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Super Nintendo Entertainment System Power Circuit Repair

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SNS-CPU-APU-01 power input section (Evan-Amos)
The power input of a North American SNS-CPU-APU-01: line filter T1, fuse F1, power-switch connector P3, the 7805 (U12, heatsink removed), surge absorber VA1 and C14. D1, D2 and C58 are marked (SHVC) and left empty on this board.

A Super Nintendo Entertainment System that shows no power light and no picture has lost its supply somewhere between the adapter and the 5 V regulator. The console takes an unregulated low-voltage supply from its adapter and passes it through a line filter, a fuse, a reverse-protection diode and the power switch to a 7805 regulator, which makes the 5 V logic supply, Vcc. A transistor stage beside the regulator makes the unregulated Vs rail for the audio amplifier.[1][2] Nintendo's diagnostic table lists the causes of a dead console, most likely first, as F1 (the 1.5 A fuse), D1, T1 (the line filter), U12 (the 7805), VA1 (the surge absorber), Q18 and P3 (the power switch).[3]

Follow that path with a meter, one stage at a time. The figures below are for the NTSC boards; PAL consoles take AC and rectify it on the board (see Board differences). Replacing the regulator itself is covered in Super Nintendo Entertainment System Voltage Regulator Replacement.

Symptoms

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Safety

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The console itself carries no more than the adapter's low voltage. The adapter is a mains transformer: test it only at its output plug. Before opening the console, switch it on with the adapter disconnected to discharge the input reservoir C67, as Nintendo's manual directs.[6] Nintendo's handling notes warn against testing ICs with a meter on its resistance ranges, because the test voltage can damage them; the checks below are voltage measurements on supply points.[7]

Tools and parts

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Tools and parts
Item Detail
Multimeter DC volts and continuity
Soldering iron and hand desoldering pump Nintendo graded the power switch, the 7805, the fuse and the RF modulator as rank B repairs, needing a screwdriver, a soldering iron and a hand-operated desoldering pump[8]
Fuse F1 1.5 A axial. Nintendo lists it as "1.5A SSTR";[8][9] the fuse on the SNS-CPU-APU-01 in Evan-Amos's photograph is marked SOC 1.5A[10]
Regulator 7805; see Super Nintendo Entertainment System Voltage Regulator Replacement
Disassembly The six case screws and the board screws; see the cartridge connector guide for the opening steps

The circuit

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SNES power input and regulator circuit (Donaldson redraw)
The power section of the NTSC GPM and RGB boards in Jonathon W. Donaldson's redraw. The supply enters at the DC jack J1 on the right and runs left through T1, F1, D1 and the power switch P3 to the 7805 (U12). Q18 at the far left feeds the Vs rail. C67, in brackets, is not fitted on every board.
Super Famicom power circuit (Nintendo service manual)
Nintendo's own power diagram for the Super Famicom: 13-14 V from the input to the regulator, 5 V after it, the LED on the 5 V side and a transistor (TR) feeding VS

Reading the redraw from the jack inwards:[2]

Supply path on the NTSC GPM and RGB boards
Stage Part Notes
1 DC jack J1 "+10V (Nominal) for NTSC"
2 T1, C30, C31 Line filter; the redraw marks T1 ZJVS5102-2P, Nintendo's parts list "ZJYS5012.2PT",[9] and the part on Evan-Amos's boards reads TDK ZJYS-2[11]
3 F1 1.5 A fuse
4 D1 Reverse-protection diode; PB1100 on the redraw, "SK.RB110C" in Nintendo's parts list[9]
5 C67 1000 µF 25 V reservoir, drawn in brackets
6 P3 Power switch, on a two-pin lead
7 VA1, C33, C63 Surge absorber (ERZC050K220 on the redraw, "ERZ.CF2MK220" in Nintendo's list) and filter capacitors[9]
8 U12 7805: pin 1 in, pin 2 ground, pin 3 out, with C34 on the input and C81 (1 µF) on the output
9 Q18, R76, C64 Transistor stage taking the unregulated rail to Vs

Procedure

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Check the adapter

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  1. Read the adapter's rating plate. The North American SNS-002 gives "Output DC10V 850mA" and is centre negative, and the console's own label says to use it with adapter SNS-002 only.[12][13] A PAL console needs an AC transformer such as the NES-002.[14]
  2. Measure the adapter at its plug with no load. It is unregulated, so it reads above its rating: Nintendo gives 13.5 ± 1.5 V off load as normal for its 10 V Famicom adapter, which is the same kind of unregulated supply.[1][15]
  3. If the adapter reads nothing, or the console works with a known-good adapter, the fault is in the adapter or its lead, not the console.

