Sony Ba5 Service Manual

							TRINITRON® COLOR TELEVISION
  SERVICE MANUAL            BA-5 CHASSIS
       MODEL NAME REMOTE COMMANDER DESTINATION  CHASSIS NO. 
KV-25FS12
9-965-902-01
KV-25FS12 RM-Y173  E  SCC-S38UA
KV-25FS12C RM-Y173  E  SCC-S38VA
RM-Y173 
						

							— 2 —
KV-25FS12 / 25FS12C
TABLE OF CONTENTS
  Specifi cations...................................................\o.................................................................................... 3
  Warnings and Cautions...................................................\o..................................................................... 4
  Safety Check-out ...................................................\o.............................................................................. 5
  Self-Diagnostic Function ...................................................\o................................................................... 6
1. Disassembly
  1-1. Rear Cover Removal...................................................\o.................................................................. 8
  1-2. Chassis Assembly Removal...................................................\o....................................................... 8
  1-3. Service Position ...................................................\o......................................................................... 8
  1-4. Picture Tube Removal ...................................................\o................................................................ 9
    Anode Cap Removal Procedure...................................................\o................................................9
2. Set-up Adjustments
  2-1. Beam Landing...................................................\o............................................................................ 10
  2-2. Convergence...................................................\o.............................................................................. 11
  2-3. Focus ...................................................\o...............................................................\o.......................... 12
  2-4. Screen (G2) ...................................................\o............................................................................... 12
  2-5. Method of Setting the Service Adjustment Mode...................................................\o....................... 13
  2-6. White Balance Adjustments ...................................................\o....................................................... 13
3. Safety Related Adjustments
  3-1. 
X R564 Confi rmation Method (HV Hold Down Confi rmation) and Readjustments ..................... 14
  3-2. B+ Voltage Confi rmation and Adjustment ...................................................\o.................................. 14
4. Circuit Adjustments
  4-1. Setting the Service Adjustment Mode...................................................\o........................................ 16
  4-2. Memory Write Confi rmation Method ...................................................\o.......................................... 16
  4-3. Remote Adjustment Buttons and Indicators ...................................................\o..............................16
    Adjustment Items...................................................\o....................................................................... 17
  4-4. MB Board Adjustments ...................................................\o.............................................................. 19
5. Diagrams
  5-1. Circuit Boards Location...................................................\o.............................................................. 21
  5-2. Printed Wiring Boards and Schematic Diagrams ...................................................\o....................... 21 
  5-3. Block Diagram...................................................\o............................................................................ 22
    A Board ...................................................\o...............................................................\o...................... 24
    CB Board ...................................................\o...............................................................\o.................... 28
    K Board ...................................................\o...............................................................\o...................... 30
    MB Board ...................................................\o...............................................................\o................... 31
    VB Board ...................................................\o...............................................................\o.................... 35
  5-4. Semiconductors ...................................................\o......................................................................... 36
6. Exploded Views
  6-1. Chassis ...................................................\o...............................................................\o....................... 37
 
7. Electrical Parts List...................................................\o...................................................\o................................ 38      SECTION TITLE PAG E 
						

							— 3 —
KV-25FS12 / 25FS12C
Television system
NTSC
Channel coverage
VHF: 2-13/ VHF: 14-69/ CATV: 1-125
Picture tube
Flat Trinitron® tube
Visible screen size
25-inch picture measured diagonally
Actual screen size
27-inch measured diagonally
Antenna
75 ohm external terminal for VHF/UHF
Supplied Accessories
Remote Commander RM-Y173
Size AA (R6) batteries (2)
Dipole Antenna
Optional Assessories
Connecting cables: VMC-810S/820S, VMC-720M,
YC-15V/30V, RK74A
U/V mixer EAC-66
SPECIFICATIONS
Design and specifi cations are subject to change without notice.
1)    1 Vp-p 75 ohms unbalanced, sync negative 2)    Y:  1 Vp-p 75 ohms unbalanced, sync negative 
     C:  0.286 Vp-p (Burst signal), 75 ohms
3)    500 mVrms (100% modulation), Impedance:  47 kilohms4)   More than 408 mVrms at the maximum volume setting (variable)
  More than 408 mVrms (fi x); Impedance (output): 2 kilohms
KV-25FS12KV-25FS12C
Power requirements120V, 60Hz 220V, 50/60Hz
Number of Inputs/Outputs
Video 
1)2
S Video 2)1
Audio 3)2
Audio Out 4)1
Headphone Out
Speaker output (W)7.5 x 2
Power Consumption (W)
In use (Max)165W
In Standby1W
Dimensions(W/H/D)
mm614.8 x 564.1 x 499.7
in24 
13/64 x 22 13/64 x 19 49/64
Mass
kg
36 kg
lbs
79 lbs 6 oz.1 
						

