Page 1
5 Troubleshooting
5-1 Parts Level Troubleshooting
Notes: Check the following circuits.
• No raster appears: Power circuit, Horizontal output circuit.
• High voltage develops but no raster appears: Video output circuits.
• High voltage does not develop: Horizontal output circuits.
5-1-1 No Power Supply
Check and replace D601 and FH1
Chirping noise exists?
No
Repeating start?
No
1
IC601 Pin 1 waveform is right?
Yes
C622 Voltage is 13 V ± 0.5V?
Yes
Yes
No
No
Check and replace IC601.
Check and replace D606.
Check and replace D614, IC601,
Q602 and ZD601.
Check and replace IC201, IC301,
IC401, Q402, Q404,
IC603, Q609,and Q611.
WAVEFORMS
100 V (IC601, #1)
1
CH1 P-P = 100 V CH1 RMS = 350.2 V
Yes
Operate normally?
Yes
Verify voltages.
Done.
AQ15VS/AQ15HS 5-1
No
Replace Main board.
Page 2
5 Troubleshooting
5-1-2 DPMS Failure
Check signal source
H/V Sync. video level.
Make No H/V Sync.
(power off mode)
LED blinks?
+12 V line off?
2
IC601 Pin 1 output
voltage exists?
Yes
Yes
No
No
No
Check IC201 Pin 40.
Check IC201 Pin 6.
Refer to 5-1-1 No Power Supply.
WAVEFORMS
100 V (IC601, #1)
2
CH1 P-P = 100 V CH1 RMS = 325.8 V
Done
Yes
5-2 AQ15VS/AQ15HS
Page 3
5-1-3 H_Deflection Failure
5 Troubleshooting
Does PWM output signal appear
3
at Pin 28 (B_out) of IC401?
Yes
Does Horizontal pluse signal
4
appear at at Pin 26 of IC401?
Yes
Does 20 Vp-p signal appear
5
at Collector of Q418?
Yes
Check Q402, Q404 and T401.
No
No
No
Does DC 12V appear at
Pin 29 of IC401?
Yes
Check IC401.
Check IC401.
Check Q418.
No
Check 12 V line.
WAVEFORMS
5.00 V (IC401, #28)
3
1.00 V (IC401, #26)
4
5-1-4 S Correction Failure
Check S1 ~ S3 signal.
S1~S3 signals are right at each
frequency block?
Yes
Check and replace Q404, Q410, Q411,
(Q409, Q414 : HT/HO)
Q415, and Q416.
No
Check and replace IC201.
5.00 V (Q418, Collector)
5
AQ15VS/AQ15HS 5-3
Page 4
5 Troubleshooting
5-1-5 H_Lin. Failure
IC201 Pin 21 voltage varies with
different H_Lin. DAC values?
Yes
IC603 Pin 14 voltage varies with
different H_Lin. DAC values?
Yes
Check Q412, Q413 and T402.
5-1-6 Invariable H_Size
IC401 Pin 28 voltage varies with
different B_OUT DAC values?
Yes
No
No
No
Replace IC201.
Check +13 V_1, Coil
Check some parts around IC603.
Check and replace IC401.
_
5 V line.
Q402 Gate output duty varies with
different B_OUT DAC values?
5-1-7 Abnormal H_Size
IC401 Pin 24 output duty
varies with different B+ offset
DAC values?
Yes
Q408 Collector waveform is
6
around D409 and L401.
right?
Yes
Check some parts
No
No
No
Check some parts around Q402,
IC401 Pin 4 ~ 6.
Check and replace IC201.
Check and replace Q405,
Q406, Q407, and Q408.
WAVEFORMS
5.00 V (Q408, Collector)
6
5-4 AQ15VS/AQ15HS
Page 5
5-1-8 Side Pin or Trap Failure
5 Troubleshooting
7
IC401 Pin 24 output exists?
Yes
Refer to 5-1-7
Abnormal H_Size
.
5-1-9 Para. or Pin Balance Failure
IC401 Pin 24 output varies with
different DAC values?
No
Replace IC401.
No
Yes
Check and replace IC401.
Refer to 5-1-7
Abnormal H_Size
WAVEFORMS
1.00 V (IC401, #24)
7
.
5-1-10 Tilt Failure
Check tilt connector connection
IC201 Pin 20 output duty varies
with different DAC values?
Yes
IC603 Pin 3 output varies with
different DAC values?
Yes
Check and replace Q301 and Q302.
No
Check and replace IC201.
