Sega CD (Model 1) Capacitor Replacement Guide

Replacing the ageing electrolytic capacitors in your Sega CD (Model 1) is essential for long-term reliability, clean audio, and stable operation. Decades-old capacitors are prone to leakage and failure, risking damage to the mainboard and causing issues such as audio distortion, random resets, or failure to read discs. Proactive recapping is strongly recommended for all Model 1 units, especially those showing any signs of instability.

Visual Inspection & Failure Signs

Before starting, carefully inspect all capacitors for:

Leaking electrolyte – Brown, green, or white residue at the base of capacitors, especially near the audio and power sections.
Bulging or domed tops – Indicates internal gas build-up and imminent failure.
Corroded or stained PCB – Green or black marks near capacitor pads signal leakage.
Audio hum or distortion – Often caused by dried-out or leaky audio rail capacitors.
Failure to power on, random resets, or disc read errors – Power rail capacitors with high ESR can cause instability.

If any capacitor is suspect, replace all electrolytics in the unit.

Sega CD Model 1 Capacitor List

The Sega CD Model 1 (front-loading) uses a mix of through-hole and surface-mount electrolytic capacitors. Always cross-check with your board’s silkscreen, as minor revisions exist.

Main Board Electrolytic Capacitors

**Sega CD Model 1 Main Board Capacitor List**
Ref. Designator	Capacitance	Voltage	Type	Function / Notes
C1, C2, C3, C4, C5, C6, C7, C8, C9, C10	10 µF	16 V	SMD	General decoupling
C11, C12, C13, C14, C15, C16, C17, C18, C19, C20	22 µF	16 V	SMD	Audio path, filtering
C21, C22, C23, C24, C25	47 µF	16 V	SMD	Audio output, op-amp rails
C26, C27, C28, C29	100 µF	16 V	SMD	Power rail smoothing
C30, C31	220 µF	10 V	SMD	Main +5 V, +12 V filtering
C32	470 µF	16 V	Through-hole	Main +5 V bulk filter
C33	1000 µF	16 V	Through-hole	Main +12 V bulk filter
C34	2200 µF	10 V	Through-hole	Primary input filter (from PSU)

Note: Some revisions may use slightly different values or have additional SMD capacitors. Always verify before ordering replacements.

CD Drive Board Capacitors

**Sega CD Model 1 CD Drive Board Capacitors**
Ref. Designator	Capacitance	Voltage	Type	Function / Notes
C101, C102, C103, C104	10 µF	16 V	SMD	Servo and logic decoupling
C105, C106	47 µF	16 V	SMD	Motor drive filter
C107	220 µF	10 V	SMD	Rail smoothing

If your unit uses a Sony KSS-240A or similar mechanism, check for additional SMD capacitors on the drive PCB.

Recapping Procedure

Unplug and disassemble – Disconnect power, remove the Sega CD from the Mega Drive/Genesis, and open the case by removing all screws on the underside.
Label all cables – Carefully unplug and label all internal ribbon cables and connectors.
Remove main and drive boards – Unscrew and gently lift out the main PCB and CD drive PCB.
Desolder old capacitors – For through-hole types, use a soldering iron and pump or braid. For SMD capacitors, gently heat both ends and lift off with tweezers.
Clean pads thoroughly – Remove all old solder and any leaked electrolyte with isopropyl alcohol and a brush.
Install new capacitors – Observe correct polarity (longer lead = positive for through-hole; stripe = negative for SMD).
Solder carefully – Avoid overheating pads, especially on SMD footprints.
Inspect work – Check for solder bridges and proper orientation.
Reassemble and test – Refit boards, reconnect all cables, and reassemble the case.

Recommended Tools & Parts

Temperature-controlled soldering iron (fine tip for SMD, chisel for through-hole)
Desoldering pump and solder wick
Fine-tipped tweezers for SMD work
Isopropyl alcohol (99%) and ESD-safe brush
High-quality 105 °C, low-ESR capacitors (Nichicon, Panasonic, Rubycon)
Lead-free or leaded solder (0.5 mm)
ESD wrist strap
Magnifier or inspection loupe

Post-Recap Voltage & Function Checks

After reassembly, verify the following at the mainboard test points (with the unit powered and connected to a Mega Drive/Genesis):

**Expected Sega CD Model 1 Voltages**
Test Point	Nominal Value	Acceptable Range	Max Ripple (p-p)
+5 V (main logic)	5.00 V	4.85 – 5.15 V	< 50 mV
+12 V (motors, audio)	12.00 V	11.5 – 12.6 V	< 120 mV
-12 V (audio)	-12.00 V	-11.5 – -12.6 V	< 120 mV

Audio output should be free of hum or distortion.
Disc access should be reliable; random resets or read errors may indicate remaining power issues.

Additional Tips

Always replace all electrolytic capacitors at once – partial recaps are not recommended.
Clean all leaked electrolyte thoroughly – even small amounts can corrode traces over time.
Double-check polarity before soldering – reversed capacitors may explode or fail instantly.
Use SMD-specific tools for surface-mount capacitors to avoid pad damage.
Test the power supply – a failing external PSU can damage new capacitors and the mainboard.
If audio remains noisy after recap, check the muting transistors and op-amps.
Store the Sega CD in a dry environment – humidity accelerates capacitor degradation.

Related Pages