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TRINITRON® COLORCOMPUTERDISPLAY
OPERATION MANUAL
TROUBLESHOOTING MANUAL
CIRCUIT DESCRIPTION
D Board (Power Supply Section) ............... 2
D Board (Deflection Section) .................... 11
A Board ................................................... 21
U Board ................................................... 24
GENERAL TROUBLESHOOTING ................ 26
PARTS LEVEL BOARD REPAIR ................. 37
17VCCHASSIS
TABLE OF CONTENTS
9-978-878-0
2
REVISED


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CIRCUIT DESCRIPTION
D BOARD POWER SUPPLY SECTION
Power Supply Electrical Circuit
The power supply is located on the D Board. It has three modes of operation that are controlled by a microprocessor. The
topology is a discontinuous mode flyback converter with photocoupler feedback for regulating the secondary voltages.
Circuit operation and troubleshooting are explained in the following sections:
Operation Modes
Secondary Circuitry
AC Input
Protection Circuits
Degauss Circuit
Troubleshooting
Primary Circuitry
USB/Audio Power Circuit
Operation Modes
The power supply has four modes of operation, off, active off, suspend/standby and active on. These modes are
related to power savings and are indicated by the front panel LED. Additional indications are failure diagnostics and aging
mode. The table below lists operation mode, condition and LED status.
Mode
Syncs
Condition
LED
Off
N/A
Power Switch Off
Off
Active Off
No H and/or V
Low Power, Heater Off
Amber
Active On
H and V Present
Phase Locked, Normal Operation
Green
Failure 1
N/A
HV Failure
Amber 0.5s<-->Off 0.5s
Failure 2
N/A
H Stop, V Stop, S Cap Failure
Amber 1.5s<-->Off 0.5s
Failure 3
N/A
ABL Failure
Amber 0.5s<-->Off 1.5s
Aging/Self Test
No H and V
Aging Raster or Test Pattern
Amber 0.5s<-->Off 0.5s
Green 0.5s<-->Off 0.5s
Amber 0.5s<-->Off 0.5s
Except for power switch off, all modes of operation are controlled by the microprocessor located on the D Board. The
failure modes are detected by the microprocessor and the power supply is forced into active off mode. These functions
are discussed later (Deflection).
With the AC cord attached to the monitor and connected to an AC source, the monitor will be off until the power switch is
turned on. When the power switch is turned on, the power supply starts and is in active off mode. The next step is active
on mode. The active off power saving mode is activated by the microprocessor based upon the absence of either H or V
sync. If H and/or V sync signals are not present, the power supply is set to active off mode.
Power supply operation control signals are "Remote Sw", "Power Sw" and "PFC Sw". During active off mode, Remote Sw
and Power Sw are digital low and PFC Sw is digital high. To enter active on mode, the microprocessor sets PFC Sw to
digital low, then 300mS later, Remote Sw and Power Sw are set to digital high.
Output
Off
Active Off
Active On
180V (B+)
0V
+13V
+179V
80V
0V
+6V
+79V
+15V
0V
+1V
+15V
-15V
0V
-1V
-15V
+12V
0V
0V
+12V
5V
0V
0V
+5V
Heater
0V
0V
+6.3V
STBY 5V
0V
+5V
+5V


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1
2
1
2
3
4
1
2
3
1
2
3
4
C604
VA601
C643
F601
C605
C660
CN600
C631
SG601
TH601
Q601
RY601
D601
D602
CN602
CN601
LF602
R604
TH600
R600
0.47
250V
4700p
250V
5A
250V
0.22
275V
4700p
250V
3P
4.5
220VRMS
:POS
DTC143ESA-TP
RELAY DRV.
D4SB60L
AC RECT.
1SS119-25TD
2P
4P
:LFT
680k
1/2W
:RC
3.9
3.84A
1
10W
DEGAUSS
12V
DGC2
NC
DGC1
THP600
THP600A
NC
N
L
NC
1. AC Input Section
The AC input section provides EMI filtering, input protection, surge limiting and CRT degauss operation.
EMI Filter
The EMI filter comprises CN600 (inlet with filter), X-capacitors C604 and C605, Y-capacitors C660 and C643 and the
line filter transformer, LF602. Input protection is provided by F601and VA601; surge current limiting by thermistor
TH600 and resistor R600. Degauss is explained in the next section.
Degauss Circuit
The degauss circuit is used to demagnetize the CRT. After power on, the microprocessor located on the D Board sets the
degauss signal to digital high and Q601 turns on relay RY601. This allows AC current into the degaussing coil through
posistor TH601. The current heats up the posistor and the resistance increases, this dampens the current in the degauss
coil to nearly zero. Duration time is approximately 5-6 seconds and the microprocessor then shuts off RY601, which
disconnects the degauss coil from the AC line. This operation should sufficiently demagnetize the CRT.
