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Super Nintendo Entertainment System Voltage Regulator Replacement

From RetroTechCollection
SNS-CPU-1CHIP-02 power section (Evan-Amos)
Power section of an SNS-CPU-1CHIP-02 with the heatsink removed. The regulator sits beside the silkscreen I, G and O (input, ground, output); F1 and the power-switch connector P3 are at the left edge.

The Super Nintendo Entertainment System makes its 5 V logic supply with a single 7805 linear regulator: U12 on the three-chip boards and U9 on the later single-chip boards.[1][2] It is replaced for one of two reasons. It can fail: Nintendo's diagnostic table lists U12 among the causes of a dead console, and Nintendo Japan priced the 7805 as a separate repair.[3][4] And on single-chip and New-Style consoles a pale vertical line down the middle of the picture is reduced or removed by fitting a higher-current regulator and a larger capacitor on its output.[5][6]

For a console with no power at all, find the fault first with the power circuit guide: replace the regulator only when its input is present and its output is not.

Symptoms

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When the regulator is the suspect
Symptom Check
Dead console, no power light 13-14 V at the regulator input and no 5 V at its output, on Nintendo's Super Famicom figures[4]
Pale vertical line down the centre of the picture, most visible at power-on and in dark scenes A single-chip or New-Style board[5][6]

The vertical line does not mean the regulator has failed; the console otherwise works normally. RetroRGB found that newer revisions of the SD2SNES cartridge reduce the line considerably, and that an RGB bypass board removes it from the RGB output but not from composite video.[5] RetroRGB's restoration article says the line is a single-chip and New-Style problem and that earlier models do not have it; the photograph of the capacitor fix on its vertical-line page, however, is of an SNS-CPU-RGB-01 board.[6][7]

Safety

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Discharge the input reservoir before work: Nintendo's procedure is to switch the console on with the adapter disconnected.[8] The 7805 runs hot, which is why it has a large heatsink; let it cool before handling.[9]

Tools and parts

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Parts
Part Detail
Regulator 7805, Nintendo's part.[4] For the vertical line RetroRGB fits the higher-current ST L78S05CV-DG[5]
Output capacitor 22 µF surface-mount ceramic in place of the original 1 µF; RetroRGB names Murata GRM21BR61C226ME44L[5]
Heatsink fittings Nintendo's SHVC-CPU-01 parts list includes, beside the 7805, a heatsink (dissipador) and an insulating washer (arruela isolante)[10]
Thermal paste Optional; RetroRGB cleaned the heatsink and added paste when refitting[6]
Tools Phillips screwdriver; soldering iron and hand desoldering pump, as Nintendo specified for this repair;[4] hot air or a fine iron for the surface-mount capacitor; multimeter

Adam Wilson replaced the 7805 in a PAL console with a TSR-1-2450 switch-mode module, which he describes as pin compatible and much cooler.[9] RetroRGB warns that some newer regulators that need no heatsink may add vertical interference to the video lines, and recommends the 78S05.[6]

Procedure

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Removing the heatsink and regulator

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  1. Open the console and lift the main board out of the lower case. The steps are on the cartridge connector guide; on a PAL SNSP-CPU-02 Adam Wilson found the board held by five Phillips screws.[9]
  2. Remove the screw that holds the regulator to the heatsink and the three screws round the heatsink's edge that hold it to the board, then lift the heatsink off.[9]
  3. Keep the insulating washer if one comes away; it is part of Nintendo's regulator fittings.[10]
  4. Identify the regulator's pins. The board is marked I, G and O beside the regulator on the SNS-CPU-1CHIP-02 and under it on the SNS-CPU-APU-01: input, ground and output, which are pins 1, 2 and 3 of the 7805 in the redraw.[11][1]
  5. Desolder the three pins and remove the regulator.[9]
SNS-CPU-APU-01 underside regulator joints and R28 (Evan-Amos)
Underside of an SNS-CPU-APU-01. The regulator's joints are marked I, G and O; the small surface-mount capacitor C61 sits beside the O and G joints.

