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THOMSON TECHNICAL COMMUNICATION
Television
Troubleshooting Flow Chart
TFC-04047
The information contained herein is provided solely to assist qualified Technician in the diagnosis of the problem described. It is not intended as a modification or alteration of the product.
REVISION DATE: Chassis: CTC211 9/23/2004
TOPIC: Audio Troubleshooting SYMPTOM: No or Distorted Audio
1
1A
Select a channel. Is there audio signals present at J16511 (in-out board) on pins 4 and 7?
No
Verify the DM 1 power supply voltages. If these test ok, suspect the DM 1 module.
Yes Table 1
2
Inputs on U11401 U11400 (R) (L) and
2B
Pins on U11400/401 Tuner Vid 1 Vid 2 Vid 3 Fav YUV 12 15 14 13 1 5 Check for audio input signals at U11400 and U11401. Use Table 1 on the left to locate which pin. Are these signals present?
No
If tuner or Fav audio is missing, check VCC (12vdc) U11402 pin 4. If this is present, check output on pins 1 and 7 of U11402. If the signal is missing, suspect U11402. If the input signals at YUV, Vid 1, 2, or 3 are missing, check the input jacks and associated components.
Yes
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Product Safety Information
Product Safety information is contained in the appropriate Thomson Service Data covering models/chassis referenced herein. All specified Product Safety requirements and testing shall be complied with prior to returning equipment to the customer. Servicers who defeat safety features or fail to perform safety checks may be liable for any resulting damages and may expose themselves and others to possible injury.
First Edition First Printing Copyright 2003 Thomson multimedia Inc. Printed in U.S.A. Trademark(s) ® Registered Marca(s) Registrada(s)
Page 1 of 3
THOMSON INC.
Table 2 Truth table for audio switching for U11400 and U11401 Pin 9 Tun Vid 1 Vid 2 Vid 3 Fav YUV L L L L H H Pin 10 H H L L L L L= 0vdc Pin 11 H L H L L H
3
3B
Check for audio output signals at pin 3 of U11400 and U11401. Use Table 2 on the left for the logic switching. Are these signals present?
No
Check for VCC (12VDC) at pin 16 of U11400 and U11401. If this voltage is missing, check U14104 and associated circuitry. If the logic is incorrect, suspect U13101 or U13102. If the logic is correct, suspect U11400 or U11401.
Yes
H= 12vdc
4
4A
Are the audio signals present at J11402 (in/out board) at pins 5 and 7?
No
Check for audio signals at pins 1 and 3 of J11402. If these signals are missing, check buffer IC's, U11301 and U11403. If the signals are present at J11402 pins 1 and 3, suspect the DM 1 module.
Yes
5
5A
Check U11800 at pins 13 and 17. If the signals are missing, check the VCC (12vdc) at pin 8 U11404 or suspect buffer IC U11404. If the input signals are present, Try reinitializing the eeprom or suspect U11800.
Are the audio signals present at pins 9 and 19 of U11800?
No
Yes
6
6A
Are the audio signals present at Pins 26 and 27 of U11800?
No
Check for audio input signals at pins 7 and 18 of U11800. If these signals are missing, check U11701 and U11702 for input /output signals. Also check U11702 switching pin 9 (SRS ENH on/high) and pins 10 and 11 (SRS on/low) and VCC - pin 16 (12vdc). If these test ok, reinitialize eeprom or suspect U11800.
Yes
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Product Safety Information
Product Safety information is contained in the appropriate Thomson Service Data covering models/chassis referenced herein. All specified Product Safety requirements and testing shall be complied with prior to returning equipment to the customer. Servicers who defeat safety features or fail to perform safety checks may be liable for any resulting damages and may expose themselves and others to possible injury.
First Edition First Printing Copyright 2003 Thomson multimedia Inc. Printed in U.S.A. Trademark(s) ® Registered Marca(s) Registrada(s)
Page 2 of 3
THOMSON INC.
7
7A
Check resistors R11912 and R11911. Also check Capacitors C11936 and C11937. Check for DC voltage present at pin 9 of U11901 and U11902. If DC is present, check the diodes CR11905, CR11904, CR11910, and CR11911 or the I/O +31vdc and -17VDC return (floating ground) .
Are the audio input signals present at pin 9 of U11901 and U11902?
No
Yes
8
8A
Check the 31vdc VCC at pins 11 and 13 or U11901 and 902. Also check the return voltage (-17vdc) at pins 8, 14, and 15. If these are present check the mute pin 10 (0vdc on and 5vdc off). If the voltage is low, check the mute circuit on U11800 pin 3 and 8. If active, reinitialize U13102. Also check the headphone jack J26105. If all these voltages test good, suspect U11901 and 902.
Are the audio output signals present at pin 1 of U11901 and U11902?
No
Yes
9
Check the INT/EXT speaker switch SW11900. Check connector J11900. Also check for speakers for open lead dress or open voice coil.
End
Product Safety Information
Product Safety information is contained in the appropriate Thomson Service Data covering models/chassis referenced herein. All specified Product Safety requirements and testing shall be complied with prior to returning equipment to the customer. Servicers who defeat safety features or fail to perform safety checks may be liable for any resulting damages and may expose themselves and others to possible injury.
First Edition First Printing Copyright 2003 Thomson multimedia Inc. Printed in U.S.A. Trademark(s) ® Registered Marca(s) Registrada(s)
Page 3 of 3
THOMSON INC.