2. Primary Circuitry Section
IC601
The heart of the primary section is the TEA1504/N2 power supply controller, IC601. The following describes the functions
of each pin.
Pin 1 Vin: This is a MOSFET drain connection internal to IC601, which is connected directly to the DC mains voltage rail.
The startup current source derives power from the DC mains via the Vin pin. It supplies current to charge the Vaux (IC
supply) capacitors C616, C617 and C681 and also provides current to the IC601 control circuitry.
Pin 2 HVS: High voltage safety spacer pin is a no connection.
Pin 3 NC: Connected to primary side DC mains return.
Pin 4 Driver: Outputs the pulse width modulated gate drive for switching transistor Q602. Maximum duty cycle is set
internally at 80%.
AC Input and Degauss


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Pin 5 Isense: Provides cycle by cycle over current protection by turning off pin 4 driver output when Q602 current
exceeds the current limit corresponding to 500mV at pin 5. This pin typically provides 425nS of leading edge blanking time.
The threshold voltage for switch over to low frequency (low power) operation is sensed by pin 5. When the voltage sensed
at pin 5 is below 165mV, IC601 transitions from operating at high frequency (56.5KHz) to low frequency (23.5KHz).
Pin 6 Vaux: IC601 supply pin. An internal current source from IC601 charges the Vaux capacitors C616, C617 and C681
for startup. Once the Vaux capacitors are charged to the startup voltage level (11V), then IC601 starts switching pin 4 driver
output. The Vaux is also supplied by an auxiliary winding from T601 on the primary side once the secondary output voltages
attain their nominal operating voltage values. Pin 6 also provides under voltage lockout detection (8V) and over voltage
protection (14.7V).
Pin 7 DS: Provides the power supply for the driver output (pin 4).
Pin 8 Iref: Controls IC601 internal bias currents, which determines the pulse width modulated switching frequencies.
High frequency is 56.5KHz during active on mode. Low frequency is 23.5KHz during suspend/standby mode.
Pin 9 Vctrl: Feedback voltage for duty cycle control.
Pin 10 NC: No connection.
Pin 11 Gnd: Connected to primary side DC mains return.
Pin 12 NC: No connection.
Pin 13 Dem: Guarantees discontinuous conduction mode operation for the power supply. Verifies that T601 is demagne-
tized by not activating the next gate drive pulse until the primary side auxiliary winding of T601 is lower than the threshold
level of 65mV as detected at pin 13.
Pin 14 OOB: On/Off/Burst mode input signal. A voltage greater than 2.5V enables IC601.
Operation
The power supply is a discontinuous-mode flyback converter with photocoupler feedback for regulating the secondary
voltages. The PWM controls the pulse width of the gate drive.
When AC is applied to the power supply and IC601 pin 14 is greater than 2.5V, start up current is supplied though IC601 pin
1 to IC601 pin 6. Startup voltage is approximately 11V. After start up, the voltage to pin 6 and pin 7 of IC601 is supplied
through D620 connected to T601 pin 1. The first mode of operation is active off mode. The output drive pulse frequency
will be in burst mode operation.
When the power supply enters active on mode, the switching frequency will be 56.5KHz. The Vaux level will be approxi-
mately 12.3 volts. OVP threshold is 14.7 volts and UVLO is 8.0 volts. Therefore, if the Vaux voltage is not correct, the
power supply will not operate properly.
Feedback from the secondary side comes through IC603 and IC604, which is connected to IC601 pin 9. (See diagram on
page 5.)
3. Secondary Circuitry Section
The secondary section consists of the following circuits: Rectifier diodes and filters for all output voltages, +5/12 volt
regulators, +5 standby regulator, heater voltage regulator, voltage feedback circuit, active off mode feedback, and protec-
tion circuits. This section will describe each circuit and its function.
Secondary Rectifiers
The secondary rectifiers supply the following voltages: 180V (B+) for deflection and video, 80V for video, ±15V for
deflection and regulators, 6.3V for heater regulator, and +5V standby regulator.