No
Check and replace IC603.
AQ15VS/AQ15HS 5-5
Page 6
5 Troubleshooting
5-1-11 V Deflection Failure
13V and –10V lines are on?
Yes
IC401 Pin 23 output exists?
8
Yes
9
IC301 Pin 6 output exists?
Yes
Check DY connector connection.
No
No
No
Refer to 5-1-1 No Power Supply
Check and replace IC401.
Check and replace some parts
around IC301.
WAVEFORMS
1.00 V (IC401, #12)
8
10.0 V (IC301, #6)
9
5-1-12 V Size or Position Variation Failure
IC401 Pin 23 output varies with
different DAC values?
Yes
Check and replace IC301.
No
Check and replace IC201 and IC401.
5-6 AQ15VS/AQ15HS
Page 7
5-1-13 High Voltage Failure
5 Troubleshooting
IC401 Pin 28 OSC pulse exists?
3
Q402 Gate driving pulse exists?
10
Q402 Drain pulse exists?
11
Done
5-1-14 ABL Failure
Yes
Yes
Yes
No
No
No
Check and replace IC401
and +12 V line.
Check and replace Q401.
Check and replace Q403 and L402.
WAVEFORMS
5.00 V (IC401, #28)
3
CH1 P-P = 2.00 V CH1 RMS = 5.868 V
5.00 V (Q402, Gate)
10
CH1 P-P = 2.00 V CH1 RMS = 7.692V
50.0 V (Q402, Drain)
11
Input full white pattern to monitor.
IC101 Pin 22 input exists and
varies with different patterns?
Yes
Check CN102.
T501 Pin 8 output exists?
Yes
IC201 Pin 26 output exists and
varies with different patterns?
Yes
No
No
No
Check and replace IC101.
Check and replace T501.
Check and replace IC201.
CH1 P-P = 50.0 V CH1 RMS = 73.7V
Done
AQ15VS/AQ15HS 5-7
Page 8
5 Troubleshooting
5-1-15 Dynamic Focus Failure
12
T502 Pin 6 output is right?
Yes
13
T502 Pin 1 input is right?
Yes
Check the connection between FBT
Focus pin and CRT Socket PCB.
No
No
Replace the C432.
Check and replace T502.
WAVEFORMS
50.0 V (T502, #6)
12
CH1 P-P = 50.0 V CH1 RMS = 75.6 V
100 V (T502, #1)
13
CH1 P-P = 100V CH1 RMS = 124.0 V
5-8 AQ15VS/AQ15HS
Page 9
5-1-16 No Video
5 Troubleshooting
Check signal cable and connection.
IC101 Pin 5, 6 and 7 inputs
14
are right?
Yes
IC101 Pin 18, 19 and 20
15
outputs are right?
Yes
IC103 Pin 1, 2 and 3 outputs
16
are right?
Yes
Cathode DC levels are right?
Yes
No
No
No
No
Check the signal cable connection.
Check I2C bus and +12V line.
Check +12V, +72V line.
Check and replace IC103.
Check +72V line.
Check and replace IC102.
WAVEFORMS
1.00 V (IC101 #5, 6, 7)
14
0.5 V (IC101 #18,19,20)
15
20.0 V (IC103, #1, 2, 3)
16
G2 voltage is right?
Yes
Change CRT.
Done.
No
Check G2 wire, CRT Socket board
and FBT.
AQ15VS/AQ15HS 5-9
Page 10
5 Troubleshooting
5-1-17 Micom Failure
IC201 Pin 11 input voltage is 5V?
Yes
17
IC201 Pin 13 and 14
inputs are right?
Yes
IC201 Pin 18 input is right?
Yes
All in/output values are right?
Yes
Done
No
No
No
No
Check Q608.
Check C202, C203 and X201.
Check Q608.
Replace IC201.
WAVEFORMS
2.00 V (IC201, #13, 14)
17
5-10 AQ15VS/AQ15HS
Page 11
5-1-18 OSD Failure
5 Troubleshooting
Check CN102 and connector Ass’y.
IC104 Pin 5 input is right?
18
Yes
IC104 Pin 10 input is right?
19
Yes
IC104 Pin 7 and 8 inputs are right?
Yes
IC104 Pin 13, 14 and 15 inputs
are right?
No
No
No
No
Check CN102 Pin 14.
Check CN102 Pin 8.
Check IC201 Pin 41 and 42.
Check IC104.
