Worklog PS1 Native VGA mod (15khz)

[Daroou]

Would it be possible to modify a PS2 component cable and wire it up to a VGA male connector? Basically make a PS1 RGB to VGAHV cable?

Another question I have: is it really necessary to use coaxial cables for the R,G, and B signals? In the end, all grounds connect to the same pin on the DB15 connector. Does the ground shroud in these cables protect against interference?

[MOD EDIT] - Merged double post.

 

[Wesk]

Would it be possible to modify a PS2 component cable and wire it up to a VGA male connector? Basically make a PS1 RGB to VGAHV cable?

No, you'd need to modify the PS1 internally to be able to use the PS2/PS3 component cables. You'd need to add an internal RGB to Component transcoder. If you were going to go that far you may as well buy the HD retrovision cables.

Another question I have: is it really necessary to use coaxial cables for the R,G, and B signals? In the end, all grounds connect to the same pin on the DB15 connector. Does the ground shroud in these cables protect against interference?

The wire itself needs to be shielded in some way to keep analogue noise out of the signal.

 

[Daroou]

Thank you @Wesk for this post! I went ahead and did the same mod on my SCPH-7501 (PU-23). I posted about it on my blog here: https://amaiorano.io/2022/04/02/ps1-vga-mod.html.

If anyone else has the same model, here's a pic of where to tap into for the different signals:

Cheers!

 

[ChipsLab]

Would love to do the VGA Mod on this PSONE. I opened it but can't find the RGB, H and V sync soldering point.

Any new info would help a lot

No idea as I believe it uses a slightly different GPU package, you'll need to do some research.


Because this is the version I own? The PSones also lack the expansion port required to use SD loaders like a PSIO.


[EDIT]

A 2min wiki search shows that the pinout on the package is the same for the PSone GPU

 

[Wesk]

Would love to do the VGA Mod on this PSONE. I opened it but can't find the RGB, H and V sync soldering point.

Any new info would help a lot

You literally quoted the post with the info you need. The H and V sync lines are here:



And the RGB lines you can pull directly from the AV port.

 

[Stitches]

Would love to do the VGA Mod on this PSONE. I opened it but can't find the RGB, H and V sync soldering point.

Any new info would help a lot

View attachment 26155

According to the silkscreen, IC203 is the bottom right chip. Wesk said the pinout is the same as the original PS1 GPU, so the HV sync pins are in the circled area. Whether there are any convenient solder points for these pins, I can't say, the image isn't zoomed in enough. You may have to solder magnet/kynar wire to the legs of the GPU, same as the Wii VGA mod.

 

[YveltalGriffin]

Looks like that's a PM-41 (2) which has the GPU RAM combined into the GPU. The pinout is "rotated" slightly compared to the original GPU, but you can still grab H-Sync and V-Sync from these convenient solder pads! Pin 64 is VSYNC and Pin 65 is HSYNC.

 

[ChipsLab]

Thanks a lot everyone !

Those two VSYNC and HSYNC solder pads will be easier to work.

It may seems obvious, but how can I identify RGB ?
If I compare to the PSX, the blue should be this one ?

Looks like that's a PM-41 (2) which has the GPU RAM combined into the GPU. The pinout is "rotated" slightly compared to the original GPU, but you can still grab H-Sync and V-Sync from these convenient solder pads! Pin 64 is VSYNC and Pin 65 is HSYNC.

View attachment 26159

 

[Wesk]

Thanks a lot everyone !

Those two VSYNC and HSYNC solder pads will be easier to work.

It may seems obvious, but how can I identify RGB ?
If I compare to the PSX, the blue should be this one ?

The AV pinout is the same across all PS1 models so you can look at the RGB wiring used earlier in the thread.

 

[ChipsLab]

IT'S WORKING !!!
The image quality is perfect

Here's in 4K

Again thanks a lot the the help =)

The AV pinout is the same across all PS1 models so you can look at the RGB wiring used earlier in the thread.

View attachment 26161

 

[DreamKai2k]

Hi
i also did the mod on a pu8 late
the stl is based on the Wesk's one.

