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 Post subject: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complete...
PostPosted: Thu May 18, 2017 1:32 pm 



Joined: 18 May 2017
Posts: 6
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=0BxXDEFhRZ50MQ0I5bFJ5M0N4YW8

the Jungle IC - TDA8841/2 datasheet - https://drive.google.com/open?id=0BxXDEFhRZ50MbUlSOXg0ajZQc1U

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=0BxXDEFhRZ50MbExmYnJ2Ykt1U2s. 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=0BxXDEFhRZ50MYVFrOHFlaS10VEE

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=0BxXDEFhRZ50MNTBpQkVuRlZPUmc

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=0BxXDEFhRZ50MSTd4UVFzM3NRTVk
https://drive.google.com/open?id=0BxXDEFhRZ50MUmhLZWNfcGZpd3M
https://drive.google.com/open?id=0BxXDEFhRZ50MNURHVXBQT2hXN2M
https://drive.google.com/open?id=0BxXDEFhRZ50MRWU5MkUyc2lSVlk
https://drive.google.com/open?id=0BxXDEFhRZ50MLVRoWGFjMEYwejA
https://drive.google.com/open?id=0BxXDEFhRZ50MMXlzX1NZU2ctdEk

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/0BxXDEFhRZ50MR2djNTFOOXJQU1U/view?usp=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/0BxXDEFhRZ50MR2djNTFOOXJQU1U/view?usp=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-Pins-Right-Angle-Type-Scart-Socket-Connector-/321474089583?hash=item4ad959526f:g:n-IAAOSwol5Y0TcH. 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=0BxXDEFhRZ50MRlVYb3J5MnU0ejg.

This is a list of LG TVs and their chassis numbers. https://drive.google.com/open?id=0BxXDEFhRZ50MTmpINVVfQnNNOFU I hope this can help other forum members to find LG TVs that are easily modified to RGB Scart.

Cheers,

MarkOZLAD


Last edited by MarkOZLAD on Fri May 19, 2017 9:33 am, edited 2 times in total.

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 Post subject: Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet
PostPosted: Fri May 19, 2017 12:42 am 


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Joined: 24 Jul 2016
Posts: 69
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!


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 Post subject: Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet
PostPosted: Fri May 19, 2017 1:02 am 



Joined: 18 May 2017
Posts: 6
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


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 Post subject: Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet
PostPosted: Fri May 19, 2017 1:06 am 



Joined: 18 May 2017
Posts: 6
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.


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 Post subject: Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet
PostPosted: Fri May 19, 2017 2:13 am 



Joined: 18 May 2017
Posts: 6
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


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 Post subject: Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet
PostPosted: Sat May 20, 2017 5:18 pm 



Joined: 18 May 2017
Posts: 6
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.


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 Post subject: Re: LG CA-20F80/Chassis MC84A RGB Scart Mod Almost complet
PostPosted: Tue May 23, 2017 2:09 am 


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Joined: 24 Jul 2016
Posts: 69
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?


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