PS1 CSYNC mod on PU-22 / SCPH-75XX model

% Leah Rowe % 2020-03-13

CSYNC (composite sync), not to be confused with composite video, is the purest sync source for RGB. Information about csync can be found on https://www.retrorgb.com/csync.html

I am selling these pre-modded on https://minifree.org/

Picture of motherboard is based on the one from: https://commons.wikimedia.org/wiki/File:Sony_Playstation_1_SCPH-7502_motherboard_top.jpg (CC-BY-SA 4.0 license)

Here’s how to do it!

Installation diagram:

Here is the multi-out pins related to this:

Connect a 470ohm resistor to the CSYNC point on the above diagram.

Remove the 220uF caps noted in the diagram and connect the other side of the resistor to the positive side on one of the caps. The negative side of the cap should be connected to pin 6 of the multi-out, or the capacitor landing pad (buzz it out with your multi-meter). Cut the trace right before pin 5 of the multi-out, and bridge pins 5+6.

Pin 5 is luma. Pin 6 is composite video. Doing this mod improves picture quality on RGB SCART, by reducing the number of jailbars. You CAN get sync from luma, without doing this mod, and the picture quality will still be excellent.

Most cables get sync from composite video. Doing this mod ensures compatibility with both types of cables but it DISABLES composite video and svideo. These are crap anyway. Nowadays there are good upscalers like OSSC or framemeister that use RGB, and most newer CRTs or PVMs support RGB.

Remarks:

You need:

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Workers of the world, unite! You have nothing to lose but your chains.
Workers of the world, unite! You have nothing to lose but your chains.
Workers of the world, unite! You have nothing to lose but your chains.
Workers of the world, unite! You have nothing to lose but your chains.
Workers of the world, unite! You have nothing to lose but your chains.
Workers of the world, unite! You have nothing to lose but your chains.
Workers of the world, unite! You have nothing to lose but your chains.
Workers of the world, unite! You have nothing to lose but your chains.
Workers of the world, unite! You have nothing to lose but your chains.
Workers of the world, unite! You have nothing to lose but your chains.
Workers of the world, unite! You have nothing to lose but your chains.