							— 4 —
KV-25FS12 / 25FS12C
WARNINGS AND CAUTIONS
CAUTION
Short circuit the anode of the picture tube and the anode cap to the metal chassis, CRT shield, or carbon painted on the CRT, 
after removing the anode.
WARNING!!
An isolation transformer should be used during any service to avoid possible shock hazard, because of live chassis. The chassis of 
this receiver is directly connected to the AC power line.
! SAFETY-RELATED COMPONENT WARNING!!
Components identifi ed by shading and ! mark on the schematic diagrams, exploded views, and in the parts list are critical for 
safe operation. Replace these components with Sony parts whose part numbers appear as shown in this manual or in supplements 
published by Sony. Circuit adjustments that are critical for safe operation are identifi ed in this manual. Follow these procedures 
whenever critical components are replaced or improper operation is suspected. 
ATTENTION!!
Apres avoir deconnecte le cap de l’anode, court-circuiter l’anode du tube cathodique et celui de l’anode du cap au chassis metallique 
de l’appareil, ou la couche de carbone peinte sur le tube cathodique ou au blindage du tube cathodique.
Afi n d’eviter tout risque d’electrocution provenant d’un chássis sous tension, un transformateur d’isolement doit etre utilisé lors de tout 
dépannage. Le chássis de ce récepteur est directement raccordé à l’alimentation du secteur.
! ATTENTION AUX COMPOSANTS RELATIFS A LA SECURITE!!
Les composants identifi es par une trame et par une marque ! sur les schemas de principe, les vues explosees et les listes de 
pieces sont d’une importance critique pour la securite du fonctionnement. Ne les remplacer que par des composants sony dont 
le numero de piece est indique dans le present manuel ou dans des supplements publies par sony. Les reglages de circuit dont 
l’importance est critique pour la securite du fonctionnement sont identifi es dans le present manuel. Suivre ces procedures lors de 
chaque remplacement de composants critiques, ou lorsqu’un mauvais fonctionnement suspecte. 
						

