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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
WAVEFORMS
1 332 Vpp (IC601, #1)
Chirping noise exists?
Yes
Check and replace IC601.
No Repeating start? Yes Check and replace D606.
No
1
IC601 Pin 1 waveform is right?
No
Check and replace IC601.
Yes C627 Voltage is 13 V ± 0.5V? No Check and replace IC201, IC301, IC401, Q590, Q490, and 12V regulator circuit.
Yes Normal operation? Yes Verify voltages. No Replace main board.
Done
LE15V*/LE17LS/LE17LT/ LE17KS/LE17KT/LE17JS/LE17JT
5-1
5 Troubleshooting
5-1-2 DPMS Failure
Check signal source H/V sync. video level.
WAVEFORMS
2 332Vpp (IC601, #1)
Make no H/V Sync. (power off mode)
LED blinks?
No
Check IC201 Pin 40.
Yes +12 V line off? No Check IC201 Pin 5/Pin 6 and Q624, Q625 operation.
Yes
2
IC601 Pin 1 output voltage exists? Yes Done
No
Refer to 5-1-1 no power supply.
5-2
LE15V*/LE17LS/LE17LT/ LE17KS/LE17KT/LE17JS/LE17JT
5 Troubleshooting
5-1-3 H_Deflection Failure
Does PWM output signal appear at Pin 28 (B_DRV) of IC401? Yes No Does DC 12V appear at Pin 29 of IC401? Yes No Check 12 V line.
3
WAVEFORMS
Check IC401. 3 12 Vpp (IC401, #28) Does horizontal pluse signal appear at Pin 26 of IC401? Yes
5
4
No
Check IC401.
Does 110 Vp-p signal appear at Collector of Q401? Yes Check Q590, Q490 and T401.
No
Check Q401. 4 2.00V (IC401, #26)
5 78 Vpp (Q401, Collector)
5-1-4 S Correction Failure
Check S1 ~ S3 signal.
S1~S3 signals are correct at each frequency block? Yes Check and replace Q451, Q452, Q453, Q454, Q458, Q457, Q456, Q455, D451, D452, D453, D454.
No
Check and replace IC201.
LE15V*/LE17LS/LE17LT/ LE17KS/LE17KT/LE17JS/LE17JT
5-3
5 Troubleshooting
5-1-5 H_Lin. Failure 5-1-6 Invariable H_Size
Check and Replace L441 (Fix Type)
IC401 Pin 28 voltage varies with different B_DRV DAC values? Yes Q590 gate output duty varies with different B_DRV DAC values?
No
Check and replace IC401.
No
Check some parts around Q590, Pin 14~16 of IC401.
5-1-7 Abnormal H_Size
IC401 Pin 24 output duty varies with different B+ offset DAC values? Yes
6
No
WAVEFORMS
Check and replace IC201, IC401. 6 1300 Vpp (Q490, Collector)
Q490 collector waveform is right? Yes Check components around D405 and L411.
No
Check and replace Q411, Q412, Q413, and Q414.
5-4
LE15V*/LE17LS/LE17LT/ LE17KS/LE17KT/LE17JS/LE17JT
5 Troubleshooting
5-1-8 Side Pin or Trap Failure
No
WAVEFORMS
Check and replace IC401. 7 0.44 Vpp (IC401, #24)
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. Yes
Refer to 5-1-7 abnormal H_Size.
5-1-10 Tilt Failure ( Only 17" Function)
Check tilt connector connection
IC201 Pin 20 output duty varies with different DAC values? Yes Q323 Base output varies with different DAC values? Yes Check and replace Q321 and Q322.
No
Check and replace IC201.
No
Check and replace Q323.
LE15V*/LE17LS/LE17LT/ LE17KS/LE17KT/LE17JS/LE17JT
5-5
5 Troubleshooting
5-1-11 V Deflection Failure WAVEFORMS
13V and 10V lines are on? No Refer to 5-1-1 no power supply 8 2.5 Vpp (IC401, #23)
Yes
8
IC401 Pin 23 output exists?
No
Check and replace IC401.
Yes
9
IC301 Pin 6 output exists?
No
Check and replace components around IC301.
