LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complete...

MarkOZLAD · Post by **MarkOZLAD** » Thu May 18, 2017 1:32 pm

SUMMARY: Found a series of LG TV that are easy to mod to add RGB Scart connection. Simply desolder the composite connector and replace it with a cheap Scart connector and change a service menu setting.

Got interested in doing an RGB mod to a CRT after seeing the original srarcade RGB mod youtube video and interacting with buttersoft on the Aussie Arcade forums.

My girlfriend had an old LG CA-20F80 stored in her garage so I thought I'd investigate.

I found the schematic - https://drive.google.com/open?id=0BxXDE ... FJ5M0N4YW8

the Jungle IC - TDA8841/2 datasheet - https://drive.google.com/open?id=0BxXDE ... Xg0ajZQc1U

I noted that the TDA8841/2 had RGB/FB inputs for an external source (which could be used by Teletext) as well as the RGBS/FB from the OSD chip. This piqued my interest and made me think the external input could be used rather than trying to hijack the OSD RGBS/FB.

After chatting with buttersoft he mentioned that on composite only TVs the external RGB inputs would be disabled in the TVs EEPROM. This was quite discouraging.

Soon after I stumbled upon this document which details how to adjust the MC84A chassis. https://drive.google.com/open?id=0BxXDE ... nJ2Ykt1U2s. On page 3 it mentioned that the EEPROM settings could be modified from the TVs service menu and described how to get there. The EEPROM settings included options to enable scart,

I got into the service menu to find this page: https://drive.google.com/open?id=0BxXDE ... HFlaS10VEE

The factory default 33 (10 0 0 0 1) setting pointed me to the fact that to enable Scart and have all other settings the same I would need to use 44 (10 1 0 0 1) from table "Table 2. Specifications for OPTION-1 data" in the adjustment table. The change was made ad I was able to shut the TV off, unplug and plug in to confirm the setting had saved. https://drive.google.com/open?id=0BxXDE ... kVuRlZPUmc

I almost downed tools at this stage but I just had to open up the TV to view the chassis. I didn't discharge the set, I just didn't touch anything and took a heap of photos. I then reviewed the photos against the MC84A schematic.

https://drive.google.com/open?id=0BxXDE ... VFzM3NRTVk
https://drive.google.com/open?id=0BxXDE ... WNfcGZpd3M
https://drive.google.com/open?id=0BxXDE ... XBQT2hXN2M
https://drive.google.com/open?id=0BxXDE ... kUyc2lSVlk
https://drive.google.com/open?id=0BxXDE ... GFjMEYwejA
https://drive.google.com/open?id=0BxXDE ... 1NZU2ctdEk

After comparison of the photos to the schematic I realised that all of the circuitry in the schematic for the Scart RGB connector appeared to be in place. On the schematic the Scart connector is labelled "PJ201 Scart Jack". https://drive.google.com/file/d/0BxXDEF ... sp=sharing

I figured I should look for that label in the photos.

I ended up finding the label, right underneath the Composite input jack. I then noticed that on the schematic it has both the "PJ201 Scart Jack" and "PJ201 Phone Jack". Look at this image again. https://drive.google.com/file/d/0BxXDEF ... sp=sharing

It turns out for the MC84A chassis there are interchangeable jacks for Composite and RGB! All that would need to be done to make Scart RGB work for this TV would be to desolder the "PJ201 Phone Jack" and replace it with a "PJ201 Scart Jack" (or similar I hope...).

I have contacted LG part suppliers and the PJ201 Scart Jack is discontinued with no substitute part. However NEO-GEO on the Aussie Arcade forums suggested this part from eBay " 21 Pins Right Angle Type Scart Socket Connector" http://www.ebay.com.au/itm/2-Pieces-21- ... Swol5Y0TcH. This has been ordered and I await arrival so I can fit and test.

Will report back when I have fitted my new Scart RGB port.

