| Optimus Concertmate 990 Electronic Keyboard | ||
| (420-4040) | ||
| Care and Maintenance | |
| Features | |
| MIDI Implementation Chart | |
| Operation I | |
| Operation II | |
| Preparation | |
| Special Functions | |
| Specifications | |
| Troubleshooting | |
| Using MIDI | |
| Exploded Views/Parts List | |
| Detailed Parts List | |