Follow the supply through the board

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Open the console as far as the main board (see the cartridge connector guide, steps 1 to 8), refit the adapter and switch on. Measure each point to ground, using the regulator's middle pin, which is ground.[2]

Test points, in order from the jack
Step Measure Expected If it is missing
1 Both ends of F1 Adapter voltage at both ends Voltage at one end only: the fuse is open. Find the cause before fitting a new one (see below)
2 Both sides of D1 A diode drop lower on the switch side Check D1. On boards where the D1 position is empty, skip this step
3 Both pins of P3, switch on The same voltage on both pins The switch or its lead is open
4 7805 input (pin 1, I) 13-14 V in Nintendo's Super Famicom diagram[4] Check VA1, C63 and the track between P3 and U12
5 7805 output (pin 3, O) 5 V[4][1] Input present but no output: replace the regulator
6 Vs, at the emitter of Q18 About 7 V per Nintendo; the redraw's sheet note gives 9 V[1][2] Console works but is silent: check Q18, R76 and C64

Sources: the redraw for the order of parts;[2] Nintendo for the voltages.

The regulator's joints are marked I, G and O beside the part on the SNS-CPU-1CHIP-02, and on the underside of the SNS-CPU-APU-01.[11][10]

SNS-CPU-APU-01 underside regulator joints and R28 (Evan-Amos)
Underside of an SNS-CPU-APU-01: the regulator's joints marked I, G and O, C61 beside them, the chip link R28 marked [SNS/SNSM], and the fuse body marked SOC 1.5A past the board edge

Fuse F1

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Adam Wilson describes the fuse as a 1.5 A single-use picofuse that is often found open circuit.[16] A fuse opens because something drew too much current. Nintendo's diagnostic table tells the technician to inspect the whole board for damaged or missing parts before any repair, and its list for a dead console continues after F1 with D1, T1, U12, VA1, Q18 and P3.[3]

  1. With the adapter disconnected, inspect D1, T1, the regulator, VA1 and Q18 for burns, cracks or bulging.[3]
  2. Desolder the old fuse.
  3. Fit a 1.5 A axial fuse in its place.[8][9]
  4. Repeat the test-point checks above. If the new fuse opens as soon as the console is switched on, work down the rest of Nintendo's list before fitting another.[3]

Wilson fitted a 1.6 A 60 V self-resetting polyfuse instead; that is a modification, not Nintendo's part.[16]

Power switch P3

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  1. Remove the two screws holding the switch and unplug its lead from the two-pin connector on the board.[6]
  2. With the switch on, check for continuity between the two contacts of the lead's connector. Open circuit means a worn switch or a broken wire; Nintendo lists P3 among the causes of a dead console.[3]
  3. On a Super Famicom, the switch is polarised to extend the life of its contacts. If the harness is resoldered or a new switch fitted, solder the red wire to the terminal marked + and the black wire to the terminal marked −.[17] On the SNS-CPU-APU-01, the board connector P3 is marked 赤 (red) at pin 1 and 黒 (black) at pin 2.[11]
Super Famicom power switch harness polarity (Nintendo service manual)
Nintendo's instruction for the Super Famicom power switch: red wire (赤線) to +, black wire (黒線) to −

Regulator, surge absorber and Vs

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  • No 5 V with 13-14 V at the input: replace the 7805. See Super Nintendo Entertainment System Voltage Regulator Replacement.[4]
  • VA1, the surge absorber across the switched supply, follows the regulator in Nintendo's list for a dead console.[3][2]
  • Picture but no sound, with 5 V present: Nintendo's sound list ends with Q18, and fullsnes notes that the console runs without the amplifier supply but makes no sound.[3][5] Measure Vs as in step 6.

