Super Nintendo General Maintenance

The Super Famicom. The Super Nintendo shares its architecture but not its board numbers.

This guide covers routine care, board identification and the board-level figures for the Super Nintendo Entertainment System — the North American SNS- boards, the European and Australian SNSP- boards and the SNES Jr / SNES mini SNN- board. The Japanese SHVC- boards are covered on Super Famicom Maintenance Guide, and the two families are not interchangeable at the designator level: an SHVC-CPU-01 has no SNS-CPU-GPM-02 in it.

Everything here that is a number comes from Nintendo's own service literature — the Playtronic Manual Técnico do Super NES and the Japanese Famicom / Super Famicom / Game Boy service manual, both hosted on this wiki — or from a named community source that says where it got it. Where a figure is not in one of those, it is not given here.

Identify the board first

Read the revision off the PCB silkscreen. It is printed along an edge of the mainboard and it, not the case, decides which capacitor list, which regulator designator and which clock figure apply to your machine.

Super Nintendo mainboard families

Silkscreen	Market	What it is
SNS-CPU-GPM-01, SNS-CPU-GPM-02	North America	Ground-plane construction. Nintendo's own redesign of the original layout
SNS-CPU-RGB-01, SNS-CPU-RGB-02, SNS-CPU-APU-01	North America	Renumbered board; the C57–C67 range of the earlier boards does not carry over
SNS-CPU-1CHIP-01/-02/-03	North America	CPU and both PPUs merged into one package
SNSP-CPU-01, SNSP-CPU-02	Europe, Australia	9 V AC input, rectified on the board. Carries the S-CLK
SNSP-CPU-1CHIP-01/-02	Europe, Australia	PAL single-chip revision
SNN-CPU-01	All markets	SNES Jr / SNES mini. No RF modulator, no eject mechanism
SHVC-CPU-01 and later SHVC boards	Japan	Super Famicom — see Super Famicom Maintenance Guide

GPM and 1CHIP are unrelated

These two get conflated constantly, and they are not the same kind of change.

GPM stands for Ground Plane Method — it is a PCB manufacturing process, documented by Nintendo in its own manual, which puts a base layer between the track layout and the solder mask. The benefit was that the lower RF shield could be deleted. Along with the process change came a shorter PCB, the removal of C67 and the 4 MHz oscillator, the sound module circuitry built directly onto the mainboard instead of on a daughtercard, TC1 changed to a through-hole part, and the cartridge lock bar deleted from the upper housing in favour of a warning label. It is an early-to-mid production change and it has nothing to do with video quality.

1CHIP is a much later silicon change: the CPU and both picture processors were merged into a single package, the S-CPUN. That is the revision sought after for its video output. A GPM board is not a 1CHIP board, a 1CHIP board is not a GPM board, and a console advertised as "1CHIP" because its silkscreen says GPM is mislabelled.

Power

North American consoles take 10 V DC at 850 mA, centre negative. Centre negative means the centre pin is 0 V and the outer sleeve is +10 V. European and Australian consoles take 9 V AC into the same style of jack and rectify it on the board at DB1. The two are not interchangeable in either direction, and a correctly rated 10 V centre-positive supply is connected backwards.

The supply is unregulated, so a high off-load reading is normal. Nintendo specifies the Famicom-family adapter as reading DC 13.5 ± 1.5 V with no load, and its power-circuit block diagram labels the 7805's input arm 13–14 V. A meter showing 13 V on the barrel of a "10 V" adapter is not a reason to throw the adapter away.

