Getting proper csync from a PS1? (CXA1645 encoder)

[cr4zymanz0r]

For various reasons I'm converting the rest of my remaining retro consoles that are using composite video as sync to just use csync. The one I'm currently working on is PS1 and I can't seem to find definitive information for PS1 systems that have a Sony CXA1645 video encoder in them. Looking at the datasheet, it doesn't appear that the CXA1645 outputs csync. I've seen variations of people grabbing (TTL?) sync from or near the sync input pin (pin 10), but nobody can seem to agree on the proper way to and the one I choose to try had issues.

I tried the method used in the first 2 images of this thread: http://assemblergames.com/l/threads/ps1 ... elp.56631/
Initially it seemed to work but then the image would start getting jittery, particularly on bright colorful screens.

Does anyone know of the proper way? Alternatively, is there any downside to using a LM1881 based sync stripper to get csync from composite video? It seems like people usually prefer to get csync from the system itself if at all possible, but if using a LM1881 would be just as good then that might turn out easier than converting a TTL sync signal in the PS1 to a proper csync signal.

[Seraphic]

Try this:
http://gamesx.com/wiki/doku.php?id=av:p ... ion_1_sync

[cr4zymanz0r]

Try this:
http://gamesx.com/wiki/doku.php?id=av:p ... ion_1_sync

That guide is wrong for the CXA1645 instructions. all that's doing is connecting composite video from the encoder to the composite video pin on the AV connector, bypassing the resistor and capacitor.

[RGB0b]

Using an LM1881 on the luma line usually works great. You can try this as well, if you have either of these chips:

[cr4zymanz0r]

Using an LM1881 on the luma line usually works great. You can try this as well, if you have either of these chips:

I did not see those, and from my understanding earlier consoles had the CXA1645, and the chips you linked replaced the CXA1645 in later revisions.

[evilsim]

i found pin 156 of the GPU (under the metal shielding on the top of the PSX main PCB) goes to pin 14 of IC502.
there was also a pad and thru-hole to the left of my CXA1645M rgb amp which connected directly via a trace to GPU pin 156.


this was on a 5501 USA NTSC PSX. this PSX did not have either the H7240 or the Sony A2160 IC's.

at last i have TTL sync from my PSX! (using a LM1881 on "y/luma" would give me the same thing tho, as retro rgb pointed out)