LL-171ME. (1) Product outline, nomenclature and function (2)Connection, adjustment, operations and function (3) Diasassembly and assembly (4) Troubleshooting (5) Block diagram (6) Hardware description - Sharp Monitor Service Manual (repair manual). Page 24

LL-171ME

HARDWARE DESCRIPTION

6 – 1

The FQ1216M is a TV tuner conforming to the PAL system (Europe) and
the SECAM-L (L') (France). (PIF 38.9MHz)
It operates on the power voltage of 5V (3, 13 pin). 
The tuner is controlled by communication between I2C bus (4, 5 pin) and
U21, performing channel selection, broadcasting system selection, and
auto tuning. 
A video signal (2Vp-p/100%) is outputted at 12pin and supplied to the video
decoder UT8. 
For audio, an FM signal (about 50mVp-p) of SIF is outputted at 11pin and
supplied to the audio processor UT10, where it is decoded. 

A video signal is inputted to the composite video signal input pin and
passed to UT7 (4 input 1 output video signal selection IC). 
UT7 is switched by the control pins (2, 3, 5 pin) and an output is sent to 10
pin then to the video decoder UT8.

This video decoder selects a composite video signal inputted and the tuner
and an external input pin, Y/C input from S pin, Y, Pb, and Pr signal from D
pin to convert it to Digital Y Pb or Pr signal, outputting to the IP conversion
U29.
The composite video signal is Y/C separated (separation into brightness
signal and color signal). 

The PW1231 converts interlace digital Y, Pb, and Pr signals from the video
decoder (UT8) into the progressive digital RGB signal. 

The PW166B converts picture data into a desired picture size and output to
LVDS, and performs as a microprocessor and controls many IC's accord-
ing to the FLASH memory (U23) information. 
It also performs PC input and tuner, the external video input PinP (Picture
in Picture), changing the frame rate, and OSD function as additional func-
tions.

The converter converts analog RGB signals of D-Sub input (W2) into digital
RGB signals and outputs to the scaler. 

This provides an interface between the scaler and the LCD panel. 
CMOS/TTL data of 28 bit are converted into LVDS data stream and sent to
the LCD panel. 

The SAA5264 decodes Teletext signals included in the television signals of
PAL and SECAM system.
The composite signal inputted from the tuner (UT1) or the external input pin
through the video decoder (UT8) to 24pin.
The SAA5264 extracts Teletext signals from composite video signals and
converts them into RGB signals and outputs to the video decoder (UT8)
and the mixer (CIRCUIT DIAGRAM UT2, PWB UT12).
Control of Teletext It is carried out by VSDA and VSCL (49, 50 pin).
The output timing of Teletext signals is determined by VSYNC and HSYNC
(36, 37 pin). 

The TA1287 is a high-speed switch IC of 2 inputs and 1 output provided
with the matrix circuit of RGB 

3

 YUV/IQ.

RGB signals from the external input pin are mixed with RGB signals con-
verted from Y, Pb, and Pr signals of the Teletext decoder IC (UT5) at a
proper ratio, and switching is performed, and the mixed signals are output-
ted to the video decoder (UT8). 

The skirt pin is the AV interface which supports COMPOSITE input, S-
VIDEO input, RGB input, audio input, and TV signal output (video, audio). 

The mode is controlled as follows ac cording to the control signal from the
connected unit.

The 74HC4052 is a CMOS switch of 2-circuit and 4-contact. 

It switches analog audio input signals from the RCA input pin and the
COMPONENT input pin and outputs audio signal of R_CH and L_CH from
3 and 13 pins. Switch control is performed at 10 pin. 

The MSP3455G decodes the SIF signal input (50 pin) of the tuner output
into stereo or monaural format and performs audio signal processes such
as sound quality setting (fixing) by Bass and Treble and sound volume set-
ting (fixing) depending on various input sources.
External input signals (41, 42 pin) and PC AUDIO input (44, 45) are
switched and outputted from 20 and 21 pins to the speaker driver. 

The supported TV broadcast systems are B/G, I, D/K, L (L'), and M (PAL).
This model does not support the NTSC-M system. 

The U27 is a BTL type (push/pull) 3W operational amplifier. It drives 8-ohm
L- and R-channel speakers. The sound signal input through Pins 6, 8 is
output to Pins 2, 4 (Lch) and 10, 12 (Rch) of the speaker, respectively, in
opposite polarity. Pin 9 is a volume control pin and varies with the range of
DC 0 V (mute) to 0.8 V (Max.).

The volume control voltage is output through DAC of the U5 by I2C control.

A voltage of 11 volts is supplied through the ripple filter (regulator) to Pin 1
as the power supply. The output is connected also to the headphone termi-
nal. When the headphone plug is inserted, the speaker is shut off and the
sound is output through the headphone.

The LM2576 is a step-down voltage regulator (3W). The voltage is input
through Pin 1 (7-40 V) and output through Pin 2. The output is then 
feedback  into Pin 4 to ensure stable voltage output. 
The feedback voltage into Pin 4 is compared with the reference voltage
1.23 V of the internal operational amplifier to determine the output voltage.

The IRF7316 and 7304 are MOSFET 2-channel power supply switch

ICs (ON resistance: 0.06ohm)
When G1 and G2 are put in low level, the input voltage from S1 and S2

are output to D1 and D2.

If the power supply line suffers overvoltage for any reason, a large cur-
rent is passed through the zener diodes to cause shorting to blow out
the fuse in a safe manner. The zener diode may short.

Input voltage 

LOW (0~2V) 

TV Mode

Mid (5~8V)

AV Mode (Wide-screen)

High (9.5~12V)

AV Mode

Input voltage

LOW (0~0.4V)

COMPOSITE,
S-VIDEO Input MODE

HIGH (1~3V)

RGB Input MODE