							— 5 —
KV-25FS12 / 25FS12C
SAFETY CHECK-OUT
After correcting the original service problem, perform the following 
safety checks before releasing the set to the customer:
1.  Check the area of your repair for unsoldered or poorly soldered 
connections. Check the entire board surface for solder splashes and 
bridges.
2.  Check the interboard wiring to ensure that no wires are “pinched” or 
touching high-wattage resistors.
3.  Check that all control knobs, shields, covers, ground straps, and 
mounting hardware have been replaced. Be absolutely certain that 
you have replaced all the insulators.
4.  Look for unauthorized replacement parts, particularly transistors, 
that were installed during a previous repair. Point them out to the 
customer and recommend their replacement.
5.  Look for parts which, though functioning, show obvious signs of 
deterioration. Point them out to the customer and recommend their 
replacement.
6.  Check the line cords for cracks and abrasion. Recommend the 
replacement of any such line cord to the customer.
7.  Check the B+ and HV to see if they are specifi ed values. Make sure 
your instruments are accurate; be suspicious of your HV meter if sets 
always have low HV.
8.  Check the antenna terminals, metal trim, “metallized” knobs, screws, 
and all other exposed metal parts for AC leakage. Check leakage 
as described below.Leakage Test
The AC leakage from any exposed metal part to earth ground and from 
all exposed metal parts to any exposed metal part having a return to 
chassis, must not exceed 0.5 mA (500 microamperes). Leakage current 
can be measured by any one of three methods.
1.  A commercial leakage tester, such as the Simpson 229 or 
RCA WT-540A. Follow the manufacturers’ instructions to use these 
instructions.
2.  A battery-operated AC milliampmeter. The Data Precision 245 digital 
multimeter is suitable for this job.
3.  Measuring the voltage drop across a resistor by means of a VOM 
or battery-operated AC voltmeter. The “limit” indication is 0.75 V, 
so analog meters must have an accurate low voltage scale. The 
Simpson’s 250 and Sanwa SH-63TRD are examples of passive VOMs 
that are suitable. Nearly all battery-operated digital multimeters that 
have a 2 VAC range are suitable (see Figure A).
How to Find a Good Earth Ground
A cold-water pipe is a guaranteed earth ground; the cover-plate retaining 
screw on most AC outlet boxes is also at earth ground. If the retaining 
screw is to be used as your earth ground, verify that it is at ground 
by measuring the resistance between it and a cold-water pipe with an 
ohmmeter. The reading should be zero ohms.
If a cold-water pipe is not accessible, connect a 60- to 100-watt trouble- 
light (not a neon lamp) between the hot side of the receptacle and the 
retaining screw. Try both slots, if necessary, to locate the hot side on the 
line; the lamp should light at normal brilliance if the screw is at ground 
To Exposed Metal 
Parts on Set
0.15  F1.5 K Ω
AC
Voltmeter
(0.75 V)
Earth Ground
Trouble Light
AC Outlet BoxOhmmeter
Cold-water Pipe
Figure A. Using an AC voltmeter to check AC leakage. Figure B. Checking for earth ground. 
						

							— 6 —
KV-25FS12 / 25FS12C
Detected Symptoms
SELF-DIAGNOSTIC FUNCTION
*If a +B overcurrent is detected, stoppage of the vertical defl ection is detected simultaneously.  The symptom that is diagnosed fi rst by the 
mircrocontroller is displayed on the screen.
**Refer to Screen (G2) Adjustments in Section 2-4 of this manual.
Display of Standby/Timer LED Flash Count
2 times
4 times
5 times
LED ON 0.3 sec.
LED OFF 0.3 sec.LED OFF
3 sec.
  Diagnostic Item    Flash Count*
  +B Overcurrent    2 times
  V-STOP      4 times
  IK (AKB)      5 times
  *One fl ash count is not used for self-diagnostic.
Stopping the Standby/Timer LED Flash
Turn off the power switch on the TV main unit or unplug the power cord from the outlet to stop the STANDBY/TIMER LAMP from fl ashing.
Standby/Timer LED
The units in this manual contain a self-diagnostic function. If an error occurs, the STANDBY/TIMER LED will automatically begin to fl ash. The number 
of times the LED fl ashes translates to a probable source of the problem. A defi nition of the STANDBY/TIMER LED fl ash indicators is listed in the 
instruction manual for the user’s knowledge and reference. If an error symptom cannot be reproduced, the Remote Commander can be used to review 
the failure occurrence data stored in memory to reveal past problems and how often these problems occur.
Diagnostic Test Indicators
When an error occurs, the STANDBY/TIMER LED will fl ash a set number of times to indicate the possible cause of the problem. If there is more than 
one error, the LED will identify the fi rst of the problem areas.
Results for all of the following diagnostic items are displayed on screen. If the screen displays a “0”, and error has occurred.
Power does not turn on 
+B overcurrent (OCP)* 
I-Prot
IK (AKB)Does not light
2 times
4 times
5 times2:0 or 2:1
4:0 or 4:1
5:0 or 5:1• Power cord is not plugged in.
• Fuse is burned out (F601). (A Board)
• H.OUT (Q502) is shorted.(A Board)
• IC702 is shorted. (CB Board)
• +13V is not supplied. (A Board)
• IC502 is faulty. (A Board)
• Viedo OUT (IC502) is faulty. (A Board)
• IC1301 is faulty.  (MB Board)
• Screen (G2) is improperly adjusted.** No. of times 
STANDBY/  TIMER 
lamp fl ashes   Diagnostic Item 
DescriptionSelf-Diagnositc 
Display/ 
Diagnostic ResultProbable Cause Location
• Power does not come on.
• No power is supplied to the TV.
• AC Power supply is faulty.
• Power does not come on.
• Load on power line is shorted.
• Has entered standby state after horizontal raster.
• Vertical defl ection pulse is stopped.
• Power line is shorted or power supply is stopped.
• No raster is generated.
• CRT Cathode current detection reference pulse  
 