Supply and rails

Item	Figure	Note
Adapter, NTSC	10 V DC, 850 mA, centre negative	Centre pin 0 V, outer sleeve +10 V
Adapter, PAL	9 V AC	Rectified on the board at DB1
Adapter, no load	12.0–15.0 V DC	Nintendo's figure is 13.5 ± 1.5 V and it is normal
F1	1.5 A, SSTR axial	Both Nintendo parts lists carry it; fullsnes records the fitted part as "SOC, 1.5A"
Regulator	7805 at U12 — U9 on the 1CHIP and SNN boards	13–14 V in, 5 V out
Vcc	5.0 V	The only regulated rail. CPU, both PPUs and the APU run from it and from nothing else
Vs	unregulated, 7 V by Nintendo's figure	Feeds only the audio amplifier. A console with Vs missing plays silently and otherwise normally

There is no +12 V rail, no 3.3 V rail and no save battery anywhere in a Super Nintendo. Nintendo's description of the supply section is a noise filter, reverse-current protection, the power switch, a spike suppressor, a ripple filter and the regulator — and two outputs, Vcc and Vs. "IC601" is not a designator on any of these boards; the regulator is U12, or U9 on the later single-chip boards.

Save batteries are in the cartridges. Nintendo's Game Pak test procedure has the technician measure the cartridge battery and expects 2.7 to 3.2 V DC; below that, saves start being lost.

Chip map

Nintendo's diagnostic tables are written against U-numbers, so it is worth knowing what they are before you follow one. This is the map for the PAL SNSP-CPU-01; the North American SNS-CPU boards of the same generation use the same numbering except that they have no S-CLK and no bridge rectifier.

SNSP-CPU-01 — component map

Designator	Part	Function
U1	Nintendo S-CPU A (5A22)	Main CPU, 65C816 core with mapper, DMA and joypad interface
U2	Nintendo S-PPU1 (5C77)	Picture processor 1
U3	Nintendo S-PPU2 (5C78)	Picture processor 2
U4, U5	32K × 8 static RAM	Video RAM
U6	Nintendo W-WRAM	Work RAM
U7	Nintendo S-ENC	RGB to composite encoder
U8	Nintendo F413	CIC lockout
U9	74HCU04 hex inverter	NTSC boards only. Clock inverter for X1 and the CIC
U10	AN1324S (LM324 equivalent)	Audio quad amplifier — runs from Vs
U11	T529D	Reset / voltage-detector IC
U12	7805	+5 V regulator
U13	Nintendo S-SMP	Sound CPU, SPC700 core
U14	Nintendo S-DSP	Sound DSP
U15, U16	32K × 8 static RAM	Audio RAM
U17	NEC µPD6376	Dual 16-bit audio DAC
U18	Nintendo S-CLK	PAL boards only. Synthesises 21.2813700 MHz and 4.43 MHz from X1
TC1	Red trimmer capacitor	Master clock adjustment
X1	D177F2 (PAL) / D214K1 (NTSC)	Master crystal
X2	24.576 MHz	APU clock
F1	1.5 A axial fuse	Supply input
T1	TDK dual-loop filter	Supply input
DB1	Bridge rectifier	AC (PAL) boards only
VR1	ZNR surge absorber	Supply input

U9 is a 74HCU04 on NTSC boards and is simply absent on PAL boards, because the S-CLK does that job instead. A PAL owner following an NTSC fault tree to "U9, the hex inverter" will be looking at an empty footprint — or, on a 1CHIP or SNN board, at the 7805.

On the cost-reduced single-chip boards the map collapses: U1 is the S-CPUN containing CPU, both PPUs and the S-CLK, U2 is the S-APU containing the S-SMP, S-DSP and sound RAM, U3 is the S-WRAM B, U7 is the S-RGB A, U8 is the F411B CIC, U9 is the 7805 and U10 is the S-MIX A.

Clocks

The master clock is region specific and the wrong target figure will send you chasing a fault that is not there.