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I
O
G
1
2
3
4
5
4
6
7
9
10
11
5
12
13
15
16
17
18
14
2
1
S
1
2
3
1
2
3
4
5
6
7
8
9
10
11
12
13
14
1
2
4
3
R613
D609
D606
D607
D608
D611
R625
C619
C620
D618
D620
R640
C647
C603
L602
D603
C611
C633
C634
C615
D612
D605
D617
R602
C608
C622
D622
R611
R617
R626
R647
R607
C612
C624
C616
C621
R627
R615
R616
D625
C656
R605
JW613
C632
T601
C618
JR019
S602
L604
L606
D610
D619
D614
C650
C665
D623
C617
C637
C630
C625
C614
R650
R608
R619
R656
R635
R654
R614
R624
R618
R642
R609
R648
R628
R620
R606
R693
R603
R643
D613
R667
R655
C663
R622
C682
R636
R660
R697
C601
C681
C641
C613
D616
D638
R621
R698
C610
R612
R623
R610
Q604
IC604
IC602
IC601
IC603
IC607
Q602
D621
FB601
Q603
VA603
R649
R657
220
100
100V
3300
16V
22
25V
1000
25V
100p
500V
B
47
250V
470p
500V
B
MTZJ-T-77-12B
UF4007G23
UF4007G23
FMC-26UA
UF4007G23
FMN-G12S
FMN-G12S
UDZ-TE-17-13B
JW(7.5)
4.7M
1/2W
4.7M
1/2W
0.47
1/2W
1
:FPRD
0.068
250V
2.2k
1/2W
0.1
:PT
100
FMN-G12S
MTZJ-T-77-12B
1SS119-25TD
1SS119-25TD
22
25V
2200
25V
1.8k
:RC
0.47
1W
:RS
1.5k
2W
:RS
22k
3W
:RS
0.39
1W
:RS
1.5k
2W
:RS
D1NS6-TA2
RGP10DG23
220
16V
PG106R
SRT
NEW
100
150k
:RN
120k
:RN
470
47p
2kV
100
3W
4.7
50V
270p
2kV
680p
:CHIP
0.01
B:CHIP
0.022
:CHIP
0.0022
B:CHIP
1.0
10V
1000
25V
0.1
:CHIP
4700p
:CHIP
6800p
:CHIP
0.1
25V
:CHIP
0
:CHIP
BT149G
0 :CHIP
JW(7.5)
470k
:RN-CP
22k
:CHIP
3.9k
:RN-CP
22
:CHIP
680k
:CHIP
1.0M
:CHIP
100
:CHIP
220
:RN-CP
33k
:RN-CP
22
:CHIP
22
:RN-CP
2.2k
:CHIP
9.1k
:RN-CP
47k
1W
390
:RN-CP
82k
:RN-CP
10k
5.6k
:RN-CP
47k
1W
1.2
1W
:RS
47
10V
100
16V
75k
:CHIP
56k
:CHIP
0.47
25V
F:CHIP
MTZJ-18
MTZJ-T-77-4.7B
MTZJ-T-77-4.7B
MTZJ-T-77-18
330
400V
22
1/4W
33
1k
:RN-CP
2SC3311A
PROT
AS431LAN
ERROR AMP
BA00AST-V5
HEATER REG.
TEA1504-N2
SW REG.
CONTROL
TLP621D4-Y
PHOTOCOUPLER
RCC CONTROL
BA05T
5V REG.
2SK2843
SW REG.
OUT
1SS119-25TD
DTC114EKA
HEATER
SW
2.2k
:RN-CP
P
WR
SW
PW
R
SW
15V
180V
-15V
80V
STBY
5V
155V-3
6.3V
3
1
2
1
5
4
OOB
DEM
NC
GND
NC
VCTRL
IREF
VIN
HVS
NC
DRIVER
ISENSE
VAUX
DS
G
N
D
V
C
C
C
T
L
O
U
T
V
A
D
J
A
B
HEATSINK
TO Q602
TO HEATER
A
B
+5/12 Volt Regulator
IC605 is the +12V regulator and IC608 is the +5V regulator. The output voltages are supplied to the microprocessor,
deflection and video circuits. The +15V line provides the input voltage for +12V regulator; the +12V line provides the input
voltage for +5V regulator. During active off mode, the +12V regulator is disabled via Remote Sw and subsequently the 5V
regulator is disabled.
+5V Standby Circuit
IC607 is the standby 5V regulator. In the active on mode the input to the regulator is supplied from T601 winding 14-13.
During the active off mode, the regulator input is supplied from T601 winding 10-13 via D612 and D613. Typical input
voltages to the regulator are active on mode: 9.5V; active off mode: 11.5V.
Heater Voltage Regulator
Heater filament voltage is supplied by T601 winding 14-13 and is regulated by IC602 to 6.3V during active on mode. IC602
output is turned on and off by the Power Sw control line at pin 1, CTL. The output is off during active off mode.
Feedback Circuit
The feedback circuit is divided into two sections. One is for active on mode; the other for active off mode. The follow-
ing two sections explains the theory and operation.
Active On Mode Feedback
Shunt regulator IC604 regulates the B+ line to 179.2V by sinking current through the opto coupler 1C603 to ground. The