 
 
 
 
output is small. 
						

							— 7 —
KV-25FS12 / 25FS12C
Self-Diagnostic Screen Display
For errors with symptoms such as “power sometimes shuts off ” or “screen sometimes goes out” that cannot be confi rmed, it is possible to bring up 
past occurrences of failure on the screen for confi rmation.
To Bring Up Screen Test
In standby mode, press buttons on the Remote Commander sequentially, in rapid succession, as shown below:
Display   Channel 5  
 
    Sound Volume -  Power ON
Self-Diagnostic Screen Display
Numeral “0” means that no fault was detected.
Numeral “1” means a fault was detected one time only.
SELF DIAGNOSTIC
2:  000 
3:  N/A 
4:  000 
5:  001 
101: N/A 
Handling of Self-Diagnostic Screen Display
Since the diagnostic results displayed on the screen are not automatically cleared, always check the self-diagnostic screen during repairs. When you 
have completed the repairs, clear the result display to “0”.
Unless the result display is cleared to “0”, the self-diagnostic function will not be able to detect subsequent faults after completion of the repairs.
Clearing the Result Display
To clear the result display to “0”, press buttons on the Remote Commander sequentially when the diagnostic screen is displayed, as shown below:
Channel 
8  ENTER
Quitting the Self-Diagnostic Screen
To quit the entire self-diagnostic screen, turn off the power switch on the Remote Commander or the main unit.
Self-Diagnostic Circuit
+B overcurrent (OCP) 
Occurs when an overcurrent on the +B (135V) line is detected by pin 18 of IC1301 (MB Board). If the voltage of pin 18 of IC1301 (MB Board) is less 
than 1V when V.SYNC is more than seven verticals in a period, the unit will automatically turn off. 
I-Prot 
Occurs when an absence of the vertical defl ection pulse is detected by pin 17 of IC1001 (MB Board). Power supply will shut down when waveform 
interval exceeds 2 seconds. 
IK (AKB) 
If the RGB levels* do not balance within 2 seconds after the power is turned on, this error will be detected by IC1301 (MB Board). TV will stay 
on, but there will be no picture.
*(Refers to the RGB levels of the AKB detection Ref pulse that detects 1K).Note that this differs from entering the Service Mode (Sound Volume 
+
 ).
MB BOARD
IC1301
Y/CHROMA JUNGLEA BOARD
IC502
V. OUTMB BOARD
IC1001
SYSTEMMB BOARD
IC1003
MEMORY
IK IN FROM
CB BOARD
IC702 PIN 5
HP/PROTECT
SDA A BOARD
FROM
IC501
PIN 318
IO-SDATO-LED REF
I-ProtIO-BDAT
BDA
DISPLAY
21
35
317
3718
365 
						

							— 8 —
KV-25FS12 / 25FS12C
1-1.  REAR COVER REMOVAL
1-2.  CHASSIS ASSEMBLY REMOVAL 1-3.  SERVICE POSITION
SECTION 1:  DISASSEMBLY
2 Screws +BVTP 4x16
Chassis Assembly
CB Board
VB Board
MB BoardA Board 2 Screws +BVTP 4x16
2 Screws +BVTP 4x16
2 Screws +BVTP 3x10
K Board 
						

