Super Famicom Troubleshooting Guide
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Fault-finding for the Super Famicom (SHVC-001). The Nintendo figures here come from Playtronic's Brazilian Manual Técnico do Super NES, which documents the SHVC-CPU-01 board,[1] and from Nintendo's Japanese Famicom / Super Famicom / Game Boy service manual.[2] Cleaning, the GPM board changes and Nintendo's colour-fault notes are on the Super Famicom Maintenance Guide; capacitor values are on the Super Famicom Capacitor Replacement Guide.
The cartridge connector first
[edit | edit source]Nintendo's diagnostic table puts the 62-pin connector first for three faults: a solid-colour screen, scrambled video, and a frozen screen or erratic play.[1] Clean the slot and the cartridge contacts with isopropyl alcohol and retest with a second cartridge before suspecting a chip.
Nintendo's instruction to its service centres was not to clean the connector but to replace it.[1] Its Japanese price list sells the connector as an upper half, changed with a screwdriver, and a lower half soldered to the board.[2]
Discharge C67 before opening
[edit | edit source]Nintendo's first disassembly step is to switch the console on with the AC adapter disconnected, to discharge C67; the manual says this capacitor is known to discharge during servicing and damage components.[1] C67 is the 1000 µF input reservoir on the SHVC-CPU-01 and GPM boards; the RGB, APU and 1CHIP boards number it C58. The Brazilian and North American GPM boards do not have it, but Japanese boards do, so do the discharge step on every Super Famicom.[3]
Power
[edit | edit source]The Super Famicom runs from the HVC-002 adapter, 10 V DC 850 mA, centre negative: the centre pin is 0 V and the sleeve positive.[4] The supply is unregulated: Nintendo gives the adapter's off-load output as 13.5 ± 1.5 V, and its SHVC power circuit shows 13–14 V into the 7805.[2] A European SNES adapter (9 V AC according to Martin Korth's fullsnes) or an NES adapter (AC) must not be used.[5][4]
| Where | Expected | Note |
|---|---|---|
| Adapter, no load | 12–15 V DC | Nintendo: 13.5 ± 1.5 V[2] |
| Plug | Centre 0 V, sleeve positive | A centre-positive adapter is connected backwards |
| F1 | Continuity | 1.5 A axial fuse; first on Nintendo's no-power list[1] |
| U12 (7805) input | About 13–14 V | U12 on SHVC-CPU-01 and SNS-CPU boards; U9 on 1CHIP boards[2][3] |
| U12 output (Vcc) | 5.0 V | The only logic supply; CPU, PPUs and sound chips run from it[1][5] |
| Vs, unregulated | 7 V (Nintendo); 9 V on the NTSC schematic redraw | Audio amplifier only; without it the console runs silently[1][6][5] |
Nintendo's no-power list, in order: F1 (1.5 A fuse), D1, T1 (line filter), U12 (7805), VA1 (surge absorber), Q18, P3 (power switch). Some of these parts were deleted from later boards.[1][3] Save batteries are in the cartridges, not the console.
Clocks and reset
[edit | edit source]The 21 MHz master clock goes to the CPU, both PPUs and the cartridge connector. The CPU divides it by 6, 8 and 12 to give 3.58, 2.68 and 1.79 MHz; it runs internally at 3.58 MHz, and DMA always at 2.68 MHz.[1]
| Console | Master clock |
|---|---|
| Japanese and North American | 21.47727 MHz |
| European (PAL) | 21.28137 MHz, made by the S-CLK chip from a 17.734475 MHz crystal |
| Brazilian (PAL-M) | 21.453666 MHz |
Sources: fullsnes and the NTSC schematic for the first two rows;[5][6] Playtronic's manual for the PAL-M figure, which it uses for the TC1 adjustment.[1] Use the figure for the console being repaired. If TC1 cannot be set or will not hold, Nintendo replaces TC1, then X1.[1]
The reset circuit is a 4 MHz ceramic oscillator (X2), a 74HCU04 (U9), the CIC and the reset switch. Nintendo accepts 3.8 to 4.2 MHz from the 4 MHz oscillator; outside that range, check X2, the 74HCU04 and the parts round them. The CIC releases PPU2 first, then PPU1, then the CPU, so a fault holding PPU2 in reset stops the whole machine. A separate reset IC (PST529DMT) holds the CPU during power faults to protect the cartridge's RAM.[1]
Symptoms
[edit | edit source]| Symptom | Work through, in order |
|---|---|
| Completely dead, no LED | Adapter off-load reading and polarity; DC jack joints; then Nintendo's list: F1, D1, T1, U12, VA1, Q18, P3[1] |