Fitting the new regulator

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  1. Fit the new regulator with its pins in the same holes as the old one: input, ground and output to I, G and O.[11][1]
  2. Solder the pins and trim the leads.[9]
  3. Clean the heatsink's contact face with isopropyl alcohol and apply thermal paste if you are using it.[6]
  4. Refit the insulating washer, the heatsink, its three edge screws and the screw through the regulator.[10][9]

Changing the output capacitor (vertical line)

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SNES power input and regulator circuit (Donaldson redraw)
The power section of the GPM and RGB boards in the redraw. C81, 1 µF, is the capacitor across the 7805's output.
  1. Find the 1 µF surface-mount capacitor on the regulator's output. RetroRGB's was C61 on an SNS-CPU-1CHIP-02;[6] on the SNS-CPU-APU-01 in Evan-Amos's photograph, C61 is the part beside the regulator's O and G joints on the underside;[11] on the GPM and RGB boards the redraw draws it as C81.[1]
  2. Confirm it with a meter; RetroRGB identifies the part this way.[6] With the board unpowered, check continuity: one end of the capacitor connects to the regulator's O pin and the other to G, as the redraw draws C81 between the output and ground.[1]
  3. Remove the capacitor and solder the 22 µF part in its place.[5]

Capacitor-only alternative

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RetroRGB also describes reducing the line without changing the regulator, credited to Paul T and others:[5]

  • A 16 V 470 µF electrolytic added to the regulator, with its negative (striped) lead on the centre pin, and 1000 µF tried if 470 µF is not enough. RetroRGB's text does not say which outer pin takes the positive lead; the photograph below shows the part fitted.
  • If the line remains, two 16 V 220 µF capacitors on the S-RGB video encoder: both negative leads to ground, pin 13, and the positive leads to the 5 V pins, 6 and 19.
SNES vertical line capacitor fix on SNS-CPU-RGB-01 (Paul T, RetroRGB)
Paul T's capacitor fix on an SNS-CPU-RGB-01, published by RetroRGB: two 220 µF capacitors on the S-RGB (left) and a capacitor across the regulator U12 (right)

Testing

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  1. Before refitting the board, power it and measure the regulator: 13-14 V at I and 5 V at O, on Nintendo's figures.[4]
  2. Run a game with a dark screen, such as the start of Super Metroid, and look for the vertical line.[5]
  3. Reassemble and run Nintendo's console test.[12]

Board differences

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Regulator position by board
Board Regulator Output capacitor
SNS-CPU-GPM-01/02, SNS-CPU-RGB-01/02 U12[1] C81, 1 µF[1]
SNS-CPU-APU-01 Marked I, G, O on the underside[11] C61, beside the O and G joints[11]
SNS-CPU-1CHIP-02 Marked I, G, O beside the part[11] C61 on RetroRGB's board[6]
Cost-down boards U9[2] Identify with a meter[6]
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References

