Nintendo Famicom General Maintenance

Nintendo Famicom HVC-CPU-07 mainboard

The Nintendo Family Computer (Famicom, ファミリーコンピュータ, HVC-001) is a robust linear-power design with very little in it that wears out electrically. Almost everything that goes wrong with one is a contact, a connector or a solder joint. This page covers preventive care and the checks worth making, and takes its figures from Nintendo's own service manual for the machine wherever they exist.

The power supply

The HVC-002 AC adapter is rated DC 10 V and is centre-negative. The centre pin of the plug is 0 V; the outer sleeve is positive. It is an unregulated transformer supply with no regulator in it — the regulation happens inside the console.

HVC-002 adapter and the console supply

Measurement	Nintendo's figure	Notes
Adapter, no load	DC 13.5 ± 1.5 V	12.0–15.0 V off-load is a healthy adapter
Adapter, rating plate	DC 10 V	The nominal figure, reached under load
7805 input	13–14 V	Unregulated, from the adapter
7805 output	5 V	The console's only logic rail
RF switch terminal, game mode	DC 5 V	The signal that flips the RF switch from aerial to game

Every figure above is Nintendo's.

A Famicom adapter that reads 13 or 14 V off-load is not faulty and is not to be thrown away. That is what an unregulated transformer supply does when nothing is drawing from it, and Nintendo's service manual says so in as many words. Advice to replace an adapter that "reads more than 11 V" costs people working hardware.

If the RF switch terminal does not show 5 V while the console is in game mode, the fault is in the RF modulator's internal power circuit or its joiner wiring, not in the RF switch.

The one supply-side repair Nintendo documents

If moving the AC adapter plug by hand makes the picture cut out, the DC jack's solder joints have fractured from the cable being pulled sideways. Nintendo's manual marks three points on the board around the jack that need reinforcing with solder, and treats this as the normal repair rather than a jack replacement. It is worth doing pre-emptively on any Famicom you open.

Board revisions

The revision is silkscreened as HVC-CPU-xx, near the cartridge slot or the board edge. Nintendo's service manual does not break its parts list down by revision and no manufacturer revision table has been published, so this page does not give one: what circulates on the web as a dated Famicom revision table has no source behind it. Read the marking off your board and treat any list that does not name it as not applying to you.

Two differences are documented rather than inferred:

• VCCI boards have a fuse; earlier boards do not. Nintendo draws two power circuits — a plain "HVC" one and an "HVC (VCCI)" one with an extra choke in the input line — and the fuse appears in the parts list flagged as a VCCI item.
• Controllers exist in square-button and round-button forms, and Nintendo's exploded views show both as separate assemblies. The button, keytop and rubber contact parts differ between them.

The AV Famicom (HVC-101, 1993) is a different machine: no RF modulator, composite video and audio out, a different power circuit. Nothing on this page about the RF section applies to it.

The controllers

Famicom controllers are hardwired to the shell but not to the board — each one ends in a connector that plugs into the mainboard. Nintendo's procedure is to release it with a small flat-blade screwdriver in the connector groove and pull, then push the replacement home with the notch upward, by hand and not with a driver. The connector housings snap easily, so work gently.

Nintendo lists the failure modes as wear of the A and B buttons and an internal break in the cable, and notes that a controller can be at fault with nothing visibly wrong with it. The symptoms it gives:

• A button does nothing.
• A button acts without being pressed.
• Bending or pulling the cable stops SELECT working.
• The selection marker moves on its own.
• The game pauses mid-play with no button pressed.
• The game misbehaves in a way that depends on the cartridge.

Most controller faults are controller 1. Nintendo's instruction is to swap controller 2 only when a controller-2 button is the thing that has stopped working. Controller 2 carries the electret microphone and has no SELECT or START.

Cleaning

Case and controllers

• Wipe the shell with a damp microfibre cloth and a little mild detergent.
• Retrobrite only if you can control temperature and UV exposure; it is not reversible and it does not stop.
• Controllers open with a Phillips No. 0–1 driver. Wash the rubber contact pads and keytops in warm soapy water, dry them completely, and do not use solvents on the conductive pill.
• A sticky D-pad pivot takes a plastic-safe silicone grease, sparingly.

Inside

• Unplug the adapter first. There is nothing inside a Famicom that stores a dangerous charge — the transformer is in the adapter.
• Shell screws take a Phillips No. 2.
• Dust comes out with a soft brush and low-pressure air.
• Clean the 60-pin card connector and the controller connectors with 99 % isopropyl alcohol on a lint-free swab. Do not use an abrasive — the contacts are plated, and once you have been through the plating the corrosion comes back permanently.
• Green or white corrosion on the board lifts with isopropyl alcohol and a fibreglass pen, used lightly and followed by a clean and a careful look at the surrounding traces.

Cartridges

• Do not blow into a cartridge or into the slot. Nintendo's own consumer maintenance sheet instructs "DO NOT touch or blow on the metal game pak edge connector"; it was written for the NES game pak, and the physics is the same for the Famicom's 60-pin cassette. The moisture in your breath is what starts the corrosion.
• Clean cartridge edge contacts with isopropyl alcohol on a lint-free swab or a cotton bud, and let them dry before insertion.
• Bent connector pins realign with a dental pick, gently, with the board out and good light.

Things that are not faults

Nintendo prints a "before you decide it is a fault" table in the manual. The entries worth repeating:

• A striped or patterned screen during play. Check that the console's channel is set to one with no broadcast on it. If switching the console off leaves the television with no picture and no sound on that channel, the console is behaving correctly.
• Snow or interference on the television with the console off. The RF switch passes the aerial straight through when the console is off. That is the switch working.
• Weak or absent colour, or the picture rolling. Nintendo's first suggestion is the television's fine tuning and its own colour and hold adjustments, not the console.
• Broadcast television stopped working after the console was fitted. Check the TV/GAME switch on the back of the console, and check that the RF switch is not connected on the wrong side of an aerial splitter.

Storage and handling

• Keep it dry and cool. Damp is what corrodes the connector, and the connector is the machine's weak point.
• Do not force a cartridge, and do not insert or remove one with the power on.
• Support the AC adapter cable so it is not pulled sideways at the console — see the DC jack note above.

Periodic checks

There is no evidence for any fixed recapping or re-greasing interval on this machine, and this page does not invent one. What is worth doing when you have the console open anyway:

1. Measure the adapter off-load and confirm it falls in Nintendo's 12.0–15.0 V window.
2. Measure the 5 V rail with the console running. It should sit at 5 V.
3. Look at the electrolytics for bulging, splitting or crust at the base.
4. Look at the DC jack, the RF module pins and the controller connectors for fractured joints.
5. Test both controllers against the symptom list above.

Related pages

• Nintendo Entertainment System
• Nintendo Famicom Capacitor Replacement Guide
• Nintendo Famicom Troubleshooting Guide
• Nintendo Famicom Service Manual
• Recommended Tools
• Capacitor Failure Symptoms