CSE78**T/CSE98**T 5-1
5 Troubleshooting
5-1 Parts Level Troubleshooting
Notes: 1. If a picture does not appear, fully rotate the brightness and contrast controls clockwise and reinspect.
2. Check the following circuits.
• No raster appears: Power circuit, Horizontal output circuit, H/V control circuit, and H/V 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 FG601, D601.
Done.
Repeating start?
Check and replace Q631, Q632, Q601,
ZD601, D603, R607 and D604.
No
Yes
IC601 Pin 1 waveform is right?
Check and replace IC601,
IC602, IC604.
Yes
No
IC602 and IC604
are right?
Replace parts and verify voltages.
Yes
No
Normal operation
Replace Main board.
Yes
Verify voltages.
Yes
No
WAVEFORMS
1
1
544 V (IC601, #1)
CH1 P-P = 544 V CH1 RMS = 332.4 V
5 Troubleshooting
5-2 CSE78**T/CSE98**T
5-1-2 DPMS Failure
Make No H/V sync (power off
mode)
Check signal source
H/V sync video level.
LED blinks
Check IC201 Pin 31.
Yes
No
+12 V line off
Check IC201 Pin 1.
Yes
No
Q632 Base driving voltage exists?
Check IC201 Pin 2.
Check and replace Q632.
Yes
No
Done
5 Troubleshooting
CSE78**T/CSE98**T 5-3
5-1-3 H_Deflection Failure
IC401 Pin 6 waveform is right?
Q405 source waveform
is right?
Check Q405, R422, R423, D406
and D415, +220 V line.
Yes
Yes
No
1. Check R401, +12 V line.
2. Check IC401 Pins 7~6, 6~5.
3. Replace IC401.
No
Q406 gate, drain
waveforms are right?
Check R426, Q406.
Check +35 V line.
Yes
No
Q407 base, collector
waveforms are right?
Check and replace Q407 and D412.
Check DY connector connection.
No
No
IC251 Pin 4 is high?
Replace IC251.
Check some parts around
Q253 and Q254.
Yes
No
Check some parts around Q252.
IC251 Pin 26 waveform
is right?
Check some parts around IC251.
Yes
No
WAVEFORMS
2
3
4
5
6
8
7
3
230 V (Q405, Source)
CH1 P-P = 230 V CH1 RMS = 150.1 V
8
12.08 V (IC251, #26)
CH1 P-P = 12.08 V CH1 RMS = 7.396 V
2
10.96 V (IC401, #6)
CH1 P-P = 10.96 V CH1 RMS = 6.180 V
5
54 V (Q406, Drain)
CH1 P-P = 54 V CH1 RMS = 22.44 V
4
11.6 V (Q406, Gate)
CH1 P-P = 11.6 V CH1 RMS = 6.944 V
6
18.6 V (Q407, Base)
CH1 P-P = 55.2 V CH1 RMS = 9.52 V
7
1.216 kV (Q407, Collector)
CH1 P-P = 1.216 kV CH1 RMS = 316 V
5 Troubleshooting
5-4 CSE78**T/CSE98**T
5-1-4 S Correction Failure
S1~S5 signals are right at each
frequency block?
Check S1 ~ S5 signal.
Check and replace Q409~Q413,
C430, C431, C433, C434, C435,
C437 and C441.
Yes
5-1-5 H_Lin. Failure
IC201 Pin 4 voltage varies with
different H_Lin. DAC values?
IC403 Pin 7 voltage varies with
different H_Lin. DAC values?
Check +12 V, –14 V line.
Check some parts around IC403.
Check L402.
Yes
Yes
No
Check and replace IC201.
No
Replace IC201.
No
7-1-6 Invariable H_Size
IC251 Pin 28 voltage varies with
different H_Size DAC values?
IC401 Pin 6 output duty varies with
different H_Size DAC values?
Check some parts around IC401,
IC251 Pin 28.
Yes
No
Check and replace IC251.
No
5 Troubleshooting
CSE78**T/CSE98**T 5-5
5-1-7 Abnormal H_Size
IC201 Pin 42 output duty varies
with different B+ offset DAC
values?
T402 Pin 8 waveform is right?
Check and replace T402.
Check some parts around D407.
Yes
Yes
No
Check and replace IC201.
Check some parts IC201 Pin 42,
IC251 Pin 28 and IC401 Pin 2.
No
5-1-8 Side Pin or Trap Failure
IC251 Pin 24 output exists?
Yes
Check and replace IC251.
Check and replace IC401.
Check some parts IC401 Pin 2
and IC251 Pin 24.
5-1-9 Para. or Pin Balance Failure
IC251 Pin 24 output varies with
different DAC values?
No
Replace IC251.
