
Just need to figure out how to get those bars out of it. This is the only thing I have to test with at the moment. I don't have any other consoles with RGB at the moment, more to come of course! So what is left to do to get this working good?
mikejmoffitt wrote:Buttersoft, your experience resembles my first attempt on a 20" trinitron TV - fading from too bright, briefly "just right", then going darker. I did not ever properly solve it, so if you figure it out, I'd be interested in what you did.
Seeing as how some of the bars go behind the characters while some go in front makes me think the problem is with the MVS and not the TV. Do you have an arcade monitor to connect it to?Devalis wrote:Trying to RGB mod my 32" Panasonic TV, model CT-32G13W. I removed the OSD lines and tapped in my RGB and pulled blank high to 5v. I hooked up my Neo Geo MVS and used the composite in for sync. Here is what I got right off.
Just need to figure out how to get those bars out of it. This is the only thing I have to test with at the moment. I don't have any other consoles with RGB at the moment, more to come of course! So what is left to do to get this working good?
Have you ever connected an MVS (or any other arcade board) to an RGB-modded TV chassis? Consoles are one thing, but impedance mismatch is giving me fits. I've been banging my head against such a project for a couple months, but can't get it quite right.mikejmoffitt wrote:I picked up another 25" TV today intending to do a tube swap on a Neo-Geo machine. If the tube swap doesn't work out, it's still a good tube and TV, so I'll see about RGB modding it. At a glance the OSD looks RGB-driven, so I bet it will not be difficult.
I've connected a bunch of MVS systems to my RGB modded TVs and nothing was out of the ordinary. I terminate my outputs with a 75 ohm resistor in series on the output, to match the termination of the TV.berq wrote:Have you ever connected an MVS (or any other arcade board) to an RGB-modded TV chassis? Consoles are one thing, but impedance mismatch is giving me fits. I've been banging my head against such a project for a couple months, but can't get it quite right.mikejmoffitt wrote:I picked up another 25" TV today intending to do a tube swap on a Neo-Geo machine. If the tube swap doesn't work out, it's still a good tube and TV, so I'll see about RGB modding it. At a glance the OSD looks RGB-driven, so I bet it will not be difficult.
If you mean the whole image gets larger when it gets brighter... It's called bloom, and no, it's not really meant to happen. It always does though, even on the best sets a tiny bit, getting slowly worse as time goes on. I think it's the caps aging, though it by no means indicates they're about to fail.Devalis wrote:when the screen goes white, the lettering at the top and bottom will move off screen. I don't know if it's supposed to do that or what.
That was a good read. Thanks. Unfortunately, even with the MVS signal divided down to the right voltage, the image is still too dark.KnuckleheadFlow wrote:How are you reducing the MVS's RGB signal (< 3 Vpp) to the TV's level (< 1 Vpp)? Earlier I posted a link to a DIY supergun with SCART RGB output. Take a look at that.
I think some monitors are worse than others regarding blooming. I fully recapped an old arcade monitor recently (some 30+ caps) and now the picture is nice and the colors are great, however, it blooms just like it did before.buttersoft wrote:If you mean the whole image gets larger when it gets brighter... It's called bloom, and no, it's not really meant to happen. It always does though, even on the best sets a tiny bit, getting slowly worse as time goes on. I think it's the caps aging, though it by no means indicates they're about to fail.
A little off topic but I hope this doesn't discourage you (or anyone else) from further modding. Don't throw that TV out yet, though. You may get there soon enough. First surface mount mods I did looked like balls. Literally; solder balls all over the place. So bad even Drakkon would've sneered at it. Surface mount stuff can be tricky, but a little practice gets acceptable results. The caveat being you need 5 other things:Shoryukev wrote:Well......it is with great sadness that I inform you I've modded my 32" sony CRT TV into one that doesn't work. I just don't have the skills required to work on things that have small surface mounted components. Time to admit defeat and just get another TV that has component YPbPr input and use a SCART converter instead.
Dang....
Hmm, shame about that. I'm thinking about making a CMVS myself, leaning towards using an 1C.berq wrote:That was a good read. Thanks. Unfortunately, even with the MVS signal divided down to the right voltage, the image is still too dark.
I'd get into more detail, but this thread is getting kinda schizophrenic with all the different projects converging on it. Which is cool. I like that so many people are pumping new life into CRTs. But I'd already started chronicling my progress over on the neo-geo.com boards. If you're ever over that way, I'd be honored if you'd stop by.
