Nintendo
Interactive Flowchart Super Nintendo (SNES / Super Famicom)
SHVC-CPU-01, SNS-CPU-GPM-02 & SNS-CPU-1CHIP-01/02/03 — 16-Bit 5A22 + S-PPU1/PPU2 & 1CHIP S-CPUN mainboards
Complete Diagnostic Flowchart: Capacitive Load, ESR & Power Rail Ripple Diagnostic Tree (Universal Retro Mainboards (C64, Amiga, ZX Spectrum, Game Gear, Consoles))
STEP 1: Measure 100Hz/120Hz Peak-to-Peak AC Ripple on the +5V / +12V Bulk Filter Cap
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Set your oscilloscope to AC Coupling, 200 mV/div, and 2.5 ms/div (20 MHz bandwidth limit ON). Probe directly across the main bulk filter capacitor (e.g. C19 2200µF / C88 1000µF on C64, or C303/C304 on Amiga) under full system load. Measure the peak-to-peak sawtooth ripple amplitude (mVpp).
Expected Reading: < 50 mVpp clean regulated rail (post-regulator) or < 350 mVpp on raw unregulated bulk DC before the 7805/7812.
STEP 2: Check Linear Regulator (7805 / 7812) Input-to-Output Dropout Margin
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Switch oscilloscope or multimeter to DC Volts and measure Pin 1 (Input) of the 7805 (+5V) or 7812 (+12V) regulator at the bottom of the ripple trough. Verify that Input Voltage remains at least 2.0V above the regulated output (e.g. ≥7.2V into a 7805, ≥14.2V into a 7812).
Expected Reading: 7805 Input ≥ 7.2V DC; 7812 Input ≥ 14.2V DC. Below this dropout threshold, ripple punches straight through to the logic rail.
STEP 3: Check Local IC Decoupling & Audio/Video AC Coupling Capacitors
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Probe audio output coupling caps (e.g. C91 100µF on C64 SID Pin 27, or C324/C334 22µF SMD on Amiga Paula) — compare upstream vs. downstream signal amplitude. Inspect SMD electrolytic pads (Amiga 600/1200, Game Gear, DMG-01) under magnification for fishy odor, dull grey solder corrosion, or lifted copper traces.
Expected Reading: Full audio/video swing across the coupling capacitor with zero DC leakage on the output side and clean, shiny solder pads.
[ISOLATED FAULT: RES-BULK-CAP] Fault Isolated: High-ESR Bulk Filter Capacitor (>100 mVpp Rail Ripple)
VERDICT
Excessive 100/120Hz sawtooth ripple on the DC rail confirms that the primary reservoir/filter electrolytics have dried out and lost effective capacitance.
[ISOLATED FAULT: RES-REG-DROPOUT] Fault Isolated: Linear Regulator Dropout / Bridge Rectifier Diode Open
VERDICT
The pre-regulator DC rail is sagging below the minimum 2V dropout headroom required by the 7805/7812 regulator.
[ISOLATED FAULT: RES-COUPLING-CAP] Fault Isolated: Open/Leaky Audio or Video Coupling Capacitor & Trace Corrosion
VERDICT
Signal attenuation, muffled audio, or DC offset hum across the coupling stage indicates dried-out or leaking coupling capacitors.
[ISOLATED FAULT: RES-RAILS-HEALTHY] Verification Passed: Power Rails, Ripple & Coupling Capacitors Within Spec
VERDICT
All measured DC supply rails, AC ripple levels (<50 mVpp), and coupling stages pass bench specification. If performing a preventive recap, use the verified board BOM below.
Summary
SNES and Super Famicom mainboards rely on surface-mount electrolytic capacitors for Multi-Out composite/S-Video coupling (C59/C60), S-DSP stereo audio coupling, and power rail filtering. Leaking SMD cans cause dark/fading video, ghosting, and distorted audio.
Interactive Bench Oscilloscope — Verify Pre- & Post-Recap Waveforms
Open Full Signal Visualizer →Click any test point below to compare a healthy recapped rail or clock against high-ESR electrolytic capacitor ripple and droop:
Safety & Warnings
Unplug the power brick and press the Power switch ON to discharge C67 before working!
If you unplug cartridges or touch the board with residual charge in C67, you will blow the green 1.5A Pico fuse (F1) next to the 7805 regulator.
Is This Your Board?
- SHVC-CPU-01 is the launch 1990 board with a removable metal SHVC-SOUND module.
- SNS-CPU-GPM-01/02 integrates the audio chips onto the mainboard.
- SNS-CPU-1CHIP-01/02/03 combines the 5A22 CPU and PPU1/PPU2 into a single S-CPUN QFP for the sharpest RGB output.
Verified
Check
Verified rows are agreed by two or more independent sources. Check rows are revision-dependent or single-sourced — confirm the value against your own board before ordering.
SNES / Super Famicom Mainboard (SHVC-CPU-01 / GPM-02)
| Ref | Value | Voltage | Type | Function | Notes | Confidence |
|---|---|---|---|---|---|---|
C57 |
10 uF | 25 V | SMD | S-ENC video encoder reference | Verified | |
C58 |
10 uF | 25 V | SMD | Chroma coupling | Verified | |
C59 |
220 uF | 6.3 V | SMD | Multi-Out Composite / Luma video coupling | Often paired in parallel with C60 (two 220 uF = 440 uF total). Dried C59/C60 causes dark/rolling video. | Verified |
C60 |
220 uF | 6.3 V | SMD | Multi-Out Luma video coupling | Verified | |
C61 |
10 uF | 25 V | SMD | Left audio channel coupling | Verified | |
C62 |
10 uF | 25 V | SMD | Right audio channel coupling | Verified | |
C63 |
47 uF | 16 V | SMD | LM324 audio op-amp rail decoupling | Verified | |
C65 |
33 uF | 25 V | SMD | Reset / CIC timing filter | Verified | |
C66 |
33 uF | 25 V | SMD | +5V logic local decoupling | Verified | |
C67 |
1000 uF | 25 V | Axial / Radial | 9V/10V DC input primary reservoir (before 7805) | Verified |
SNES / Super Famicom Mainboard (SHVC-CPU-01 / GPM-02) — shopping list
- 4 x 10 uF 25 V SMD
- 2 x 220 uF 6.3 V SMD
- 1 x 47 uF 16 V SMD
- 2 x 33 uF 25 V SMD
- 1 x 1000 uF 25 V Axial / Radial
Recap Tips
- Solder an extra 470 uF or 1000 uF 16V low-ESR capacitor across the 7805 output legs (or in the unpopulated C67 spot on later boards) to eliminate the faint vertical white bar in the centre of the screen.
Related Symptoms
- Completely dead - red power LED does not light Check the 1.5A Pico fuse F1 on the left edge near the 7805 regulator.
Sources & References
- Console5 TechWiki - Super NES Per-revision SNES SMD capacitor lists.