Other Notes:

It seems there are numerous LG Chassis that have interchangeable Scart and Composite jacks. I note that the MC-049A also shares this design. See service manual https://drive.google.com/open?id=0BxXDE ... 3J5MnU0ejg.

This is a list of LG TVs and their chassis numbers. https://drive.google.com/open?id=0BxXDE ... VVfQnNNOFU I hope this can help other forum members to find LG TVs that are easily modified to RGB Scart.

Cheers,

MarkOZLAD

buttersoft · Post by **buttersoft** » Fri May 19, 2017 12:42 am

I've run up against the Toshiba 884X jungle IC's before, as have others on here. Your set is an Australian non-teletext TV, and the OSD was being muxed into the RGB outputs. So it was likely the inputs had been switched off via the IE1 control bit, as Viletim pointed out to me. That's not always going to be the case, but it might be something to watch out for.

Here's hoping it all works when you put it together!

MarkOZLAD · Post by **MarkOZLAD** » Fri May 19, 2017 1:02 am

Here is the link the the original Shmups forum thread about RGB Scart modding Tvs.

http://shmups.system11.org/viewtopic.php?f=6&t=56155

MarkOZLAD · Post by **MarkOZLAD** » Fri May 19, 2017 1:06 am

buttersoft wrote:I've run up against the Toshiba 884X jungle IC's before, as have others on here. Your set is an Australian non-teletext TV, and the OSD was being muxed into the RGB outputs. So it was likely the inputs had been switched off via the IE1 control bit, as Viletim pointed out to me. That's not always going to be the case, but it might be something to watch out for.

Even though that info was discouraging at the time I wouldn't have got to this point without knowing about it, so it was invaluable and I thank you for telling me about it.

buttersoft wrote:Here's hoping it all works when you put it together!

Me too, might open up this process to a whole new group of users that otherwise would've found it too difficult. Plus the personal satisfaction, that's always nice.

MarkOZLAD · Post by **MarkOZLAD** » Fri May 19, 2017 2:13 am

Have compiled an excel spreadsheet to list LG Chassis and Model numbers to try and help people identify model numbers that are easy to mod to Scart. It's not exhaustive and there are likely errors. Message me if you find out a chassis/model is moddable and I'll modify the lists.

https://drive.google.com/open?id=0Bx...Xoyb01PN3hGdUE

The only true way to be sure is to find the service manual/schematic for the model you are looking at and inspect it. A way to find the chassis number for your model is to find a spare parts list for the TV by model. For example for this model we can see the spare chassis is the 84A http://spares.bigwarehouse.com.au/in...59_24766_25883

MarkOZLAD · Post by **MarkOZLAD** » Sat May 20, 2017 5:18 pm

Hey @buttersoft,

This TV seems to always want to go to tuner when you turn it on. I want to use this in an arcade cabinet so I will want the TV to come on and always show the RGB Scart input signal.

If I get the Fast Blanking voltage correct is the TV likely to go straight to AV1 and display the Scart input when the TV is turned on?

If not I was thinking I might be better to try and send the voltage through the fast blanking line that says to the jungle chip that it is teletext that is enabled. Teletext is shown whilst tv is in tuner mode. Does this seem feasible to you?

https://drive.google.com/open?id=0BxXDE ... TFOOXJQU1U

I guess some trial and error will tell anyway. Will wire up a potentiometer and see.

buttersoft · Post by **buttersoft** » Tue May 23, 2017 2:09 am

You can probably do what you suggest, yes. Other alternatives might be a timed relay to activate the AV button on the chassis itself, assuming it has one. Or some combination of If This Then That commands that I can't think through right now. Is that the right name for the App I'm thinking of?

MarkOZLAD · Post by **MarkOZLAD** » Fri Jun 09, 2017 12:04 pm

I successfully completed the modification today. The hardest part was removing the old connector from the chassis. Just required a bit of force whilst soldering that I required assistance with. The part purchased on eBay was a perfect fit for the circuit board. Just needed a small bit of change to the TV case to allow access, used a hacksaw blade, pliers and a Stanley knife to do it.

