RGB on your crappy NTSC TV

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mikejmoffitt
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RGB on your crappy NTSC TV

Post by mikejmoffitt » Sat Sep 20, 2014 11:16 pm

I think NTSC is a super-turd, and I did this ages ago, but only just now bothered writing it up. People here like old game hardware (though this is ironically not pertinent to the NES) so maybe you guys can find this useful.

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MottZilla
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Re: RGB on your crappy NTSC TV

Post by MottZilla » Sun Sep 21, 2014 10:36 am

That's pretty awesome if you're handy enough to be able to do such a mod. Very nice to be able to get a 32" screen for it as well. I use a Sony PVM for my consoles. Unfortunately it's not so easy to get a 32" PVM.

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Re: RGB on your crappy NTSC TV

Post by SkinnyV » Mon Sep 22, 2014 10:47 am

That's an awesome mod for us North American with almost no access to RGB TV. I have been looking for such a mod for a long time. I always thought it should be possible to mod regular TV for RGB but I am not knowledgeable enough to poke around a CRT TV. I am a bit scared of messing around with them because of the massive amount of voltage stored in the tube...

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Memblers
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Re: RGB on your crappy NTSC TV

Post by Memblers » Mon Sep 22, 2014 6:15 pm

It is a pretty cool hack.

I thought it was interesting too that there is information from the arcade repair community about CRT compatibility with the various kinds of arcade monitor control boards. So alternatively, I think if one had the right kind of TV, one might be able to just plug in a different board set for RGB.

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Re: RGB on your crappy NTSC TV

Post by Memblers » Tue Sep 23, 2014 2:22 pm

Sorry for the double post, but on second thought and after talking with kevtris about it, I wanted to add an important disclaimer. I imagine there is a lot of variation in TVs, but arcade monitors are almost always "hot chassis". So they are powered through an isolation transformer (1:1, like 110V in, 110V out). My understanding is that some TVs are hot chassis, but instead of isolating everything, they might isolate only the A/V in/out. Bypassing that would be very dangerous.

I've discharged a few CRTs, and yeah it's a little thrilling hearing that SNAP the first couple times. While it is high voltage, it's a tiny current, and isn't nearly as dangerous as any voltage at 10+ Amps. So anyone thinking of modding their TV, please check that it (and therefore yourself) remains isolated from the line voltage.

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mikejmoffitt
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Re: RGB on your crappy NTSC TV

Post by mikejmoffitt » Tue Sep 23, 2014 2:49 pm

Memblers wrote:Sorry for the double post, but on second thought and after talking with kevtris about it, I wanted to add an important disclaimer. I imagine there is a lot of variation in TVs, but arcade monitors are almost always "hot chassis". So they are powered through an isolation transformer (1:1, like 110V in, 110V out). My understanding is that some TVs are hot chassis, but instead of isolating everything, they might isolate only the A/V in/out. Bypassing that would be very dangerous.

I've discharged a few CRTs, and yeah it's a little thrilling hearing that SNAP the first couple times. While it is high voltage, it's a tiny current, and isn't nearly as dangerous as any voltage at 10+ Amps. So anyone thinking of modding their TV, please check that it (and therefore yourself) remains isolated from the line voltage.
Whoops, I'm so used to working on CRTs that I just sort of take that stuff as the granted "duh" information. I should edit it to put something in there. I think the hot-chassis TVs are mostly older ones, but I'm only saying that because literally every TV I've worked on has not been like that. Most late-90s arcade chassis designs have the isolation transformer and can just plug into mains voltage as well.

Before anyone tries this make sure you discharge the tube, even if you are pretty sure it has a bleeder circuit of its own! I did all of my work on this with the set unplugged from mains as well.

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cubeboy
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Re: RGB on your crappy NTSC TV

Post by cubeboy » Fri Sep 26, 2014 7:40 am

Definitely need to mention about properly discharging before modding any old TVs. This was common knowledge for anyone interested about 10 years ago, but I'm guessing most on the internet looking to mod would probably not know that they could kill them selves if not super careful.

