3DO 240p with the VP536A, and RGB with the BU3616K

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3DO 240p with the VP536A, and RGB with the BU3616K

Post by airs » Mon Mar 23, 2015 8:09 pm

Hey everyone, first post here. I'm a longtime fan of the 3DO - purchased one and a couple games at launch back in the day. Apparently teenage me had $800 burning a hole in my pocket and I gladly traded those USD $100 bills for a shiny new Panasonic FZ-1. Anyway, for quite some time I've wondered about how to increase the image quality of the system and a few years ago I came across some information about adding RGB output to the system. I eagerly ordered one of the kits from Otaku's store and installed it as soon as it arrived. While I was pleased with the improvement over S-Video, I felt the image was blurry and lacked detail. I had read that 480i was the only resolution available for the 3DO and wondered if that was the reason for the bland image.

I began to collect information about 3DO programming and graphics rendering. Reading various forums and whatever technical documents I could get my hands on revealed that the 3DO rendered everything at 320x240 resolution and used a curious form of pseudo anti-aliasing (interpolation) to produce its 480i image. The 3DO graphics programming documentation showed how two lines of code could be used to disable the effect:

Code: Select all

int32 DisableHAVG( Item screenItem )
int32 DisableVAVG( Item screenItem )
This was quite exciting to read. Why didn't any developers utilize this mode? Perhaps they felt that their games looked better on consumer CRT displays with it enabled. In any event, these lines of code were mostly useless to me since I would need to somehow inject this code into every game that I wanted to use progressive scan with. However, it showed that the interpolation engine could be turned off. If it could be turned off with software, perhaps it could be turned off with hardware..

Since I had an FZ-1 with the BT9101 video encoder, I focused my efforts on finding information about it. After exhaustively searching Google, forums and even patents for tidbits of information, I began emailing suppliers who listed the chip as something they could produce. I asked them if they could send me a datasheet and while I got plenty of replies, none of them were able to provide a datasheet. I had run out of ideas and gave up on the BT9101.

A couple of months went by and my interest in the subject was renewed when I happened upon a reasonably priced Goldstar unit on eBay. I searched Google a bit for information about the Goldstar model and found that it used a different chip for it's video encoder - the VP536A, for which a datasheet was readily available on the internet! I only had to read to the second page of the PDF to find this:


I couldn't believe it - progressive scan was available by manipulating two pins on the chip! But would this actually work in practice? I didn't hestitate - I hit Buy it Now.

When the Goldstar arrived, I verified that it was working properly and sure enough, it was outputting 480i over S-Video into my XRGB Mini. I disassembled the unit and soldered wires to two pins, 52 (CTRLB1) and 55 (VAA):


I held my breath and turned on the unit and saw this (apologies for the poor image quality):


240p! Everything looked so much sharper, even over S-Video, and the interlacing artifacts on fast moving objects were gone!

The only thing left to do was to mod this console to output RGB. Since I already had a console with the Otaku's store RGB board, and cost of it was quite high (~$70 USD with shipping), I wanted to go a different route. I remembered seeing a different 3DO RGB mod on a Japanese website using an off the shelf RGB DAC. After a bit of searching, was able to find it again - the chip they had used was the BU3616K. There were pictures of the mod, but they were small and the textual information was limited and hard to understand with Google Translate. So I mostly relied on the datasheet for the BU3616K, which included an example that made it seemed fairly straightforward:


I ordered the necessary parts on eBay (BU3616K, QFP44 breakout adapter) and after waiting a couple weeks, the packages arrived from China. I soldered the DAC onto the breakout board and started wiring up the pins according to the datasheet, with one exception: I swapped out the resistor connecting pin 2 to pin 1. I had read on one of the Japanese pages that 6.8k Ohms was too dark and 1.8k was a better value:


I then soldered some 30AWG wire to the RGB pins of the VP536A, and took some time to make cutouts for a new AV output connector (3D printed Nintendo AV Multiout) and a switch for going from 240p to 480i:


Here's another shot of the 3D printed Nintendo AV output and 240p/480i switch:


Finally, I hooked everything up to my XRGB Mini and captured some footage (please watch in 720p/60fps):

480i RGB vs 240p RGB

240p S-Video vs 240p RGB

Well I think this is a long enough first post! Please tell me what you guys think and if you have any suggestions/comments. I've probably left a bunch of stuff out so feel free to ask questions.

High res images: 1, 2, 3, 4, 5

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Re: 3DO 240p with the VP536A, and RGB with the BU3616K

Post by 3DO Si » Tue Mar 24, 2015 7:45 am

That is an awesome mod, thanks for sharing and taking the time to write up such a detailed post. I checked out the YouTube videos and there's definitely a marked quality increase.

If you could make this mod commercially, I think you could make some decent money selling on eBay. If we as a community could get the BT9101 chip info for the FZ-1 so you could mod that then even better, anyone have any helpful info on that?

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Re: 3DO 240p with the VP536A, and RGB with the BU3616K

Post by Lemmi » Wed Mar 25, 2015 4:17 am

i cant see a difference off craptube, of course it might help if i had a videocard lol
but i still get perfect video though AV cables on my 27inch 1999 samsung TV :P
Ex-3DO collector extraordinaire , but i still have my collection
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Re: 3DO 240p with the VP536A, and RGB with the BU3616K

Post by NeoGeoNinja » Wed Mar 25, 2015 11:20 am

Lemmi wrote:but i still get perfect video though AV cables on my 27inch 1999 samsung TV :P
No you don't.

Living in America, you didn't have common access to SCART and RGB like we've had since the early 90's, here in Europe/UK :wink:

If you ran your 3DO via pure RGB on an excellent RGB CRT (or PVM), your eyes would pop! :shock:

It's only these years later that Component has finally become common place. Pretty much as good as RGB :P

Pretty much :mrgreen:

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Re: 3DO 240p with the VP536A, and RGB with the BU3616K

Post by CasetheCorvetteman » Wed Mar 25, 2015 2:37 pm

And if you ran your 3DO via RGB to a display device such as the amazing NEC XG CRT projector, your eyes would probably fall out of their sockets....

NEC made the best CRT displays known to man.

Component is fine for 240p provided the display will leave the signal unchanged, but it has nothing on RGB for bandwidth. Its around 50MHz vs as high as 400MHz.
The man that beat the self proclaimed "best in the world" at The Need For Speed...

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