With the new connector in and the service menu already adjusted Scart Rgb mode worked immediately with a dramatic increase in picture clarity.

If you're a newbie like me this is a good way to get a scart RGB modded TV. Keep an eye out for the LG CRT's and check the model number/chassis and service manuals for Composite AV inputs that can be switched out for Scart ports.

MarkOZLAD · Post by **MarkOZLAD** » Sat Jun 10, 2017 10:14 am

Some photos from the process. (May be out of order)

https://drive.google.com/file/d/0BxXDEF ... sp=sharing
https://drive.google.com/file/d/0BxXDEF ... sp=sharing
https://drive.google.com/file/d/0BxXDEF ... sp=sharing
https://drive.google.com/file/d/0BxXDEF ... sp=sharing
https://drive.google.com/file/d/0BxXDEF ... sp=sharing

hellbelly · Post by **hellbelly** » Sat Jun 10, 2017 10:23 am

Wow, that is impressive

what a sense of achievement finishing that off!!

viletim · Post by **viletim** » Sat Jun 10, 2017 11:35 am

MarkOZLAD wrote:Have compiled an excel spreadsheet to list LG Chassis and Model numbers to try and help people identify model numbers that are easy to mod to Scart. It's not exhaustive and there are likely errors. Message me if you find out a chassis/model is moddable and I'll modify the lists.

https://drive.google.com/open?id=0Bx...Xoyb01PN3hGdUE

The only true way to be sure is to find the service manual/schematic for the model you are looking at and inspect it. A way to find the chassis number for your model is to find a spare parts list for the TV by model. For example for this model we can see the spare chassis is the 84A http://spares.bigwarehouse.com.au/in...59_24766_25883

I'm pretty sure all LG brand CRT TV sets sold in Australia from about 2000 (not sure which year exactly) onwards have this SCART connector spot, but the SCART connector is never fitted. There's no need to make a list of model numbers.

MarkOZLAD · Post by **MarkOZLAD** » Sat Jun 10, 2017 12:05 pm

hellbelly wrote:Wow, that is impressive what a sense of achievement finishing that off!!

Not sure if you're taking the piss but I'm pretty happy with my effort here. I had never so much as unscrewed a single screw from a CRT before this.

I knew after the research that the physical procedure would be dead simple but I had to go through much of the process of the RGB OSD modding, learning the theory, finding service manuals and analysing schematics, disassembling the TV and discovering what was required. My skill was in the research phase, not the wiring. Once I had realised that I could just put a remove the AV jack and replace with a Scart jack I came upstairs to my girlfriend laughing at how simple it was. I wanted to add this thread to the knowledge base so other interested parties could have a simple method for getting an RGB Scart TV and perhaps save some CRT's from landfill.

Truth be told, part of me was quite disappointed that it was so easy to RGB mod this TV. I wanted to do a more complex mod.

If it were common knowledge (and it plainly isn't) that "all LG brand CRT TV sets sold in Australia from about 2000 (not sure which year exactly) onwards have this SCART connector spot, but the SCART connector is never fitted" I wouldn't have had to bother going through the process,I wouldn't have learned what I did and wouldn't have been able to go on and perform a more complex RGB mod as I have recently done.

hellbelly · Post by **hellbelly** » Sat Jun 10, 2017 4:15 pm

Definitely not taking the piss. I'm impressed with all aspects of of this including not giving up

MarkOZLAD · Post by **MarkOZLAD** » Sun Jun 18, 2017 7:30 am

Hold the phone!!!

This TV is NOT displaying RGB. It is displaying Composite video over Scart.

Currently investigating, next step is to review the EEPROM data with view to editing and enabling RGB Blanking.

Turns out there are some juicy issues to solve here.

tjsynkral · Post by **tjsynkral** » Fri Jun 23, 2017 4:05 pm

MarkOZLAD wrote:Hold the phone!!!

