Sony 17VC Troubleshooting
REVISED
17VC
OPERATION MANUAL
TROUBLESHOOTING MANUAL
CHASSIS
TABLE OF CONTENTS
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
TRINITRON® COLOR COMPUTER DISPLAY
9-978-878-02
- 1 -
CIRCUIT DESCRIPTION
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A
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 Of
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
Active Of
ctive On
- 2 -
AC Input and Degauss
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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%.
- 3 -
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 approximately 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 protection 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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+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 following 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
- 5 -
Feedback Circuits
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reference voltage at IC604 pin 1 determines the sink current into pin 3. The reference voltage is set to 2.5 volts by
resistor divider R608, R650, R648, and R609. Since the B+ is connected to the resistor divider, any change in B+ voltage
is detected at the reference terminal. The shunt regulator will either increase or decrease the current into pin 3 in order
to decrease or increase the B+ voltage respectively and try to maintain the reference voltage to 2.50 volts. IC603 biases
it's phototransistor accordingly and drives IC601 pin 9 (Vctrl) which changes the duty cycle at IC601 pin 4 (driver) to
regulate the B+ voltage at 179.2V.
Active Off Mode Feedback
Power Sw control line is low (heater off) during active off mode and respectively Q603 is off. Voltage pulses from T601 pin
10 flow through C620, R636, and R660 triggering the gate of thyristor D613. D613 turns on effectively shorting the B+ rail
to the standby 5V regulator input; current flows from T601 pin 10 through D612 and D613 to the standby 5V regulator input.
When the standby 5V regulator input is increased to approximately 12.7V it forward biases zener diode D605 turning on
Q604 and sinks current through IC603 to ground. The standby 5V input supplies this current to IC603 pin 1. IC603 biases it's
phototransistor and drives current through D609 into IC601 pin 14 (OOB) triggering burst mode operation. IC601 pin 4
(driver) is pulled low turning off switching transistor Q602. T601 pin 1 (auxiliary winding) feedback pulses are discontinued and IC601 pin 6 (Vaux) decreases to 8V. IC601 internal current source then charges pin 6 (Vaux) to the startup voltage
level (11V) which starts switching pin 4 driver output. The feedback cycle is then repeated. The burst repetition rate is
approximately every 110mS and when IC601 pin 4 is switching its frequency is 23.5KHz.
- 6 -
J
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M
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4. Protection Circuits
Protection Circuits
-
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1
The following are protection circuits: OCP, OVP, UVLO and secondary short circuits. OCP is pulse by pulse and is performed
on the primary side. OVP detects excessive output voltages. UVLO detects output under voltages. The following will explain
the operation of these functions.
OCP
OCP is activated if there is too much current passing through the switching power MOSFET, Q602. This condition will
occur if either the B+ line or 80 volt line is shorted.
R614 and R654 are the current sense resistors. Current through these resistors will produce a positive voltage. R623,
R624, R657 and C650 provide a voltage divider and filter to IC601 pin 5 (Isense). If the voltage level exceeds 0.5 volts, the
IC does pulse by pulse current limit and the output voltages are reduced. This condition can be audible and characterized by
a chirping sound.
OVP and UVLO
The OVP and UVLO functions are detected by IC601 pin 6 (Vaux). Vaux is typically 12.3V. In the event the regulation control
loop were to fail, the output voltages would either increase or decrease; then Vaux would increase or decrease respectively
via T601 transformer coupling. IC601 pin 6 will detect an OVP at 14.7V and UVLO at 8V turning off the driver output and
initiating a low dissipation safe-restart mode.
Secondary Short Circuits
Safe operation during secondary short circuits is provided by the demag function of IC601 pin 13. Demag protection
reduces the switching frequency, thereby reducing the input power level and providing safe operation. Demag also
provides a soft start function during startup gradually increasing the switching frequency until fixed frequency operation
is attained.
