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pierrot
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Re: How do I adjust the picture on my Sony Trinitron ?

by pierrot Tue Sep 25, 2018 10:17 pm

Ziggy587 wrote:My service menu current values:
Code: Select all
SYS   1
AFC            1
VPOS   14
VSIZ           25
VLIN   7
VSCO   5
HPOS   8
GDRV   17
BDRV   15
GCUT   7
BCUT   6
TOT           1
NR           0
SCON   9
SHUE   9
SCOL   11
SBRT   33
SSHP   8
RON   1
GON   1
BON   1
PREL   4
AXIS   1
DCOL   0
REF           2
ABLM   2
CROM   1
OSDL   0
Y-DC   5
GMMA   0
VEXT   1
VZOM   4
CDMD   0
RGBL   3
YDLY   0
SBAL   7
SBAS   9
STRE   7
PHOR   15
PE-W   30
PCOR   8
PTRP   30
HCMP   8
DSIP   7
PADJ   32
ID0           25
ID1             1
ID2            0
ID3            0
ID4             17

I think I can discern what a number of these would be:

First few seem to be screen area settings, obviously.

The next few seem like they might be:
GDRV - Green Drive
BDRV - Blue Drive
GCUT - Green Cut
BCUT - Blue Cut

These seem like they would be your gain (drive) and offset (cut) values for setting the white-point, with red being used as a reference, I guess. I'm not sure these would really help you, unless green or blue were saturating before something else.

After that, it looks like there's Contrast, Hue, Color, Brightness, and Sharpness, which you have in the user menus anyway.

These three are kind of curious: RON, GON, BON. Seems like you should be able to set RON, and GON to 0, and get a blue only, picture. I always like to set color and hue that way, with test patterns that have overlapping areas of blue, cyan, and magenta. You could achieve the same thing with a blue filter sheet, though.

I don't really see much else aside from gamma (GMMA), which I personally don't even really like the concept of, since it's a not linear function. Also, there appear to be balance, bass, and treble settings for the sound, but that's not really relevant.

Maybe some of those other settings in between do something magical, but in terms of DKC, I found that game to be pretty dark when I was playing it. The stop-go level was basically pitch black when the lights were off, for instance. Do those settings in DKC give you a better color gradient in the test suite? Might be too much to expect perfect results with composite video, though.
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Re: How do I adjust the picture on my Sony Trinitron ?

by Ziggy587 Tue Oct 16, 2018 9:30 am

The 8-bit Guy put out a video a few days ago where he modified his (NTSC) Samsung consumer TV for RGB input. I've heard about people doing this years ago, but I always assumed it would be completely over my head. But after watching his video, and a few more videos, it appears that it's relatively easy. At least, it's easy to figure out where to inject RGB. Figuring out how to attenuate the signals, if needed, is something that's still above my head though. So I was thinking about modifying my Trinitron TV for RGB input, but ultimately I decided against it.

I bought a 13" PVM off eBay, so same size as the TV I was using. I can't wait to see how it looks. I already have an assortment of RGB SCART cables because of the Framemeister, so I'll just have to grab a BNC breakout and I'm all set!
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Re: How do I adjust the picture on my Sony Trinitron ?

by pierrot Tue Oct 16, 2018 1:01 pm

Ziggy587 wrote:The 8-bit Guy put out a video a few days ago where he modified his (NTSC) Samsung consumer TV for RGB input. I've heard about people doing this years ago, but I always assumed it would be completely over my head. But after watching his video, and a few more videos, it appears that it's relatively easy. At least, it's easy to figure out where to inject RGB. Figuring out how to attenuate the signals, if needed, is something that's still above my head though.

Interesting. Do you mean that he modified it to accept RGB signals through scart/BNC?

In general, attenuation is just a "gain" factor (technically, attenuation isn't gain, but--) with magnitude less than unity (one). In other words, if you have some gain/attenuation factor, A (multiplicative with the input signal, x(t)), then attenuation corresponds to | A | < 1, and gain corresponds to | A | >/= 1. How that would relate exactly to your TVs gain settings, I couldn't really say, though.
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Re: How do I adjust the picture on my Sony Trinitron ?

by Ziggy587 Tue Oct 16, 2018 4:59 pm

pierrot wrote:Interesting. Do you mean that he modified it to accept RGB signals through scart/BNC?


