Board is a bit dusty but very clean nonetheless. Some very specific chips are rusty, probably due to some rodent fluid. Tracks are invisible and located in the core of this 4-layer board making the inner tracks very fragile when pulling a chip out.
Game starts when powering the board with full sound and some graphics. The title screen has a white background instead of black as it should be. A similar white background appears during attract mode:
Cross-testing the board with a good one points the fault to the bottom board (graphics board). On this board I started probing the 8 EPROMs filled with the background graphics data. Some pins are quite corroded, so I decided to dump them to check their contents against MAME data:
As a result, EPROMs 10 and 14 are dead. I burnt two replacement EPROMs and that brought the background back:
Background is back but the sprites are blinking, they are misplaced and have bad colors. Sprites are generated by the custom chip Mitsubishi M60002-0118P and displayed through twenty 4164 DRAMs. These are known for having a high failure rate. I will focus my investigations in this area:
Probing the D-OUT pins of these DRAMs (pin 14), 8 DRAMs out of 20 shows an output signal stuck low or even floating when the game has to display sprites:
I pulled these 8 D-RAMs:
All of them were confirmed bad out of circuit.
I fit 8 brand-new replacement DRAMs. Some sprite glitches are still visible – two other DRAMs have just gone bad. I took those out and replaced them. Now the sprites and backgrounds appeared to be rendering properly. However, the sprites motion is still jerky.
Rygar shares the same hardware as Silkworm and has schematics available. In the schematics, we can see that two 6116 SRAMs handles foreground and background graphics and a third one is dedicated to sprite positioning (SP/POSITION.RAM as per the schematics). This is the area I will inspect.
Inspection of the SRAM chip at location 6L doesn’t show anything abnormal. While probing around the area, I came across a signal stuck high on a 74LS193 binary counter (BORROW output) located at 7K. I double-checked it with my logic comparator:
Red light indicated a bad output – I pulled the suspect:
Confirmed bad out of circuit:
Replacing this chip fixes the jerkiness. Game is perfectly playable. Sound and controls tested OK.
GeneralComments Off on New Section – Arcade PCB Encyclopedia
Apr132024
I’m introducing a new section of JAMMArcade.net that I believe will be very useful for arcade repair technicians – the Arcade PCB Encyclopedia.
I have long admired the Console 5 Wiki as a comprehensive source of information for video game consoles. A typical console page will have a capacitor list, describe common faults, and collect manufacturer white papers. The JAMMArcade.net Arcade PCB Encyclopedia will attempt to accomplish the same thing for arcade boards.
My goal is to eventually document the following information in one page each for most arcade boards:
High quality photos of the boards – both originals and bootlegs
Notable ICs and their function
Capacitor list
Common faults and solutions to those faults
Protection mechanisms
Schematics and Datasheets
Links to other reference resources on the Internet
Given the number of arcade games produced, it may take several years to assemble these resources for every game, but I want to at least start with the most popular and most documented ones.
The Encyclopedia launches today with information on three boards and I will try to write up 1 – 2 more each week – each one takes a while to research!
I highly value credit for the original researchers and strive for proper attribution. Please contact me if you notice any mistakes in the Encyclopedia entries and I welcome other contributors as well.
The Sega System 16B main board contains all the processing logic to run the game. The Sega part number for it is 171-5347.
Note that these boards are NOT JAMMA pinout and need an adapter to be properly connected to a JAMMA harness.
Depending on the protection scheme used for the particular game, the Main CPU may utilize encryption, the Sound CPU may utilize encryption, and an MCU may or may not be present – see Protection Measures below for more details.
System 16B Main Board w/standard CPUs and no MCU Photo Credit: ShootTheCoreSystem 16B Main Board Rear Photo Credit: ShootTheCoreSystem 16B Main Board w/171-5521 ROM Board and encrypted Main CPU Photo Credit: ShootTheCore
Notable ICs
IC
Function
Location
Hitachi FD1094 CPU (encrypted) Signetics SCN68000C8N64 68000 CPU (unencrypted)
10.0 Mhz Main CPU
C9
NEC MC-8123B CPU (encrypted) Zilog Z8040004PSC Z80 CPU (unencrypted)
The Sega System 16B board was identical between regions for the full lifecycle of the hardware. However, it was heavily bootlegged and thus there is a wide variety of cloned boards. Compared to the original games, cloned boards may have differences in graphics, sound, gameplay and speed. The bootlegs look dramatically different from the Sega originals and are easy to distinguish from the real thing.
System16B boards are NOT JAMMA pinout and need an adapter to be properly connected to a JAMMA harness.
System16B boards draw more power than average, so adjust your arcade PSU accordingly when swapping one into your cabinet or SuperGun.