5. Troubleshooting
Warning
Before attempting to fix the power supply, safety should be considered first. Never connect test probes to the primary side
circuits, unless proper isolation has been installed. If isolation for the AC mains is not present, serious harm can occur.
Never assume you are safe.
- 7 -
Caution: C610 has a Slow Voltage Discharge
If the front panel power on/off button is switched to the off position prior to the AC mains input power being removed from
the monitor, then electrolytic capacitor C610 discharges with a long time constant. When the monitor cabinet cover and/or
EMI shield are removed, making the D board circuitry accessible during servicing or repair by qualified personnel, the
following procedure is recommended: Always remove the AC mains input power from the monitor prior to switching the
front panel on/off button to the off position. The AC mains input power should be removed from the monitor for a minimum of 30 seconds before the front panel on/off button is switched to the off position.
Caution: Do NOT Touch IC610 Component Tab or Heat Sink
IC610 component tab has an electrical voltage potential equivalent to the primary side return (approximately AC mains
input voltage potential). If IC610 heat sink insulator pad and/or shoulder washer busing are damaged or not assembled
correctly, then the IC610 heat sink will have an electrical voltage potential equivalent to primary side return (approximately
AC mains input voltage potential).
No Power
In the event that the monitor does not turn on, first verify input power is applied to CN600 and the front panel power button
is turned on; then check F601. If F601 is blown, the primary side circuitry should be checked. If the fuse is not blown, then
check the secondary side circuitry, especially the protection circuits. If these circuits are causing a no power symptom, the
problem can be more readily found.
AC Input and Degauss Circuit Trouble Shooting
For no power or nonoperating power supply, the AC input circuitry should be checked. Open or short circuit elements will
cause non-operation. Check F601, CN600, D601, R600, TH600 and R605 on the D Board. Check the front panel power
button for continuity.
If all elements are correct, check whether F601 breaks when power is applied and the power button is closed. If the fuse
does blow, there probably is a component shorted in the prmary circuitry.
The degauss will malfunction if CN601 is not connected. One problem could be loss of degauss signal from the microprocessor. This can be verified by using the manual degauss command found in the OSD menu. If the signal does not appear at
Q601 base, then it is possible that the microprocessor does not function correctly or standby 5V is not functioning.
The second step is to place a short across the AC terminals of RY601 for less than two seconds. If degauss operates then
check Q601 and RY601. If degauss does not work, check TH601 for an open condition and C631 for a short condition.
Primary Section
Three main areas can diagnose primary circuit failures. These are IC601, Q602 and Feedback system.
Visible checks of these areas will aid in finding problems. The following will discuss each section.
IC601
First apply AC to the monitor and check IC601 pin 4 output. If the output on pin 4 is not present, there could be problems
with Q602 and related parts or pin 14 could be less than 2.5 volts. Further, check Vaux level at pin 6. If it less than 11V,
the IC could be in safe-restart mode. If the voltage is very low, there could be a short on any of the IC pins. In reference
to ground, check the impedance of pin 1, 8 and 14. If any of these pins are shorted, replace the IC and check components
connected to the related pins. Take care that C616, C617 and C681 are fully discharged before replacing the IC.
Q602
The switching transistor can be damaged in various ways. These are related to voltage, current and temperature.
Check whether the transistor is shorted across drain and source terminals. If there is a short, F601, R605, R614, R654,
R623, R624, R657 and C650 should be checked. Additional components to check are D608, R603, R612 and IC601. If
Q602 is shorted, all these parts should be replaced.
Failure of a secondary rectifier diode can also cause Q602 to fail. Check 180V and 80V diodes for open or short
conditions. There is also a clamp circuit, which is used to clip the turn off spike found on Q602 drain. If the clamp
circuit is broken, it can cause Q602 failures. Check D606, C612 and R635. Also check the snubber circuit components
C613, D607, R619 and R656.
Secondary Circuit
Failure in the secondary circuits can be categorized by rectifier diodes, regulators, feedback loops and protection circuits.
- 8 -
These sections are interrelated and failure in one can affect another. Consequently, some failures will also affect the
primary circuitry.