This TV is NOT displaying RGB. It is displaying Composite video over Scart.

Currently investigating, next step is to review the EEPROM data with view to editing and enabling RGB Blanking.

Turns out there are some juicy issues to solve here.

Is SCART pin 16 high? If your SCART cable is crappy enough to carry composite video (instead of sync), chances are it isn't pulling the fast blanking pin high either.
You may want to install a switch that connects FB to VCC (with a small resistor like 100) to force SCART when your cable can't do it.

MarkOZLAD · Post by **MarkOZLAD** » Wed Jun 28, 2017 12:27 pm

Thanks for the reply TJ.

The Composite video is coming from the DVD player. I don't see what the Scart cable has to do with that.

I have checked the blanking voltage at the end of the Scart cable and it is about 3.2 volts. Above spec. When it was connected to my Jamma to Scart adapter it was getting true Composite synch and 5V blanking signal. No RGB. I then reduced the voltage to 2.7 volts but still no go.

MarkOZLAD · Post by **MarkOZLAD** » Fri Sep 01, 2017 5:01 am

I'm going to revisit this again soon. I'm starting to think I need to wire up a potentiometer to the blanking signal and change the resistance/voltage.

I found this line in the TDA8842 datasheet.

S.3.9

input voltage to blank the RGB
outputs to facilitate ‘On Screen
Display’ signals being applied to
the outputs
only on pin 26 (pin 38 for the
TDA 885X)

4 - - V

MarkOZLAD · Post by **MarkOZLAD** » Tue Sep 05, 2017 11:40 am

Ok, I finally got this working today. I have gone down the wrong path with this TV for ages and I ended up finding the solution was simple.

LG had purposefully left out two components. Jumper J99 and resistor R557, a 510 ohm resistor. Without these there was no path for the blanking signal to get to the Jungle I/C's blanking pin.

If it wasn't for my work helping Marcos with his Phillips 21GX1669 mod I would've continued to believe I needed to send a serial command to the Jungle I/C to get it into RGB mode. Marcos' TV had a very similar Jungle that had identical behaviour for the blanking. This made me determined to revisit the blanking voltage.

I checked the schematic today and compared to my photos of the chassis and identified the missing resistor. I put one in but still no go. I inspected the base of the chassis PCB with a multimeter and was able to identify Jumper J99. Found a thin paper clip right on the workbench next to the TV and soldered it in as the replacement jumper. (amazing that the paperclip was even there!)

Voila, hooked up the Scart and plugged it in my WonderBoy PCB's scart adapter and it worked!

I know for sure I'm running RGBs now because that's all my arcade PCB produces.

Best of all this TV now works as though it was Scart from the factory. Doesn't require a switch, the blanking signal coming through the scart does the job.

Will attach photos shortly. TV needs focus adjustment and some other tweaking.

So in short, all that was needed for this mod was...

1) A PCB mountable Scart port with 90 degree angled pins
2) A change to the service menu
3) A 510 ohm resistor
4) A small paperclip
5) Mulitmeter/Soldering Iron/Solder....

Unlikely to find many easier RGB mods....and it still took me months to get it right!

MarkOZLAD · Post by **MarkOZLAD** » Wed Sep 06, 2017 8:48 am

To make this mod more complete I am now attempting to get the Scart pin 8 12V signal to force the TV into AV. I haven't been able to trace the path completely in my photos but I have found it is missing at least one 10K resistor, R36. I assume it will also be missing R37, another 10K resistor.

I will install these resistors and make sure there is a path from Scart Pin 8 to the Micom's pin 29. Then see what happens.

EDIT: Have found the route, requires two Jumpers and two 10K resistors. Took quite a while to just find R37 then to work out the weird jumpering used to get to the AV-ID pin on the MICOM. Will be simple enough now I know how though.

