Tatung C5GSE Schematic

MODEL:C5GS

SERIES

Low Radiation Extended VGA

PLUG & PLAY COLOUR MONITOR

SERVICE MANUAL

TABLE OF CONTENTS

PAGE

1. Precaution and Notices ....................................................................................... 1

2. Specifications ....................................................................................................... 3

3. Control Location and Functions ....................................................................... 5

4. Disassembly Instructions ................................................................................... 7

5. General Connection & Applications ................................................................. 9

6. Electronic Circuit Description ......................................................................... 10

7. Adjustment ........................................................................................................ 19

8. Troubleshooting Flow Chart ............................................................................ 22

9. Block Diagram .................................................................................................. 28

10. PCB Layout ....................................................................................................... 29

11. Circuit Diagram ................................................................................................ 30

12. Electrical Parts List .......................................................................................... 31

13. Mechanical Disassembly .................................................................................. 45

14. Mechanical Parts List ....................................................................................... 46

1. Precautions and Notices

1.1 Safety Precautions

1) Observe all cautions and safety related notes located inside the display cabinet and on the display
chassis.

2) Operation of these displays outside the cabinet or with the cover removed involves a shock hazard
from the display power supplies. Work on the display should not be attempted by anyone who is
not thoroughly familiar with precautions necessary when working on high voltage equipment.

3) Do not install, remove or handle the picture tube in any manner unless shatter-proof goggles
are worn. People not equipped should be kept away while handling picture tube.

4) The picture tube is constructed to limit X-RADIATION to 0.5mR/HR at 300 microamperes anode
current. For continued protection, use the recommended replacement tube only, and adjust the
voltage so that the designated maximum rating at the anode will not be exceeded.

5) Before returning a serviced display to the customer, a thorough safely test must be performed to
verify that the display is safe to operate without danger or shock. Always perform an AC leakage
current check on the exposed metallic parts of the cabinet. Proceed as follows :

Connect the monitor power lead to the mains supply, via an isolation transformer, and switch on.
Using the test circuit shown in Fig.1-1, measure the AC leakage current between each pole ( L
and N) of the supply and all accessible metal parts. The earth leakage current must not exceed 3.5
mA.

L
Mains N
Input E
Connect to
Exposed Metal
Parts

Measuring Circuit

mA

Resistance=2000 ohms

Fig.1-1 AC Leakage Current Test Circuit

1.2 Product Safety Notice

1) Many electrical and m echanical parts in this chassis provide special visual safet y protection.
The protection afforded by them cannot necessarily be obtained by using replacement
components rated for higher voltage, wattage, etc.

2) Before replacing any of these components, read the parts list in this manual carefully. The us e
of substitute replacement parts which do not have the same safety characteristics as
specified in the parts list may create shock, fire, X-Ray radiation or other hazards.

1.3 Service Notes

1) When replacing parts or circuit boards, wrap the wires around terminals before soldering.

2) When replacing a high wattage resistor (more than 1/2 W) on a circuit board, keep the resistor
about 10mm (1/2in.) away from circuit board.

3) Keep wires away from high voltage or high temperature components.

4) Keep wires in their original position so as to reduce interference.

2. Specifications

2.1 Monitor Specification

Power Source

Power
Consumption

Picture Tube
Viewable Image

Size
Maximum

Resolution
Input Signals

Synchronization

Display Colours
Active Display

Area
Plug & Play

Operating
Temperature
Operating
Humidity
Storage
Temperature
Storage
Humidity
High Voltage
Dimension

Weight

AC 100 ~ 240V , 50 / 60Hz
LED color is green Normal Operation (Max.70W)

LED color is amber Stand By / Suspend Mode (Max.15W)
LED color is amber Off Mode (Max. 3W)

15" (Diagonal), glare, non- glare, anti-static, 90°Deflection,

0.28mm dot pitch, Low Radiation, Mini-Gun Tube.

13.9" (Diagonal)
Horizontal 1024 Pixels (Non-Interlaced)

Vertical 768 Lines (Non- Interlaced)
Video Analog 0.7 Vp-p / 75 ohm Positive

Separate Sync.

