Source : https://bitbuilt.net/forums/index.php?threads/ps1-native-vga-mod-15khz.4118/
I recently picked up a SCPH5502 model PS1 for the intention of pairing with a PSIO. As my main CRT only has composite or component video input I felt I was required to purchase the HD Retrovision component cables to get the best video quality.
However the retrovision cables are quite pricey at over $70aud and I already have a VGA to Component transcoder (Which I use to get 15khz component out of my Dreamcast) so I did some quick searching and found that the PS1's GPU actually has H and V sync readily available.
So I figured I'd take a roll on it and see if I could get native 15khz VGA. Using shielded coaxial wire I ran from the RGB lines and used some kynar for the sync lines.
And well...it just worked. Razor sharp 15khz VGA natively from a PS1.
Next step is to remove the system link port from the PS1 mainboard and design a mounting mechanism.
Serial port removed:
Mounting mechanism partially complete - a few more iterations needed to get it sitting rock solid:
Once I've got the mount 100% all that is left is to tidy the wiring.
So here is the final design on the VGA mount, the top piece is designed so that when the case is closed there is just enough pressure on the top of the port that it won't move vertically.
Wiring has been tidied up:
Unfortunately due to the height of the VGA port the top shielding needs to be trimmed to accommodate it:
A final look at the rear + bonus image:
And here is a comparison between the standard composite output and the VGA modded output:
STL's of the VGA mount have been provided if you want to have a go at this yourself. Your mileage may vary however as the vias for H ∧ V sync will be different depending on the board revision but will remain the same on the GPU. Now all I have to do is wait for the PSIO to ship.... Attachments
PS1 VGA Mount.zip 6.1 KB
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Following Wesk's guide, I was able to successfully mod my SCPH55xx (PU-18) PS1 as well.
Although I don't have a 15Khz CRT at home, I stumbled upon this wiki and was delighted to see that I have 2 monitors at home that support 15Khz inputs:
My BenQ GH24DHD and Acer KH2711 both successfully display the PS1's image. Interestingly it must be left in FULL display mode to work. Changing the picture type to something like Aspect or Pixel removes the 15Khz support, and all that is shown is "Out of Range"
Wiring to the VGA port isn't as clean as I'd have liked - but after an hour of desoldering and resoldering to determine the RGB order it got a little messy. Trust me though, no shorts, despite what the image may suggest
To save everyone else the hassle, I have color coded the RGB points on the 55x board:
Here are a couple nice side by side's in the classic that is Disney's Hercules. Composite on Left, VGA on Right,
And finally because we're just tapping into the multi-out, the delightful side bonus that you can run Multi-out and VGA in parallel, allowing for real time side by sides comparisons!
Big thanks to Wesk for helping me out during this mod, and assisting with troubleshooting and validating everything! I have a 7502 I plan to mod next, and will provide the H&V pad locations once found.