Testing

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  1. Switch on with a known-good cartridge. The power light comes on.[4]
  2. Measure 5 V at the regulator output and Vs at Q18.[4][1]
  3. Run Nintendo's console test: Super Mario World, both controllers, colour, picture and sound, and the RF and A/V outputs.[18]

Board differences

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Power input by board
Board Difference
SHVC-CPU-01 C67 fitted; Nintendo's first disassembly step discharges it[6]
GPM (Playtronic's description) C67 removed[19]
SNS-CPU-APU-01, SNS-CPU-1CHIP-02 (North American) D1 and C58 positions marked (SHVC) and empty on Evan-Amos's boards; D2 also empty on the APU-01; a chip link R28 marked [SNS/SNSM] fitted on the APU-01 underside.[11][10] With no diode at D1, a centre-positive adapter is not blocked
Cost-down boards 7805 at U9[5]
SNSP-CPU (PAL) 9 V AC input, rectified by bridge DB1, fitted only to the AC version[5]
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References

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  1. ↑ 1.0 1.1 1.2 1.3 1.4 Nintendo / Playtronic, Manual Técnico do Super NES, Rev. 01/94, p. 1-1 (the AC adapter converts 120 V AC to an unregulated 10 V DC) and p. 2-1 (power section: noise filter, reverse-current protection, power switch, spike suppressor, ripple filter and voltage regulator; outputs Vcc, 5 V regulated, and Vs, 7 V unregulated, used by the sound amplifier), hosted as File:Manual Tecnico do Super NES Rev 01-94.pdf.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Jonathon W. Donaldson, Super Nintendo (NTSC) Revision 2 Motherboard, community redraw, rev. 1.5, 24 February 2014, hosted at SNES Schematic as File:Snes schematic.pdf. Covers SNS-CPU-GPM-01/02 and SNS-CPU-RGB-01/02. Power section: DC jack J1 "+10V (Nominal) for NTSC", line filter T1 ZJVS5102-2P with C30 and C31 (0.01 µF 50 V), F1 1.5 A, D1 PB1100, C67 1000 µF 25 V drawn in brackets, C32 0.1 µF 50 V, power switch P3, C33 0.1 µF 50 V, VA1 ERZC050K220, C63 33 µF 25 V, U12 7805 (pin 1 IN, pin 2 GND, pin 3 OUT) with C34 0.1 µF and C81 1 µF, and Q18 2SC2412 with R76 1.8 kΩ and C64 33 µF 25 V feeding VS. Sheet note: VCC 5 V, VS 9 V. Not a Nintendo document.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Nintendo / Playtronic, Manual Técnico do Super NES, Rev. 01/94, p. 2-29 (console diagnostic table, "no power": F1 1.5 A fuse, D1, T1 line filter, U12 7805 regulator, VA1 spike absorber, Q18, P3 power switch, in order of priority; "distorted or no sound": sound module, P5, U1, U10, Q18), hosted as File:Manual Tecnico do Super NES Rev 01-94.pdf.
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 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), 1992, p. 12, "電源回路" (power circuit): input, line filter, fuse, series diode, capacitor, power switch, 7805 regulator with "IN 13~14V" and "OUT 5V", power LED on VCC, and a transistor feeding VS; the span from the input to the regulator is marked 13-14 V and the regulator output 5 V. Hosted at Nintendo Famicom Service Manual.
  5. ↑ 5.0 5.1 5.2 5.3 Martin Korth, fullsnes (retrieved 2026-10-25). "SNES Controllers Pinouts": the joypad connectors and power LED are on a daughterboard joined to the main board by an 11-pin connector. "SNES Power Supply": PAL 9 V AC converted to DC inside the console; NTSC 10 V DC 850 mA through a diode, so the internal supply may drop to around 9 V; the CPU, PPU and APU run only from 5 V; the audio amplifier runs from the unregulated supply, and the console works without it but makes no sound. "SNES Chipset": SNSP-CPU-01 with F1 "SOC, 1.5A" fuse, T1 "TDK, ZJYS-2", DB1 AC-DC bridge on the PAL/AC version only, U12 7805; cost-down boards with the 7805 at U9. Community reference.
  6. ↑ 6.0 6.1 6.2 Nintendo / Playtronic, Manual Técnico do Super NES, Rev. 01/94, p. 2-14 (general disassembly instructions: discharge C67 with the adapter disconnected; six security screws; power switch held by two screws with its lead on a two-pin connector), hosted as File:Manual Tecnico do Super NES Rev 01-94.pdf.
