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using Composite to VGA converters


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#26 Tursi OFFLINE  

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Posted Wed Dec 31, 2014 4:03 AM

I never worried about it much on the TI, but when I was messing around on the Playstation, I used to write everything for 50hz. If the console was 60hz, it just dropped every 6th frame for an equivalent frame rate. ;)

You just have to be careful on a real 50hz console - they have more time in the vertical blank than NTSC, so if you are really pushing things during the blank you might right out of time when that code moves to 60hz. Not as big a concern going the other way. :)

#27 wyerd OFFLINE  

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Posted Wed Dec 31, 2014 8:47 AM

I might still have my PAL console that came over with me from the UK. It's in a bit of a state externally I vaugely remember. I last remember seeing it in the loft a while back, but if I can find it, it's yours.

#28 wyerd OFFLINE  

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Posted Fri Jan 2, 2015 2:25 PM

Thanks to all of you....as I've looked around and read several articles, I have a much clearer (no pun intended) understanding of the issues at hand.

 

it's frustrating that PAL consoles seem to fair better with these low cost converters than NTSC systems do. I've found countless pages of European TI users using the cheapest converter and having it work first time (exactly the opposite of what I read from North American TI users)...But there is no arguing that a $79 F18A ($92 CAD - Thank you OPEC) is cheaper than a $468 xRGB (a whopping $543 CAD). Especially considering the console cost me $100 including shipping and import fees!

 

It was encouraging to hear that I "might" luck into a cheap unit that works, but if I have to go through 2 or 3 to find one, then the F18A is still cheaper (and as someone else mentioned, provides other enhancements as well),

 

As always the AtariAge TI crew demonstrates a more finely tuned synapse-firing mechanism than I posess in such matters. I guess I've got to get myself a second console, keeping one stock, and making the other one a 1981 sci-fi hybrid by adding an F18A. In the interim, I found a sweet little 12" (13"?) Flat Screen (CRT) Trinitron for $10 on craigslist that I pick up next week, which will be far more practical than this honkin' 20" mofo I'm using now.

 

If I do break down and try another one of these converters, and find one that works, I will be sure to provide the sku in this thread.

 

I found my old PAL console. PM me if you're interested.

 

img_1229.jpg

 

img_1226.jpg

 

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Keyboard needs attention as it bounces on some keys

 

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#29 Fredrik Öhrström OFFLINE  

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Posted Wed Jan 7, 2015 10:39 AM

Is the only difference between a PAL and NTSC ti994a the VDP (and its supportive electronics) chip? I.e. the ROMS, GROMS etc are identical but the vertical irq just happens to trigger at 50/60 Hz depending on the VDP chip?



#30 PeBo OFFLINE  

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Posted Wed Jan 7, 2015 3:14 PM

I found a device that works...with a few caveats.

 

It is the StarTech.com COMP2VGA

 

I had already hooked my console up to my living room LED TV via le composite connector, and was pretty dissapointed with the picture quality. Well, the output from this device is about the same.

 

(the thumbnailed picture doesn't really reflect the muddy washed out image...in fact I WISH it looked this good in reality!)

 

First there is no hardware upscaling in the device so it passes the raw 256x192 image  directly to the monitor, which applies it's own rudementary upscaling to the closest resolution available (640x480) which is already a pretty blurry rez on this monitor.

 

Further, after reading what I have on this topic, I'm guessing that the device is applying some kind of de-interlacing filter...which blurs the image further. (looks like that's what's happening anyway)

 

I reduced all colour channel (R G B) intensities to about 30% each, dropped the brightness and contrast (contrast is now at zero), and I've achieved a "tolerable" image. The best description would be to say it looks similar to Classic99's 2xSal filter, but with analog colour bleed artifacting (which looks gawdawful on an LCD).

 

Now what I haven't tried (since I no longer own such a beast) is hooking it up to a VGA CRT monitor...I'm guessing that THAT would be excellent, since CRTs are not "locked" to a particular "best" resolution and the scanlines would help lessen the effects of  the colour bleed. I'll try to borrow one and see how I fair in that regard.

 

But if you want to connect a stock 4A to a VGA LCD monitor, and your unit has had problems doing so, this device WILL work in colour...

