DOWNLOAD Sharp LC-28HM2E (serv.man2) Service Manual ↓ Size: 707.1 KB | Pages: 48 in PDF or view online for FREE

Microprocessor

EEPROM

Flash ROM

Memory

Video line input (1Vp-p)

PC input (0.7Vp-p)

Sync 
signal

External device control

Video 
signal

Sync signal selector

3ch AD converter

Clamp/bias/gain adjustment

Encoder IC

G/A group

»

 Frequency detection (PC line)

»

 Video enlarge, reduce and 

    complement

»

 EN signal and Dotclk 

   production

»

 OSD synthesis

Video signal 
and 
timing signal

Encoded 
signal

(1) Selection of analog video input signal of 2 systems
(2) Enlargement, reduction (including wide angle processing) and complement of video signals
(3) Production of signals required for the display in the steps to follow
(4) Synthesis of OSD (channel call, menu, etc)
(5) Encoding of the prepared video signal and timing signal for output
(6) Control of external devices (video adjustment, video source selection, power supply, etc) (Same as ordinary

microprocessor)

(7) Storage of information such as adjustment data

Program data and OSD data are stored in the flash ROM and can be rewritten externally.

Æ

Æ 

Symptom

P

ossib

le cause

P

ossib

le f

ault location

Counter

measure

System cab

le and connector

.

P

anel side decoder IC sync

output and the circuits to f

ollo

w

.

P

anel side decoder IC

.

PC I/F Unit.

System cab

le and connector

.

A

VC System:

 TXD_M and RXD_M

line Monitor

: MTXD and MRXD

line

.

System cab

le and connector

.

SMPO

W line and per

ipherals

.

System cab

le and connector

.

CCKM line and per

ipherals

.

Shor

t-circuit in the per

ipherals of

po

w

er line

P

o

w

er line shor

t-circuit mode with

such troub

le as anti-static de

vice

b

u

rnout.

Same as left.

Replace cab

le or connector

and chec

k connection.

Chec

k the circuits f

ollo

wing the

sync output of the decoder IC

.

P

anel side decoder IC

.

Replace PC I/F Unit.

Replace cab

le or connector

and chec

k connection.

Chec

k the line in question.

Replace cab

le or connector

and chec

k connection.

Chec

k the line in question.

Replace cab

le or connector

and chec

k connection.

Chec

k the line in question.

Chec

k the line in question.

Chec

k diodes and others

betw

een signal line and po

we

r

line on the ter

minal board.

Replace PC I/F Unit.

»

With this model, neither the displa

y unit nor the A

VC system can perf

or

m the independent oper

ation in the nor

mal mode

.

»

Star

t-up ma

y not be possib

le in some cases because of the lamp f

ailure or other cause

. In this case

, star

t up with the process adjustment

mode of the monitor unit independently

, and initializ

e the times of lamp f

ailures recorded.

 (See the Ser

vice Man

ual.) 

T

o

 simply chec

k the

times of lamp f

ailures

, ref

er to the process adjustment mode page 1 LAMP NG CHECK.

Video signal (sync signal) is

not f

ed into the panel control

G/A (Detected b

y sync

signal).

T

ransmission f

ailure between

displa

y and A

VC system.

F

ault in control line from the

displa

y unit to tur

n on the

po

w

er at the A

VC system.

F

ault in pow

er star

t-up chec

k

line and per

ipher

als

.

A

VC system s

witching po

w

e

r

cut-off b

y

 o

v

er

load protection

circuit, or b

u

rnout fuse

.

PC I/F Unit G/A damage

.

Blue screen.

No bac

klight illumination, although both displa

y

LED and A

VC system LED are lit in g

reen.

When the po

w

er is s

witched on, the 

displa

y 

unit

’s

po

w

er rela

y is tur

ned on, b

ut the A

VC system po

w

e

r

rela

y is not tur

ned on in succession.

When the po

w

er is s

witched on, the 

displa

y 

unit

’s

po

w

er rela

y is activ

ated, and then the A

VC system

po

w

er rela

y is tur

ned on once b

ut it is tur

ned off

immediately

. The po

w

er is tur

ned on when the

process adjustment is entered b

y displa

y b

utton

oper

ation while k

eeping connection betw

een the

displa

y 

and the center

.

When the po

w

er is s

witched on, the 

displa

y 

unit

’s

po

w

er rela

y is activ

ated, and then the A

VC system

po

w

er rela

y is tur

ned on once b

ut it is tur

ned off

immediately

.  

The po

w

er is not tur

ned on when tr

ying

to enter the process adjustment b

y displa

y b

utton

oper

ation while k

eeping connection betw

een the

displa

y 

and the center

.

No OSD appear

ing (Remote control is oper

ativ

e).

»

AC power connection at Display unit.

»

AC power connection at AVC system unit

»

System cable connection tying the Display unit and the AVC system unit

1

Turn on the main power switch positioned at the top of the Display unit.

2

Main power supply of the Display unit sends out +5V main power for microprocessor (P2001_5).

3

After resetting the display microprocessor, +5V output is present at SMPOW (J4001_22).

(At the same time, the power is supplied to each line.)

4

Main power relay switch is turned on at the AVC system unit.

(At the same time, the power is supplied to each line.)

5

After the AVC system unit has been initialized, the backlight illumination command is emitted to the Display

unit.

6

Start-up sequence is terminated when the backlight is ON.

»

As power source, use the stable AC power.

»

Note that, when the power is switched on for the first time, it takes approx. 10 seconds before the unit starts up
because E

2

P needs to be initialized. (Both monitor side LED and AVC center side LED are lit in green, with the

backlight being OFF.)
Never turn off the power during this time.
When restarting the system the first time after the power interruption caused by power failure, etc., execute
P6L5 “CENT EEP RST S/C ONLY” for resetting before doing adjustment.

»

When the data has been updated in the program more than once, updating the program will not re-write the
adjustment value in most cases. Any time the program has been updated, it is recommended to follow the
procedure; (a) save the data of the adjusted items in memorandum, (b) initialize the EEPROM once at both AVC
center and monitor, and then (c) write in the adjustment values recorded.

1

Going into the process adjustment mode

[Procedure]

(1) Using remote controller

Connect the display and the AVC center using the system cable in the specified manner. Switch on the
power. After start-up, press [PROCESS ADJUSTMENT] button of the remote controller.

(2) Using main unit key

Connect the display and the AVC center using the system cable in the specified manner. While pressing
[BRIGHTNESS] and [VOL–] buttons simultaneously, switch on the power.

[Contents]

Various adjustments can be made manually.

2

Going into the inspection process mode

[Procedure]

Go into the process adjustment.
Turn P1L6 “SIGNAL INFO” to “ON”.
Terminate the process adjustment mode with remote controller operation.

[Contents]

The bar display items such as volume and video/sound adjustments are made switching in the sequence of
minimum, medium and maximum.

3

 How to make presetting

[Procedure]

(1) When remote controller capable of outputting the “preset” code is not available

Go into the process adjustment.
Turn P27L1 “INDUSTRY INIT” to “ON”, and the press [ENTER] button of the remote controller.
The process is finished when “/ / / / / / / / / / / / / / / / / / / / / / / / / / / / ” display disappears.

(2) When remote controller capable of outputting the “preset” code is available

Go into the process adjustment.
Press [PRESET] button of the remote controller.
The process is finished when “INDUSTRY INIT NOW” display disappears.

[Contents]

User adjustment value can be made as default setting. The data adjusted in the process adjustment is not
altered.