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Super Nintendo Entertainment System Video Output Repair

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SNS-CPU-APU-01 video encoder, audio mixer and Multi Out (Evan-Amos)
The Multi Out connector P4 of an SNS-CPU-APU-01, with the video encoder U7 (S-RGB A) at the lower right and the audio mixer U10 (S-MIX A) at the lower left

The Super Nintendo Entertainment System makes its picture in the second picture processor, PPU2, which produces red, green and blue signals. A video encoder turns them into composite video and S-Video, and transistor buffers drive each output on the 12-pin Multi Out and the RF modulator.[1] When the picture is wrong on one output and right on another, or is in black and white, the fault is usually after PPU2. Nintendo's service manual gives a procedure for narrowing it down by comparing the outputs.[2] The steps below follow that procedure and trace each output through the circuit in Jonathon W. Donaldson's redraw of the NTSC GPM and RGB boards.[3]

Symptoms

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Picture faults after PPU2, from Nintendo's procedure
Symptom Nintendo's suspects, in order
Black-and-white picture Master clock (TC1, then X1); then, if RF only, the RF modulator; if composite too, U7 then PPU2
Wrong colours on RGB, S-Video and composite PPU2, or a missing red, green or blue signal: check round Q3 to Q9, then replace PPU2
Only RGB correct The encoder U7 or the colour filters C14 and C16

Source: Nintendo's colour-fault procedure.[2]

Faults in the picture itself, such as vertical lines, corrupted characters or a mosaic screen, are PPU, CPU or video RAM faults; Nintendo's replacement orders for them are on the Super Nintendo Troubleshooting Guide.[4] A pale vertical line down the centre on single-chip and New-Style consoles is a power-filtering effect; see Super Nintendo Entertainment System Voltage Regulator Replacement.

Before opening the console, rule out the leads. Nintendo's console test switches between RF and A/V and moves each plug while watching the picture, to catch a bad connection.[5]

Safety

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The board runs from the adapter's low voltage. Discharge C67 before opening by switching on with the adapter disconnected.[6] Do not measure the ICs on a resistance range; Nintendo warns that the meter's test voltage can damage them.[7]

Tools and parts

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  • An oscilloscope, to see the video signal at each stage, and a frequency counter for the master clock.[2]
  • A 75 Ω load for the output being tested. fullsnes gives the Multi Out levels as 1 V peak to peak into 75 Ω for composite, S-Video and sync, and 1 V peak to peak on a 1 V DC offset for red, green and blue.[8]
  • Replacement transistors as the fault shows: 2SA1037 for the RGB buffers and 2SC2412 for the composite and S-Video buffers. Nintendo's SHVC-CPU-01 parts list has six 2SA1037 and ten 2SC2412.[3][9]

The circuit

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SNES video encoder and output buffers (Donaldson redraw)
Video output section of the GPM and RGB boards in the redraw. Red, green and blue from PPU2 enter at the left through the 2SA1037 pairs; the encoder U7 sits in the middle; the composite (VO'), luminance (YO') and chroma (CO') buffers are at the right.
Output paths on the NTSC GPM and RGB boards
Output Multi Out pin Path in the redraw
Red 1 PPU2 red, Q3 and Q4 (2SA1037), R'
Green 2 PPU2 green, Q5 and Q6, G'
Blue 4 PPU2 blue, Q7 and Q8, B'
Composite 9 U7 VO (pin 7), Q10 (2SC2412), C57 220 µF, R33 56 Ω, VO'; also the RF modulator's video feed
S-Video Y 7 U7 YO (pin 23), Q11, C59 220 µF, R42 39 Ω, YO'
S-Video C 8 U7 CO (pin 6), Q12, C20 0.047 µF, R46 100 Ω, CO'

Sources: the redraw for the parts and pins;[3] fullsnes agrees on the Multi Out pin numbers.[8]

SNES Multi Out connector P4 (Donaldson redraw)
The Multi Out connector P4 in the redraw

Procedure

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Open the console and expose the main board as on the cartridge connector guide, then refit the power switch lead and the controller board so the console can run.

