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In this issue:
	RE: Turbo/PCE S-Video mod
	RE: Turbo/PCE S-Video mod

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From: owner-turbo-list@joyce.eng.yale.edu
Date: Sat Apr  3 05:07:10 EST 2004
Subject: RE: Turbo/PCE S-Video mod


Dean, 

Thanks for the info. I was curious if you are able to make the boards so
people can just do the install like you had mentioned on the
digipress.com forums. Are you using CXA1645 or either the CXA2075 or
AD725? What is the difference when using those? And how close is this to
what you are doing:

http://www.nexusuk.org/projects/rgb2svid/circuit.php

I would be doing this on an NTSC system, so I would have to use a
different crystal. I have no idea what I am looking at for parts on this
project, mind giving me a ballpark? 

Thanks for the awesome info, and your work is extremely professional! 

Erik

-----Original Message-----
From: owner-turbo-list@joyce.eng.yale.edu
[mailto:owner-turbo-list@joyce.eng.yale.edu] On Behalf Of Dean Dragoli
Sent: Friday, April 02, 2004 3:27 PM

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From: d-lite@neo-geo.com
Date: Sat Apr  3 12:28:58 EST 2004
Subject: RE: Turbo/PCE S-Video mod


I use the CXA1645P chip, which is the same as on that UK webpage.  The 
CXA2075 is possible too, but haven't tried the AD725 yet (in the very 
near future though).  Should be generally the same. Yes, the website you reference is for the PAL format encoder.  The 
crystal for NTSC is 3.579....., but I just use a oscillator sine is 
saves time and space from building your own clock. 
To make the circuit, you'd need basically everything on that webpage, 
but I would go straight to the Sony Tech Doc for the CXA1645 (easily 
found with a Google search for "CXA1645") and use that.  And please 
note, EVERYTHING in the tech doc should be implemented.  Every ground, 
resistor, cap, ALL of it. 
You'll need lots of parts:
680K metal resistors
75 ohm resistors
0.1 uF caps
47 uF caps
10 uF caps
LM1881N chip - sync separator
3.579 MHz oscillator
and various other parts.

Here's a pic of my encoder next to the JROK 3.0 (commercial), next to 
an 8PDT switch (3 inches long, for reference): http://home.earthlink.net/~ddragoli/sitebuildercontent/SVidCircuit.jpg

The key, obviously, is getting the CXA1645 chip.  My source is 
definitely going to be different from yours since I got the larger "P" 
chips from NOS sale.  All gone :) BUT, 2 other easy sources:
Sega Saturn
PlayStation, early models (1001, 5001, 5501)

Those are the "M" chip, SMT's so they're a bit smallish to work with.  
I plan on doing a FAQ on those chips too since it'll be what nearly 
everyone uses. 
To answer your other question, Yes, I'll be offering premade boards if 
people want them in the future.  At the moment, I don't have many to go 
around (most sold into mods for people). 
Remember, this mod takes PATIENCE!  Even if you're good and everything 
works the first time, building the whole circuit from scratch will take 
you minimum 3 hours.  Getting the chip from the Saturn is a different 
story since you'll probably be able to keep some of the resistors and 
caps intact. 
More info in the future!
Dean

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On Sat, 03 Apr 2004 05:07:10 -0500, "Duo_R"  wrote:

 >  Dean, 


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