Rectifier Section
Rectifier diode failures are not common, but do occur. Deflection, video and high voltage circuitry failures contribute to
diode damage. In the event a voltage is not present, check for shorts to ground, open or short diodes.
+5/12 Volt Regulator
If +12V or +5V output line is not available or the wrong voltage, IC605 or IC608 may be damaged. Before replacing
either IC, check for shorts or damaged parts along the output lines. If +12 volt does not appear, check the Remote Sw
signal from IC901 pin 6.
Standby 5V Circuit
Failure of this circuit can be affected by IC607. In case the circuit does not work properly, check D605, D614, R611 and
Q604. If these components are good, check the remaining circuit parts. Another possible influence can be the heater
circuit. Since both the standby 5V and heater voltages are produced by T6-1 winding 13-14.
Heater Voltage Regulator
This circuit may be affected by R697 or D619. If these parts are good, check the regulator output for a short to ground.
Shorts can occur on the video board. In the case of Power Sw signal.
Feedback Circuit
Problems with feed back can cause power supply shut down and low or high output voltages. First determine whether the
power supply is operating in active off, active on modes or not at all.
The power supply can be stuck in active off mode. The Remote Sw signal, Q603, Q604, D605 and IC603 can affect this
condition. Likewise, if the power supply is always in active on mode, the same items should be checked, along with
D612, D613, D621, C619, C620, R626, R636 and R660.
Checking for voltages at IC603 pins 1 and 2, IC604 pins 1 and 3 can solve more difficult problems. Additionally, IC603
pins 3 and 4, and IC601 pin 9 should be checked. If there are problems with these devices, 180V or standby 5V line, the
feedback systems will not work correctly. Also check the protection circuits.
Protection Circuits
OCP occurs when there is excessive current through Q602. Failures with Q510, Q507 or the video section could cause
this condition. These areas should be checked. OCP condition can also occur if R614 or R654 are open; if R623 or
R657 are shorted; or if R624 is open.
OVP usually occurs when the feedback loop is open, or loss of standby 5V. Isolate the OVP trigger condition, by first
checking the operation of the feedback loop.
6. USB/Audio Power Circuit
CAUTION: Do not touch IC610 component tab or heat sink. The IC610 component tab has an electrical voltage
potential equivalent to the primary side return (approximately AC mains voltage potential). If the IC610 heat sink insulator
pad and/or shoulder washer bushing are damaged or not assembled correctly, then the IC610 heat sink will have an electrical
voltage potential equivalent to the primary side return (approximately AC mains voltage potential).
The USB/Audio power supply circuit is a flyback converter that uses an integrated power mosfet and switch mode pwm
control IC (IC610). The circuit consists of IC610, T602, D633, PH601, IC611 and associated circuitry. Start up is
initiated when C675, connected to the CONTROL pin 1 is charged via a high voltage current source internal to IC610.
When CONTROL pin 1 reaches 5.8V, the control circuitry and mosfet are activated and a 10mS soft-start begins. The
typical mosfet DRAIN pin 7 switching frequency is 130 KHz with a ±4KHz jitter. The feedback loop consists of shunt
regulator IC611 and optocoupler PH601 that will regulate the secondary side output voltage at 6.5V and provide feedback
current to CONTROL pin 1. During normal operation, T602 bias winding pins 3-4 provide the charging current to maintain
CONTROL pin 1 at 5.8V; additionally the CONTROL pin 1 charging current that is regulated by IC611 and PH601 controls
the mosfet duty cycle to provide closed loop regulation.
The front panel power button controls the on/off function for the USB/Audio power circuit. When the power button is in
the OFF position, the MULTIFUNCTION pin 3 is shorted to CONTROL pin 1, turning off the power circuit. When the
power button is in the ON position, the MULTIFUNCTION pin 3 is shorted to primary side DC mains return, which enables
the power circuit.
