Pin Details of IC LA7521
Functions :
- Video IF amplifier
- Video detector & Video pre-amplifier
- Sound IF amplifier & limiter
- Discriminator & audio pre-amplifier
- AFT & Automatic gain control amplifier
- Sound mute circuit
Pin No. | FUNCTION | Voltage |
1. | FM discriminator(5.5MHz.crystal) | 4.8 |
2. | Audio frequency output from FM detector | 5.2 |
3. | Audio signal input to attenuator(DC volume control) | 2.8 |
4. | Negative feedback(output to input)for audio amplifier | 4.2 |
5. | Audio frequency output from audio driver amplifier | 4.8 |
6. | Ground(-Ve)supply voltage | 0 |
7. | Mute circuit(sound) | 4.6 |
8. | Decoupling capacitor for quality improvement | 4.4 |
9. | Video IF signal input | 4.4 |
10. | Video IF signal input | 4.4 |
11. | Decoupling capacitor for quality improvement | 4.4 |
12. | RF-AGC delay control | 2.1 |
13. | RF-AGC control voltage for tuner(delayed AGC control) | 9.6 |
14. | Mute circuit (for sound section) | 4.6 |
15. | Video signal output | 3.8 |
16. | Video signal output | 3.8 |
17. | AFT oscillator signal output for horizontal oscillator(15625Hz) | 8.9 |
18. | Frequency tuning circuit for automatic frequency tuning (AFT)amplifier | 3.8 |
19. | Video detector frequency tuning circuit | 4.2 |
20. | Video detector frequency tuning circuit | 9.3 |
21. | Frequency tuning circuit for automatic frequency tuning (AFT)amplifier | 4.2 |
22. | Composite chroma (colour)video signal output | 4.9 |
23. | Positive (+Ve)supply voltage for video section | 12.9 |
24. | Regulated supply voltage for sound section | 12.9 |
25. | Sound IF signal output from sound IF detector | 12.3 |
26. | Decoupling capacitor for biasing of sound IF amplifier | 3.1 |
27. | 5.5MHz inter-carrier sound signal input | 3.1 |
28. | 5.5MHz. inter-carrier sound signal input to FM detector | 3.1 |
29. | Mute circuit(sound) | 0.1 |
30. | FM detector | 5.6 |