Horizontal 30KHz - 57KHz continuous
Vertical 50Hz - 120Hz continuous

Analog Input 16 million colours
Horizontal 260 mm
Vertical 195 mm

DDC1 / 2B
+5• ~ +35•

10 % ~ 80 % (Non-Condensing)

-20• ~ +65•

15 % ~ 80 %
25KV

Width 360 mm
Height

Depth 388 mm

TTL Level
Horizontal : Positive / Negative
Vertical : Positive / Negative

384 mm (With Base)
Height of Base : 58mm

11.3Kg (Net weight)/ 13.5Kg (Gross weight)

2.2 Preset Timing Table(I) for HP

Mode Resolution H-Freq. V-Freq. Hs. pol. Vs. pol.

1
2
3
4
5
6
7
8
9

Preset Timing Table(II) for others

Mode Resolution H-Freq. V-Freq. Hs. pol. Vs. pol.

1
2

720 x 400 31.47 kHz 70.08 Hz Negative (-) Positive (+)
640 x 480 31.47 kHz 59.95 Hz Negative (-) Negative (-)
640 x 480 35.16 kHz 56.25 Hz Negative (+/-) Negative (+/-)
800 x 600 37.88 kHz 60.32 Hz Negative (+/-) Negative (+/-)
640 x 480 37.86 kHz 72.81 Hz Negative (+/-) Negative (+/-)
640 x 480 37.50 kHz 75.00 Hz Positive (-) Positive (-)
800 x 600 48.08 kHz 72.18 Hz Positive (+/-) Positive (+/-)

1024 x 768 48.36 kHz 60.00 Hz Negative (-) Negative (-)

800 x 600 53.67 kHz 85.00 Hz Positive (+) Positive (+)

720 x 400 31.47 kHz 70.08 Hz Negative (-) Positive (+)
640 x 480 31.47 kHz 59.95 Hz Negative (-) Negative (-)

3
4
5
6
7
8

640 x 480 37.50 kHz 75.00 Hz Negative (-) Negative (-)
640 x 480 43.30 kHz 85.00 Hz Negative (-) Negative (-)
800 x 600 46.88 kHz 75.00 Hz Positive (+) Positive (+)

800 x 600 53.67 kHz 85.00 Hz Positive (+) Positive (+)
1024 x 768 48.36 kHz 60.00 Hz Negative (-) Negative (-)
1024 x 768 56.47 kHz 70.00 Hz Negative (-) Negative (-)

3. Control Location and Functions

Front View Rear View

1. 2. 3. 4. 1. 2.

1. Indication LEDs 1. AC Power Plug

2. Control Buttons 2. Signal Cable

3. Power Switch's LED

4. Power Sw itch

3.1 Indication LEDs :

When one of the digital controls is selected, the corresponding LED(s) are lit.

CONTRAST : To adjust the contrast of the display.

BRIGHTNESS : To adjust the brightness of the display.

H-POSITION : Adjust the horizontal position of the entire screen image.

H-WIDTH : Adjust the horizontal width of the entire screen image.

V-POSITION : Adjust the vertical position of the entire screen image.

V-HEIGHT : Adjust the vertical height of the entire screen image.
PINCUSHION : If the vertical sides of the screen image curve in or bulge out,

you can correct the pincushion distortion using this adjustment.
TRAPEZOID : If the picture is wider at the top or bottom, you can correct the

trapezoid distortion by using this adjustment.
P ARALLEL : If the sides of the screen image are tilted, you can use this

adjustment to correct the parallel distortion.

ZOOM : This is used to adjust H-width and V-Height, simultaneously.

RECALL : This is used to recall the original factory display settings.

3.2 Control Buttons :

The Select Button (the left button) selects a digital control. The selected control is indicated by
the corresponding indication LED. The Down (down arrow) and UP (up arrow) buttons allow you to
decrease or increase the value of the selected control.

Press the Down (down arrow) and up (up arrow) simultaneously, Then it will degauss the

display.

3.3 Power Switch and LED

Push to power on the monitor and push again to power off. The indicator LED will be green

when the power switch is ON and the power cord is properly connected. The color of the LED
depends on the power state of the monitor. When the LED color is permanently green, it
indicates the monitor is at normal state. And when the power LED is amber, it indicates the monitor
is at a power saving state.

We recommend you switch on the monitor first, before switching on the computer!

4. Disassembly Instructions

1) Face Down the Monitor : ( Fig.4-1 )

2) Swivel Base Removal : First press the stopper, then slide the swivel ball down and remove it.
( Fig.4-2 )

3) Back Cover Removal : Remove 4 screws (A) ( Fig.4-3 ) and (B) (Fig. 4-4) from the back cover.
Then remove the back cover.

