Service Manuals, User Guides, Schematic Diagrams or docs for : RCA TV ctc203_201_203

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ctc203_201_203


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CTC203
TROUBLESHOOTING

                  Main Troubleshooting Flow Chart

                     Dead Set                 7-2

                     EEPROM Error Codes       7-3

                     System Control           7-4

                     Power Supply             7-5

                     Horizontal               7-6

                     Vertical                 7-7

                     Tuner                    7-8

                     Tuner Band Switching     7-9

                     Color                    7-10

                     Video                    7-11

                     Buttons                  7-12

                     Infrared                 7-12

                     OSD                      7-13

                     Gemstar                  7-14

                     F2PIP                    7-15

                     Analog Comb              7-16

                     General Audio Problems   7-18

                     Distorted Audio          7-20

                     Stereo Seperation        7-20

                     No Stereo                7-21

                     Sound Logic              7-22




                                   Page 7-1          Return To Main Flow Chart
CTC203
TROUBLESHOOTING


                  DEAD SET TROUBLESHOOTING


                   Set Will Not Turn On



                     Degauss Relay
                       Switching            Check EEPROM Error Codes
                                   YES
                       ON/OFF?                 Using Chipper Check
                          NO




                    Microprocessor
                    U13101 Reset YES           Check System Control
                     Pin 51 = 5V?
                          NO




                  Check Power Supplies




                                 Page 7-2              Return To Main Flow Chart
CTC203
TROUBLESHOOTING

                                    EEPROM Error Codes




 Error code:   Chassis:            Error:                                               Action

HEX     DEC                POWER CONTROL ERRORS
 00     0      ALL           No Errors
 01     1      ALL           16V_STBY fault                                   Check Power Supplies
 03     3      ALL           12V_RUN fault                                    Check Power Supplies
 08     8      ALL           T4chip XRP (X-ray protection)                    Check Power Supplies
 09     9      ALL           T4chip POR (power on reset)                      Check Horizontal
 0A     10     w/ F2PIP      F2PIP POR                                        Check F2PIP
 0B     11     ALL           Stereo Decoder POR                               Check General Audio
 10     16     ALL           Run I2C bus latched                              Check System Control
 12     18     ALL           Standby I2C bus latched                          Check System Control
 HEX    DEC                I2C ACKNOWLEDGE ERRORS
 22     34     w/Gemstar     Failure to get acknowledge from Gemstar module   Check Gemstar
 2C     44     w/ F2PIP      F2PIP fault                                      Check F2PIP
 66     102    w/Gemstar     Gemstar bus fault                                Check Gemstar
 80     128    ALL           Stereo Decoder fault                             Check General Audio
 A0     160    EEPROM        EEPROM bus fault                                 Check System Control
 BA     186    ALL           T4chip fault                                     Check System Control
 C4     196    ALL           Main Tuner PLL bus fault                         Check Tuner
 C6     198    ALL           Main Tuner DAC bus fault                         Check Tuner




                                                Page 7-3                        Return To Main Flow Chart
CTC203
TROUBLESHOOTING

                           System Control Troubleshooting

                              Microprocessor
                                 U13101                    Check Micro Reset Circuit.
                                                  NO
                               Pin 51 = 5V?                  Q13501, Q13503, etc.
                                    YES



                                                                                 Check R13128,
                                EEPROM                                           R13181,Q13104.
                                  U13102                      U13101              U13101 Pin 20
                                Pin 8 = 5V?
                                                  NO
                                                           Pin 20 ~4.5V? NO      should be High
                                                                YES
                                    YES                                           Impedance. If
                                                                                   not replace.
                                                         Replace Q13104
                               Microprocessor
                                   U13101                Replace 4MHz Crystal Y13101,
                                               NO
                             Pins 40,42 = 4MHz?             R13107,C13106,C13107
                                    YES




                            Plug in AC. Check Bus
                           Activity on U13101 Pins
                                                               Check EEPROM and Power
                           23,24. Do Transmissions NO
                          Stop after a few moments?                    Supplies
                                   YES




                               Microprocessor
                                U13101 KD1
                              Pin 5 = 5V Pulse?
                                                  NO     Check Power Supply
                                    YES




   Note: Pin 5, Drive
   Line, should have a       Microprocessor
   20ms pulse. If this      U13101 Sense Lines           Check Front Panel for Stuck or
   pulse is seen on a       Pins 6,7,8 = Steady NO       Shorted Button or Missing 5V.
   sense line then a        5V with No pulses?
                                    YES
   button is closed.