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RETROGAMING-MODS
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Re: RGB on your crappy NTSC TV

Post by RETROGAMING-MODS » Mon Nov 10, 2014 12:10 pm

I have done this with a handful of tvs successfully, If done right It can be just as good as a pvm if the tv used is of decent quality, of the tvs ive done so far Sony Trinitrons seem to be the easiest to do. Also Samsungs tend to be cake when it come to this they usually have a scart provision on the pcb inside and its silk screened you just have to get the service manual and put the scart connector and make the appropriate connections on the board which also require missing components that would be resistors you may or may not have to play with different resistor values to get the picture right but the service manual should say. Its obvious that samsung saved money by using the same chassis for USA and the UK. In the case of the sony trinitron its a matter of tapping the ext rgb input on the jungle ic, you will need a service manual for this as well, but it is designed to properly take in an RGB connection just wasn't used. There are some cases where the OSD menu of the set is occupying the only rgb input on the tvs jungle ic. in this case you have to design a way to switch back and forth dip switches work well here or rotary. There are some tvs where you have to tap the guns directly these tend to be hard to get right, basically disconnecting the rgb out from the jungle ic that goes to the neck board and connecting your rgb here and it does require experimenting with different resistor values and there maybe other issues with the image, you would feed the composite imput sync in this case and the deflection circuits would stay put. Sometimes there is a additional connector that is fed to the neck board that has to be removed and fed a lower voltage if i can remember correctly sometimes it says 12v and if you feed it 5 it improves the performance of the picture quality with this method. These are my experiences and can differ greatly depending on the set in question.

If you are interested in having your tv rgb hacked and live in the west cost USA. you can contact me and we will see if its feasible I reside in Nevada so this would be for those who live close by since shipping a CRT is not only expensive but risk of implosion or damage to shadowmask/apturegrille.

http://www.retrogaming-mods.com/

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Re: RGB on your crappy NTSC TV

Post by Devalis » Tue Nov 29, 2016 11:04 am

I am trying to do the same thing to my 32" Panasonic TV, model CT-32G13W. I couldn't get any schematics, but I did some poking around and figured out what chip the composite goes into. I looked up the datasheet for the chip (AN5165K) and wouldn't you know, it has RGB input and output lines! I traced them out and they go to another chip, which from what I could find, runs the OSD. My plan is to remove the jumpers (lucky me!) and tap in there. The only question is where do I tie in sync? The chip has lines for H and V sync, but not just a plain old sync pin. I was wondering if I could just plumb it in over the existing composite connection and run it that way. Any thoughts?

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mikejmoffitt
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Re: RGB on your crappy NTSC TV

Post by mikejmoffitt » Tue Nov 29, 2016 1:37 pm

It might help if you check out the thread I started on shmups for this purpose: http://shmups.system11.org/viewtopic.php?f=6&t=56155

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Re: RGB on your crappy NTSC TV

Post by Devalis » Tue Nov 29, 2016 8:46 pm

Partial success!

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Re: RGB on your crappy NTSC TV

Post by tepples » Tue Nov 29, 2016 8:51 pm

Looking good. Now you just need to cotton swab the CHA board's connector to fix the bad connection on one of the sprite data bus bits.

Devalis
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Re: RGB on your crappy NTSC TV

Post by Devalis » Tue Nov 29, 2016 9:07 pm

Might just need to clean the Jamma connector.

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Re: RGB on your crappy NTSC TV

Post by tepples » Tue Nov 29, 2016 9:18 pm

As I understand it, the JAMMA connector carries input, analog RGB video, and analog audio, like the controller ports and AV connectors of an NES Control Deck. Poor connection there wouldn't cause the sort of vertical stripes you're seeing here. The CHA board in a Neo Geo game corresponds to the CHR half of an NES game's 72-pin connector, and a bad connection on the data bus produces 1-pixel-wide vertical stripes for the same reason (bit planar graphics). So cleaning the MVS's JAMMA connector would be like cleaning the yellow RCA jack.

Devalis
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Re: RGB on your crappy NTSC TV

Post by Devalis » Tue Nov 29, 2016 9:34 pm

so just blow on the cartridge? LOL. I'm kidding. I should take it apart and take the good old pink eraser to the cart contacts.

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