| Solid-colour or black screen | Nintendo's list: 62-pin connector; sound module; poor solder; U1 (CPU); U3 (PPU2); U6 (WRAM); U2 (PPU1); U7 (RGB encoder); X1; U8 (CIC). Also check 5 V, the 21 MHz clock and the 4 MHz clock (3.8–4.2 MHz)[1] |
| Frozen screen or erratic play | 62-pin connector; poor solder; U1; U3; U2[1] |
| Scrambled video | 62-pin connector; poor solder; U3 (PPU2); U1; U2 (PPU1); U4 or U5 (256K SRAM)[1] |
| Picture, no sound | The Vs supply to the amplifier; then Nintendo's list: sound module; connector P5; U1; U10 (amplifier); Q18[1][5] |
| Poor or no colour | TC1 adjustment; U3 (PPU2); U7 (RGB encoder); X1. See the colour notes on the maintenance guide[1] |
| No reset (the reset line) | U8 (CIC); X2 (4 MHz oscillator); U9 (74HCU04)[1] |
| Snowy picture (RF) | RF modulator[1] |
| Controllers intermittent or dead | Front unit board; FFC harness, fitted with its unprinted side as the contact face; connector P2; U1[1][2] |
| Power cuts out when moving the plug | Cracked solder at the DC jack; Nintendo marks the jack joints for reinforcement on the Famicom[2] |
| Power switches off when the cartridge is pulled | Normal on older consoles: the power switch has an anti-eject lever that rides in a notch in the cartridge[5]. GPM consoles have a warning label instead of the lock bar[1] |
Probing safely
[edit | edit source]From Nintendo's IC handling notes:[1]
- Do not test ICs with a multimeter or signal tracer: the meter's test voltage can damage them. If you must measure an IC's resistance, use the lowest range.
- Earth yourself through a resistance of several MΩ, avoid synthetic clothing, use an earthed soldering iron, and do not reuse removed ICs.
- Disconnect power before fitting or removing ICs.
When reassembling, solder the power switch harness red to + and black to −; the switch is polarised.[2]
Related pages
[edit | edit source]- Super Famicom Maintenance Guide
- Super Famicom Capacitor Replacement Guide
- Super Nintendo Troubleshooting Guide
- Nintendo Super NES Technical Manual (Playtronic, Rev. 01-94)
- Nintendo Famicom Service Manual
- SNES Schematic
- Capacitor Failure Symptoms
- Recommended Tools
References
[edit | edit source]- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 Playtronic / Nintendo, Manual Técnico do Super NES, Rev. 01/94, hosted at Nintendo Super NES Technical Manual (Playtronic, Rev. 01-94). Theory of operation, section 2: supply section (noise filter, reverse-current protection, switch, spike suppressor, ripple filter, regulator; Vcc 5 V regulated, Vs 7 V unregulated for the audio amplifier); 21 MHz master clock divided by 6, 8 and 12 to 3.58, 2.68 and 1.79 MHz; reset section (4 MHz oscillator, 74HCU04, CIC, reset switch; CIC reset to PPU2, then PPU1, then the CPU; reset IC holds the CPU through power faults to protect cartridge RAM). Parts lists pp. 2-6 to 2-8 (F1 1.5 A, U12 7805, reset IC PST529DMT). p. 2-14 (disassembly). Fault-finding pp. 2-24 to 2-27 (4 MHz clock 3.8 to 4.2 MHz; TC1). Console diagnostic table pp. 2-28, 2-29. IC handling pp. 8-1, 8-2.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Nintendo, ファミコン・スーパーファミコン・ゲームボーイ サービスマニュアル (Famicom / Super Famicom / Game Boy Service Manual), dated 7 August 1992, hosted at Nintendo Famicom Service Manual. HVC p. 2 (HVC-002 adapter 13.5 ± 1.5 V off load); HVC p. 6 (DC jack solder points); SHVC pp. 11–12 (power-switch polarity, FFC harness, power circuit 13–14 V into the 7805); p. 15 (price list: 1.5 A SSTR fuse, 7805, upper and lower 62-pin connectors, sound module); p. 21 (repair ranks).
- ↑ 3.0 3.1 3.2 Console5 TechWiki, "SNES" (retrieved 2026-10-01). Chip maps and capacitor lists by revision; transcription of Nintendo's diagnostic table.
- ↑ 4.0 4.1 Famicom World, "Famicom Power Adaptor" (retrieved 2026-10-01).
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Martin Korth, fullsnes, sections "SNES Power Supply" (9 V AC PAL; 10 V DC 850 mA NTSC through a diode; 7805; the unregulated supply feeds only the audio amplifier, and the console runs silently without it; anti-eject lever on the power switch of older consoles) and "SNES Timing Oscillators" (NTSC and PAL master clocks). Community reference.
- ↑ 6.0 6.1 SNES Schematic, Jonathon W. Donaldson, rev. 1.5, 2014, hosted at SNES Schematic: "VS = 9V".