WAVEFORMS
2.00 V (IC104, #5)
18
2.00 V (IC104, #10)
19
1.00 V (IC101, #18,19,20)
20
IC101 Pin 18, 19 and 20
20
outputs are right?
Check and replace IC103.
Done
Yes
No
Check and replace IC101.
Yes
AQ15VS/AQ15HS 5-11
Page 12
5 Troubleshooting
5-1-19 User Control Failure
Does the DC level change at
Pin 36 of IC201 when you push the
button S/W?
Yes
Check IC201.
5-1-20 Degaussing Failure
Check degaussing connector.
RL601 operation is right?
Yes
Q601 base input is right?
No
No
No
Check the button.
(SW201 ~ SW204)
Check D-coil and TH601.
Check and replace Q601.
Yes
IC201 Pin 4 output is right?
Yes
Done
No
Check and replace IC201.
5-12 AQ15VS/AQ15HS
Page 13
5-2 General Troubleshooting
5-2-1 No Picture
5 Troubleshooting
LED blinks?
LED is green color?
Check G2 voltage, high voltage
and R, G, B cathode voltage.
5-2-2 Shut Down
Blinking LED’s?
No
Refer to 5-2-2 Shut down.
Yes
No
Check Micom.
Yes
No
Check power supply.
Yes
Scan failure?
No
Video failure?
No
Check and replace IC201.
Done
Yes
Yes
Check horizontal, vertical deflection
system and check power supply
secondary voltages.
Check Video board.
AQ15VS/AQ15HS 5-13
Page 14
5 Troubleshooting
5-2-3 Missing Color
Proper Video levels are
on CN101 (D-Sub) Pin 1, 3 and 5?
Yes
Proper Video signal is
21
on all cathodes?
Yes
Proper DC voltage is
on all cathodes?
Yes
G2 voltage is right?
Yes
Heater voltage is right?
No
No
No
No
No
Check signal generator.
Refer to 5-1-16 No Video.
Check IC101 Pin 15, 16 and 17.
Check IC102.
Check T501. (VT/VO)
Check DR05, DG05 and DB05.
(HT/HO)
Check D608, Q604 and T601.
WAVEFORMS
10.0 V (R,G,B, Video)
21
CH1 P-P = 10.0V CH1 RMS = 17.02V
Yes
Yes
G1 voltage is right?
Yes
Replace CRT.
Done
No
No
Check D504, Q502 and T501.
5-14 AQ15VS/AQ15HS
Page 15
5-2-4 Visible Retrace
5 Troubleshooting
Check white balance adjustment.
G2 voltage is right?
Yes
Blank pulse is on Pin 3 of IC401?
Yes
22
23
V_FLB pulse is on
Collector of Q502?
Yes
Does approve the Vertical pulse
on the CRT Socket G1?
No
No
No
No
Check D502 and Adjust G2.
Check IC401.
Check Q502.
Check CN102 and CN201.
WAVEFORMS
5.00 V (Q502, Collector)
22
50.00 V (CRT Socket, G1)
23
Done
Yes
AQ15VS/AQ15HS 5-15
Page 16
5 Troubleshooting
5-2-5 Unsynchronized Image
Check input signals Pin 2
and 3 of CN202.
Signals are right?
Yes
Signals at Pin 28 and 29 of
IC201 are right?
Yes
Signals at Pin 30 and 31 of
IC401 are right?
Yes
Check circuits on Main board.
Done
No
Check Video Cable
No
Check IC201.
No
Check IC401
5-16 AQ15VS/AQ15HS
Page 17
5-2-6 Misconvergence
Try readjusting convergence.
5 Troubleshooting
The convergence is now
within spec.?
No
Readjust convergence.
No
The convergence is now
within spec.?
No
Change CRT and readjust
convergence.
Done
Yes
Done
Yes
Done
AQ15VS/AQ15HS 5-17
Page 18
5 Troubleshooting
5-2-7 Poor Focus
Adjust focus VR of FBT.
Improved focus?
Check focus leads from FBT
to CRT Socket.
Check the CRT Socket.
Dynamic focus circuit is right?
AQ15VS
Replace the CRT and verify focus.
No
Yes
Yes
No
Aging monitor and check for focus
change.
Refer to 5-1-15 Dynamic
Focus Failure.
5-2-8 Purity Failure
Degaussing
Purity is right?
Degaussing circuit is right?
Replace CRT and verify purity.
Yes
Done
No
No
Refer to 5-1-20 Degaussing Failure.
Yes
5-18 AQ15VS/AQ15HS
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