- 9 -
2
1
S Cap Sws
H Deflection Circuit
TO:
180V
H Lin and
Ringing Circuit
12V
C575
FB506
5
R581
3
D518
Q521
T505
Q520
B+CHOP
R582
HST
3
C574
HDY-
4
HDY-
3
1
D516
L503
HOC
FB504
T504 HDT
1
H DY+
2
8
H DY+
1
1
2
6
TO: IC901 #32 pin
H FLY
Q508
D502
4
IC902 #14 pin
C521
C518
D506
R518
R517
R513
Q511
C522
Q507
H-OUT
C510
FB507
R522
R511
FB508
-15V
C543
R551
C563
20
3
R553
Out
H Reg
IN
H Def
IN
HD
PWM IC501
IN
H SHAPE
IC902
E/W PIN #9
8
2
R569
R584
R583
C582
- 10 -
C576
12V
12V
R504
R933
CN801
R509
C502
Q501
R594
Q903
HD output pin #17
IC902
R508
D501
Q502
1
8
2
3
4
5
6
1
2
4
3
1
2
3
1
2
3
4
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6
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C
6
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6
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5
V
To SW 602
USB/Audio Power Circuit
A voltage clamp to limit the peak voltage on DRAIN pin 7 is provided by D635 and D636. Bypass capacitor C677 is
utilized to improve high frequency noise immunity.
IC610 provides the following protection functions: a 10mS soft-start function, a cycle-by-cycle peak current limit function, a shutdown/auto-restart function if an out of regulation condition occurs and an over temperature protection function.
D BOARD DEFLECTION SECTION
1. Horizontal Deflection Circuit
Overview
These circuit drive the DY (Deflection Yoke) for Horizontal Deflection. The H size and H shape control (IC501 and around)
is included in this page as well.
H Drive, H Out, Feedback
+12Vp-p HD pulse is generated by the inverter Q903 using the Jungle IC902 H. out pin #17. And switch Q511 through A
push-pull amplifier (Q501 and Q502) buffers. The drive current which introduced in HDT (T504) by this switching will
drive Q507 (H out Tr) and 1000V pulse appears on collector. D506 is the "Damper Diode" which avoid the negative pulse
and discharge the energy for next Horizontal Drive. Q508 is the buffer for the "H BLK" feed back to Jungle IC 902 H. FLY
pin #14 and it will be the reference of phase / jitter control of Jungle. HST (T505) is to sense the deflection current
through DY. The voltage appeared on secondary side will be the feed back for H Size/Shape control.
H Size/Shape control
HD pulse also triggering the H Size/Shape control IC501 pin #8. IC501 is "PWM IC" and it controls H and HV B+
chopper duty. H Shape and H size information is already included and coming from Jungle IC902 E/W pin #9. It will be
supplied to IC501 pin #2. H reg output pin #20 is switching pulse of Q520 (B+ chopper). The energy supplement from
180V to H Def circuit (through L503 HOT) is controlled by the duty of this pulse. The H Shape input and feedback
voltage from T505 are compared by error amp (in IC501) and H Reg out pulse duty is controlled to keep the level of
these two the same.
- 11 -
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(BOARD)
D
H. LINEARITY AND RASTER DISTORTION CORRECTION CIRCUIT
- 12 -
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(BOARD)
D
(17VC H. CENTERING CIRCUIT)
- 13 -
Troubleshooting
See attached FLOW CHART and confirm if its really an H Deflection issue.
No H Deflection / No Power
Check Q507, Q520 and D506 first. In case any of these shorted, check T504, Q511, R511 and D502.
Those parts might have been damaged.
If both of Q507, 520 were not broken, check the HD pulse at the gate of Q511.
If no pulse, check Q501, Q502, Q903.
Otherwise, check R582, D518 or try changing IC501.
Bad Distortion
Check pin#2 of IC501 and confirm that proper DC level and AC waveform.
If the distortion is on only right side, check all above (No H Deflection).
Otherwise, refer to the Troubleshooting of next section (H Lin and Ringing Correction).
