Nintendo NES Mainboard Revisions (NTSC) PCB revisions run from NES-CPU-01 to -11.  Revisions below -05 will have noticeably poorer video output than later revisions.  Revisions -10 and -11 use circuitry to try to defeat the lockout defeaters of the unlicensed cartridges. NES-CPU-02 - 2A03E/2C02E-0 The original US release of the NES (fewer than 10,000 were made). 1985 copyright on PCB VRAM and WRAM are NDIP-only 3193 Non-A CIC NES-CPU-03 Unreleased NES-CPU-04 - 2A03E/2C02E-0 1986 copyright on PCB VRAM and WRAM are NDIP-only 3193 Non-A or 3193A CIC some have a 74HC139 at U3 instead of 74LS139 NES-CPU-05 - 2A03G/2C02G-0 1986 copyright on PCB VRAM and WRAM are NDIP-only 3193A CIC NES-CPU-06 - 2A03G/2C02G-0 1987 copyright on PCB VRAM and WRAM are NDIP or DIP NES-CPU-07 - 2A03G/2C02G-0 1987 copyright on PCB VRAM and WRAM are NDIP or DIP NES-CPU-08 - 2A03G/2C02G-0 1989 copyright on PCB VRAM and WRAM are NDIP or DIP NES-CPU-09 - 2A03G/2C02G-0 or 2A07/2C07-0 1987 copyright on PCB VRAM and WRAM are NDIP or DIP Has one resistor between CIC pin and cart connector to prevent CIC stun attacks NES-CPU-10 - 2A03G/2C02G 1987 copyright on PCB VRAM and WRAM are NDIP or DIP Has two resistors between CIC pins  and cart connector to thwart more CIC voltage stun, some later revisions have a diode to nearby GND vias as well to prevent the -5V attack NES-CPU-11 - 2A03G/2C02G or 2A07[A]/2C07[A] 1987 Copyright on PCB VRAM and WRAM are NDIP or DIP Has two resistors and two diodes between CIC pins, cart connector and GND to prevent CIC stun and -5V attacks Product Sheets NES Mainboard (NTSC) Capacitor Guide Capacitors play a crucial role in maintaining a steady flow of current to other components. With a typical lifespan of 20–30 years—and considering the age of most NES consoles—the original capacitors have likely reached or exceeded their expected service life. For optimal performance and reliability, replacing them is strongly recommended. When installing new capacitors, be sure to observe the correct polarity. The longer lead indicates the positive side, which corresponds to the "+" symbol in the diagram. Capacitor Location 1uF 50v C23 100uF 6.3v C1 2.2uF 50v C9   Board Layout Mitsumi Capacitor Kit Capacitor Guide Capacitors play a crucial role in maintaining a steady flow of current to other components. With a typical lifespan of 20–30 years, and considering the age of most NES consoles, the original capacitors have likely reached or exceeded their expected service life. For optimal performance and reliability, replacing them is strongly recommended. Mitsumi TDK-T31V Capacitor Location 100uF 10v C25 100uF 16v C22 10uF 16v C6 2200uF 25v C21 Mitsumi TDK-T12V Capacitor Location 100uF 16v C29 2200uF 25v C8 100uF 25v C31 1uF 50v C2 10uF 16v C32 1uF 50v C6   Mitsumi MTM-8V-0 Capacitor Location 10uF 35v C5 100uF 16v C21 100uF 10v C24 2200uF 25v C20 Alps Capacitor Kit (NTSC) Capacitor Guide Capacitors play a crucial role in maintaining a steady flow of current to other components. With a typical lifespan of 20–30 years, and considering the age of most NES consoles, the original capacitors have likely reached or exceeded their expected service life. For optimal performance and reliability, replacing them is strongly recommended. Alps FR853   Capacitor Location 100uF 10v C25 2200uF 25v C21 100uF 25v C23 1uF 50v C35 10uF 16v C36 1uF 50v C29 400v Diodes Locations: D1, D2, D3, D4 The gray stripe on this diode represents the negative/cathode end. It should match the position in the diagram. Alps SH-SH5 / FS074 Capacitor Location 1uF 50v C29 100uF 25v C23 100uF 10v C25 10uF 16v C36 1uF 50v  C37 2200uF 25v C21 400v Diodes Locations: D1, D2, D3, D4 The gray stripe on this diode represents the negative/cathode end. It should match the position in the diagram.