Service manual

MODELS: LT-3280D/LT-3780D
Page 29
2.2.
2.2.
2.
Audio circuitsAudio circuits
Audio circuitsAudio circuits
Audio circuits
It explains the audio circuits and speaker system of LT-3780,LT-3280.
Our design spec is as follows.
- Power outputs : Total 10W(5W*2(L,R))
- Impedance : 8+/-1.2 ohms
- Compact sound 2 way bass reflex speaker box.
(Refer to an attached “Audio block diagram of LT-3780, LT-3280”, regarding as the flow of audio signal.)
2-1. Audio process circuits
(M)IC301 : Audio processor IC (MSP3440G : Micronas)
This models are used the MSP3440G as the audio processor.
This IC’s functions are as follows.
- Volume control
- Tone control
- Surround
- L/R mixing
- Audio line output
This model has some sound effect features on user menu, Bass, Treble, Balance, Surround, Level
Sound.
Audio adjustment of those in this model is performed by this IC.
2-2. Audio amplifiers circuits
(N)IC370, IC380 : Single Ended Audio Amplifier IC (MP7720DS-Z : MPS)
This model apply digital Audio Amplifier in order to decrease power consumption.
This amplifier voltage is 14V and SAMPVCC(for Sub Woofer)).
2-5. Speakers
No. ITEM SPECIFICATION
1 Nominal 8 ohms +/- 1.2%
2 Lowest Resonance 180 +/- 36Hz
Effective / Rated F0~20KHz
Frequency Range OUT PUT SPL-10dB
4 Rated Input 10W
5Maximum Input15W
3