Saturday, February 13, 2016

Sony Kanji Video Titler XV-J550: the inside

A video titler is the equipment responsible to create title screens, credit lists, captions, subtitles, etc. You know, the kind of video editing that today is done by a software in any computer or even in cellphones. In the XV-J550's days this was done by specialized equipment: the video titler.

Last post we present the XV-J550 and XV-T550 video titlers. One is targeted to Japanese market and the other to western markets, this difference reflects in some changes between both models. Being a video titler, XV-J550's main function is to put text on screen, since it's aimed for Japanese market, it needs to support Kanji characters, so it have, at least, more ROM than XV-T550, to store these Kanji Fonts.

Although they have the same outward appearance, XV-J550 and XV-T550 have different PCBs. Evidence suggests that the XV-T550's PCB was prepared to be shared with the XV-J550, there are some unpopulated placements for ROM on XV-T550's mainboard that can be used by Kanji ROM.

This is the mainboard from XV-T550, take a look in the two unpopulated
placements for ROM chips and the shielding over V9938
(picture from this MSX Village thread)

By now, all (three) XV-J550 that I saw the insides had the same PCB's look (maybe different minor revisions, but the same overall shape). And this PCB's appearance is consistently different from the one that I saw in pictures of XV-T550 and is printed in its service manual:

This is the XV-J550 mainboard seen from solder side.
The two chips that you can see are the Sony custom mapper
and the MSX-System II

And this is the XV-T550 mainboard, picture from XV-T550 Service Manual.
You can see that many components are in different locations on the board.

My guess: the XV-J550 was first released in Japan. Seeing that it's a good product and there is a broader home video market, Sony wanted to sell it in Europe, but had to make some revisions on the board for this release; this new board was meant to be shared by the two versions of the titler (XV-J550 and XV-T550), but for some reason the XV-J550 with the new PCB did not reached the market (or we didn't yet found any XV-J550 with this new board). I believe that, instead release the same old product with a new internal organisation, Sony did launched new video titlers, like the XV-J770.

What's inside XV-J550?

There is two big boards (and some small boards) in XV-J550. One with all the MSX hardware and other responsible to handle the AV inputs and outputs. The designers made a very compact unit, the other video titlers from Sony have almost two times the height of the XV-J550/XV-T550:

XV-J550 on top of XV-J777.

This compactness made the XV-J550 a beautiful equipment, but compromises the "hacking" possibilities. It's impossible to use the cartridge slot  while XV-J550 is closed and is very hard to fit any additional circuitry in this limited space.

How you can use the XV-J550/XV-T550 cartridge slot

XV-J550 have most of what can be expected from a MSX2 system, but it have only one joystick port, one MSX slot and the keyboard connector doesn't have all pins connected to use a complete MSX keyboard.

CPU: Z80 @ 3.58Mhz
VDP: Yamaha V9938 with 128KB VRAM
PPI: MSX-System II
Sound: PSG equivalent inside MSX-System II
Storage: 64KB SRAM energized by a CR2032 battery
Keyboard: separated keyboard customized for video production functions
Additional features: Superimposer
I/O ports: two stereo AV inputs and two stereo AV outputs, one keyboard connector, one joystick port and one MSX slot.

There is no external storage in XV-J550, but you can save your title sequences in the battery backed SRAM. The MSX slot lacks some pins too, namely: +12/-12 volts, SOUNDIN, SW1, SW2 and BUSDIR.

The XV-J550's mainboard. All ROMs are populated, there is
a big OKI chip connected and no shielding over the V9938.
It's in the same position of the XV-T550's mainboard that
we previously show, so you can easily compare both boards.

Without the RAM and ROM chips, the main ICs on processor board are:

Oki M71H003: Unknown
Sharp LH0080A: Z80 compatible
Sony MB64H444:Custom memory mapper
Yamaha S1985: MSX-SYSTEM II
Yamaha V9938: Video Display Processor

Here you can see the Z80, the mysterious OKI chip
and some RAMs and ROMs. You can't see the slot connector
because there is a MegaFlashROMSCC+SD 512 connected there.

The V9938 and the 128KB VRAM

MSX-System II from Yamaha

Sony custom mapper. Probably a Fujitsu MB64H444PF gate array

There is many ROM chips on this circuit board, but I still don't know what is in each one of those. This mystery will be solved when we read the contents of those ROMs in a EPROM reader. Since the Sony HB-F1XD uses the same set of S1985+MB64H444, I won't be surprised if the BIOS and SUB-ROM are also the same in the XV-J550 and HB-F1XD.

The encoder board have a more sparse look and, as said before, handles the AV inputs and outputs. There is only one IC on the backside of this circuit board.

The "other" board

The lonely IC on "other" board backside: SONY D1030

I did not found the usual SONY V70X0 chips inside the XV-J550, they are very common on MSX2 machines that have digitizer and/or superimposer features. But there are a lot of "washed" chips on the encoder board, any of those chips can be a V70X0 IC, so we can't really say that this machine hasn't the Sony video chipset.

Next post, more Sony video equipment!

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