It is common for the battery in the Main CPU or Sound CPU to die if they are encrypted, causing the game to either not boot or not have sound respectively. See “Copy Protection” below for details and resolution.
It is common for the TL084 OpAmp located at D19 to fail, resulting in faint or garbled audio output. Replacement parts are easy to source.
Due to the variety of ROM boards used across the System16B games, consult the MAME Driver for game-specific ROM assignments.
When replacing a mask ROM with an EPROM, consult this reference chart by twistedsymphony:
Protection Mechanisms
Sega implemented four different protection mechanisms to prevent arcade operators from swapping one System 16B game to another by installing a new set of ROM chips. Games may implement one or more of these protection mechanisms:
Some games encrypt the 68000 code executed by the Main CPU. Those games use a Hitachi FD1094 CPU, which is a Motorolla 68000 clone with a RAM-based decryption key that matches up with the encryption key used on Main CPU ROMs. If the battery that maintains the RAM storing the decryption key dies then the key is lost and the main CPU will crash at boot – the game will sit at a black screen at boot (“suicide”).
Hitachi FD1094 Encrypted Main CPU Photo Credit: ShootTheCoreX-Ray of the Hitachi FD1094 CPU Photo Credit: Eduardo CruzHitachi FD1094 CPU with the top cover removed and the battery exposed Photo Credit: Eduardo Cruz
If the battery hasn’t died yet, it can be replaced while maintaining the onboard decryption key if power is maintained to the supply pins with a bench PSU while the old battery is desoldered and a new battery is soldered in.
Similar to the Main CPU, some games utilize an NEC MC-8123B CPU with an onboard decryption key maintained by battery-backed RAM, paired with encrypted Sound CPU code in the ROMs. If the battery inside the CPU dies, the decryption key is lost, the Sound CPU will crash at boot, and the game won’t have sound.
Solutions are identical to an encrypted Main CPU – if the battery hasn’t died yet, it can be replaced by removing the cover, powering the battery leads from a bench PSU, and soldering in a fresh battery. If the battery has died, swap the NEC CPU out for a standard 4.0 Mhz Z80 CPU, swap the Sound CPU ROMs out for decrypted equivalent EPROMs, and the game’s sound should then function again.
Some games utilized an Intel i875 MCU (or clone) that sits between the CPUs and specifically encrypted ROMs that “scrambles” the memory addressing such that a game won’t function without a matching ROM set and MCU.
Golden Axe MCU Photo Credit: WombleAnother Golden Axe MCU Photo Credit: Ebay
Decrypted ROM sets for every System 16B game are available so that the MCU socket can be left empty on the board, and the encrypted mask ROMs can be swapped with decrypted EPROMs to get a fully-functional game.
ROM Board Variants
As mentioned above, Sega utilized four different ROM board variants with the System 16B hardware across the game library. Assuming that no other protection mechanisms were in place, an arcade operator still wouldn’t be able to change one System 16B game over to another one by swapping ROMs unless the same ROM board was used with both games.
MAME documents the ROM board and configuration settings (if applicable) on the ROM board for each game.
Schematics& Datasheets
Original Sega schematics are available for System 16B, but there seem to be discrepancies between them and the real hardware.
Last Updated: 1/17/2025 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.
Early CV1000-B Front w/Serial Port Photo Credit: ShootTheCoreEarly CV1000-B Front w/out Serial Port Photo Credit: ShootTheCoreLater CV-1000B Front Photo Credit: ShootTheCoreCV1000-D Front Photo Credit: ShootTheCoreEarly CV1000-B Rear Photo Credit: ShootTheCoreLater CV-1000B Rear Photo Credit: ShootTheCoreCV1000-D Rear Photo Credit: ShootTheCore
Notable ICs
IC
Function
Silkscreen Label
Hitachi SH3
Main CPU
U5
Yamaha YMZ770
Audio
U22
Altera Cyclone EP1C12F324C8
Graphics Rendering
U8
Altera CA011
CPLD used for address decoding of the U2 flash, YMZ770 audio and RTC 9701.
U13
RTC 9701 (CV1000-B)
Real-Time Clock with embedded EPROM for saving board settings and high scores
U10
AD8061
Color amplifier for the Red, Green and Blue output
U14, U15, U16
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.
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
CV1000-B board with a leaking capacitor Photo Credit: ShootTheCore
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.
CV1000 with degraded Red color amplifier Photo Credit: System11The same CV1000 after the Red color amplifier was replaced Photo Credit: System11
Flash Deterioration (credit: Buffi)
Corrupt graphics in Espgaluda due to U2 flash deterioration Photo Credit: buffiCorrupt graphics in Muchi Muchi Pork due to U2 flash deterioration Photo Credit: EOJ
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
Resistor Array 101 and 103 replaced to resolve an issue with a stuck button input Photo Credit: ShootTheCore
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 .
