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View topic - SMS 3 TECTOY PAL-M to NTSC

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  • Joined: 23 Jan 2018
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SMS 3 TECTOY PAL-M to NTSC
Post Posted: Tue Jan 23, 2018 12:29 pm
I have a SMS 3 TECTOY Pal-M system and I live in the usa. I have already modded my system to have composite.

My board uses the mb3514 chip. However my other chips are not the same as a SMS 2, so I'm unsure what I need to do to convert to ntsc. My video and
audio work perfect now, but video is totally in Black and White. But picture is stable.

My asic chip is a 315-5681 Sega chip. However, I can't find any info on pinouts or data sheets.

And my z80 chip is a Z84C0006VEC.

I know I'll need to change the crystal in the system, which I plan to get from an old Sega Genesis 2.

If anyone can help it would help appreciated.

Board pic below

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  • Joined: 19 Oct 1999
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Post Posted: Tue Jan 23, 2018 12:39 pm
The crystal should be OK as PAL-M uses the NTSC frequency. Is it as simple as tying the NTSC pin to 5V?
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  • Joined: 23 Jan 2018
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Post Posted: Tue Jan 23, 2018 6:03 pm
That would be pin 7 on the mb3514 chip. I will do that this evening.
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  • Joined: 25 Feb 2006
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Post Posted: Tue Jan 23, 2018 10:10 pm
AFAIK, PAL-M and NTSC are both built on top of broadcast system M; as a result, luma encoding is identical; the difference lies exactly on how the chroma is encoded.
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Post Posted: Tue Jan 23, 2018 11:06 pm
Attaching pin 7 to 5v was no help.
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Post Posted: Wed Jan 24, 2018 6:35 am
Did you disconnect it from ground?
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  • Joined: 05 Sep 2013
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Post Posted: Wed Jan 24, 2018 8:58 am
color subcarrier frequency is different (according to wikipedia)
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Post Posted: Wed Jan 24, 2018 11:10 am
Hmm, PAL-M is 3575611 vs NTSC at 3579545 and PAL at 4433618. I'd read the first two as "close enough". Maybe this is helpful - I can't read it well enough to tell:

http://retrogaming.com.ar/forum/viewtopic.php?f=4&t=13461&start=10
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  • Joined: 31 Oct 2007
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  • Location: Estonia, Rapla city
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Post Posted: Wed Jan 24, 2018 12:14 pm
You have to change the crystal visible with 10.738635MHz one. You can supply 3.579545Hz to the RGB encoder but you'll get lot more video artifacts that way due to no synchronity between VDP output and color carrier.
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