                         Check EEPROM Error Codes
                            Using Chipper Check




                                              Page 7-4                  Return To Main Flow Chart
CTC203
TROUBLESHOOTING

                            Power Supply Troubleshooting


                        Raw B+
                       @TP14210       NO
                                                Check F14201, R14202,
                        ~ 150V ?                 CR14201-CR14204
                          YES




                      +16V stanby
                    Cathode CR14108   NO         Check CR14108
                         ~ 16V?
                          YES




                     RegB+ Cathode
                       CR14106                 Check RegB+ Circuit. R14116,U14101,U14102,
                                      NO
                        ~ 130V?                  Q14102,Q14103,Q14106,Q14107,Q14101
                          YES




                       +5V stanby
                                                      U14103 Pin 1
                      U14103 Pin 3    NO
                                                        ~ 14.8V? NO     Check CR14110
                         ~ 5.2V?                          YES
                          YES
                                                                      Replace Q14104,Q14105
                                                Replace U14103
                      +12V Switch                                              YES
                      U14104 Pin 3                    U14104 Pin 1       U13101 Pin 19~5V
                                      NO                 ~ 16V? NO       with Power Button
                        ~ 12.2V?                                              Pressed?
 If the Degaus            YES
                                                         YES
                                                                               NO
Relay is clicking
then the +12Vs                                  Replace U14104
and +7.5Vs will                                                         Troubleshoot System
  be ON only                                                                 Control
momentarily at
    turn ON.          +7.5V Switch
                      U14150 Pin 3                    U14150 Pin 1
                                      NO                 ~ 10V? NO      Check R14151
                         ~ 7.3V?
                                                         YES
                          YES



                                                Replace U14150
                    Power Supplies OK




                                           Page 7-5                   Return To Main Flow Chart
CTC203
TROUBLESHOOTING

                           Horizontal Troubleshooting
      NOTE:    If the Set is going into XRP shutdown the Degaus Relay will click
               and the pulses below will only be present momentarily at turn ON

                          T4 Chip
                           U12101         NO              Check U14150
                        Pin20 =7.6V?
                              YES




                        T4 Chip U12101                   T4 Chip U12101                 Troubleshoot
                        Pin 22 =7.2Vp-p                  Bus Activity on
                                          NO                                 NO           System
                         Square Wave?                      Pins 43, 44?                   Control
                              YES                              YES




                                                         Replace U12101
                                                        (See Note at Top)
                         Q14302 Emitter
                           = 5.3Vp-p      NO            Replace Q14302
                         Square Wave?
                              YES




                        Q14301Collector
                         = 224Vp-p ?      NO            Replace Q14301
                              YES




                         Q14401 Base                     With Set OFF is
                                                         there Continuity                 Replace
                          ~ 3.1Vp-p?      NO                                 NO
                                                                                          T14301
                                                            in T14301?
                              YES                              YES




                                                     Check Base Components
                             Q14401
                            Collector                 Check Bad Q14401, Shorted or open
                                          NO
                          = 1060 Vp-p?               T14401, Bad Horizontal Yoke Winding.
                              YES
                                                      Check C14403, CR14403 and RegB+.



                        EEPROM Code
                         indicates XRP                   Horizontal Test
                             Fault?
                                          NO
                                                           Complete
                              YES



              Check XRP Circuitry Q14901, CR14902,
                     R14902, R14903, R14905
                                          Page 7-6                          Return To Main Flow Chart
CTC203
TROUBLESHOOTING

                          Vertical Troubleshooting

                  T4 Chip U12101                      T4-Chip
                   Pin 15 ~2.4V    NO
                                                     U12101 Pin                Check U14150
                                                                NO
                    Sawtooth ?                       26 =7.6V?
                                                         YES
                       YES



                                                      T4-Chip
                                                     U12101 Pin                Check R14153
                                                                NO
                                                     20 =7.6V?
                                                         YES


                                           Reinitialize EEPROM Vertical
                                          Settings. Replace U12101 if Reinit
                                                     doesn't work
                   U14501 Pin 1
                  ~2V Parabola ?   NO                Replace RN14501
                       YES




                    U14501
                  Pin 2 ~ 23V?     NO           Troubleshoot Power Supply
                       YES




                    U14501
                  Pin 6 ~ 23V?     NO                 Check CR14501
                       YES




                    U14501
                  Pin 3 ~ 1.5V?    NO                 Replace U14501
                       YES




                   U14501 Pin 5
                   ~50V Vertical   NO                 Replace U14501
                      Ramp?
                       YES




