ACCURACY DISCLAIMER: This information is compiled from various sources and may contain inaccuracies. Component locations and values should be verified against the official Akai service manual. We cannot guarantee the correctness of this information. Always double-check with official documentation before performing any repairs.
Note: The
Akai GX-4000D is a semi-professional reel-to-reel deck featuring Akai's famous glass & crystal ferrite (GX) heads. Capacitor replacement should be performed carefully to preserve its audio quality.
Component locations based on general information about similar Akai models - verify with service manual
Critical Capacitors to Replace
Power Supply Section
- Main filter capacitors - C701, C702 (large electrolytic cans)
- Voltage regulator capacitors - C703, C704
- Rectifier circuit smoothing capacitors - C705, C706
- DC protection circuit capacitors - C707, C708
Capacitor numbering may vary between production runs - verify with service manual
Audio Signal Path
- Input coupling capacitors - C101-C104 (Record amp), C201-C204 (Playback amp)
- Equalization circuit capacitors - C105-C108 (Record), C205-C208 (Playback)
- Bias oscillator capacitors - C301, C302
- Output coupling capacitors - C209-C212
Specific capacitor numbers should be verified against your unit's board
Motor Control Circuits
- Capstan motor run capacitors - C501, C502
- Reel motor capacitors - C503, C504
- Speed control timing capacitors - C505, C506
- Braking circuit capacitors - C507, C508
Motor control board layout may differ between units
Capacitor Replacement Reference Table
| Location/Board |
Capacitor Codes |
Type |
Recommended Replacement |
| Power Supply Board |
C701-C708 |
Electrolytic |
Low-ESR, 105°C rated |
| Record Amplifier |
C101-C112 |
ElectrolyticFilm |
Audio-grade for signal path |
| Playback Amplifier |
C201-C212 |
ElectrolyticFilm |
Audio-grade, precise values |
| Bias/Oscillator Circuit |
C301-C306 |
FilmCeramic |
High-voltage, stable values |
| Motor Control Board |
C501-C508 |
ElectrolyticCeramic |
Stable temperature characteristics |
Table based on general information - specific values and locations may differ
Common Symptoms of Failing Capacitors
- Hum or buzz in audio output (especially 60/120Hz)
- Weak, thin, or distorted sound
- Inconsistent tape speed or wow/flutter
- Motor not starting or running erratically
- Functions not working properly (play, record, rewind)
- Complete failure to power on
- Bias oscillator not functioning (affects recording)
Warning: Always discharge large capacitors before working on the unit. The power supply section can hold dangerous voltages even when unplugged. Use appropriate safety equipment.
Safety information is accurate and should be followed carefully
Replacement Recommendations
- Use high-quality replacement capacitors from reputable brands (Nichicon, Panasonic, Elna)
- For electrolytics, use 105°C rated capacitors for longer life
- In audio signal paths, consider using film capacitors instead of electrolytics where possible
- Match or slightly exceed the original voltage rating
- Note polarity when replacing polarized capacitors
- For the bias circuit, use capacitors with stable values over temperature
Board-Specific Capacitor Locations
Power Supply Board
- C701, C702: Large main filter capacitors (usually 2200μF/35V)
- C703, C704: Voltage regulator filters
- C705, C706: Secondary filter capacitors
- C707, C708: Regulation/filter capacitors for various voltage rails
Board layout may vary - consult service manual for accurate component locations
Record/Playback Amplifier Board
- C101-C104: Input coupling capacitors (Record section)
- C105-C108: EQ network capacitors (Record section)
- C201-C204: Input coupling capacitors (Playback section)
- C205-C208: EQ network capacitors (Playback section)
- C209-C212: Output coupling capacitors
Specific capacitor numbering should be verified on your unit's board
Bias/Oscillator Board
- C301, C302: Main oscillation capacitors
- C303-C306: Bias adjustment and filtering capacitors
Bias circuit configuration may differ between production runs
Motor Control Board
- C501, C502: Capstan motor run capacitors
- C503, C504: Reel motor capacitors
- C505, C506: Speed control timing capacitors
- C507, C508: Braking circuit capacitors
Motor control implementation may vary - verify with service manual
General Maintenance Tips
- Clean all switches and potentiometers with contact cleaner
- Lubricate moving parts with appropriate lubricants (not on brakes or belts)
- Check and replace worn belts and tires
- Demagnetize the tape heads regularly (Akai GX heads require careful handling)
- Adjust tape head alignment after any significant maintenance
- Check and adjust bias current after capacitor replacement
- Clean capstan and pinch roller with isopropyl alcohol
- Check reel motor torque settings
Service Manual: For precise adjustments, obtain the Akai GX-4000D service manual which contains detailed schematics, alignment procedures, and calibration specifications. The GX-4000D requires proper calibration after capacitor replacement.
The service manual is the only truly accurate source of information for your specific unit
