Last Updated: 4/18/2024
Article Credit: ShootTheCore, Ikotsu, rtw, Trap15, ekorz, twistedsymphony, channelmaniac

The Seibu Kaihatsu SPI platform was offered in two configurations:

• Two Board – Main Board and cartridge ROM Board
  • Region locked: Main Board must match country of cartridge ROM Board. This protection can be bypassed – see “Protection Mechanisms” below.
  • Optional Stereo audio.
• Single Board
  • Only runs the one game that was loaded onto it at the factory.
  • Offered with two different audio setups- Yamaha YM-271-F or dual OKI MSM6295
  • Mono audio only.

This article will address the two configurations separately.

Two-Board Configuration: Main Board

The SPI main board contains all the processing logic to run the game. It was released with two revisions, both of which can run the same ROM game cartridges. The marking on the board for each revision is:

• (C)1995 SXX2C-MAIN V2.0
• (C)1998 SXX2D-MAIN V2.1

Stereo sound output is available on the two-board SPI configuration through the CN1 connection header. Everten sells a nice add-on board that adapts the CN1 header to standard RCA stereo audio ports.
https://shewfly.com/products/seibu-kaihatsu-spi-stereo-board-by-everten
https://www.candycabclub.com/product/everten_spi

The video and audio quality is said to be better with the SXX2C-MAIN V2.0 revision.
Source: https://shmups.system11.org/viewtopic.php?t=43308

The SPI system has onboard flash memory used for both region lockout and to store part of the game. The V2.0 board restricts write access to the flash memory by a jumper labeled JP072. The V2.1 board does not have any flash write access restriction jumper.

When swapping game cartridges, you will need to change the jumper (V2.0 only), install the new cart, power on, wait for the game to write to the flash memory (the message “NOW UPDATING. PLEASE WAIT A MOMENT.” will be displayed), power down and flip the jumper back (V2.0 only). Even after flashing, the ROM cartridge must stay attached for the game to operate.

Notable ICs

Two Board Configuration – ROM Cartridge Board

Cartridge boards include DIP socket EPROMs, SMD mask ROMs, SRAM and a custom decryption IC – see Protection Mechanisms below. It is not possible to reliably convert one SPI game cart to another at this time, although it is possible to upgrade the same game to a different version (ie Viper Phase One to Viper Phase One NV).

ROM Board model numbers

• SXX2C ROM SUB
• SXX2C ROM SUB2
• SXX2C ROM SUB4
• SXX2C ROM SUB8
• SXX2C ROM SUB10

Common Issues and Quirks

CHECKSUM ERROR or HARDWARE ERROR (credit: rtw & Trap15 and channelmaniac)

The two-board SPI platform stores part of the game inside onboard flash storage. The flash storage is also initialized from the factory with a country code. If the country code stored in the first byte of u1053 flash on the mainboard does not match the country code stored in the last byte of the PRG0 EPROM on the ROM cart then you will see the message CHECKSUM ERROR XXXX or HARDWARE ERROR XXXX during the flash process where XX is a two or four digit error code.

It is possible to desolder the u1053 flash chip from the main board to reprogram it with a new code. A list of the country codes is in the opening comments of the MAME driver.

Alternatively, Trap15 developed a software solution named SPI Revive that can rewrite the country code on the mainboard by swapping the PRG0 EPROM on a Raiden Fighters or Raiden Fighters 2 cart. If SPI Revive is unable to change the country code then the u1053 flash chip should be replaced.

SPI Revive: https://bitbucket.org/trap15/spi_revive/src/master/

Source: https://shmups.system11.org/viewtopic.php?t=62636

There have also been cases where the flash chips are holding the correct country code data but the board isn’t reading that data correctly. The Yamaha YM271-F sound chip controls access to the flash storage, so check the connections and traces on it.

Reflowing the solder on all of the large SMD ICs is recommended for HARDWARE ERROR and CHECKSUM ERROR messages if the earlier methods of writing the country code do not resolve the problem.
Credit: ChannelManiac

Boot Failure or Vertical Lines (jailbars) through graphics (credit: twistedsymphony)

It is common for the large SMD ICs to have pins separate from the PCB due to board flexing.