							— 9 —
KV-25FS12 / 25FS12C
1.  Discharge the anode of the CRT and remove the anode cap.
2.  Unplug all interconnecting leads from the defl ection yoke, neck 
assembly, degaussing coils and CRT grounding strap.
3.  Remove the CB Board from the CRT.
4.  Remove the chassis assembly.
5.  Loosen the neck assembly fi xing screw and remove.
6.  Loosen the defl ection yoke fi xing screw and remove.
7.  Place the set with the CRT face down on a cushion and remove 
the degaussing coil holders.
8.  Remove the degaussing coils.
9.  Remove the CRT grounding strap and spring tension devices.
10. Unscrew the four CRT fi xing screws [located on each CRT 
corner] and remove the CRT  [Take care not to handle the CRT 
by the neck].
1-4. PICTURE TUBE REMOVAL
WARNING: BEFORE REMOVING THE ANODE CAP
High voltage remains in the CRT even after the power is disconnected. To avoid electric shock, 
discharge CRT before attempting to remove the anode cap. Short between anode and CRT 
coated earth ground strap.
Coated
Earth
Ground
Strap
ANODE CAP REMOVAL PROCEDURE
WARNING: High voltage remains in the CRT even after the power is disconnected. To avoid electric shock, discharge CRT before attempting to 
attempting to remove the anode cap.  Short between anode and coated earth ground strap of CRT. 
NOTE:  After removing the anode cap, short circuit the anode of the picture tube and the anode cap to either the metal chassis, CRT shield, or 
carbon painted on the CRT. 
HOW TO HANDLE AN ANODE CAP
1.  Do not use sharp objects which may cause damage to the surface of the anode 
cap. 
2.  To avoid damaging the anode cap, do not squeeze the rubber covering too hard. 
A material fi tting called a shatter-hook terminalis built into the rubber. 
3.  Do not force turn the foot of the rubber cover. This may cause the shatter-hook 
terminal to protrude and damage the rubber.
101
9
8
76
5
4
3
2
a
b
Anode Button
c
Turn up one side of the rubber cap 
inthe direction indicated by arrow 
a
 .1Use your thumb to pull the rubber
cap fi rmly in the direction indicated
by arrow 
b .
2When one side of the rubber cap separates from 
the anode button, the anode cap can be removed 
by turning the rubber cap and pulling it in the 
direction of arrow 
c .
3 
						

							— 10 —
KV-25FS12 / 25FS12C
The following adjustments should be made when a complete 
realignment is required or a new picture tube is installed. 
These adjustments should be performed with rated power supply 
voltage unless otherwise noted.
Set the controls as follows unless otherwise noted:
VIDEO MODE: Standard
PICTURE CONTROL: Normal
BRIGHTNESS CONTROL: Normal
SECTION 2:  SET-UP ADJUSTMENTS
Perform the adjustments in order as follows:
  1.  Beam Landing
  2.  Convergence
  3.  Focus
  4.  Screen (G2)
  5.  White Balance
Note Test Equipment Required:
  1.  Color Bar Pattern Generator
  2.  Degausser
  3.  DC Power Supply
  4.  Digital Multimeter
2-1.  BEAM LANDING
Before beginning adjustment procedure:
1.  Degauss the entire screen.
2.  Feed in the white pattern signal.
ADJUSTMENT PROCEDURE
1.  Input a raster signal with the pattern generator.
2.  Loosen the defl ection yoke mounting screw, and set  the purity control 
to the center as shown below:
Purity Control
3.  Turn the raster signal of the pattern generator to green.
4.  Move the defl ection yoke backward, and adjust with the purity control 
so that green is in the center and red and blue are even on both 
sides. 
Blue Red
Green
5.  Move the defl ection yoke forward, and adjust so that the entire screen 
becomes green. 6.  Switch over the raster signal to red and blue and confi rm the 
condition.
7.  When the position of the defl ection yoke is determined, tighten it with 
the defl ection yoke mounting screw.
8.  If landing at the corner is not right, adjust by using the disk magnets. 
a
c
b
d
b a
cd
Purity control
corrects this area
Disk magnets
or rotatable disk
magnets correct
these areas (a-d)
Deflection yoke positioning
corrects these areas