4) PCB Assembly Removal :

CAUTION: When serving or replacing the CRT, disconnect the anode and discharge the anode

completely. As high voltage (25.0KV) may remain on the anode for an ex tended time after
power off.

( Fig.4-1 ) ( Fig.4-2 )

Stopper

(A) (B)

( Fig.4-3 ) ( Fig.4-4 )

a) Unplug grounding connectors and the de gaussing coil grounding connector from the CRT

drive shield.
b) Remove CRT drive board (C) from CRT neck. (Fig.4-5)
c) Unplug the DY connector, AC connector, Degaussing coil connector and the CRT

grounding connector from the FBT shield.
d) Discharge the remaining static electricity by shorting CRT anode and ground, then remove
the FBT anode connector.
f) Press two clips(D) from left and right side of front cover(Fig.4-5) to remove main chassis.

5) CRT Removal :
CAUTION : Do not lift the CRT by the neck.

a) CRT is supplied as ITC.
b) Remove 4 screws (E) from the front cover (Fig.4-6) to move the CRT.

( Fig.4-5 ) ( Fig.4-6 )

5. General Connection & Applications

Procedure for installing and using your Multi-Sync. display.

5.1 Connecting the monitor to the computer

1) Set up the display at the desired operation location , on top of or beside your personal computer .
Plug the power cord into the moni tor and t hen con nect the ot her end of th e power cord into an
AC outlet. The three-wire power cord is shielded type and is provided as a safety precautions to
ensure proper electrical grounding.

2) Connect the 15-pin color display shield signal cable to the video adapter output on your
computer, then lock both screws to ensure proper grounding. The connector information is as
follows :

PIN Description

1 Red
2 Green

3 Blue
4 Open
5 Return
6 Red Ground
7 Green Ground
8 Blue Ground
9 +5V ( PC97)
10 Ground
11 Open
12 SDA
13 H.Sync.
14 V.Sync.
15 SCL

3) First turn the PC power switch ON.Then apply power to the display by pressing the Power

ON/ OFF Switch to turn the monitor on. The power indicator LED will illuminate.

Allow about five seconds for the display tube to warm up, data will be displayed on screen.

NOTE : Don't force the cable into the connector; line it up carefully so that you don't bend the pins.

6 . Electronic Circuit Description

6.1 Switching Mode Power Supply ( SMPS )

The switching mode power supply for this monitor is a full range type, i.e. universal power input
of AC 100V ~ 240V is compatible. When AC input is supplied through the slow blow fuse F801, the
line choke L803 to the rectifier D811 ~ D814, the rectified DC voltage is about 125V ~ 335V and then
fed to the switching transformer T801.

Prior to start, a small current flows to C808 via R828 and R831. I801 is to operate immediately
when the voltage across C808 reaches 16V. At the same time, Q801 is on, the rectified current flows
through the primary winding of T801 and the energy is stored in it .

When Q801 is off, the stored energy is transferred to the secondary winding, the auxiliary
winding is close-coupled and in phase with the secondary winding. It will provide a holding voltage
on C808 and fed to pin7 of I801 via R820 and D808. I801 will keep working provided that the voltage
across C808 is over 10V. The oscillating frequency of the switchin g mode power supply is around
20KHz, which is determined by the timing components R822 and C813. C813 is char g ed to 2.8V via
the 5V reference voltage at pin8 of I801and discharged to 1.2V during the discharged time interval.
The oscillator generates a series of blanking pulses, which cause the output at pin6 of I801 to go low.

The fly-back pulse from T403 is applied via D816 and R807 to force C813 to discharge, so that
the oscillating frequency is synchronized a nd kept in phase with tha t of horizontal fr equency to avoid
interference on display screen.

In case of voltage variations due to the change of input AC or output loading, the auxiliary
winding will reflect these variation to pin2 of I801 via D818, R812, R813, I803 and I802. The voltage
at pin2 of I801 is compared with the internal 2.5V reference voltage to produce an error voltage inside
I801.

This error voltage is limited to 1V by internal Zener diode and is compared with the voltage at
pin3 of I801 which is supplied from the voltage detected across R825 and R823, while Q801 is on.
Q801 is off only when the voltage drop across R825 and R823 has reached that of the error voltage, or
1 Vp-p maximum, that is, the duty cycle of the pulse width modulator is controlled by the combined
error voltage to regulate the output voltage.

If over-load or short circuit occurs at the secondary, the voltage across R825 and R823 reaches
1Vp-p rapidly, thereby blocking the power output, the voltage at pin7 of I801 then decrease to below
10V, I801 is forced off.