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  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 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. U12 7805: pin 1 IN, pin 2 GND, pin 3 OUT; C34 0.1 µF on the input; C81 1 µF on the output to VCC; C63 33 µF 25 V on the input rail. Not a Nintendo document.
  2. ↑ 2.0 2.1 Martin Korth, fullsnes (retrieved 2026-10-25), section "SNES Chipset": the SNSP-CPU-01 has its 7805 at U12; the cost-down boards have the 7805 (marked 17805) at U9. Community reference.
  3. ↑ Nintendo / Playtronic, Manual Técnico do Super NES, Rev. 01/94, p. 2-29 (console diagnostic table, "no power": F1, D1, T1, U12 (7805 regulator), VA1, Q18, P3), hosted as File:Manual Tecnico do Super NES Rev 01-94.pdf.
  4. ↑ 4.0 4.1 4.2 4.3 4.4 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, hosted at Nintendo Famicom Service Manual. P. 12, Super Famicom power circuit: 13-14 V into the 7805 and 5 V out. P. 15, repair price list, item 5: three-terminal regulator 7805. P. 21: the three-terminal regulator is a rank B repair (screwdriver, soldering iron and hand desoldering pump).
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 Bob, "SNES Vertical Line", RetroRGB (retrieved 2026-10-25). A vertical line down the centre of the screen, most noticeable at power-on and in dark games such as Super Metroid; believed to be caused by the power drop during DRAM refresh, an inefficient power filter. Fixes: replace the 7805 with the higher-current ST L78S05CV-DG; replace the 1 µF surface-mount capacitor on the regulator's output with 22 µF (Murata GRM21BR61C226ME44L); in RetroRGB's testing the regulator made the biggest difference. Alternative capacitor fix with Paul T's photograph: add a 16 V 470 µF capacitor to the regulator with its negative lead to the centre pin, trying 1000 µF if needed; then two 16 V 220 µF capacitors on the S-RGB with their negative leads on ground pin 13 and their positive leads on the 5 V pins 6 and 19. ArcadeTV's variant replaces the 2200 µF capacitor and adds three 220 µF capacitors. Newer SD2SNES revisions significantly reduce the line; an RGB bypass removes it from RGB but not composite.
  6. ↑ 6.00 6.01 6.02 6.03 6.04 6.05 6.06 6.07 6.08 6.09 Bob, "Restoring A Super Nintendo", RetroRGB, 31 May 2020 (retrieved 2026-10-25). The white line plagues 1CHIP and Mini (New-Style) consoles and earlier models do not have it; the 78S05 replaces the 7805; the 1 µF surface-mount output capacitor, C61 on the 1CHIP-02 worked on, is replaced with 22 µF, and a multimeter identifies the right capacitor on any revision; the heatsink was cleaned and given thermal paste; avoid newer regulators that need no heatsink, which may add vertical interference to the video.
  7. ↑ Paul T, photograph published by RetroRGB on "SNES Vertical Line", hosted here as File:SNES vertical line capacitor fix on SNS-CPU-RGB-01 (Paul T, RetroRGB).jpg. The board silkscreen reads SNS-CPU-RGB-01; capacitors added to the S-RGB and across the regulator U12.
  8. ↑ Nintendo / Playtronic, Manual Técnico do Super NES, Rev. 01/94, p. 2-14 (discharge C67 with the adapter disconnected before disassembly), hosted as File:Manual Tecnico do Super NES Rev 01-94.pdf.
  9. ↑ 9.0 9.1 9.2 9.3 9.4 9.5 9.6 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: main board held by five Phillips screws; the 7805 heatsink held by one Phillips screw on the regulator itself and three around the heatsink's edge into the main board; the 7805 is inefficient and produces a lot of heat, hence the large heatsink; replaced in that restoration with a TSR-1-2450 switch-mode regulator, a pin-compatible part fitted by desoldering the original and soldering in the new one.
  10. ↑ 10.0 10.1 10.2 Nintendo / Playtronic, Manual Técnico do Super NES, Rev. 01/94, p. 2-6 (SHVC-CPU-01 parts list: 7805, "Dissipador", "Arruela Isolante", screws 3×10 and 3×7) and p. 3-4 (GPM parts list: the same 7805, heatsink and insulating washer), hosted as File:Manual Tecnico do Super NES Rev 01-94.pdf.
  11. ↑ 11.0 11.1 11.2 11.3 11.4 11.5 Evan-Amos, "Super-Nintendo-1Chip-Motherboard-Top-Flat.jpg" (SNS-CPU-1CHIP-02, top) and "Nintendo-Super-NES-Mk1-Motherboard-Bottom.jpg" (SNS-CPU-APU-01, underside), Wikimedia Commons, public domain. Silkscreen I, G and O beside the regulator; on the APU-01 underside, C61 beside the regulator's O and G joints.
  12. ↑ 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.
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