Master clock by television standard

Standard	Crystal	Master clock
NTSC (North America, Japan)	21.4772700 MHz at X1	21.47727 MHz
PAL (Europe, Australia)	17.7344750 MHz at X1	21.281370 MHz, synthesised by the S-CLK
PAL-M (Brazil, Playtronic)	21.453666 MHz at X1	21.453666 MHz

TC1 trims the master oscillator, and Nintendo's remedy for a colour fault that survives everything else is to set it to the region-correct frequency; if it will not adjust or will not hold, replace TC1 and then X1. Do not apply the Brazilian figure to a European or North American console.

The CIC runs from a separate 4 MHz ceramic oscillator at X2 on the earlier boards, and Nintendo gives the acceptable window as 3.8 to 4.2 MHz. On later consoles the CIC clock is derived instead as 3.072 MHz from the 24.576 MHz APU oscillator.

The reset order is deliberate: the CIC's reset reaches PPU2 first, which introduces a delay, then PPU1, then the CPU, so that both picture processors are running before the CPU is released. A fault that holds PPU2 in reset therefore stops the whole machine and looks exactly like a dead CPU.

Opening the console

Nintendo's first disassembly instruction is not about screws.

Before disassembling, switch the console's power supply ON with the AC adapter disconnected, in order to discharge capacitor C67. This capacitor is known to discharge during maintenance, causing damage to components.

C67 is the reservoir on the supply input and it holds its charge after the adapter comes out. Flicking the power switch with nothing plugged in empties it through the console's own load. GPM boards have no C67 and the later boards carry the reservoir under a different designator — see Super Nintendo Capacitor Replacement Guide — but the step costs nothing and you do not always know which board you have until it is open.

• Six security screws in the lower case, taking a 4.5 mm Gamebit driver.
• The sound module, where fitted, comes off with two screws on its far side and lifts straight up.
• SNS-CPU-1CHIP, SNSP-CPU-1CHIP and SNN-CPU boards have no sound module to remove — the sound circuitry is on the mainboard.

Do not meter the ICs

Nintendo's own IC handling notes say plainly that a multimeter or signal tracer applies a significant voltage to determine resistance and will damage the device; if you must measure an IC at all, use the lowest resistance range and accept the risk. Probe supply pins and passives, not chips.

The cartridge connector

A 62-pin edge connector on a non-standard 2.5 mm pitch, taking a 1.2 mm board. Nintendo's diagnostic table puts it at the head of the probable causes for three separate faults, and Nintendo's instruction to its own service centres was blunt: do not clean 62-pin connectors, replace them.

That was written for centres with a parts bin, and Nintendo supplied the connector as two service parts, an upper and a lower half. For a modern restorer with no source of new connectors, cleaning is what there is, and it usually works — but if a console keeps coming back after cleaning, Nintendo's view was that the connector itself was the problem.

• Clean the cartridge contacts as well as the slot; a tarnished cartridge will re-dirty a clean console.
• Isopropyl alcohol on a lint-free swab or a contact-cleaning card. Never metal polish, never an abrasive on gold plating — once you are through the plating, oxides form and then transfer to every cartridge you insert.
• Inspect for bent pins and for cracked joints where the connector meets the mainboard. Nintendo lists "poor solder" as a probable cause of four separate symptoms.

Unlike the NES-001, this is a conventional edge connector, so inserting and removing a cartridge wipes the contacts. That is why the SNES does not share the NES's reputation for needing constant attention.

Cleaning

Case and controllers

• Damp microfibre cloth and mild detergent on the shell. No abrasives.
• Controller ports: soft brush and isopropyl alcohol; a wooden cocktail stick for anything lodged.
• Open controllers with a Phillips driver, wash the button caps and D-pad in warm soapy water, dry them thoroughly, and clean the PCB contacts with isopropyl alcohol. Replace the conductive pads if buttons stay dead.

Inside

• Discharge the reservoir first, as above.
• Anti-static brush and compressed air on the board; isopropyl alcohol and a soft brush on corrosion.
• Keep moisture away from the cartridge connector and the sound module.