2. H Linearity and Raster/Distortion Ringing Correction Circuit
This section includes HLC Control circuit, S cap switching and HLC/S-Cap Damping circuits. These circuits are placed
directly on the cool side of DY which is in series with deflection current line. H Centering circuit will be explained in
next section.
HLC Balance Control and HLC Damping
HLC (L508) effectiveness is changed by LCT (T506) for each fH since T506 and L508 are in parallel. LCT is the Cross
Transformer that can change its inductance accordingly to the DC current of the secondary side. The current of the
secondary side is controlled by the DAC output of Micro (IC901 - pin 4) through Q519. It can be changed by the register
"HLIN_BAL_LOFH", "HLIN_BAL_MDFH" and "HLIN_BAL_HIFH". D505, C581 and R577 make up the damping
circuit to avoid Raster Ringing (mainly on the left side of the picture) caused by HLC, DY and S-caps.
S-Cap switching and S-cap Damping
H Def current is distorted by resonance between S-Cap and DY to correct the linearity. Since the resonance frequency
has to be changed for each fH, S-Cap switching is controlled by MICRO
S-Cap Switch - FETs (Q512, Q513, Q514, Q515, Q516) are "On" when its gate is Hi(5V) and that moment, drain voltage
should be grounded (0V).
L506, R578 and C573 is damping circuit to avoid Distortion Ringing (mainly on top of the picture) caused by S-caps and
H Control loop gain. L505, R575 and C572 is also the same purpose as above but only works when Q514 (Switch for the
Biggest S-Cap) is On.
Troubleshooting
See attached FLOW CHART and confirm if its really H lin issue.
Bad Linearity
Confirm that Raster is approximately in the center of the Bezel. If not, refer to next section (Raster Centering Circuit).
Check S-cap switches (Q512, 513, 514, 515, 516, HLC switch (Q519)) and confirm that H Linearity changes proportional to the value of S-Cap DAC. Confirm that H.LIN BAL changes by the register value of "HLIN_BAL_LOFH",
"HLIN_BAL_MDFH" and "HLIN_BAL_HIFH". If not working, check Q519, C508 or T506.
Bad Top Distortion/ Left side Raster Ringing
Check damping circuits explained above.
3. H. Raster Centering Circuit
Overview
H center circuit is changed from D99 type in which the Power OP-Amp is used
H Center Circuit
H Centering is changed by rotating RV502 to change the current through HCC (L510). Micro is no longer controlled.
Troubleshooting
See attached FLOW CHART and confirm if its really H Center Circuit issue.
No Raster Centering Control
Check R526, R529 and L510 first. Then, check D530, and D531. If these parts are good, check RV502.
- 14 -
#1, 2 PIN
Rotation Coil (CN701)
R563
R562
Rotation/Vertical Key Circuit
STBY
5V
R558
+15V
IC502
C549
5
V+
1
+
V-
-
2
3
4
R559
R560
C547
ROTATION
3
IC901
R566
-15V
C513
4. Rotation Circuit
Rotation is a PWM waveform at approximately 125kHz measuring 5Vp-p at pin #3 of the micorprocessor IC901. Then
filtered by R560 and C547 combination. The DC current is output by powered OP-amp (IC502). The output current from
pin #4 of IC502 flows through R563 and the rotation coil and returns to ground through R566. The feedback is sensed at
R566 and sent back to the amplifier through R562.
No Rotation Control
Check the waveform pin #3 of microprocessor IC901 if it is 5Vp-p PWM and approximately 125kHz. Otherwise, check
around IC502.
5. Dynamic Focus Circuit
Overview
Both H and V Dynamic Focus are combined through DFT (T503).
H DF
Horizontal Parabola is injected into the secondary side of the focus transformer (DFT:T503). In order to keep the amount
of parabola constant over the horizontal frequency range the values of the AC coupling capacitors are changed by the
transistors, which switch the s-caps. This signal is amplified by the turns-ratio to the primary side of the transformer.