Black-and-white picture

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  1. Measure the master clock with a frequency counter. fullsnes gives cartridge-slot pin 1 as the master clock line. NTSC consoles run at 21.47727 MHz; PAL consoles at 21.28137 MHz, made by the S-CLK from a 17.734475 MHz crystal; Brazilian PAL-M consoles at 21.453666 MHz.[8][2]
  2. Adjust TC1 to bring the frequency to the figure for the console's standard. Nintendo's figure, 21.453666 MHz, is the PAL-M one.[2]
  3. If TC1 will not bring it to frequency, or the setting drifts, replace TC1, then the crystal X1.[2]
  4. With the clock right, compare the RF picture with the composite picture. If only RF is in black and white, replace the RF modulator.[2]
  5. If composite is also in black and white, inspect the parts around the encoder U7 for poor solder joints and damage, then replace U7, then PPU2 (U3).[2]

Wrong colours on every output

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  1. Look at the red, green and blue outputs (Multi Out pins 1, 2 and 4) in turn on the scope. A missing or weak channel shows which colour is lost.[2][8]
  2. Follow the missing colour back through its transistor pair (Q3 and Q4 red, Q5 and Q6 green, Q7 and Q8 blue) to PPU2, checking for poor joints and damaged parts.[2][3]
  3. If all three colours leave PPU2 correctly and the fault remains, Nintendo's next step is PPU2 itself.[2]

Only RGB correct

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  1. Check the parts around U7 for poor joints and damage, including the colour filters C14 and C16.[2][3]
  2. Check that the red, green and blue signals reach U7's AR, AG and AB inputs (pins 20, 21 and 22) through C6, C7 and C8.[3]
  3. Replace U7.[2]

One output missing

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  1. Find the dead output in the table above and follow its path back from the Multi Out pin with the scope.[3]
  2. Signal at the encoder pin but not at the buffer's emitter: the transistor or its parts. Signal at the emitter but not at the Multi Out: the coupling capacitor (C57, C59 or C20) or the series resistor.[3]
  3. Composite missing on both the Multi Out and RF points at the encoder or Q10, which feed both.[3]

Testing

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  1. Check each output at the Multi Out against fullsnes's levels: 1 V peak to peak into 75 Ω, with red, green and blue on a 1 V DC offset.[8]
  2. Run Nintendo's console test: colour, picture and sound on RF channels 3 and 4 and on A/V, moving the plugs while watching.[5]

Board differences

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Video encoder by board
Board Encoder and notes
SHVC-CPU-01 BA6592F at U7, with discrete RGB buffer transistors[9]
SNS-CPU-GPM, SNS-CPU-RGB As drawn in the redraw[3]
SNSP-CPU-01 (PAL) S-ENC at U7; master clock from S-CLK at U18 and a 17.734475 MHz crystal[8]
SNS-CPU-APU-01 S-RGB A (BA6596F) at U7, in Evan-Amos's photograph[10]
Cost-down boards S-RGB A at U7;[8] RetroRGB describes the RGB amplifier as internal to the chip on single-chip consoles[11]
SNS-CPU-1CHIP-03 No composite sync on the Multi Out: RetroRGB reports that this revision lacks components fitted to the other single-chip boards[12]

On an SNS-CPU-1CHIP-03, an RGB cable that takes its sync from pin 3 gives no picture. Use a cable that takes sync from composite video, or fit the missing parts; RetroRGB shows them in a photograph on its cable page.[12]

