok until I hooked it up with the composite cables and saw how bright it was compared to RGB input. I have the same TV as the OP sitting in my garage. I was thinking of doing the mod to that TV and comparing the picture on the two TVs with the same SNES source.

[knohbody]

Try switching back to the osd and adjusting the brightness or contrast on the component input. I know a couple tvs that have different settings for different types of input.

[tjstogy]

Why do people mod tvs for RGB? Is it because they can't find broadcast monitors or is it because broadcast monitors are too small?