            Check Connection P14501
             and Choke Continuity




                                        Page 7-7                         Return To Main Flow Chart
CTC203
TROUBLESHOOTING

                                            Tuner Troubleshooting
              NOTE: If the GEMSTAR is set up to use a DSS or Cable Box the Tuner may be locked
                to the input channel for that device. The OSD will still show a channel change but the
                     Channel DOES NOT change therefore the tuning voltages will NOT change

                      Check Supplies to Tuner.
                         +5,+9,+12,-12,+33


                                 All Supplies
                                  Present?      NO          Troubleshoot Power Supplies
                                     YES




                                                                    Does OSD                        Troubleshoot
                                Does Set Tune? NO
                                                                    Change?         NO             Control System
                                     YES                                YES


      See Note at Top of page

Goto Band Switch                                                 U17401 Pins18,19.
Troubleshooting           NO
                             Do All Bands                          Is There Bus NO                  Troubleshoot
  on next page.                 Tune?                                Activity?                     Control System
                                      YES                               YES



                                                                                     See Note at Top of page
 Check U12101                Does AGC Voltage                   U17401 Pins 5,6,7,8.
   Pin 5 and                                                    Are Voltages Close NO
                          NO Change when Input                                                     Replace U17401
 components in                 is Attenuated?                   To Voltage Chart?
  AGC Line.                          YES                                YES




                           Use Chipper Check to                   U17301 Pin 11.
                           Check Tuner alignment                   Does Voltage
                           and EEPROM Values                       change with   NO                Replace Q17402
                                                                     Bands?
                                                                        YES




                                                               Does AGC Voltage
                                                               Change when Input NO                Replace U17301
                                                                 is Attenuated?
                                                                        YES




                                                                 Troubleshoot Video




                                                     Page 7-8                            Return To Main Flow Chart
CTC203
TROUBLESHOOTING

                     Tuner Troubleshooting (continued)

                            Troubleshoot Band Switches


                Check Supplies to Tuner.
                   +5,+9,+12,-12,+33

                                        See Note at Top of previous page
                    U17401 Pins 5,6,7,8.
                    Are Voltages Close NO           Replace U17401
                    To Voltage Chart?
                           YES




                          Q17404
                         Switching     NO             Replace Q17404
                     Voltages Correct?
                           YES




                          Q17402
                         Switching     NO             Replace Q17402
                     Voltages Correct?
                           YES




                       Set Tunes                      Replace CR17101, CR17114,
                       Band 3?        NO             CR17102, CR17103, CR17301,
                                                         CR17304 & Q17101
                           YES




                       Set Tunes                             Q17403
                      Either Band     NO
                                                            Switching     NO        Replace Q17403
                         1 or 2?                        Voltages Correct?
                           YES                                   YES




       Check Diodes CR17105, CR17112,               Replace CR17106, CR17107,
        CR17109, CR17110, CR17303.                 CR17108, CR17111, CR17113,
              Replace as needed                        CR17302 & Q17102.




                                       Page 7-9                            Return To Main Flow Chart
CTC203
TROUBLESHOOTING

                          Color Troubleshooting

                      No Color

                   U12101 Pin 42                Check Input Signal strength.
                   Color Burst >   NO           Troubleshoot Tuner if strong
                     200mV?
                       YES
                                                 signal is attached to input.


                   U12101 Pin 40
                   Color Burst >
                                   NO       Troubleshoot Video Module
                     100mV?
                        YES


                                            NOTE: Color Killer is active if Pin 39 ~1.5V
                   U12101 Pin 39            Check R12801, R12802, R12804 and
                    Color Killer   NO        C12801. If components are good
                      ~3.5V?
                       YES
                                                    Replace U12101



                   U12101 Pin 13            Check attached components and for
                   Chroma APC      NO
                      ~5.5V?
                                                         7.6VrA
                        YES




                   U12101 Pin 41            Check attached components and for
                    Test Filter    NO
                      ~5.5V?                             7.6VrF
                        YES




                  Replace U12101




                                    Page 7-10                        Return To Main Flow Chart
CTC203
TROUBLESHOOTING

                            Video Troubleshooting

                         No Video


                      U12101 Pin 42                 Check Input Signal strength.
                        ~ 2Vp-p?        NO          Troubleshoot Tuner if strong
                           YES
                                                     signal is attached to input.



