"Tint issue" on modified Toshiba HX-10 (LVA510 related ?)

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By tvalenca

Paladin (728)

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29-10-2015, 04:00

@sd_snatcher,

I don't think there's anything about the Color Burst, even because the "Color Burst" only exists on color encoder chip; these VDPs output video as component signal, so color aren't really encoded, just reorganized in a way that makes easier to convert either to NTSC or PAL. But since the Expert isn't NTSC nor PAL, I think Gradiente's engineers thought that was better convert to RGB before converting to PAL-M because of that.

By maxis

Champion (512)

maxis's picture

29-10-2015, 08:38

NTSC - Never The Same Colour Wink

By tvalenca

Paladin (728)

tvalenca's picture

29-10-2015, 13:33

you're saying that because you don't know brazilian color system (PAL-M, which is an european color encode over M broadcast system - same used on NTSC). It could be better, but got stuck on 70's technology and image quality)

By maxis

Champion (512)

maxis's picture

29-10-2015, 16:00

l_oliveira wrote:

Not even a clue. I

Ok, sorry for a late response, but actually there is some LVA510 DOC available online.
To get it take this document:
http://msx.hansotten.com/uploads/msxdocs/yamahacx5myis503sm.pdf
Go to the page 20 (pdf page #21) which is called "Encoder circuit diagram". See the U2 circuit. It is LVA510 in PAL mode.

Now, to get the detailed description of LVA510 internals, go to this link:
http://msx.hansotten.com/uploads/msxdocs/yamahacx5myis503ts.pdf and read the pages 95 - 98. On the figure 6-8-3 you have your LVA510 inside out with the pin names!

More application references you will find here:
LVA510 in PAL mode Page#35 and LVA510 in NTSC mode Page#36 of this document:
http://msx.hansotten.com/uploads/msxdocs/yamahacx5msm.pdf

tvalenca wrote:

you're saying that because you don't know brazilian color system

Hm, hm, inside your cell phone it is likely my PAL/NTSC/SECAM B/G/L/M/D/K encoder design ;) Beware, if I don't know, then no color on your brazilian TV ;)

By tvalenca

Paladin (728)

tvalenca's picture

29-10-2015, 16:09

I'm not saying that you don't know. I'm saying PAL-M encoders are real pieces of crap. If you get any tv set, it has best image quality on NTSC than on PAL-M. (and look! Brazilian TV stations are still broadcasting analog signals encoded with PAL-M! it was supposed to be an still-in-developement technology!) Even if NTSC Never shows Twice the Same Color!!! (yeah, i got your joke)

Are you related to DSCALER develop team?

By sd_snatcher

Prophet (3052)

sd_snatcher's picture

29-10-2015, 21:18

Thank you so much for pointing these service manuals, Maxis! You solved a very old mystery. Smile

Quote:

I don't think there's anything about the Color Burst, even because the "Color Burst" only exists on color encoder chip;

By looking at the documents kindly pointed by Maxis, It seems indeed that the difference was only in the LVA510 chip. The pin-8 seems to select the color matrix to be used: YIQ (NTSC) or YUV (PAL). The TMS VDPs are innocent. Wink

By maxis

Champion (512)

maxis's picture

30-10-2015, 00:47

sd_snatcher wrote:

Thank you so much

You are welcome, SD_snatcher Wink

By l_oliveira

Hero (526)

l_oliveira's picture

30-10-2015, 01:08

sd_snatcher wrote:

Thank you so much for pointing these service manuals, Maxis! You solved a very old mystery. Smile

Quote:

I don't think there's anything about the Color Burst, even because the "Color Burst" only exists on color encoder chip;

By looking at the documents kindly pointed by Maxis, It seems indeed that the difference was only in the LVA510 chip. The pin-8 seems to select the color matrix to be used: YIQ (NTSC) or YUV (PAL). The TMS VDPs are innocent. Wink

Actually no, it's the opposite. The VDPs are guilty of being different based on the video system they are targeting for. But it only makes sense they be different as keeping the output identical on both VDPs would make the video encoder more complex.

To be compatible with both video norms, the LVA510 chip has a toggle pin.

Thanks for the pointers, maxis. I believe that the PCB on the Yamaha MSX actually match what I found on the VG8235 computer. To be able to use the LVA510 with V9938 a RGB to Y/R-Y/B-Y conversion is necessary.

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