Sony KV-27EXR25 PHOTOFACT Technical Service Data

PHOTOFACT,

Technical Service Data

INDEX

Adjustment and Alignment Tools

....

1

Convergence Adjustments

..........

6

GridTrace

Location Guide

ABoard ....................

.8

..9

GBoard ....................

.9
.8

PBoard-TopBoard

...........

8

UlBoard

.9

...................

.9

Important Parts Information

........

10

Miscellaneous Adjustments

.........

6

PartsList ................. 9,10,11

Photos

ABoard ..................

.7,8

CBoard ....................

.9

Cabinet - Rear View

...........

1

CRT Neck Assembly

..........

6

GBoard ....................

.9

HBoard ....................

.8

PBoard-BottomBoard .....

.7,8

PBoard-TopBoard

........

.7,8

Ul

Board

.................

.4,9

U2Board .................

.8,9

!

Troubleshooting Quick-Checks

ABoard ....................

.7

CBoard ....................

.9

PIP Adjustments

..................

6

Placement Chart

.................

.5

Safety Precautions

...............

1

Safety Related Adjustments

.........

6

Schematics

CRT

.......................

.2

Control

...................... .

D/A Converter

................

2

MTS Decoder

...............

.3

PIP

..........................

4

Power Supply

................

.4

Television

...................

.2

Terminal Guides and Notes

........

.7

Test Equipment

...................

1

Troubleshooting

...................

1

Tuner Terminal Guide

.............

6

Tuner Voltage Chart

...............

6

For Supplier Address,

See PHOTOFACT Annual Index

SONY

Model

W-27EXR25

(Chassis SCC-D50F-A)

Complete coverage

for servicing a television receiver...

l

Schematics

l

Component
locations

l

Parts lists

l

Troubleshooting

guide

Coverage includes this additional model and chassis:

MODEL

CHASSIS

KV-27EXR20

SCC-DSOE-A

HOWARD

W.

SAMS & COMPANY

DECEMBER 1991 SET 2910

TROUBLESHOOTING

POWER SUPPLY

Check AC Fuse F60 1.

If

F60

1 is open:

Check Bridge Rectifier Diodes (D601, and D602), Resistor

(R601), Capacitors. C601, C603 thru C606, Electrolytics C607,

and C650, Power Converter IC (IC65

l),

and Power Transformer

(T604).

Apply 120V and check for

17.OV

at the (+) lead of D602.

If

17.OV

is missing:

Check Line Filters (T601, T602), Power Transformer (T604),

Capacitors C608, C609, Electrolytic C610, and

D602.

If

17.OV

is present, check for

15OV*

at the (+)

lead

of D601.

If

15OV*

is missing:

Check the voltages, waveforms, and components associated
with Power Relay (RY601), and Relay Driver Transistor

(Q601), and D601.

Note: The set may be in shutdown. Refer to the “High Voltage
Shutdown” section of this Troubleshooting guide.

If

15OV*

is present at the (+) lead of D601, check for the proper wa-

veform at pin 1 of IC65 1.
If the waveform is missing:

Check the voltages, waveforms, and components associated
with IC65 1, Transfer IC (IC652), Converter Transformer

(T651), and Soft Start Transistor

(4612).

If the proper waveform is present at

pin

1 of IC65 1:

Check the voltages, waveforms, and components associated
with T6.5 1.

* Taken from isolated ground.

HIGH VOLTAGE SHUTDOWN

The

high voltage is monitored by Diode D531, rectifying pulses

from the Horizontal Output Transformer (T500). Should the high

,voltage increase, the rectified voltage at the cathode of Diode D531

will also increase, This will cause the voltage at pin 8 of Protect
Module (PM501) to increase and turn on Protect Transistors (Q607,

4608)

which causes Relay Drive Transistor (4601) to turn off and

remove power from the set.
To troubleshoot, remove Resistor R629 fom the circuit. Use a

variac

for AC power. Start at 90VAC and increase as

necessary

to locate

and repair the defect. Return R629 to the circuit.
Note: Care should be taken in defeating the high voltage shutdown

circuit, as this may cause excessive X-radiation and damage the
CRT,

TSOO,

and associated components. Monitor the high voltage

and troubleshoot.