...you just might miss how much better your TI looked on a TV.

 

Looks like sticking with CRT's or installing an F18A will be my only options after all.

 

Guess I'm buying a second console.

 

 

Attached Files



#31 TMA-1 OFFLINE  

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Posted Wed Jan 17, 2018 2:46 PM

I have yet another solution, for probably $10 USD.

 

I had the same problem as the original poster--the output from a cheap AV-to-VGA converter was badly banded black & white.  So I sold that eBay converter on Kijiji (for a profit--shhh,...), and used a $5 (eBay) AV-to-HDMI converter, in conjunction with a $4 (eBay) HDMI-to-VGA converter.

 

Double conversion works.  The AV-to-HDMI converter does a better job of interpreting the raw signal captured from the TI-99/4A, (which was originally supposed to go to the modulator), than the AV-to-VGA had.  The final output is somewhat washed and blurred, but nothing I consider serious. It is an easy solution which saves me having yet another output device on my crowded workbench.  And of course it fits my primary criteria:  cheap.

 

Ian

 

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#32 Ksarul OFFLINE  

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Posted Sat Jan 20, 2018 10:31 PM

That's an interesting solution! I recognize the AV2HDMI box, but which HDMI2VGA box are you using (as we know your pairing works--and with the cheap stuff, that ism't always guaranteed with a different pairing)?



#33 TMA-1 OFFLINE  

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Posted Sat Jan 20, 2018 11:19 PM

I don't think that part of the equation is the difficult one, as it's the AV-to-HDMI converter that is doing the "hard" work of digesting the improper AV signal.  Once you have good HDMI I think it's clear sailing from there.  But to answer your question,...

 

The HDMI-to-VGA is a "robust connector" type affair, which can be seen in my second photo, connected to the Mini AV2HDMI.  It's black so somewhat hard to see.  Here are a couple of better pictures.  They can be had on eBay for 3 to 6 dollars or so.  Note: try to get one with the audio output.  Not all of them have that--then you pipe both video and sound into your existing monitor and computer speakers.

 

eBay examples at the time of writing, including but not limited to item numbers:  172695857361  122486456926   162736693760  You get the idea.

 

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Edited by TMA-1, Sat Jan 20, 2018 11:28 PM.


#34 chris36 OFFLINE  

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Posted Mon Dec 3, 2018 6:32 PM

https://www.pagetable.com/?p=672

 

I had a TI with the no color issue.  I swapped out the crystal as mentioned in the above thread which fixed it.  Add this info?



#35 OLD CS1 OFFLINE  

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Posted Mon Dec 3, 2018 8:38 PM

https://www.pagetable.com/?p=672

 

I had a TI with the no color issue.  I swapped out the crystal as mentioned in the above thread which fixed it.  Add this info?

 

This is interesting. I wonder if this could also resolve problems with some modern monitors and converters synchronizing as the black-and-white photo looks identical.  (Also, will be moving these two posts to a relevant thread when I dig it up...)



#36 chris36 OFFLINE  

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Posted Mon Dec 3, 2018 9:13 PM

Just to add more specific detail. The TI in question did show up as color when using an adapter cable to go to an LCD component input.  The TI showed black and white when going through the RF modulator to a small CRT TV I have.  The same RF modulator worked fine with two other TI's I have on the same CRT TV.  So in my case, the crystal swap fixed a black and white via RF modulator to CRT problem.



#37 OLD CS1 OFFLINE  

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Posted Tue Dec 4, 2018 7:17 AM

Just to add more specific detail. The TI in question did show up as color when using an adapter cable to go to an LCD component input.  The TI showed black and white when going through the RF modulator to a small CRT TV I have.  The same RF modulator worked fine with two other TI's I have on the same CRT TV.  So in my case, the crystal swap fixed a black and white via RF modulator to CRT problem.

 

The issue of which I speak is similar otherwise in that some devices can synchronize and others cannot.  It has been assumed to be related to the 240p problem, in which a device is expecting an interlaced signal but receives a progressive signal.  Some devices will not show a screen, some devices will show black and white, and some devices will show the screen but treat it as interlaced.






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