It hasn't discouraged me, but I know my boundaries. I am just terrible with dealing with really small parts right now lol, I'm sure at some point I'll get better at it. Kinda sucks I butchered the TV, but I got it off craigslist for free a few years ago anyways so I'm not sweating it. I really need to get a magnifying glass and an articulating table clamp to hold things while I work on them. I've modded several of my consoles and enjoy the projects.KnuckleheadFlow wrote:A little off topic but I hope this doesn't discourage you (or anyone else) from further modding. Don't throw that TV out yet, though. You may get there soon enough. First surface mount mods I did looked like balls. Literally; solder balls all over the place. So bad even Drakkon would've sneered at it. Surface mount stuff can be tricky, but a little practice gets acceptable results. The caveat being you need 5 other things:Shoryukev wrote:Well......it is with great sadness that I inform you I've modded my 32" sony CRT TV into one that doesn't work. I just don't have the skills required to work on things that have small surface mounted components. Time to admit defeat and just get another TV that has component YPbPr input and use a SCART converter instead.
Dang....
1) a temp controlled soldering iron. There are good-enough Hakko knockoffs like the $24 YiHUA 936
2) small (0.8-1.2mm) wedge/screwdriver tips. Forget those bullshit cones.
3) fine and ultra fine solder. Having 0.015" diameter really helps with small stuff
4) magnification. Not to inspect, but to use while you work. I use a stereo microscope, but one of those big magnifying lenses on a flexible arm, or those glasses with the jeweller's loupe things should do. My vision is like the one thing that hasn't started going to shit, I really didn't think I needed magnification but I always wanted a microscope and got a good deal on eBay. I quickly realized having one that everything blownup like that made my movements significantly finer somehow. And I'm rather clumsy working with my hands.
5) *copious* amounts of flux paste. Smear that shit. Plain rosin flux is cheap, works good though it can be a little annoying to clean
With those, it really just takes a handfull of times practicing on junk PCBs to get you there. That said, though I can lay down a hundred picture perfect joints on surface mount ICs, caps and resistors still give me headaches and often end up slightly askew. So it goes.
Dave Jones of the EEVBlog on youtube has some good, detailed videos for this. Some people can't stand his voice but it never bothered me lol.
Don't attempt to drive the neck board with the signal directly from an AV device. It's not going to work.buttersoft wrote: I'm guessing the problem i have with delivering amped RGB direct to the neckboard lies in delivering too much current, and there's some sort of feedback loop reacting to that. Or possibly that the RGB im' producing isn't amped right, and the black level is resetting, again via some sort of loop. But those are just guesses - Tim will no doubt come in and tell me I'm wrong again ;) I think if I build a two stage amp, using back-to-back 7314's, i can get a stable picture,but i want to confirm that. And doing so produces a ton of noise. Earlier in this thread I did read about turning down the contrast, colour and brightness to nothing. I'll give that a try, and try to measure the RGB coming out of the Micom directly as well.
The micro's OSD out is muxed with the output of the jungle IC because some versions of the chassis require the RGB input for SCART. If one version has to be this way, might as well make them all like that. The TV design engineers don't want to work too hard. The OSD is digital and is generated by the TV itself. Because it's digital there's no need to bother with clamping and blanking. It restricts the generated video to what it can safely do without beam current feedback.buttersoft wrote:Nice to know I'm in good company. As i said, the schematics for Asia (and presumably for Australia) show a separate Micom chip, and that separate chip feeds the neckboard directly. I don't see why you'd bother, if you didn't have a cheaper Jungle IC that didn't take RGB-in. The Euro version, or some instances of it, had SCART - and I note that cheaper versions of the chassis used exactly the same components, but had a SCARTkill resistor to jump the ability to switch SCART on, in some way. My board seems to have that resistor, but removing it made no change.
Sometimes you’re so far ahead of me I have trouble following. The last 6-7 pages of the schematic are the connection diagrams. The Euro version’s TTX micro feeds the TDA8842’s RGB inputs (though not the blanking pin?) My version has the Non-TTX micro, which feeds the neckboard. And it has a TDA8841, without SECAM capability, not the 8842 shown. Is that what you were saying...? Aren't there two versions, that work slightly differently?viletim wrote:The micro's OSD out is muxed with the output of the jungle IC because some versions of the chassis require the RGB input for SCART. If one version has to be this way, might as well make them all like that.
You sure that's the right chip? Pins 4, 5 and 6 on that datasheet show 0-5 V square pulse input; in other words, digital RGB.Devalis wrote:anyone get a chance to look at the datasheet I posted, see if it can handle the output of the MVS?
Low cost TV chassis are often desiged to accomodate lots of variants. In you case I there's a version with and without teletext. With and without SCART. It appears one combination requires SCART and OSD at the same time, hence the OSD connected past the jungle IC. This jungle IC is designed for operation like this it seems. There's a note about it on page 15 of the datasheet.buttersoft wrote:Sometimes you’re so far ahead of me I have trouble following. The last 6-7 pages of the schematic are the connection diagrams. The Euro version’s TTX micro feeds the TDA8842’s RGB inputs (though not the blanking pin?) My version has the Non-TTX micro, which feeds the neckboard. And it has a TDA8841, without SECAM capability, not the 8842 shown. Is that what you were saying...? Aren't there two versions, that work slightly differently?viletim wrote:The micro's OSD out is muxed with the output of the jungle IC because some versions of the chassis require the RGB input for SCART. If one version has to be this way, might as well make them all like that.
