Tatung VM9AF Schematic

VM-9AF

SERVICE MANUAL

CONTENTS

1 SPECIFICATION

2 OPERATING INSTRUCTIONS

3 IMPORTANT SAFEGUARDS

4 ADJUSTMENT PROCEDURE

5 BLOCK DIAGRAM

6 SERVICE NOTES

7 CIRCUIT DIAGRAM

8 LAYOUT DIAGRAM

9 EXPLODED DRAWING

10 PARTS LIST

1 SPECIFICATION

9” Mono Chrome Monitor

CRT SIZE : 10” 90 DEGREES, 20 O

PHOSPHOR : H68

FACEPLATE : SILICA NON-GLARE

SCAN FREQ. : HOR. 31, 5KHZ, 35.5KHZ, 38KHZ
VERT. 50-90HZ

RESOLUTION : 640X480, 800X600, 1024X768

BANDWIDTH : 26MHZ, 35MHZ, 45MHZ

VIDEO SIGNAL : R.G.B. INPUT, 1V p.p. MAX.

SYNC INPUT TYPE : H-SYNC, V-SYNC TTL

INPUT CONNECTOR : 15PIN D SHELL

USER CONTROL : BRI, CON, POWER SW, V-LINE, H-PHASE

INPUT VOLTAGE : AC 100 ~ 240V, 50/60Hz (AUTO)

POWER CONSUMPTION: 32W MAX.

DIMENSION : 237W X 237H X 248D mm

NET WEIGHT : 3.8Kg

SAFETY : UL, CSA, DHHS, TUV-GS, MPR II

EMI : FCC-B, CE

2

2-1 POWER SWITCH

2-2 POWER-ON INDICATOR

2-3 BRIGHTNESS CONTROL

2-4 CONTRAST CONTROL

2-5 HORIZONTAL-PHASE CONTROL

2-6 VERTICAL-SIZE CONTROL

2-7 FOCUS CONTROL

OPERATING INSTRUCTIONS

Power on/off switch is a push button. To turn on the power of the unit,
press this switch. To turn off the unit, press it again.

The power-on indicator when the power is turned on.

Turn the brightness control clock-wise to increase the brightness and
counter clock-wise to decrease it.

Turn the contrast control clock-wise to increase the contrast and counter
clock-wise to decrease it.

Turning the control clock-wise will adjust the screen to the left and counter
clock-wise will adjust the screen to the right.

To adjust vertical size for all modes: turn the control clock-wise or counter
clock-wise until a suitable height is achieved.

The focus control can be adjusted for optimum focus.

3 IMPORTANT SAFEGUARDS

For your own safety, read all of these instructions and save them for later
reference.

3-1 POWER PLUG

This display monitor is equipped with a 3-wire grounding type power plug.
The third pin provides a safety ground for the display frame and will fit
only into the power outlet of compatible configuration.

Contact your technician to replace the obsolete outlet. Do not defeat the
safety purpose of the grounding plug.

3-2 POWER INPUT

This display should be operated only from the types of power source
indicated on the label. If there is any question about the type of power
supplied to the outlet, consult your technician or dealer.

3-3 VENTILATION

Openings on the cabinet back and bottom are provided for ventilation. To
insure reliable operation and to protect the display from overheating, these
openings must not be blocked or covered. Do not place the display near or
over a radiator or heating vent. If this unit is installed within another
enclosure be sure that adequate ventilation has been provided.

Never push objects of any kind through the cabinet openings. They may
touch dangerous voltage points or cause short circuits that could result in
fire or electrical shock.

3-4 ATTACHMENTS

Signal sources must be of approved types and properly grounded. If safety
standards are to be maintained ask the service technician to perform routine
safety tests to determine that all equipment is in safe operation condition.

Overloaded or poorly grounded AC power systems can cause severe
difference in ground potential between the display and the signal source,
particularly on long video lines where the display and the source are
plugged into different AC power circuits. Besides causing signal
instability, ground potential may be great enough to present a shock hazard.
Ground potential tests should be part of the routine safety check ma de by
the service technician.

3-5 CLEANING

Unplug the power cord from the outlet before cleaning the display . Use
only a damp cloth and mild detergent. Do not use strong liquid cleaner or
aerosol sprays. Do not attempt to clean the interior of the unit: this action
must be performed by the service technician as required during normal
maintenance.

3-6 SERVICE

Removal of the back by an unauthorised person may expose the user to
dangerous voltage or other hazards.

Refer all servicing to qualified service personnel. Unplug the display from
the power outlet and notify the service technician should any of the
following occur

(a) If liquid has been split into the display.
(b) If the display has been exposed to rain or water.
(c) If the display has been dropped or the cabinet damaged.
(d) If fuses continue to blow.
(e) If the power cord is damaged or frayed.
(f) If a distinct change from normal operation is apparent.

4 ADJUSTMENT PROCEDURE

This alignment procedure is for adjusting/testing picture performance. In
order to obtain the optimum result the follow ing adjustment sequence must
be followed step by step:

4-1 Check B+ voltage:

(a) test pattern: cross hatch
(b) set up external brightness and contrast VR to central position
(c) make sure 28Vdc±0.1Vdc use digital m ultimeter positive leader test

D909 negative point, negative leader to ground.

4-2 Vertical Linearity adjustment:

(a) test pattern: cross hatch
(b) set up external brightness and contrast VR to central position
(c) adjust VR301 to make equal distance between top-centre and bottom-

centre.

4-3 Horizontal-hold adjustment

(a) test pattern: cross hatch
(b) set up external brightness and contrast VR to central position
(c) turn off horizontal-sync (pin to ground)
(d) adjust VR402 to make pattern upright.

4-4 Geometric distortion pattern adjustment:

(a) test pattern: cross hatch
(b) set up external brightness and contrast VR to central position
(c) adjust eight magnets on the deflection yoke to make picture to its

best condition.

4-5 Video centering adjustment:

(a) test pattern: cross hatch
(b) the video is centered by rotating the two small rotary controls at the

rear of the yoke.

4-6 Horizontal-width adjustment:

(a) test pattern: cross hatch
(b) set up external brightness and contrast VR to central position
(c) adjust L403 to make picture width within 165±4 mm

4-7 Vertical height adjustment

(a) test pattern: cross hatch
(b) set up external brightness and contrast VR to central position.
(c) Adjust VR302 to make height to 120±4 mm.

4-8 Vertical-hold (Free-run 52Hz) adjustment:

(a) disconnect video signal
(b) use frequency counter ⊕ leader, measure vertical yoke point,

adjustment VR303 make frequency value to 52Hz.

4-9 Raster adjustment:

(a) disconnect video signal
(b) set up external brightness VR to maximum, external contrast VR to

maximum.

(c) Adjust VR403 to have luminance equal to 0.5 ~ 1.0 FL.

4-10 Brightness check:

(a) test pattern: full white
(b) set up external brightness and contrast VR to maximum position
(c) over 60 FL.

4-11 Focus adjustment:

(a) test pattern: “H” character pattern
(b) set up external brightness and contrast VR to central position
(c) adjust VR404 have central picture and 4 corners to be distinguished.