No
WAVEFORMS
9
9
29.8 V (T402, #8)
CH1 P-P = 29.8 V CH1 RMS = 7.14 V
5 Troubleshooting
5-6 CSE78**T/CSE98**T
5-1-10 Tilt Failure
IC201 Pin 6 output duty varies
with different DAC values?
IC403 Pin 8 output varies with
different DAC values?
Check and replace IC403.
Check and replace CRT.
Yes
Yes
No
Check and replace IC201.
No
Check tilt connector connection
5-1-11 V Deflection Failure
±14 V line is on?
IC251 Pin 23 output exists?
Check and replace IC251.
Yes
Yes
No
Refer to 7-1-1 No Power Supply
No
IC301 Pin 1 input exists?
Check R262 and R309.
Yes
No
IC301 Pin 5 output exists?
Check and replace some parts
around IC301.
No
No
Check V DY connector connection.
5 Troubleshooting
CSE78**T/CSE98**T 5-7
5-1-12 V Size or Pos. Variation Failure
IC251 Pin 23 output varies with
different DAC values?
Yes
Check some parts around IC301.
Check bias voltage.
Check and replace IC251 and IC301.
No
5-1-13 High Voltage Failure
+220 V is on Q502 collector?
Q501 gate driving pulse exist?
Check +35 V line.
Check and replace Q501, Q253,
Q254, IC251 and Q502.
Yes
Yes
No
Check and replace Q502.
No
Q502 base driving pulse
exists?
Check and replace R504, T501,
D503 and Q503.
Yes
No
Q503 drain driving pulse
exists?
Done
No
Yes
Check and replace Q504, Q507,
IC501, R515, R521, VR501, C521,
C522, T502 and T503.
WAVEFORMS
10
11
12
10
11.36 V (Q501, Gate)
CH1 P-P = 11.36 V CH1 RMS = 6.944 V
11
808 V (Q502, Base)
CH1 P-P = 808 V CH1 RMS = 244 V
12
234 V (Q503, Drain)
CH1 P-P = 234 V CH1 RMS = 171.5 V
5 Troubleshooting
5-8 CSE78**T/CSE98**T
IC5 Pin 12 input exists and
varies with different patterns?
Check and replace IC5.
Input full white pattern to monitor.
No
Yes
No
T502 Pin 8 output exists?
Check and replace T502.
Yes
No
IC201 Pin 3 output exists and
varies with different patterns?
Check and replace IC201.
Yes
No
Check and replace Q202,
Q201 and +12 V line.
Check CN103.
5-1-14 ABL Failure
5-1-15 Dynamic Focus Failure
IC251 Pins 18 and 15 output
are right?
Check and replace IC251.
Yes
No
Some parts around Q551,
Q552, Q554 and Q553 are right?
Replace failed part.
No
No
Some parts around T551 are right?
Replace failed part.
Check the connection between FBT
Pin 12, CRT Socket PCB.
Yes
No
13
14
13
2.20 V (IC251, #15)
CH1 P-P = 2.20 V CH1 RMS = 2.776 V
14
580 V (T551, #1)
CH1 P-P = 580 V CH1 RMS = 278.2 V
WAVEFORMS
5 Troubleshooting
CSE78**T/CSE98**T 5-9
5-1-16 No Video
IC5 Pins 5, 8 and 10 inputs
are right?
IC5 Pins 21, 24 and 26
outputs are right?
Check I2C bus and +12 V line.
Yes
Yes
No
Check IC1.
No
IC03 Pins 4, 6 and 14 outputs
are right?
Check +12 V line.
Check and replace IC03.
Yes
No
Cathode DC levels are right?
Check +220 V line.
Check and replace Q108 and IC06.
No
No
G2 voltage is right?
Check G2 wire, CRT Socket board,
and FBT.
Change CRT.
Yes
Done.
No
Check signal cable and connection.
5 Troubleshooting
5-10 CSE78**T/CSE98**T
5-1-17 Micom Failure
IC201 Pin 25 input is right?
IC201 Pins 32 and 33 inputs
are right?
Check X201, C213 and C214.
Yes
Yes
No
Check IC606.
No
IC201 Pin 40 input is right?
Check IC202.
Yes
No
All in/output values are right?
Replace IC201.
No
No
Done
15
16
15
3.42 V (IC201, #33)
CH1 P-P = 3.42 V CH1 RMS = 2.500 V
16
3.16 V (IC201, #32)
CH1 P-P = 3.16 V CH1 RMS = 2.560 V
WAVEFORMS
5 Troubleshooting
CSE78**T/CSE98**T 5-11
5-1-18 OSD Failure
IC04 Pin 17 input is right?
IC04 Pin 6 input is right?
Check and replace Q101.
Yes
Yes
No
Check and replace Q303 and D304.