It's a good idea to verify that the manual and chassis match. Service manuals are notorious for errors and ommisions.buttersoft wrote: Schematic - https://my.mixtape.moe/zwwyvm.pdf
Jungle IC - https://my.mixtape.moe/hiflqk.pdf
The datasheet for the TDA8841 indicates RGB inputs, I just can’t get them to work. If they’ve been disabled internally, or by the micro, would replacing the chip, maybe with a higher-end 884X, work? If not, or if I can’t find one, is there a chip you’d suggest?
Thanks for the reply, the help you provide is amazing. If you’re willing to post, I’m willing to listen.
EDIT: I do wonder if there's a mistake in the schematic, in that the EU version's TTX micro does feed the blanking pin. The TTX-Bus connection on the micro shows a wire for it.
berq wrote:That was a good read. Thanks. Unfortunately, even with the MVS signal divided down to the right voltage, the image is still too dark.KnuckleheadFlow wrote:How are you reducing the MVS's RGB signal (< 3 Vpp) to the TV's level (< 1 Vpp)? Earlier I posted a link to a DIY supergun with SCART RGB output. Take a look at that.
I'd get into more detail, but this thread is getting kinda schizophrenic with all the different projects converging on it. Which is cool. I like that so many people are pumping new life into CRTs. But I'd already started chronicling my progress over on the neo-geo.com boards. If you're ever over that way, I'd be honored if you'd stop by.
On page 16 of the datasheet:KnuckleheadFlow wrote:You sure that's the right chip? Pins 4, 5 and 6 on that datasheet show 0-5 V square pulse input; in other words, digital RGB.Devalis wrote:anyone get a chance to look at the datasheet I posted, see if it can handle the output of the MVS?
Well, I still have lots to learn lol. To be fair, the waveform for those pins does look like TTL, doesn't it?viletim wrote: On page 16 of the datasheet:
This is should be OK for arcade video. Just connect it directly not resistors or anything. Disconnect the line to Ys (pin 3) and connected a DC level between 3.0 and 6.0 V to enable fast blanking. Put the sync signal into the composte video (via a 470 ohm resistor) input and set the TV to AV mode. Should work.
- External input pin for OSD
- Output linearly changes according to input level
- Recommended use range: 0 V to 6 V
This jungle IC's OSD input does not have a video clamp so it's not compatible with standard 75 ohm RGB video (SCART, etc).
Thanks Tim! I'd worked out the I2C control on the TDA8841 was probably getting in the way, but wasn't really sure where to go from there. As it stands, the blanking pin does blank everything, but the RGB inputs don't show up. Certainly the micro is using it for the OSD, but it's probably just timing its delivery of the blanking signal and inserting a portion of each relevant line to the RGB output lines as shown. (The micro is receiving both H & V-sync). I guess the blanking should be timed to the sync signals, as you noted further above - that's the capability I'd be turning on with the EEPROM, right?viletim wrote:Anyway, let's work out how to get RGB into TDA8841. It's got one of those paper-saving datasheets, 10 different parts for extra confusion. The TDA8841 is a 56 pin DIP isn't it? Page 5 for pinout. R, G, B, into pins 23, 24, 25. 'Fast blanking' (RGB enable) into pin 26 (0.9 to 3.0 V). Page 15 of the datasheet mentions that fast blanking for RGB-1 is controlled by the IE1 bit in some internal register. If it's not set to 1 (active) then the blanking input isn't going to work. If this is the case then you'll need pull out the serial EEPROM connected to the micro and dump it. Compare the EEPROM dump to the register map on page 17. See if you can work out which byte contails the IE1 bit. If you're stuck try adjusting the colour saturation and reading it again.
buttersoft wrote:How will the TV know it's receiving RGB through those pins, and to display it? I understand you're seeing internal blanking elsewhere, and the set is capable of it, but I'm not sure that equates to it working automatically. I have a Samsung PoS that when set to the auxiliary AV channel looks blue until fed sync, whereupon it blanks itself. So if you get the RGB to display, but something else is displaying behind it, or even just the blue, you might try that. I couldn't find a way to turn my RGB inputs on though, as I think it was I2C controlled. I'd be interested to hear how you get on as it might help me get furthercruzlink2 wrote:In this diagram you can see that the OSD is done internally inside the jungle IC, so therefore no need for external blanking. I am starting to think that the rgb points are just an extra input that might have been used in a more expensive model, I read the user manual and it points to unused ports that are for a optional component input/scart in the European model. So maybe this input does not need any blanking I think because it's an actual input and not an OSD/RGB in for the menu. I will give a shot to just plugging in the pins and seeing what I get.
EDIT: I think my problem might be that without the remote I can't get to the primary AV channel, only to the secondary one, which won't display RGB.