If an SPI board fails to boot at all on a known-good ROM cartridge, try reflowing the solder on each SMD IC, starting with the 386 Main CPU – it seems particularly susceptible to this issue.

If an SPI board has vertical lines running through the graphics, reflow the solder on the two SEI400 and SEI600 graphics rendering ICs.

Single Board Variants

In some regions, Seibu Kaihatsu released some of their games on cost-reduced, all-in-one single boards. These boards are “locked” to the game they ship with, do not have stereo output available, and in some cases use lower-quality dual OKI MSM6295 ICs for audio instead of the Yamaha YM271-F IC that the two-board SPI platform utilized.

• SYS386I -Raiden Fighters 2 Operation Hell Dive 2000 (AMD 386 CPU and dual OKI MSM6295 Audio)
• SYS386F – E-Jan Sakurasou (Intel 386 CPU and Yamaha Audio)
• SYS386H – Raiden Fighters Jet 2000 (AMD 386 CPU and dual OKI MSM6295 Audio)
• SXX2F – E-Jan Sakurasou (Intel 386 CPU and Yamaha Audio)
• SXX2G – Raiden Fighters Jet (AMD 386 CPU and Yamaha Audio)

The SPI hardware and games was never bootlegged or cloned by another company.

Daughterboards

The SPI platform only utilized one daughterboard – the SXX2C Mahjong adapter used with E-Jan Sakurasou.

Capacitor List – V2.0 and V2.1 (credit: ekorz)

Film / Ceramic Resistors – Optional

ROM Details (credit: MAME, twistedsymphony)

Due to the variety of ROM boards used across the SPI games, consult the MAME Driver for game-specific ROM assignments.

The DIP EPROMs can be replaced with a 27C040 EPROM. Replacement of a faulty SMD Mask ROM with an SMD flash might be possible depending on which mask ROM it is.

Protection Mechanisms

Sprite data is encrypted differently for each game and paired to a specific sprite data decryption IC on the cartridge board. This proved to be an effective deterrent against cartridge game conversions and bootlegging.

Schematics & Datasheets

Schematics for the SPI hardware are not available.

Additional Resources

Last Updated: 1/29/2025
Article Credit: ShootTheCore, rtw, buffi, Arcade Otaku Wiki, Alamone, System11, DragonMinded, Mike J Moffat

Overview

The Cave CV1000 PCB has three major revisions: Early CV1000B, Later CV1000-B and CV1000-D.

• Early CV1000-B
  • Gold plated JAMMA connector
  • 9 Pin connection header mounted on the right side with some boards.
    It is unused with the released games but theoretically could have been used to link two boards together via serial communication since the connector is identical to the serial connector on PC motherboards.
  • P2 connection pin header in the center of the board populated.
• Later CV1000-B
  • Tin plated JAMMA connector
  • 9 Pin connection header and P2 connection header unpopulated.
• CV1000-D
  • Tin plated JAMMA Connector
  • Battery for the real-time clock removed
  • SDRAM doubled from 64Mb to 128Mb

The battery in the upper-right corner of the CV1000-B PCB is used to maintain a real-time clock in later games such as Ibara and Pink Sweets. Ibara also displays a clock in one level of the game that matches the board’s clock setting. High scores and game settings are stored in the RTC’s EPROM.
CV1000-D removed the battery – high scores and game settings are stored in NAND instead of EPROM with games running on that hardware.

Notable ICs

Board Variants

Reproductions of both CV1000-B and CV1000-D boards from Chinese sellers began surfacing in early 2024. These reproduction boards can be distinguished from Cave originals with the following characteristics:

• The JAMMA connector is gold plated. Although early CV1000-B boards (Mushihimesama) also had gold plating on the JAMMA connector, all original CV1000-D boards had tin plating.
• Via “pinholes” are not visible on the back of the reproduced board.
• A Cave serial number sticker is not present.
• Some of the reproduction boards do not have the P4 header in the center of the board populated.

At this time, it is believed that the reproduction boards run the games identically to the Cave original hardware. The major IC parts (CPU, Graphics FPGA, Audio, etc) are the same. The build quality seems to be inconsistent though – many of the repro boards have already needed repairs even though at the time of this writing they are less than one year old.