However, in order to allow auto-recovery from power saving off state, the SMPS circuit is
designed as an unlatched type, the DC current flows via R828, R831, Q813 and D828 to charge C808
again. When the voltage across C808 has reached 16V, I801 is turned on again. Once the peak voltage
across R825 and R823 is over 1Vp-p, I801 will be forced off again. Consequently, I801 is turned on
and off repeatedly, under this situation, if the power does not be switched off, Q801, R825 and R823
may finally be over stressed and fail.

6.2 Power Management Circuit

Power
Switch

ON

OFF x x 1 0 OFF

I201

STATE
NORMAL 1 1 1 1 GREEN
STAND BY 1 0 0 1 AMBER
SUSPEND 0 1 0 1 AMBER
OFF 0 0 0 0 AMBER

I201 #40

(Vs)

I201 #39

(Hs)

I201 #29

(PM1)

I201 #28

(PM2)

D891 LED

When the display signal enters into "Stand By" or "Suspend" state of power saving, with either H.
Sync. or V. S ync. off, the voltage at pin29 of I201 is low, both Q808 and Q809 are switched off to
block the 16V voltage supply, thereby shut down the oscillation of the horizontal and vertical
deflection, power conservation is achieved.

When the display signal enters the "Off" state of power saving with both H. Sync. and V. S ync.
off, the voltage at pin28 and pin29 of I201 are low , then all Q805, Q806, Q808 and Q809 are switched
off. 1 1V and 16V voltage supply for the loading circuit are blocked. The overall power dissipation is
significantly reduced to less then 3W watt.

Automatic recovery from "Off" state to "NORMAL" state is achieved once the recovery H. Sync.
and V. Sync. trigger I201 via R254 and R256, the voltage at pin28 and 29 of I 201 will go high again to
turn on Q809, Q806 via Q808 and Q805.

Power Indicator

The power indicator D891 is composed of two LED in one. The 5V voltage is applied through
R244 to lighten the Green LED and through R243 to lighten the Yellow LED of D891. D891 is
controlled by the power management voltage, result in Green or Amber color for Normal or Stand By ,
Suspend, Off State respectively.

Heater Voltage

The heater element in the CRT is supplied with 6.3±0.3V during normal operation and reduced
to 5.0±0.5V during Stand By or Suspend state. To achieve this, Q805, Q806 and associated circuit is
introduced, when at normal state, PM2 is HIGH level then Q805 ON, to trigger Q806 ON, 10V from
D815 to Q806, R841, R991 and heater, the heater voltage is 6.3V±0.3V.

When at Suspend, Stand-By state the horizontal output is shut down, there is no horizontal pulse,
PM1 is Low level, the feedback voltage at pin2 of I801 is higher than that of normal state. This will
force the output voltage at secondary side of T801 drop down, the heater voltage is reduced to 5.0±

0.5V .

6.3 Automatic Degaussing Circuit

The posistor R803 and the degaussing coil L891 comprise an automatic degaussing circuit to
demagnetize the shadow mask and the interna l shield of the CR T in order to pr otect the display screen
from color impurity.

The resistance value of the posistor is originally low (7 ohm) during power off. Right after the
display is powered-on, the voltage at pin26 of I201 is HIGH, then Q803 ON and RL01 triggered a
large AC current flows through the posistor into the degaussing coil for demagnetization.

Meanwhile, the resistance of the posistor increase rapidly due to rising of its temperature, the
degaussing current thus decreases to less then 100mAp-p in a few seconds so that display screen
settles quickly, degaussing function is then complete. After 5 seconds, the voltage at pin26 of I201 is
LOW, then Q803 OFF and RL01 release.

6.4 Micro Control Circuit

MTV212AN32 / MTV212AN64

The monitor uses an advanced CPU I201 to control the Contrast, Brightness, H. Position, H.
Width, V. Position, V. Height, Pincushion, Trapezoid and Parallelogram, Zoom, Recall.

The horizontal sync. and vertical sync. are via R254, R256 then fed to pin39, pin40 of I201. The
output sync signals are fed to pin1 and pin2 of deflection processor I401 via pin33, pin32 of I201.

The control signals on pin1, pin2 are for PWM (Pulse Width Modulation) which are converted
into DC voltages via integration circuits. With the Brightness control signal as an example, the PWM
control signal is derived from pin2 of I501 which is fed into a integration circuit R209, C202