 

[CMYK]

Signed up to ask this question, long-time lurker first-time poster

I have a SCPH-5502 as well, however never worked with VGA before.

How/Where do I connect the ground contact(s) on the board? Based on the pictures from @Wesk and @buzzyc, it looks like you split the R, G, B cables into two and use the respective cable for both ground and the R/G/B signal, and no ground for H/V signal? Is that correct?

Can I just find a video ground connection on the board and connect it to pin 6 (for example) of the VGA connector? If so, where would I find that contact on the board? I can see where it's located on the SCPH-7501 based on the picture further up the thread, but cannot find the same spot for the SCPH-5502.

I tried to find a video ground connection by looking at the service manual, but completely failed at understanding any of the (really) badly copied diagrams.

//EDIT:
Is it this one for VGND?

 

[Wesk]

Signed up to ask this question, long-time lurker first-time poster

I have a SCPH-5502 as well, however never worked with VGA before.

How/Where do I connect the ground contact(s) on the board? Based on the pictures from @Wesk and @buzzyc, it looks like you split the R, G, B cables into two and use the respective cable for both ground and the R/G/B signal, and no ground for H/V signal? Is that correct?

Can I just find a video ground connection on the board and connect it to pin 6 (for example) of the VGA connector? If so, where would I find that contact on the board? I can see where it's located on the SCPH-7501 based on the picture further up the thread, but cannot find the same spot for the SCPH-5502.

I tried to find a video ground connection by looking at the service manual, but completely failed at understanding any of the (really) badly copied diagrams.

//EDIT:
Is it this one for VGND?
View attachment 27926

GND is GND, you can use any ground point for shielding the video lines. H and V sync don't need to be shielded in this particular instance.

 

[CMYK]

Perfect, thanks for confirming!

I'll try to connect it like this:

 

[DarkDuckling]

Hello there guys! this mod is so great...been thinking to try on my ps1 7502 PU22 model...but I cannot find any of the vias needed,has someone already done it?

 

[Y2K]

Hello there guys! this mod is so great...been thinking to try on my ps1 7502 PU22 model...but I cannot find any of the vias needed,has someone already done it?

For PU-22, the process is exactly the same as PU-18 and a lot of other revisions. The GPU is the same between these revisions and also breaks out the H/V sync lines into convenient vias and test points.

Sorry for the crude diagrams, did them on my phone. Theres 2 locations for H/V sync, firstly some vias on the top of the board near the GPU:

Secondly, some test points on the bottom of the board (actually is where the vias on the top of the board connect to, just use whatever is easier):

As for your RGB lines, they can be pulled from the usual places on the motherboard, such as the A/V multi-out or elsewhere, that won't be much different compared to other revisions.

Hope this helps!

 

[DarkDuckling]

DUDE thank you so MUCH for quick reply !! really appreciate it!
I'm doing the mod tonight! I'm gathering all the stuff now! thank you really kindly!
I would like to ask you if the R G B signal are all universal and can be taken from the AV port like in this comment!
thank you!

IT'S WORKING !!!
The image quality is perfect

Here's in 4K

Again thanks a lot the the help =)
View attachment 26165

 

[Stitches]

DUDE thank you so MUCH for quick reply !! really appreciate it!
I'm doing the mod tonight! I'm gathering all the stuff now! thank you really kindly!
I would like to ask you if the R G B signal are all universal and can be taken from the AV port like in this comment!
thank you!

The AV port pinout is universal, yes. All PS1s take the same cables

 

[DarkDuckling]

I've done the mod, but it is not working for me, I've followed the old replies for the R G B signal and everything seems to be good, but no signal on my crt... Maybe there is some sort of problem on the board because I've noticed that pin 157 of the gpu is missing (?) and there is a bridge near, I've read that.. That pin controls the H signal?

 

[Wesk]

I've done the mod, but it is not working for me, I've followed the old replies for the R G B signal and everything seems to be good, but no signal on my crt... Maybe there is some sort of problem on the board because I've noticed that pin 157 of the gpu is missing (?) and there is a bridge near, I've read that.. That pin controls the H signal?

Does your monitor accept 15khz signals?