Board Re-initialization (credit: MAME)

Some games (such as Mushihimesama and Espgaluda II) do not have a high score reset function. Any CV1000 can be reinitialized to the factory default high score and board settings with the following procedure:

• During boot, hold P1 Right+A+B+C and P2 Left+A+B+C until the startup checks are complete.

Common Issues and Quirks

CV1000 boards draw less power than your average PCB. Be sure to adjust your arcade PSU down when swapping in one of these boards so you don’t inadvertently over-volt the board!

Leaking Large Capacitor

The large capacitor labeled C109 in the upper-left corner that filters power for the sound amplifier often leaks. The part is rated for 2200 uF at 25 V.

Part number MAL216099606E3 has the same dimensions as the original part, while UCX1E222MNS1GS has the same footprint, but a lower height and a more supportive base. Source: System11

Color Amplifier Degradation (credit: System11)

The Red, Green and Blue color amplifiers located at U14, U15 and U16 respectively can degrade over many hours of use, resulting in a pale or incorrectly tinted display. Replacing the AD8061 color amplifier ICs with fresh parts should resolve the issue. Also note that the Service Menu has a brightness adjustment setting that may need to be changed afterwards.

Missing Red and Blue Colors (credit: rtw and System11)

Switch 4 of DIP Switch block S2 will disable the Red and Green output if it is switched On. If your board has this issue, try flipping that switch Off and On a few times to clean any gunk out of the switch. If that doesn’t help, use a multimeter to check continuity across the switch – if the meter shows continuity across the switch even when it’s disabled then replace the switch block.

Flash Deterioration (credit: Buffi)

The flash chip at U2 is known to suffer from data corruption, causing glitching in the graphics. The chip model is Samsung K9F1G08U0. The CV1000 does a manufacturer check at startup to make sure the flash chip is a K9F1G08U0, and will reboot if it is not. Buffi worked out a way to remove these checks, allowing the U2 flash chip to be replaced with an equivalent from another manufacturer.
https://github.com/buffis/cv1k_research/tree/main/U2_Replacement

Alamone worked out a way to fix graphics issues from deteriorating flash by comparing CV1000 U2 dumps and generating relocated NAND blocks:
https://github.com/alamone/u2_compare

Stuck Control Inputs

CV1000 uses three sets of twin resistor banks and individual 130nF ceramic capacitors as ESD protection between each player control input and the signal pins 176-208 on the SH3 CPU. If a resistor array becomes damaged then a control input may be “stuck” – always on or always off. It’s also possible for an ESD charge to make it through the ESD protection and fry the input line on SH3 CPU – the only resolution then is to replace the entire CPU. You can check the game’s reading of the control inputs in the Service Menu.

• Resistor Array with 101 marking – replacement part number: 742C163101JP
• Resistor Array with 103 marking – replacement part number: 742C163103JP

CPU Stuck in a Boot Loop – Nothing on Screen (credit: Mike J Moffat)

If the CPU is stuck in a boot loop, the LED at L6 will pulse every second to a darker color. Ensure that the 32.768 Khz crystal resonator (it’s not an oscillator) located at X2 is intact and functioning. Measurements for the part are 4.9mm X 1.8mm .

Source: https://gamerepair.info/hardware/37_cave_cv1000

Board Does Not Boot at All (credit: Buffi)

If the EPM7032AE CPLD at location U13 fails then the board will not start up. Buffi has devised a replacement bitstream that can be programmed onto a replacement CPLD to revive the board.
https://www.arcade-projects.com/threads/u13-replacement-for-cave-cv-1000-pcb-repair.17007/
https://github.com/buffis/cv1k_research/tree/main/U13_Research

Protection Mechanisms

Game resources are stored on flash chips located at U2, U4, U23 and U24. The U2 and U4 chips can be accessed by the on-board JTAG connector, but U23 and U24 are not on the JTAG bus and can only be rewritten if the chips are physically desoldered and removed from the board.

The U2 flash is a Samsung K9F1G08U0. The games check the flash ID at boot and if it doesn’t match the expected flash model then the game reboots.

Capacitor List

ROM Details (credit: rtw World of Arcades)

Source: rtw World of Arcades

Schematics & Datasheets

Original Cave schematics are unavailable for CV1000.

Buffi collected datasheets on the components used in CV1000.

• cv1k_datasheets

Additional Resources