9 50 Vpp (IC301, #6)
Yes Check DY connector connection.
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
LE15V*/LE17LS/LE17LT/ LE17KS/LE17KT/LE17JS/LE17JT
5 Troubleshooting
5-1-13 High Voltage Failure WAVEFORMS
3
IC401 Pin 28 OSC pulse exists?
No
Check and replace IC401 and +12 V line.
3 12 Vpp (IC401, #28)
Yes
10
Q590 gate driving pulse exists?
No
Check and replace Q501 and Q502.
Yes
11
Q590 drain pulse exists?
No
Check and replace Q590, L501 and D501. Check 50V Line.
10 12 Vpp (Q590, Gate)
Yes Done
5-1-14 ABL Failure
11 150 Vpp (Q590, Drain)
Input full white pattern to monitor.
IC102 Pin 22 input exists and varies with different patterns? Yes Check CN201.
No
Check and replace IC102.
T501 Pin 8 output exists?
No
Check and replace T501.
Yes IC201 Pin 26 output exists and varies with different patterns? Yes Done No Check and replace IC201.
LE15V*/LE17LS/LE17LT/ LE17KS/LE17KT/LE17JS/LE17JT
5-7
5 Troubleshooting
5-1-15 Dynamic Focus Failure ( Only 17" Function)
IC401 Pin 32 output is right? No
WAVEFORMS
Replace the IC401. 12 0.58 Vpp (IC401, #32)
12
Yes Some parts around Q551 are right? No Replace failed part.
Yes
13
T561 Pin 6 input is right?
No
Check and replace C443.
13 50.0 V (T561, #6)
Yes
14
T561 Pin 1 output is right?
No
Replace the T561.
Yes Check the connection between FBT focus pin and CRT socket PCB. 14 380 Vpp (T561, #1)
5-8
LE15V*/LE17LS/LE17LT/ LE17KS/LE17KT/LE17JS/LE17JT
5 Troubleshooting
5-1-16 No Video
Check signal cable and connection.
WAVEFORMS
15 1.00V (IC102 #5,6,7)
15
IC102 Pin 5, 6 and 7 inputs are right? Yes
No
Check the signal cable connection.
16
IC102 Pin 19, 20 and 21 outputs are right? Yes
No
Check I2C bus and +12V line. 16 1.00V (IC102 #19,20,21)
17
IC106 Pin 2, 4 and 6 inputs are right? Yes Cathode DC levels are right?
No
Check +12V, +80V line. Check and replace IC106.
No
Check +80V line. Check and replace IC106. 17 20.0V (IC106, #2,4,6)
Yes G2 voltage is right? No Check G2 wire, CRT socket board and FBT.
Yes Change CRT.
Done
LE15V*/LE17LS/LE17LT/ LE17KS/LE17KT/LE17JS/LE17JT
5-9
5 Troubleshooting
5-1-17 MICOM Failure
No
WAVEFORMS
Check IC621. 18 5 Vpp (IC201, #13, 14)
IC201 Pin 11 input voltage is 5V?
Yes
18
IC201 Pin 13 and 14 inputs are right? Yes IC201 Pin 18 input is right?
No
Check C202, C203 and X201.
No
Check and replace IC201 and R225.
Yes All in/output values are right? No Replace IC201.
Yes Done
5-10
LE15V*/LE17LS/LE17LT/ LE17KS/LE17KT/LE17JS/LE17JT
5 Troubleshooting
5-1-18 OSD Failure
Check CN203 or CN201 and connector ass'y. Yes
19
WAVEFORMS
19 1.00 V (IC102, #24) No Check and replace IC105, C101, and R102, ZD104.
IC102 Pin 24 input is right?
Yes
20
IC102 Pin 1 input is right?
No
Check CN102 Pin 8. 20 1.00 V (IC102, #1)
Yes IC102 Pin 11 and 12 inputs are right? Yes IC102 Pin 19, 20 and 21 outputs are right? Yes Check and replace IC102. No Check and replace IC102. 21 1.00 V (IC102, #19,20,21) No Check IC201 Pin 41 and 42.
