3DO 240p Mod

3DO Game consoles normally output 480i, but with an easy mod, you can enable 240p output on any 3DO console with a VP536 chip.  Unfortunately, none of the BT chips are compatible with this mod.

 

Description / Disclaimer:
In February 2015, Assemblergames member Airs discovered that you can enable 240p output on any 3DO console with a VP536, by wiring a switch to two pins on the chip. In most cases, you have to boot the 3DO in it's normal 480i mode and then after the game has loaded, toggle the switch to enable 240p. Please note:

- If the switch is in the "on" position when powering on the console, or before loading the game, there's a chance you won't get any video on the screen all.  Powering the console off and back on (with the switch off) will fix the problem.

- It's common for 240p mode to lock into an incorrect line placement, resulting in a blurry image.  Good news though!  The fix is simply to toggle the switch back to 480i, then to 240p again.  Unfortunately, it sometimes takes 2 or 3 tries to get it right, but it's literally just a flick of a switch, while the console is already running.  Below (and the above pic) are picture examples provided by Assemblergames member abdominalpillaging, who has more 3DO / 240p captures on his YouTube page.  Click for full-sized:

480i

240p correct 

240p Incorrect 

 

 

Video Demonstration:
Airs uploaded a video of his mod in action.  As shown above, the differences through an upscaler are very noticeable!

 

Compatible Consoles:
Only 3DO consoles with the VP536 chip are compatible.  You need to open your console to find out for sure, but in the limited experience I've had the FZ-10 top-loader's generally have the VP536, while the FZ-1 front-loaders have the BT9101 chip.  I've heard the Goldstar 3DO's are also compatible, but once again, please open your console to find out (sorry about the red line in the Bt pic!):

 

Performing the mod:
Tools needed:
- Basic soldering skills.
- Philips head screwdriver (medium and small).
- Soldering gun & solder.
- Wire & wire cutters
- On-off toggle switch

Start by disassembling the console.  If you're using an FZ-10, simply remove the 7 screws from the bottom plastic and lift the cover off.  Then remove the 5 screws from the metal shield, remove the plastic light pipes (they're not held in by anything) and peel the tape from the CDROM drive.  You should be able to lift the metal shield off without removing any other components:

 


After the metal shielding is removed, locate the VP536 chip:


Solder two separate wires to pins 52 and 55 of the VP536 chip:


Then connect those wires to a basic on/off switch.  I don't like to cut any of my console's plastic, so I ran mine through the RF module holes and mounted my switch externally.  Airs mounted his right in the back of his console and it looks great.  Either way, my only suggestion is that it's easily accessible, so you can toggle while the console is on.

 

Technical Information:
The 3DO's frame buffer is 320x240, meaning the actual resolution of the games is 240p.  Then, 480i interpolation is activated inside the VP536 display generator as the signal is passed through it.  On the VP536 chip, setting CTRLB1 high (pin 52) disables this interpolation.  Here's a screenshot of a table from the datasheet (linked below):

Here are links to the full VP536 datasheet, as well as other helpful information regarding the 3DO:

VP536 datasheet: 
http://www.retrorgb.com/files/3DO/VP536A-VP536B_NTSC-PAL_DIGITAL_VIDEO_ENCODER.pdf

Frame Buffer:
http://hackipedia.org/Platform/3D0/html,%203DO%20SDK%20Documentation/Type%20A/ppgfldr/ggsfldr/gpgfldr/2gpgb.html

Introduction to 3DO Graphics Systems:
http://hackipedia.org/Platform/3D0/html,%203DO%20SDK%20Documentation/Type%20A/ppgfldr/ggsfldr/gpgfldr/1gpgb.html

Display Generator:
http://hackipedia.org/Platform/3D0/html,%203DO%20SDK%20Documentation/Type%20A/ppgfldr/ggsfldr/gpgfldr/2gpga.html#XREF23830

Controlling interpolation:
http://hackipedia.org/Platform/3D0/html,%203DO%20SDK%20Documentation/Type%20A/ppgfldr/ggsfldr/gpgfldr/4gpgj.html#XREF13296

According to patent documentation and the link above, it's possible control interpolation via software, via two lines of code:
int32 DisableHAVG( Item screenItem )
int32 DisableVAVG( Item screenItem )

Assemblergames thread on this topic:
http://assemblergames.com/l/threads/3do-240p-output-vp536a-encoder.55470/

 


Conclusion:

While a software flag to disable 480i mode might be a more elegant solution, it's my opinion that this mod is a must-have for all 3DO owners with the correct video chip.  The improvement in video quality is huge...especially considering how easy it is to complete the mod!

 

 

Feel free to go back to the main 3DO page, or if you'd like info on mods for other systems, head to the Getting RGB From Each System page. Also, check out the main page for more retro-awesomeness.