Yes. A lot of people are doing this actually. So TVs deal in RGB, even if they don't have an RGB input. It's just a matter of finding somewhere you and inject the RGB signal. It seems like the common and easy way are TVs that use an RGB signal for the overlay system menu.

https://www.youtube.com/watch?v=DLz6pgvsZ_I

pierrot wrote:In general, attenuation is just a "gain" factor (technically, attenuation isn't gain, but--) with magnitude less than unity (one). In other words, if you have some gain/attenuation factor, A (multiplicative with the input signal, x(t)), then attenuation corresponds to | A | < 1, and gain corresponds to | A | >/= 1. How that would relate exactly to your TVs gain settings, I couldn't really say, though.


What I mean is, if I have to weaken or strengthen the RGB lines I wouldn't know what I'm doing. I could do it so it "looks right," but not know if I'm slowly burning an IC out from a hot signal. Or something like that.
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Re: How do I adjust the picture on my Sony Trinitron ?

by pierrot Tue Oct 16, 2018 8:24 pm

Oh, sorry. I didn't realize you were talking about the resistors in the voltage divider network. Very interesting video. I wouldn't be too worried about selecting the wrong resistor values, though. The ones he added (75 ohm) are mostly to lift the injected signals up from ground. Using Superposition, the attenuation factors for the RGB signals from either the MCU, or the console/computer are going to be set by the same voltage divider resistors that were already there. It's just that the numerator is set by the opposite resistor, for the injected signal.

In other words, if R1 is the resistor connected to the MCU, and R2 is the resistor to ground (or at the junction of the injected source, and the added resistor, in the post-mod case), the Superposition theorem will give an attenuation factor of R2 / (R1 + R2) for the signal from the MCU, and R1 / (R1 + R2) for the injected RGB signal. Theoretically, the attenuation will be independent of the added resistor. Although in reality, there's a source resistance from the injected signal that would be in parallel with the added resistance. If that source resistance is 75 ohms, then it adds 37.5 ohms to R2 for the MCU attenuation factor. In the video, his R2 was 820 ohms, so 37.5 ohms is fairly negligible (4.35% error).
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Re: How do I adjust the picture on my Sony Trinitron ?

by Ziggy587 Wed Oct 17, 2018 9:28 am

Well, I might try it at some point. I have plenty of consumer CRT TVs, and I would eventually like to try this on at least one. But to be honest, the number one reason for my hesitation is I'm afraid of high voltages. Yes, I know the discharge process is easy. I've seen plenty of videos of people discharging them. But I have some kind of fear of it. I'm equally afraid to service my guitar tube amp, even though the discharge process is equally easy. I really should get over it, being that I own so many devices that I will have to service at some point.

But for now, I got a PVM coming!
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Re: How do I adjust the picture on my Sony Trinitron ?

by pierrot Wed Oct 17, 2018 12:42 pm

Ziggy587 wrote:But for now, I got a PVM coming!

Oh, well, yeah. You're all set then.

Ziggy587 wrote:But to be honest, the number one reason for my hesitation is I'm afraid of high voltages.

I don't blame you at all. Making a mistake in the procedure could be really costly. Of course, you could just make a Faraday cage for yourself, but that's probably not worth the trouble, and raw materials.
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Re: How do I adjust the picture on my Sony Trinitron ?

by Ziggy587 Wed Oct 17, 2018 7:44 pm

pierrot wrote:Oh, well, yeah. You're all set then.


Until I have to recap it or something! :P

I'll probably revisit RGB modding the TV at some point, but there's a bunch of other stuff I'd like to do first. Like RGB modding a NES, which I've been putting off for years.

Also, I think RB needs an official CRT thread for all CRT related talk.
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Re: How do I adjust the picture on my Sony Trinitron ?

by samsonlonghair Wed Oct 17, 2018 7:49 pm

Ziggy587 wrote:Also, I think RB needs an official CRT thread for all CRT related talk.

At this point we have multiple long-running threads about CRTs. There was one particular thread that was started by artphotodude that had a lot of traction. It’s not official, but I think that’s the defacto CRT thread.

Let me see if I can dig up a link...
Edit: Maybe I misremember. I just checked artphotodude’s posting history. He started more than one thread about CRTs, but none that I could find ran longer than two pages. On the other hand, I did manage to find this thread: viewtopic.php?f=28&t=49940
Eleven pages of CRT discussion.
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Re: How do I adjust the picture on my Sony Trinitron ?

by Ziggy587 Mon Oct 22, 2018 12:48 pm

samsonlonghair wrote:On the other hand, I did manage to find this thread: viewtopic.php?f=28&t=49940
Eleven pages of CRT discussion.


Ah, right. I remember that one now. I'm gonna start posting in that one again since this thread can only get off-topic now. Maybe I'll come back to this thread one day if I decide to mess with the service menu or RGB modding.
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