MarkOZLAD · Post by **MarkOZLAD** » Thu Sep 07, 2017 12:26 pm

Added in the missing jumpers and resistors. All checked out on the multimeter but the TV doesn't auto switch to AV.

Dramaking9 · Post by **Dramaking9** » Fri Jun 19, 2020 11:37 am

Hey MarkOZLAD,

I stumbled across your three year posting re LG Crt today. I have an old LG crt lying around and opened it up to find the scart connection you're talking about. After reading your post I was getting quite excited but the crt has a different chassis number and doesn't have the jumper you're talking about. The chassis is MC049B and service menu options are there to enable. Have you had any experience with these? Perhaps another forum member can help as it seems this could be as simple a mod as you've experienced.

Thanks

Dramaking9 · Post by **Dramaking9** » Sun Jun 21, 2020 1:32 am

Hi,

I know this thread is three years old but I stumbled across it as I have an old LG TV lying around as well. The model is RT-21FB75V but has a different board set to yours - MC-049B. As I'm a newb any guidance would be gratefully received. It too has the scart connection but I'm sure I'm missing something to enable RGB blanking as the picture is jumping and not syncing properly. I haven't made any changes yet apart from attaching the scart connector. The IC is VCT49xyI and the inputs are through pins 75-78. Unlike your experience there's no jumper pin near the scart input. Pictures are attached with schematic first.

https://drive.google.com/file/d/11disQw ... sp=sharing
https://drive.google.com/file/d/1At71u6 ... sp=sharing
https://drive.google.com/file/d/18h5q2Z ... sp=sharing
https://drive.google.com/file/d/1rLNLWi ... sp=sharing
https://drive.google.com/file/d/12d4TOo ... sp=sharing
https://drive.google.com/file/d/184CdB4 ... sp=sharing

Thank you

MarkOZLAD · Post by **MarkOZLAD** » Tue Jun 23, 2020 3:27 am

Take a heap of photos on top and bottom of chassis. Look for missing components/jumpers and places where stuff is jumpered to ground.

Fill in the blanks to make it match schematic.

MarkOZLAD · Post by **MarkOZLAD** » Tue Jun 23, 2020 10:11 am

You will also need to change the service menu to enable the scart jack

Dramaking9 · Post by **Dramaking9** » Tue Jun 23, 2020 9:34 pm

ok, will do. I've enable scart in the service menu

Dramaking9 · Post by **Dramaking9** » Sun Jul 19, 2020 8:02 am

Hi,

I studied the schematic and found three capacitors missing in the RGB lines. I also found missing jumpers further up and wired those also. All of this made no difference whatsoever. Upon turning on (arcade game) the screen jitters and pulses with a B&W shimmer. Any thoughts gratefully received.

MarkOZLAD · Post by **MarkOZLAD** » Sun Jul 19, 2020 11:43 am

Check if the blanking voltage is reaching the jungle chip.

Dramaking9 · Post by **Dramaking9** » Sun Jul 19, 2020 12:36 pm

I don't think it is. Continuity suggests it's going to ground which I'm sure it shouldn't be. No difference when connected but unlike your experience there's no missing resistor in the path.

MarkOZLAD · Post by **MarkOZLAD** » Sun Jul 19, 2020 3:14 pm

Dramaking9 wrote:I don't think it is. Continuity suggests it's going to ground which I'm sure it shouldn't be. No difference when connected but unlike your experience there's no missing resistor in the path.

Check for a jumper to ground somewhere on the blanking line.

MarkOZLAD · Post by **MarkOZLAD** » Mon Jul 20, 2020 11:41 am

MarkOZLAD wrote:
Dramaking9 wrote:I don't think it is. Continuity suggests it's going to ground which I'm sure it shouldn't be. No difference when connected but unlike your experience there's no missing resistor in the path.
Check for a jumper to ground somewhere on the blanking line.

R203 is a jumper to ground, needs to be replaced with a 75 ohm resistor.

shmups.system11.org

LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complete...

LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complete...

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet

Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet