Getting best possible RGB picture out of PS1

General information to do with the PlayStation 1 Hardware. Including modchips, pinouts, rare or obscure development equipment, etc.
clavicus
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Post by clavicus » June 28th, 2017, 7:39 am

I think I was wrong about DOUT, seems to be part of the CD DSP. I'll try poking around with DATO again as it's the name given to the pin that's responsible for sending the bitstream to the DAC in the 5500 series and earlier, it has to be that but I sure hope it's functional somehow, otherwise digital audio is only possible on older versions.

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Post by clavicus » June 28th, 2017, 4:40 pm

Nope DATO just won't budge, perhaps it can be enabled somehow? Seems strange that it would be hardware disabled, it even has its own test pad. I'll work on video for now at least.

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Post by rama3 » June 28th, 2017, 11:52 pm

There is a tutorial for a digital sound mod somewhere on this forum. I believe it only works up to a certain board revision though.
Anyway, sound seems very afterthought'y to me. Picture is the awesome stuff :p

Update:
Not only digital out, but also digital in! (What? Why? I don't know!)
http://hitmen.c02.at/html/psx_hardware.html

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Post by Medis » June 30th, 2017, 9:12 pm

I really wonder, If you can get digital video out of PS1, you guys rock I would have no idea at all how to do it. Bassicaly bypassing DAC and make a digital video processing unit (aka what the nintendo HDMI mod does).

Yet ...would digital audio be better anyhow?
And bassicaly, what is superiour on SCPH100X in meaning its audiophile's best when it comes on quality?
I have an option to get a SCPH100X which has a dead CD drive, but I wonder If I could replace it with other... I am not sure how difficicult is get one of these, I bought the KSM 440 AEM pretty easily unsure about the 100X one tho

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Post by rama3 » July 1st, 2017, 5:21 am

"SCPH100X" (in reality, only PU-7 and EARLY PU-8 mainboards) have a decent DAC and dual opamps for audio output.
Somehow the DAC alone created the legend of early PSX models being the ultimate CD player.
LATE PU-8 and onwards dropped one opamp. All their audio comes out inverted. Yet it's still the ultimate CD player, because, well, it has those phono jacks! :p
These consoles are nice for their historical value but technically, they're just okay.
The video output is very clean with an upscaler but good luck finding the necessary *perfect* drive unit that works with them.

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Post by clavicus » July 1st, 2017, 5:26 am

rama3 wrote:There is a tutorial for a digital sound mod somewhere on this forum. I believe it only works up to a certain board revision though.
Anyway, sound seems very afterthought'y to me. Picture is the awesome stuff :p

Update:
Not only digital out, but also digital in! (What? Why? I don't know!)
http://hitmen.c02.at/html/psx_hardware.html
Yeah, sadly that will only work up to the 5500 series because they still have a separate DAC like I mentioned.
Medis wrote:Yet ...would digital audio be better anyhow?
I doubt the digital output itself would be that much better, but if you want to get audio through HDMI it has to be digital, which means for 7000+ it'll need a separate ADC to convert the analogue audio back again, unless we can find a register setting or something that enables the digital out pin on the SPU...

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Post by Medis » July 24th, 2017, 1:28 am

https://www.etsy.com/listing/528592871/ ... od-chipped

What the heck ? Should I get this in instant?

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Post by rama3 » July 24th, 2017, 8:49 am

It's nice but it's "just" an RGB upscaler.

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Post by Medis » November 17th, 2017, 12:12 am

Just ordered PSIO cartridge hehe, anyway how is the HDMI mod going?

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Post by New Nova » December 27th, 2019, 12:20 pm

TheShadowRunner wrote: June 21st, 2017, 6:38 am If anyone's interested, I modified the original Sony PS1 RGB Cable (EURO-AV as they call it), to replace Composite by Luma-Sync. Here's what it looks like.
IMG_4436.jpg
IMG_4437.jpg
It's pretty hard to open so take your time! 8-)
Hello there.
I take the composite sync to pin 5 on my scart cable, like you did.
BUT I have terrible noises, darker image, buzzing, and the image looks shifted, broken on some lines.
Do I need to modify my console too ?
I run on scph 1002 Pal system.
Development PC : Compaq PC, Intel Pentium III 600MHz, 256MB RAM, NVIDIA GeForce4 MX 440 (AGP)
Development Unit : DTL-H2000 board + DTL-H2010 CD-ROM drive
Retail Unit : SCPH-1002 + XplorerFX + caetla + modchip + activity LED mod

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Post by New Nova » December 27th, 2019, 12:49 pm

I figured put by accident that putting ground wire on red worked. Wtf.
Development PC : Compaq PC, Intel Pentium III 600MHz, 256MB RAM, NVIDIA GeForce4 MX 440 (AGP)
Development Unit : DTL-H2000 board + DTL-H2010 CD-ROM drive
Retail Unit : SCPH-1002 + XplorerFX + caetla + modchip + activity LED mod

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Post by New Nova » December 27th, 2019, 12:53 pm

Oh no it's the 5v pin, i understand.
Development PC : Compaq PC, Intel Pentium III 600MHz, 256MB RAM, NVIDIA GeForce4 MX 440 (AGP)
Development Unit : DTL-H2000 board + DTL-H2010 CD-ROM drive
Retail Unit : SCPH-1002 + XplorerFX + caetla + modchip + activity LED mod

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Post by retroleah » February 8th, 2020, 6:29 am

EDIT: ignore the stuff below. I decided to make a dedicated new post instead: see http://www.psxdev.net/forum/viewtopic.php?f=47&t=3554

hey there, bumping this thread because i see some iffy info in it.

Here's how to do csync on ps1:

on older GPU on very first pu7/pu8 boards just grab csync from video encoder... use 75ohm resistor and 220uF cap, cut traces to pins 5 and 6 on multi-out and bridge the attenuated composite sync from encoder to multi-out pins 5 and 6. this disables composite video and luma, but makes all RGB SCART cables work out of the box

NOTE: I've never tried the above on the old GPU because they're RARE AF so i rarely get them in, but I do do the below very often and with success:

on newer 208 pin GPU, pin 156 is TTL 3V csync output. cut trace from it and connect directly to it the 470ohm resistor and a 220ohm cap. again, cut traces for pin 5/6 on multi-out and bridge the attenuated csync output to both of them

pretty simple!

the reason for pins 5 and 6 is because 5 is luma and 6 is composite video. some rgb scart cables pull sync from luma and some pull it from composite video pin

EDIT: you don't need to cut pin 156's trace from the GPU but I do it anyway to reduce trace inductance issues. i would lift the pin but the pin is very small and weak so all i do is trace cut


PS: fun fact pins 158 and 159 are separate hsync and vsync,3v ttl level... can use 470ohm and 220uF on those aswell, to create an RGBHV output for PVMs...
hope this helps

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