HORIZONTAL

Determine if the TV is in shutdown:

Refer to the “High Voltage Shutdown” section of this
Troubleshooting guide.

If the TV is not in shutdown, inject a horizontal signal at the base of
the Horizontal Output Transistor

(4502).

If horizontal deflection is now present:

Check the voltages, waveforms, and components associated
with pins

37,39,41,

and 45 of Y/C/J IC (IC301), and

Horizontal Drive Transistor (Q501).

If there is no horizontal sweep:

Check the voltages, waveforms, and components associated
with

4502,

and Horizontal Output Transformer

(T500),

and
check components associated with Diodes D5 17, D5 19, D520,
D521, and D531 for defects.

The high voltage rectifier is part of T500 and if defective will effect
the performance of the horizontal circuits.

If the horizontal oscillator is off frequency:

Check the voltages, waveforms, and components associated
with AFC-DET Transistor (Q307), and Buffer Transistor

(Q3W.

Horizontal linearity or

foldover

problems may be caused by Capaci-

tors C506, C507, and C509 beiig defective.

VERTICAL

Inject a vertical drive signal at pin 3 1 of Y/C/J IC (IC301).
If vertical deflection is now present:

Check the voltages, waveforms, and components associated

with pins 29

thrn 34,38,

and 44 of IC301.

If there is still no vertical deflection:

Check the voltages, waveforms, and components associated

with Vert Out IC

(ICSOO).

Vertical linearity or

foldover

problems may be caused by pincush-

ion, vertical feedback and

bias

circuits:

Check the voltages, waveforms, and components associated
with Pin Correction IC (IC531) and Pin Out Transistor (4530).

Also check Electrolytics C328, C538, C540, C562, C563, and

C566 for defects.

IF-AGC

Inject a video signal at the IF input and check for video on the CRT.
If video is present:

Check the tuner, tuner control, and tuner AFC circuits.

TROUBLESHOOTING

continued

If there is no video on the CRT, check for a video waveform at
TP12.

If video is present at TP12:

Refer to the “Video” section of this Troubleshooting guide.

If there is no

video

at TP12:

Check the voltages, waveforms, and components associated
with IF Module

(IF201),

and AGC Mute Transistor

(Q102).

A defective AGC circuit can cause an overloaded picture, excessive

snow or loss of audio and video.
See the AGC Voltage Chart for AGC voltages with signal.

AGC Voltage Chart

IF201

pm 1 5.3v

SYNC

If there is no vertical or horizontal sync:

Check the voltages, waveforms, and components associated
with Y Buffer Transistor (4301).

If there is no vertical sync:

Check the voltages, waveforms, and components associated

with pins 38, and 44 of Y/C/J IC

(IC301), V/Sext

1 Transistor

(Q302), V/Sext

2 Transitor

(Q303),

and

V/Sext

3 Transistor

(Q3W.

If there is no horizontal sync:

Check the voltages, waveforms, and components associated
with pins 41, and 45 of

IC301.

VIDEO

Inject a signal at

TP12,

and check for video on the CRT

If video is present:

Refer to the

“IF-AGC”

section of this

Troubleshooting

guide.

If there is no video on the CRT, check for a video waveform at pin 6
of Comb Filter (CM1301).

If video is missing at pm 6 of CM1301:

Check the voltages, waveforms, and components associated
with Buffer Transistors (4409,

Q410),

and AV-Switch IC

(IC444),

and CM1301.

If video is present at pin 6 of CM1301, check for a video waveform
at the emitter of Y Amp Transistor (4305).

If the video is missing:

Check the voltages, waveforms, and components associated
with 4305, Buffer Transistor

(Q416),

and Y Switch IC

(IC402).

If the waveform is present at the emitter of 4305:

Check the voltages, waveforms, and components associated
with pins

3,4,8,26,

and 27 of Y/C/J IC

(IC301),

Buffer

Transistors (43

lO,Q3 13),

Gamma Comp 1 Transistor (43

15),

and Equalizer Transistor (43

14).