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.
Last Updated: 4/19/2024 Article Credit: ShootTheCore, wickerwaka, ekorz, System11, Apocalypse
Main Board
The Main Board is largely identical across all Irem M92 games. It is labeled either M92-A-A or M92-A-B.
GunForce A Board Photo Credit: ShootTheCoreHook A Board Photo Credit: ShootTheCore
Early boards have less Object RAM (16K) installed at locations IC43 & IC44 than later boards (64K) – selectable by jumper J2 – but all M92 games are confirmed to function correctly with the 16K board. Thus, the difference in RAM was likely determined by parts cost at the time of manufacture.
16K Object RAM on Mystic Riders A Board Photo Credit: ShootTheCore64K Object RAM on Major Title 2 A Board Photo Credit: ShootTheCore
Notable ICs
IC
Function
Silkscreen Label
Location
NEC D71036L V33
Main CPU
H8
Nanao GA20
Sound FX Samples
IC32 GA20
B6
Nanao GA21
SRAM DMA and Address Generation for GA22
IC42 GA21
M7
Nanao GA22
Graphics Rendering
IC63 GA22
M10
YM2151
FM Sound Chip
IC33
C6
YM3014
Sound D/A Converter
IC208 YM3014
C5
Secondary Board
The Secondary Board layout varies across the M92 games.
The Sound CPU resides on the secondary board and utilizes an encryption mechanism – see “Copy Protection” below.
GunForce B Board – Model M92-B-A Photo Credit: ShootTheCoreHook B Board w/Repair – Model M92-D-A Photo Credit: ShootTheCoreNinja Baseball Batman B Board – Model M92-Z-C Photo Credit: Ebay
Game
Board Model
Sound CPU Model
Notes
Blade Master / Cross Blades
M92-B-A M92-D-A
Dream Soccer 94
GunForce
M92-B-A
GunForce II / GeoStorm
Hook
M92-D-A
In The Hunt / Kaitei Daisensou
M92-E-B
Lethal Thunder / Thunder Blaster
M92-C-B
Major Title 2 / The Irem Skins Game
M92-B-F
Only M92 game to utilize an EPROM for saving scores.
Mystic Riders / Gun Hoki
M92-B-B
Ninja Baseball Bat Man / Yakyuu Kakutou League-Man
M92-F-A M92-Z-C
Perfect Soldiers / Superior Soldiers
R-Type Leo
M92-C-N
Undercover Cops
M92-E-B
Notable ICs
IC
Function
Silkscreen Label
Nanao 08J27261A1 V35
Sound CPU
IC10
Nanao GA23
ROM Addressing (Assumed)
IC23 08J27504A1
Board Variants
M92 boards manufactured for the Korean region have several noticeable differences from boards manufactured for other territories:
The green silkscreen is a lighter shade of green.
The JAMMA connector does not have a key notch.
SRAM ICs on M92 boards for other regions are manufactured by NEC whereas on the Korean boards they are manufactured by Hyundai and Goldstar.
The amplifier heatsink is physically smaller, and is colored silver rather than black.
One or both boards may be missing markings for the board type on the silkscreen.
A metal serial number tag is not present in the upper-right corner of the A Board.
Korean Ninja Baseball Bat Man A Board Photo Credit: ShootTheCoreKorean Ninja Baseball Bat Man B Board Photo Credit: ShootTheCore
There are also single-board bootlegs of several M92. They are much smaller than original M92 boards and thus are easily distinguished. Compared to the original games, bootlegs often omit animation frames, shorten the music tracks and gameplay slows down more frequently.
Ninja Baseball Batman Bootleg Photo Credit: ShootTheCore
Common Issues and Quirks
The factory-installed capacitors are colored green or brown. The ELNA brand brown-colored capacitors are notorious for leaking and should be replaced ASAP.
Video output is darker than average with this hardware.
Protection Mechanisms
The Nanao 08J27261A1 V35 Sound CPU on the B Board enforces a security scheme where each game’s sound CPU code is encrypted in ROM and then decrypted by a key specific to the model of CPU. Thus, if the game ROMs are swapped to another game without decrypting the sound CPU code of the new game and re-encrypting the code to match the encryption scheme of the old game, the sound CPU will crash and the game won’t have sound.
Changing jumpers J1 and J6 adjacent to the Sound CPU from “S” to “N” disables the decryption mechanism and allows the CPU to run decrypted Sound CPU code directly.
Original Irem schematics are unavailable for M92. wickerwaka developed a MiSTer FPGA core for the Irem M92 platform, and generated the following schematics (Source):