                       U12101 Pin 38                Troubleshoot Video Module
                         ~ 1Vp-p-?      NO
                                                     (F2PIP or Analog Comb)
                           YES




                      U12101 Pin 30,
                      31,32 ~ 2.5Vp-p
                       Video Signal?
                                        NO               Replace U12101
                           YES




                      Video present at
                        collectors of
                      Q12701, Q12702, NO            Replace Faulty Transistors
                         Q12703?
                           YES




              Check that pins in connec-
              tor are soldered properly.

                    12VrK Present at
                    bases of Q12701,    NO           Troubleshoot 12V supply
                    Q15102, Q15103?
                           YES




                     Video present at
                       collectors of
                     Q15101, Q15102, NO             Replace Faulty Transistors
                        Q15103?
                           YES




                  Check the CRT Screen
                   Control and that the
                  Filaments are glowing.




                                        Page 7-11                     Return To Main Flow Chart
CTC203
TROUBLESHOOTING

                                    User Interface Troubleshooting
                           If a Button is shorted or stuck closed the set will not
                          respond to either the Remote Control or Button Press.

                     Set does not respond to some
                            button presses.

                                 U13101Pin5
                                ~ 20ms Square                   Troubleshoot System Control
                                                  NO
                                    Wave?
                                      YES




                               U13101 Pin 6,7,8                     Check 5V and R13113,
                                   = 5V?          NO
                                                                      R13118, R13119.
                                      YES




 When Power, Volume Up, or Volume Down is pressed there should be ~20ms
  low pulse on their respective sense line. If pulse is not present check for a
 bad switch. If Channel Up, Channel Down or Menu is pressed their respec-
   tive sense line should go Low for the duration of the button press. If not
                             check for a bad switch.



                          Set does not respond to
                             Remote Control.


                               Set Responds to
                                 all buttons?     NO                Troubleshoot Buttons
                                      YES




                               5V at VCC Pin of
                                 IR receiver?     NO             Troubleshoot Power Supply
                                      YES




                              ~5Vp-p Transmis-
                              sion at Output Pin NO                  Replace IR Receiver
                                of IR receiver?
                                      YES




                        Troubleshoot System Control
                              U13101 Pin 36.


                                                       Page 7-12                    Return To Main Flow Chart
CTC203
TROUBLESHOOTING

                                OSD Troubleshooting

            Set does not have Channel
                Numbers or Menus


                    U13101Pin 35
                     Horizontal
                      Present?
                                        NO                    Check Q13301
                         YES




                    U14150 Pin 3 ~
                        1.5V?           NO                    Replace U14150
                         YES




                    U13101 Pin 34
                                                     Check Pin 3 U14150, JC14105,
                   Vertical Present ?   NO
                                                            13320, R13314.
                         YES




                    Press "Menu".
                    U13101Pin 26,
                     27,28 is OSD       NO                   Replace U13101
                       Present?
                         YES



                    Press "Menu".
                    U12101Pin 34,
                                                         Check components between
                     35, 36 is OSD NO
                       Present?                             U13101 and U12101
                          YES




          If Video is normal replace U12101.
           If Video is missing Troubleshoot
                         Video




                                             Page 7-13                    Return To Main Flow Chart
CTC203
TROUBLESHOOTING

                            GEMSTAR Troubleshooting
           Tune set to a channel with valid GEMSTAR program information on the
            Vertical Blankin Interval (VBI). Gemstar is auto-detected by the micro-
           processor. Select the Main menu. If GEMSTAR has been detected there
                           will be a menu item "Guide Plus+ Menu".

                                                                             If item is not present check
                  Main Menu                    Module Cables              the cable(s) to the GEMSTAR
               displays "GUIDE                 seated Properly            module to make sure they are
                                  NO                               NO
               PLUS+ Menu" ?                           ?                    seated properly. Select the
                                                      YES
                                                                          menu again, item will show up
                      YES
                                                                              if this was the problem.

                                                 +5.2V present
                                                U26401 pins 12,            Troubleshoot +5.2V network
                                                 24, 31, 42, 51,   NO
                                                                                   and supply
                                                  61, 65, 73?
                                                      YES



                                                4.03MHz OSC
                                                                          Check for proper components
                                                on U26401 Pins
                                                                   NO    and that all parts are soldered.
                                                    66,67?
                                                                               Replace Y26401.
                                                      YES




                                                  Pulsed Bus               Check bus lines and compo-
                                              activity on U26401 NO        nents and that all parts are
                                                 Pins 69, 70?                      soldered.
                                                      YES                  Check U13101 pins 13,14.


