Editing Nintendo Famicom Service Manual (section)

== What it settles ==

'''Handling precautions (p1).''' Nintendo's rules for working on these boards, several of which are still repeated wrongly online: earth yourself through a resistance of several&nbsp;M&#937; rather than directly; wear cotton rather than synthetics; use a non-leaking soldering iron; store LSIs at &minus;20&nbsp;to&nbsp;+70&nbsp;°C and ICs at &minus;40&nbsp;to&nbsp;+125&nbsp;°C; and — the one most often ignored — '''do not use a multimeter's high-resistance range for continuity checks''', because it applies 4.5&nbsp;to&nbsp;22.5&nbsp;V and can destroy the device.

'''HVC section (pp. 2&ndash;10).''' A whole-system diagram that names each block — aerial, 75/300&nbsp;&#937; transformer, RF switch, AC adapter, RF modulator, power section, 60-pin card connector, CPU board, both controllers — and prints, against each, the symptoms that block produces when it fails. It states the Famicom AC adapter as '''DC 10&nbsp;V''', with '''DC 13.5&nbsp;±&nbsp;1.5&nbsp;V off load''' as the normal reading. It also warns that a dirty cartridge edge produces the same symptoms as a faulty card connector, so a known-good cartridge should be tried first. Exploded views follow for the console and for '''both controller variants''' — the square-button and round-button types — with numbered parts and the tools needed (Phillips No.&nbsp;2 driver, long-nose pliers, tweezers, a non-leaking or IC-rated iron of about 30&nbsp;W, and a solder sucker).

'''SHVC section (pp. 11&ndash;15).''' Repair method and part names: soldering the power-switch harness the right way round (the switch is polarised for contact life — red to the + mark, black to the &minus; mark), fitting the front unit and its ferrite core, routing the FFC harness through the ferrite core and which face of the connector is the contact face, and assembling the cassette cover spring. The section ends with a '''power circuit diagram''': '''13&ndash;14&nbsp;V in, 5&nbsp;V out''' of the regulator.

'''DMG section (pp. 16&ndash;20).''' Assembly cautions for the joiner wires (4C-49L, 4C-64L, 21C-63L) and lead 42L-Y, with the warning that if the 21C-63L joiner is not folded as drawn the insulating sheet shifts and component legs can pierce it and short; small jack board repair notes, including that a reversed electrolytic '''still passes the functional test''', so polarity must be checked by eye; and cautions for replacing the DC-DC converter. The section ends with the '''DMG power circuit''', which gives the converter's outputs as '''+4.5&nbsp;to&nbsp;+5.5&nbsp;V''' and '''&minus;15&nbsp;to&nbsp;&minus;21&nbsp;V''' — the second being the LCD bias, and the reason a Game Boy with a dead converter shows no display at all.