V DF
V DF waveform is buffered by Q505 and amplified by Q504 to about 130Vp-p. VDF is controlled by Jungle IC902 pin #12.
300v Vcc is made by FBT through D515. This voltage is also used for HV Protector.
Troubleshooting
See attached FLOW CHART and confirm if it is really a DF issue.
Bad H DF
Check H. Linearity. If there is no problem, change T503 (DFT).
Bad V DF
Confirm that waveform is around 1Vp-p from Jungle pin 12 of IC902. If its more than 2.0Vp-p, change Jungle IC902.
Check 300v from FBT.
- 15 -
+
Y
O
D
T
H
Dynamic Focus Circuit
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- 16 -
6. High Voltage Protect Circuit
This circuit generates the High Voltage supply for the anode. It consists of a high voltage driver and regulator similar to a
switching power supply function. In addition, there are High Voltage and Beam Current protection circuits. All those
circuits are similar to D99 chassis circuits.
High Voltage Regulation and Output Circuit
The HV Drive pulse is generated by IC501 and synchronized with Horizontal drive pulse. It is supplied to the Gate of Q510
the HV Out FET.
The HV Out Pulse approximately 700V, is generated by Q510 switching with the peak voltage being controlled by the
switching duty of Q503 (B+ chopper). Internal resistors and R540 and RV501 divide HV generated in the FBT. Since this
voltage is the feedback for HV Regulation control. Adjusting RV501 will result in changing the HV Regulation level(= HV
level). HV Feedback voltage is returned to IC501 at pin#12 to be compared with an internal reference voltage of IC501 at
pin#13. According to this feedback level, IC501 changes the pulse duty cycle. This pulse is felt at pin #18 of IC501 thereby
controlling the output of B+ chopper drive Q503.
G1 Voltage (-33Vdc)
D510 and C528 through R532 rectify -57Vdc developed by a -57V winding of FBT. It is then regulated by D503 and C533
to be -33Vdc typ through R539. -33Vdc is supplied through R570 to the A Board via CN510.
HV Protect Circuit
HV Protect circuit will be activated by the Microprocessor when the signal at HV DET, Microprocessor pins#18 reaches a
+5vdc level. HV DET indicates the level of the primary current developed by the 270V winding of the FBT through R543,
D515.
Beam Current Protect
Beam Current Protect will be activated when ABL DET at microprocessor pin#16 reaches a level of 0V when operating in
main mode. ABL DET level is corresponding to the Beam Current which is supplied to FBT through R596, R550 and R548.
The voltage current relationship is inversely proportional Voltage (down) Current (up).
Troubleshooting Hints
See attached FLOW CHART to confirm if is really an HV/Protect Circuit issue.
No HV / No Power
Perform basic checks of Q510 and Q503 first. If both Q510 and Q503 were not broken, check the HV Drive pulse at the
gate of Q503. If no pulse, check R534 and D509. Otherwise, check R520, D504 or try changing IC501.
No G1 Voltage
Check R532, D503 and D510
Protect Malfunction
To see if HV Prot or ABL Prot are suspect check the Shutdown Log data at the Shutdown Log register. Refer to Shutdown
Log Table below.
When an HV Shutdown is indicated, check R917, R921, R543, D515 and D517 or, replace T501 (FBT).
Where ABL Shutdown is indicated, check the voltage T901 pin#11.
If it is higher than 0.5v immediately prior to shutdown. Should the voltage reach and remain at the 0 volt level, even after
the first 2.0 seconds of Power On, check D514 or check White Balance.
SHUTDOWN LOG TABLE
Bit Register value Shutdown Mode Comment
bit7 128 N/A N/A
bit6 64 N/A N/A
bit5 32 S Cap Shutdown Explained later
bit4 16 ABL Shutdown Hardware Controlled
bit3 8 HV Over Hardware Controlled
bit2 4 HV U Shutdown Not Used
bit1 2 No Vertical Scan Explained later
bit0 1 No H Scan Explained later
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