  7. ↑ Nintendo / Playtronic, Manual Técnico do Super NES, Rev. 01/94, pp. 8-1 and 8-2 (handling ICs; do not test ICs with a multimeter or signal tracer, because the voltage the instrument applies can damage them; switch off before fitting or removing ICs), hosted as File:Manual Tecnico do Super NES Rev 01-94.pdf.
  8. ↑ 8.0 8.1 8.2 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, 1992, p. 15 (Super Famicom repair price list: item 5, three-terminal regulator 7805; item 7, fuse 1.5 A (SSTR); item 25, power switch) and p. 21 (repairs by rank: rank B for the Super Famicom covers the power switch, the three-terminal regulator, the RF modulator, the fuse and the reset switch, with a screwdriver, soldering iron and hand desoldering pump), hosted at Nintendo Famicom Service Manual.
  9. ↑ 9.0 9.1 9.2 9.3 9.4 Nintendo / Playtronic, Manual Técnico do Super NES, Rev. 01/94, p. 2-6 (SHVC-CPU-01 parts list: fuse "1,5A SSTR axial", 7805, heatsink, insulating washer, screws 3×10 and 3×7, "Jack Power", line filter "ZJYS5012.2PT", diode "SK.RB110C", varistor "ERZ.CF2MK220", transistor 2SC2412), hosted as File:Manual Tecnico do Super NES Rev 01-94.pdf.
  10. ↑ 10.0 10.1 10.2 Evan-Amos, "Nintendo-Super-NES-Mk1-Motherboard-Bottom.jpg", Wikimedia Commons, public domain. Underside of an SNS-CPU-APU-01: the fuse marked SOC 1.5A; the regulator joints marked I, G and O with C61 beside them; R28 marked [SNS/SNSM]; power-switch pads 1 and 2.
  11. ↑ 11.0 11.1 11.2 11.3 Evan-Amos, "Nintendo-Super-NES-Mk1-Motherboard-Top.jpg" (SNS-CPU-APU-01) and "Super-Nintendo-1Chip-Motherboard-Top-Flat.jpg" (SNS-CPU-1CHIP-02), Wikimedia Commons, public domain. Top side: T1 marked TDK ZJYS-2; axial fuse F1; P3 with pin 1 marked 赤 (red) and pin 2 marked 黒 (black) on the APU-01; D1, D2 and C58 marked (SHVC) and empty; regulator beside the silkscreen I, G and O on the 1CHIP-02; VA1; C14 33 µF 25 V.
  12. ↑ Evan-Amos, "Nintendo-Super-NES-Power-Supply.jpg", Wikimedia Commons, public domain. SNS-002 rating plate: "Input AC120V 60Hz 17W, Output DC10V 850mA", "for use with Super NES and Virtual Boy only", centre-negative polarity symbol.
  13. ↑ Nintendo of America, Authorized Service Center Manual, revision June 2002, chapter 6 (Super NES), p. 38: photograph of the SNS-001 base label, "Rating: DC10V 850mA", "Use with AC adapter No. SNS-002 only". Hosted as File:Nintendo Authorized Service Center Manual June 2002.pdf.
  14. ↑ Nintendo of Europe, Super Nintendo Entertainment System Bedienungsanleitung, PAL version, form HW(G)-SNSP-NOE, p. 9, hosted as File:Super Nintendo Entertainment System Bedienungsanleitung HW(G)-SNSP-NOE.pdf: run the console only from a toy safety transformer such as the Nintendo NES-002.
  15. ↑ 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, 1992, p. 2 (the Famicom AC adapter is marked DC 10 V and reads DC 13.5 ± 1.5 V with no load) and p. 6 (the same figure among the HVC voltage checks), hosted at Nintendo Famicom Service Manual.
  16. ↑ 16.0 16.1 Adam Wilson, "1993 Super Nintendo Entertainment System (SNES) Restoration & Modifications", Adam's Vintage Computer Restorations, 9 December 2024 (retrieved 2026-10-25). PAL SNSP-CPU-02: the on-board 1.5 A picofuse is single-use and can often be found open circuit, and in that restoration was replaced with a 1.6 A 60 V self-resetting polyfuse; 7805 heatsink held by one Phillips screw on the regulator and three around its edge; 7805 replaced with a TSR-1-2450.
  17. ↑ 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, 1992, p. 11, section 1 (soldering the power-switch harness: the SHVC power switch has polarity to improve contact durability; solder the red harness wire to the side of the switch marked + and the black wire to the side marked −), hosted at Nintendo Famicom Service Manual.
  18. ↑ Nintendo / Playtronic, Manual Técnico do Super NES, Rev. 01/94, p. 2-23 (console test procedure), hosted as File:Manual Tecnico do Super NES Rev 01-94.pdf.
  19. ↑ Nintendo / Playtronic, Manual Técnico do Super NES, Rev. 01/94, p. 3-1 (GPM board: C67 and the 4 MHz oscillator removed), hosted as File:Manual Tecnico do Super NES Rev 01-94.pdf.
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