Y Clamp Transistor (43

17),

and Gamma Comp 2 Transistor (4316).

If brightness is inadequate or

camrot

be

controll&

Check the voltages, waveforms, and components associated
with pin 5 of v901.

CHROMA

Check for a chroma waveform at pm 5 of Y/C/J IC (X301).
If the waveform is missing:

Check the voltages, waveforms, and components associated
with Buffer Transistor

(Q417),

C-Switch IC

(IC403),

and pin 4

of Comb Filter (CM1301).

If chroma waveform is present at pin 5 of

IC30

1, cheek for the

pmp

er waveforms at pins

20,22,24

of

IC301.

If these waveforms are missing:

Check the voltages, waveforms, and components associated
with pins

5,6,7,19

thru 25 of

IC301.

Check the

3.58MHz

oscillator at pin 7 of

IC301.

If the proper wavforms are present at pins

20,22,24

of

IC301:

Refer to the “Raster” section of this Troubleshooting guide.

RASTER

Check the CRT and CRT voltages. Cheek the voltages, waveforms,
and components associated with Buffer Transistor

(Q711),

SW 1

Transistor

(Q710),

and SW 2 Transistor (4712).

If there is no Red:

Cheek the voltages, waveforms, and components associated
with pin 20 of Y/C/J IC

(IC301),

Red Output Transistor

(4708).

Video Amp Transistor

(Q709),

and Red 1K Det Transistors

(Q707,Q7

16).

If there is no Green:

Check the voltages, waveforms, and components associated
with pin 22 of

IC301,

Green Output Transistor

(Q704),

Video

Amp Transistor

(Q705),

and Green 1K Det Transistors (4706,

47 15).

If there is no Blue:

Check the voltages, waveforms, and components associated
with pm 24 of

IC301,

Blue Output Transistor

(Q701),

Video

Amp Transistor

(Q702),

and Blue 1K Det Transistors

(4703,

47 14).

If the raster has a keystone shape:

Check the Deflection Yoke

(L550).

TROUBLESHOOTING

continued

SET 2910 Page 1

If the raster has height or width problems:

Refer to “Vertical”, “Horizontal”, and “Power Supply” sections
of this Troubleshooting guide.

AUDIO

Select an

active TV channel and check for an audio waveforms at

pins 1 and 2 of MTS Decode IC (IC25 1).
If there is no audio:

Check the voltages, waveforms, and components associated
with IC25 1, and pin 10 of IF Module (IF201).

If audio waveforms are present at pins 1 and 2 of IC251, cheek for
audio waveforms at pins 1 and 5 of Audio Amp IC (IC405).

If audio waveforms are missing:

Check the voltages, waveforms, and components associated
with Audio Buffer Transistors (4430, Q431), and Buffer
Transistors

(4202,Q203).

If audio waveforms are present at pins 1 and 5 of IC405:

Check the voltages, waveforms, and components associated

with IC405, Audio Mute Transistors

(4432,

Q433), and Mute

Transistor (Q 103).

PIP HORIZONTAL

Check for the proper waveforms at pin 9 of A/D Conv IC (IC2206),
and pin 24 of PIP Control IC (IC2204).

If the waveforms are missing:

Check the voltages, waveforms, and components associated
with pins

4,6

thru 10, and 28 of Y/C/J IC (IC2103), pins 8 and

9 of IC2 104, Horizontal Pulse Transistor

(42 120),

Horizontal

Out Transistor (4212

l),

and Horizontal Drive Transistor

(42122).

If waveforms are present, cheek for the proper waveform at pin 60 of

IC2204.

If waveform at pin 60 of IC2204 is missing:

Check the voltages, waveforms, and components associated
with Horizontal Width IC (IC2

102),

Horizontal Pulse Transistor

(Q2117), and pin 39 of Y/C/J IC (IC301).

If waveform at pin 60 of IC2204 is present:

Check the voltages, waveforms, and components associated
with IC2204, and IC2206.