No
IC04 Pins 7 and 8 inputs are right?
Check IC201 Pins 29 and 30.
Yes
No
IC04 Pins 20, 21 and 22
outputs are right?
Check and replace IC04.
No
No
IC5 Pins 1, 2 and 3 inputs
are right?
Check and replace R106,
R107 and R173.
Check and replace IC5.
Yes
Done
No
Check CN202 and connector Ass’y.
5 Troubleshooting
5-12 CSE78**T/CSE98**T
RL601 operation is right?
Q601 base input is right?
Check and replace Q601.
No
No
Yes
Check D-Coil, Pos 601.
Yes
IC201 Pin 7 output is right?
Check and replace IC201.
Check user function key.
Yes
No
R206 and R630 are right?
Replace R206 and R630.
Done
Yes
No
Check degaussing connector.
5-1-20 Degaussing Failure
5-1-19 User Control Failure
IC201 Pins 11 and 12 inputs are
right at each function.
Check and replace function key.
Check and replace IC201.
Done
Yes
No
Check connector Ass’y.
5 Troubleshooting
CSE78**T/CSE98**T 5-13
5-2 General Troubleshooting
5-2-1 No Picture
LED blinks?
LED is green color?
After restart monitor LED don’t
come on, repair power circuit.
Check signal cable.
Check G2 voltage, high voltage,
R, G, B cathode voltage.
Yes
No
No
LED is Amber color?
No
Yes
5-2-2 Shut down
Yes
5-2-2 Shut Down
Blinking LED’s?
Scan failure
Check horizontal, vertical deflection
system and check power supply
secondary voltages.
No
Yes
Yes
Check power supply.
No
High voltage failure?
Check high voltage system.
Check and replace IC201.
Done
No
Yes
Video failure?
Check Video board.
No
Yes
5 Troubleshooting
5-14 CSE78**T/CSE98**T
5-2-3 Missing Color
Are proper Video levels
on CN101 (D-Sub) Pins 1, 2 and 3,
R-BNC, G-BNC and B-BNC.
Are proper AC voltage on all
cathodes?
Refer to 5-1-16 No Video.
Yes
Yes
No
Check signal generator and cathode.
No
Are proper DC voltage on all
cathodes?
Check IC5 Pins 15, 16 and 17.
Check QR01, QR02, QG01,
QG02, QB01 and QB02.
Change the CRT.
Done
Yes
No
Is G2 voltage right?
Check G2 wire, G2 control, volume
and FBT.
Yes
No
5 Troubleshooting
CSE78**T/CSE98**T 5-15
Is G2 voltage right?
Is blank pulse on Pin 19 of IC5
on Video board?
Check Q102, CN103 and T402 Pin 8.
Yes
Yes
No
Check G2 control volume and FBT.
No
Is blank pedestal on
Pins 21, 24 and 26 of IC5?
Check IC5 and related components.
Yes
No
Is V_FLB pulse on
Pin 17 of IC04?
Check Q303.
Done
Yes
No
Is blank pedestal on all cathodes?
Check Pins 15, 16 and 17 of IC5.
Check QR01, QR02, QG01, QG02,
QB01 and QB02.
No
No
Check white balance adjustment.
5-2-4 Visible Retrace
5 Troubleshooting
5-16 CSE78**T/CSE98**T
Are signals right?
Signals at Pins 1, 13 and 15 of
CN102 are right?
Check IC6 on Video board.
Yes
Yes
No
Check Video cable.
No
Signals at CN201 Pin 1, CN204
Pins 6 and 8 are right?
Check wire dressing and connections.
Check circuits on Main board.
(IC201 and IC251)
Yes
Done
No
Check input signals Pins 2, 13
and 14 of CN101 and G-BNC.
5-2-5 Unsynchronized Image
5 Troubleshooting
CSE78**T/CSE98**T 5-17
Is the convergence now
within spec?
Readjust convergence.
No
Done
Yes
Is the convergence now
within spec?
Done
Change CRT and readjust
convergence.
No
Done
Yes
Try readjusting convergence.
5-2-6 Misconvergence
5 Troubleshooting
5-18 CSE78**T/CSE98**T
Improved focus?
Check focus leads from FBT
to CRT Socket.
Check the CRT Socket.
No
Aging monitor and check for focus
change.
Yes
Is dynamic focus circuit right?
Refer to 5-1-15 Dynamic
Focus Failure.
Replace the CRT and verify focus.
Yes
No
Adjust focus VR.
5-2-7 Poor Focus
5-2-8 Purity Failure
Purity is right?
Degaussing circuit is right?
Refer to 5-1-20 Degaussing Failure.
Replace CRT and verify purity.
Yes
No
No
Done
Yes
Degaussing
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