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References

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  1. ↑ Nintendo / Playtronic, Manual Técnico do Super NES, Rev. 01/94, p. 2-3 (display section: PPU1 and PPU2 with the video RAM, the RGB amplifier circuit, the RGB encoder and the sync and video output amplifiers; PPU2 creates the RGB picture signals and the RGB encoder makes composite video and S-Video from them), hosted as File:Manual Tecnico do Super NES Rev 01-94.pdf.
  2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 Nintendo / Playtronic, Manual Técnico do Super NES, Rev. 01/94, p. 2-26 ("colour tone faults": mainly a faulty circuit after PPU2, narrowed down by which picture is wrong (video, RGB, S-Video or RF). Monochrome picture: check the 21.453666 MHz oscillation; if it cannot be adjusted or is unstable replace TC1, then X1; check the picture outputs: if only RF is wrong replace the RF modulator; if both are wrong check the parts around the RGB encoder U7 for solder faults and damage, then replace U7, then PPU2 U3. Wrong colours (reddish, bluish) on RGB, S-Video and video: a faulty PPU2 or a missing or broken red, green or blue signal from the RGB output; check around the transistors Q3 to Q9 that amplify the RGB signal, then replace PPU2. Only the RGB picture normal: the RGB encoder or the colour signal filters C14 and C16; check around U7, then replace U7), hosted as File:Manual Tecnico do Super NES Rev 01-94.pdf.
  3. ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 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. Video: PPU2 R, G and B through 2SA1037 pairs Q3 and Q4 (red), Q5 and Q6 (green), Q7 and Q8 (blue) to R', G' and B', and through C6, C7 and C8 (0.1 µF) to the AR, AG and AB inputs (pins 20, 21, 22) of U7, drawn as S-ENC (BA6592F); colour-difference filters with C14 and C16 (1 µF); composite buffer Q10 with C57 220 µF and R33 56 Ω to VO' and the RF video feed; luminance buffer Q11 with C59 220 µF and R42 39 Ω to YO'; chroma buffer Q12 with C20 0.047 µF and R46 100 Ω to CO'; master oscillator X1 21.47727 MHz with trimmer TC1 20 pF; Multi Out P4: 1 Red, 2 Green, 3 CSYNC, 4 Blue, 5 and 6 GND, 7 Y, 8 C, 9 composite, 10 VCC, 11 Audio-L, 12 Audio-R. Not a Nintendo document.
  4. ↑ Nintendo / Playtronic, Manual Técnico do Super NES, Rev. 01/94, p. 2-27 (picture faults: vertical lines, mosaic and corrupted characters, wrong priority, shaking, shifting window, faults with one game, with replacement orders among PPU1, PPU2, CPU and VRAM), hosted as File:Manual Tecnico do Super NES Rev 01-94.pdf.
  5. ↑ 5.0 5.1 Nintendo / Playtronic, Manual Técnico do Super NES, Rev. 01/94, p. 2-23 (console test procedure: check colour, picture and sound on RF channels 3 and 4 and on A/V, moving the RF connector and the multi-out plug while connected), hosted as File:Manual Tecnico do Super NES Rev 01-94.pdf.
  6. ↑ 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.
  7. ↑ Nintendo / Playtronic, Manual Técnico do Super NES, Rev. 01/94, pp. 8-1 and 8-2 (do not test ICs with a multimeter or signal tracer), hosted as File:Manual Tecnico do Super NES Rev 01-94.pdf.
  8. ↑ 8.0 8.1 8.2 8.3 8.4 8.5 8.6 Martin Korth, fullsnes (retrieved 2026-10-25). "SNES Audio/Video Connector Pinouts": Multi Out pin assignments; pins 1, 2 and 4 red, green and blue, 1 V DC offset and 1 V peak to peak into 75 Ω; pins 3, 7, 8 and 9 sync, S-Video Y, S-Video C and composite, 1 V peak to peak into 75 Ω; pin 10 +5 V. "SNES Cartridge Slot Pinouts": pin 1 carries the 21 MHz master clock (MCK). "SNES Timing Oscillators": NTSC 21.47727 MHz; PAL 17.734475 MHz crystal and 21.28137 MHz master clock from the S-CLK. "SNES Chipset": SNSP-CPU-01 U7 S-ENC, TC1 trimmer on X1; cost-down boards with the S-RGB A at U7. Community reference.
  9. ↑ 9.0 9.1 Nintendo / Playtronic, Manual Técnico do Super NES, Rev. 01/94, p. 2-6 (SHVC-CPU-01 parts list: BA6592F RGB encoder, transistors 2SA1037 ×6 and 2SC2412 ×10, 21.453666 MHz crystal (PAL-M)), hosted as File:Manual Tecnico do Super NES Rev 01-94.pdf.
  10. ↑ Evan-Amos, "Nintendo-Super-NES-Mk1-Motherboard-Top.jpg", Wikimedia Commons, public domain. SNS-CPU-APU-01: U7 marked S-RGB A, BA6596F; U10 marked S-MIX A; U14 marked 6379A.
  11. ↑ Bob, "Restoring A Super Nintendo", RetroRGB, 31 May 2020 (retrieved 2026-10-25): an RGB bypass on 1CHIP consoles routes the signals around the internal RGB amplifier.
  12. ↑ 12.0 12.1 Bob, "SNES RGB Cables / csync", RetroRGB (retrieved 2026-10-25). Every large NTSC and PAL SNES outputs composite sync on the Multi Out except the 1CHIP-03, which is missing components found on the other 1CHIP revisions; use composite video as sync, fit the missing components, or, less well, a jumper wire.
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