PIP VERTICAL

Check for the proper waveform at pin 23 of PIP Cont IC (IC2204).
If the waveform is missing:

Check the voltages, wavefotms, and components associated
with pins 10 thru 13 of IC2104, Vertical Pulse Transistor

(Q2119), and pins 5 and 36 of Y/C/J IC (IC2103).

If waveform is present at pin 23 of IC2204, check for the proper wa­veform at pin 61 of IC2204.

If waveform is missing:

Check the voltages, waveforms, and components associated
with pins 1 and 2 of IC2 104, and Buffer Transistor

(43

12)

If waveform is present at pin 23 of IC2204:

Check the voltages, waveforms, and components associated
with IC2204.

PIP SYNC

If there is no vertical or horizontal sync:

Check the voltages, waveforms, and components associated
with V Buffer 3 Transistor (Q2125), and Buffer Transistor

(42130).

If there is no vertical sync:

Check the voltages, waveforms, and components associated
with pm 5 of Y/C/J IC (IC2103).

If there is no horizontal sync:

Check the voltages, waveforms, and components associated
with pin 4 of IC2103.

PIP VIDEO

Check for the proper waveform at pin 34 of Y/C/J IC (IC2103).
If video is missing at pin 34 of IC2 103:

Cheek the voltages, waveforms, and components associated
with V Buffer 1 Transistor (Q2245), V Buffer 2 Transistor

(Q2123), Buffer Transistor (Q413), and AV-SW IC (IC444).

If video is present at pin 34 of IC2103, check for a

video

waveform

at pin 16 of A/D Conv IC (IC2206).
If the waveform is missing:

Check the voltages, waveforms, and components associated
with Y Out Transistor (Q2139), Y Buffer 2 Transistor

(Q2102),

Y Amp Transistor

(42

10

l),

Y Buffer 1 Transistor

(42 116),

and

pins

14,21,23,25,30,32,33,

of Y/C/J IC (IC2103).

If waveform is present at pin 16 of IC2206, check for the proper wa­veform at pm 4 of Y D/A Conv IC (IC2201).

If the waveform is missing at at pin 4 of IC2201:

Check the voltages, waveforms, and components associated
with IC2201, pins

1,46

thru 5 1, and 54 of IC2204.

Cheek for the proper waveform at the emitter of YS Buffer Trans­mitter (42244).

TROUBLESHOOTING continued

If the wave form is missing at the emitter of

Check the voltages, waveforms, and components associated
with 42244, pins 3 thru 6 of IC2 104, and pin 3 1 of IC2204.

If the waveform is present at pin 4 of IC2201:

Check the voltages, waveforms, and components associated
with Y Buffer Transistor (42202).

42244:

PIP CHROMA

Check for the waveforms at pins 20 and 22 of\Y/C/J IC (IC2103).
If the waveforms are missing:

Check the voltages, waveforms, and components associated
with pins 16 thru 22, and 31 of IC2 103.

Check the 3.58MHz oscillator at pins 15 and 18 of IC2103.
Check the voltages and components associated with Sub Color

Control and pin 13 of IC2103.
Check the voltages and components associated with Sub Hue

Control and pin 12 of IC2103.

If chroma waveform is present at pins 20 and 22 of IC2103, check
for the proper waveforms at pins 17 and 18 of A/D Conv IC

(IC2206).

If the waveforms are missing at pins 17 and 18 of IC2206:

Check the voltages, waveforms, and components associated
with R-Y Out Transistor (Q2103), and B-Y Out Transistor
(42114).

If the waveforms are present at
the proper waveforms at pins 4 of R-Y D/A Conv IC (IC2202), and
B-Y D/A Conv IC (IC2203).

If the waveforms am missing at pin 4 of IC2202, and IC2203:

Check the voltages, waveforms, and components associated

with IC2202, IC2203, PINP Conv IC (IC2204), and IC2206.

If the waveforms are present at pin 4 of IC2202, and IC2203:

Check the voltages, waveforms, and components associated

with R-Y Buffer Transistor (Q2203), B-Y Buffer Transistor

(Q2204), Red Drive Transistor (Q2106), Blue Drive Transistor

(Q2107), and Green Drive Transistor (42109).

pins

17 and 18 of IC2206, check for

SET 2910 Page 1