Yellowed plastic

The North American SNES uses two greys that were never the same colour and have aged differently, so a "yellowed" console is often partly original two-tone. Compare the underside of a panel with its face before deciding anything has discoloured at all. European and Japanese shells are a single light grey and yellow more evenly.

Treatment is possible; see Retrobrite for the chemistry, the procedure and its risks. Two things worth knowing first:

• The discolouration is in the body of the plastic, not on the surface, so cleaning will not touch it.
• Over-treated ABS goes brittle and the finish goes chalky. Watch the temperature and exposure, and stop early rather than late.

Capacitors

Most of the electrolytics on the SNS- and SNSP- boards are surface-mount, which is what makes this machine worth opening rather than ignoring: an SMD capacitor that has begun to leak hides the evidence under its own body, and the corrosion only shows once the can is off.

The SNES is nonetheless not a machine where recapping is mandatory. Open it, look, and act on what you find. Symptoms that justify pulling the board:

• Buzzing, distorted or missing audio
• Unstable video, rolling or colour shift
• Random resets or failure to power on
• Any brown, yellow or white residue around a capacitor, or green discolouration on the pads

Per-revision lists are on Super Nintendo Capacitor Replacement Guide. See also Capacitor Failure Symptoms.

Self-inflicted faults

• Not discharging the reservoir before working on the board. Nintendo's own stated reason for the step is that the capacitor discharges during maintenance and damages components.
• Fitting the front-unit flat cable the wrong way round. The unprinted face is the contact face. Reversed, you get dead controller ports on a console that is otherwise perfectly healthy.
• Reversing the power-switch harness. Nintendo marks + and − on the switch body and specifies the red lead to + and the black to −.
• Fitting a centre-positive supply. The jack is centre negative; a correctly rated 10 V centre-positive adapter is connected backwards.
• Fitting a PAL adapter to an NTSC console or the reverse. One is 9 V AC, the other 10 V DC.
• Taking an abrasive to the cartridge connector.
• Metering the ICs.

Things that are not faults

• An adapter reading 13 V or so off load. Nintendo's own figure is 13.5 ± 1.5 V.
• The 7805 running hot. It is dropping around 8 V at whatever the console draws, and that is where the heat goes.
• The console switching off as a cartridge is pulled. Earlier consoles carry an anti-eject lever on the power switch that rides in a notch in the cartridge; on cartridges with a diagonally cut notch it switches the console off as the cartridge comes out. Nintendo deleted the lock bar on GPM machines and substituted a warning label.
• No sound module on the board. GPM, 1CHIP and SNN boards do not have one.
• No C67. GPM boards do not have one.

Tools

• 4.5 mm Gamebit driver, Phillips drivers
• Digital multimeter; a frequency counter or a scope if you are setting TC1
• Fine-tip temperature-controlled soldering iron, flux, desoldering braid or pump
• Hot air station for surface-mount capacitors
• Isopropyl alcohol (99 %), anti-static brush, lint-free swabs
• Contact cleaner, plastic spudger

See Recommended Tools.

Preventive maintenance

1. Confirm the adapter type and polarity before connecting it — DC and centre negative for an NTSC console, 9 V AC for a PAL one.
2. Clean the cartridge and the slot when games start needing a second insertion.
3. Reseat the AV and controller plugs if the picture or a controller becomes intermittent.
4. Reflow the DC jack, the Multi Out and the controller port joints if intermittents appear. Nintendo identifies three solder points around the DC jack as needing reinforcement.
5. Keep the console out of direct sunlight — the plastics are the part most likely to be ruined by storage.

Related pages

• Super Nintendo Entertainment System
• Super Nintendo Capacitor Replacement Guide
• Super Nintendo Troubleshooting Guide
• Super Famicom Maintenance Guide
• Nintendo Super NES Technical Manual (Playtronic, Rev. 01-94)
• Nintendo Famicom Service Manual
• SNES Schematic
• Retrobrite
• Capacitor Failure Symptoms