21
Done
LE15V*/LE17LS/LE17LT/ LE17KS/LE17KT/LE17JS/LE17JT
5-11
5 Troubleshooting
5-1-19 User Control & Power Switch Failure
Does the DC level change at Pin 37 & 38 of IC201 when you push the S/W button? Yes Check IC201. No Check the button. (SW201 ~ SW205)
5-1-20 Degaussing Failure
Check degaussing connector.
RL601 operation is right?
Yes
Check D-coil and TH601.
No Q621 base input is right? Yes Check and replace Q621.
No IC201 Pin 10 output is right? No Check and replace IC201.
Yes Done
5-12
LE15V*/LE17LS/LE17LT/ LE17KS/LE17KT/LE17JS/LE17JT
5 Troubleshooting
5-2 General Troubleshooting
5-2-1 No Picture
Yes
LED blinks?
Refer to 5-2-2 shut down.
No LED is green color? Yes Check MICOM.
No Check G2 voltage, high voltage and R, G, B cathode voltage.
5-2-2 Shut Down
Blinking LED's?
No
Check power supply.
Yes Scan failure? Yes Check horizontal, vertical deflection system and check power supply secondary voltages.
No Video failure? Yes Check video board.
No Check and replace IC201.
Done
LE15V*/LE17LS/LE17LT/ LE17KS/LE17KT/LE17JS/LE17JT
5-13
5 Troubleshooting
5-2-3 Missing Color WAVEFORMS
Proper Video levels are on CN101 (D-Sub) Pin 1, 3 and 5? Yes
22
No
Check signal generator.
22 10.0 V (R,G,B, Video)
Proper video signal to all cathodes? Yes
No
Refer to 5-1-16 no video.
Proper DC voltage to all cathodes?
No
Check IC102 Pin 14, 15 and 16. Check IC104.
Yes G2 voltage is right? Yes Heater voltage is right? No Check D622, Q623 and R625. No Check T501.
Yes G1 voltage is right? Yes Replace CRT. No Check D504, Q512 and T501.
Done
5-14
LE15V*/LE17LS/LE17LT/ LE17KS/LE17KT/LE17JS/LE17JT
5 Troubleshooting
5-2-4 Visible Retrace
Check white balance adjustment.
WAVEFORMS
23 5.00V (Q511, Collector)
G2 voltage is right?
No
Check T501.
Yes Blank pulse at Pin 3 of IC401? No Check IC401. 24 20.00V (CRT Socket, G1) No
Yes
23
V_FLB pulse at collector of Q511? Yes
Check Q511.
24
Valid the vertical pulse on CRT socket G1? Yes Done
No
Check CN102 and CN201.
LE15V*/LE17LS/LE17LT/ LE17KS/LE17KT/LE17JS/LE17JT
5-15
5 Troubleshooting
5-2-5 Unsynchronized Image
Check input signals Pin 2, 3 and 5 of CN202.
Signals are right?
No
Check video cable
Yes Signals at Pin 28 and 29 of IC201 are right? Yes Signals at Pin 1 and 2 of IC401 are right? Yes Check circuits on main board. No Check IC401 No Check IC201.
Done
5-16
LE15V*/LE17LS/LE17LT/ LE17KS/LE17KT/LE17JS/LE17JT
5 Troubleshooting
5-2-6 Misconvergence
Adjust convergence.
Convergence is now within spec.? No Readjust convergence.
Yes
Done
Convergence is now within spec.? No Change CRT and readjust convergence.
Yes
Done
Done
LE15V*/LE17LS/LE17LT/ LE17KS/LE17KT/LE17JS/LE17JT
5-17
5 Troubleshooting
5-2-7 Poor Focus ( Only 17" Function)
Adjust focus VR of FBT.
Improved focus?
Yes
Align monitor and check for focus change.
No Check focus leads from FBT to CRT socket.
Check CRT socket.
Dynamic focus circuit is right?
No
Refer to 5-1-15 dynamic focus failure.
Yes Replace the CRT and verify focus.
5-2-8 Purity Failure
Degause
Purity is correct?
Yes
Done
No Degaussing circuit is correct? No Refer to 5-1-20 degaussing failure.
Yes Replace CRT and verify purity.
5-18
LE15V*/LE17LS/LE17LT/ LE17KS/LE17KT/LE17JS/LE17JT