                                               Replace U26401

                GUIDE Menu is                 Vertical present on          Check line and components
                  present ?       NO           U26405 pin 2 ? NO               back to J13103.
                                                                            Troubleshoot Vertical.
                      YES                             YES




                                              Vertical present on
                                               U26401 pin 36 ? NO                Replace U26405

                                                      YES




                                                 Horizontal
                                                 present on                       Check Q26403
                                                                   NO
                                               U26401 pin 39 ?
                                                      YES



                                NEXT PAGE


                                          Page 7-14                          Return To Main Flow Chart
CTC203
TROUBLESHOOTING

                   GEMSTAR Troubleshooting (cotinued)
                           FROM PREVIOUS PAGE



                                         U26401Reset pin              Check line to J13103.
                                           71 ~5.2V ?      NO
                                                                   Troubleshoot System Control
                                                 YES



                                      Check components attached
                                      to U26401pins 62,63. These
                                      control the OSD dot clock.



                                           RGB present
                                           U26401 pins     NO            Replace U26401
                                            48,49,50?
                                                 YES




                                          FSW present
                                         U26401 pin 53 ?   NO            Replace U26401

                                                 YES



                                        Check Connector J13103
                                          Troubleshoot Video
                                       Make sure set is tuned to GEMSTAR data provider. Select
                  Valid Data              "MainMenu", select "GUIDE Plus+ Menu", select
                   Stored in   NO        "GUIDE Plus+ Setup". On the Remote Control Press
                  GUIDE ?              "Go Back" and then "TV". This will bring up the Factory
                     YES                                   Diagnostic Screen.



                                            ROM Test
                                             Passed?       NO            Replace U26402
                                                 YES



                                            RAM Test
                                             Passed?       NO            Replace U26403
                                                 YES



                                            VBI Test
                                            Passed?        NO       Tuned to Non-VBI channel?
                                                                     Check Q26405 composite
                                                 YES
                                                                    Video also Q26404,Q26408
                                                                   which supply sync during "set
           Check Owners manual on GIUDE Plus+ Setup                       off" downloads.
                         procedures.


                                     Page 7-15                       Return To Main Flow Chart
CTC203
TROUBLESHOOTING

                         F2PIP Troubleshooting
             EEPROM Error indicates a
                  F2PIP error.

                                                 Check Y18100, 14.318MHz
                   Does set turn               crystal. Should be within 1Khz
                      ON?
                                   NO
                                                  of nominal to guarantee
                        YES                           proper operation

                                                      Check 3.3V supply.
                   Set has a Main                Check Data and Clock Lines.
                      Picture?    NO
                                                Check main Video Signal path.
                        YES                     If above is good replace U18100




                  PIP Turns ON?                 Check for proper Vert. &
                                               Horz. Sync at U18100 Pin 24
                                   NO

                        YES




                    PIP Picture                  Check PIP contrast and
                     Visible?      NO            Brightness alignments.
                        YES
                                                 Check PIP signal Path



                    PIP Picture
                    Distorted ?    NO              PIP Normal
                        YES




             Use Chipper Check to check
                  PIP Alignments.




                                   Page 7-16                     Return To Main Flow Chart
CTC203
TROUBLESHOOTING

                      Analog Comb Troubleshooting
              Connect a signal generator to the Tuner Input and to
               the Video Input Jack. Check 5V and 12V supplies.


                       U26903
                      Pin 6 = TV        NO           Troubleshoot Video Signal
                     Video Signal
                          YES




                        U26903
                     Pin 3 = Input      NO
                                                       Check R11406, C11403,
                     Video Signal                             R26921
                          YES




                      U26903 Pin 4                  Check Q26903 and insure that
                      0V =TV Video NO
                                                     switching voltage is present
                   5.1V = Input Video
                                                            from U13101
                          YES




                      U26903 Pin 8.
                      Signal can be
      Luma
                  switched between TV
                                     NO                 Replace U26903
                    Video and Input
                         Video?
                           YES



                    Luma & Chroma
                    present at Pins 3
                                        NO              Replace FL2601
                     & 5 on FL2601
                          YES




                    Chroma present at
                      Pin 8 U26902 NO                   Replace U26902
                          YES
     Chroma

                     Luma present at                    Luma present at                 Replace
                      Pin 6 J26901      NO               Pin 8 U26901      NO
                                                                                        U26901
                          YES                                YES




                   Analog Comb OK                      Replace Q26901

                                        Page 7-17                         Return To Main Flow Chart
CTC203
TROUBLESHOOTING

                             General Audio Troubleshooting
          Connect a generator to the set. Adjsut "Sound Processor" Menu to "Speak-
                   ers ON", Fixed Level Mode OFF", "Sound Logic OFF".

          Sound Quick Checks:
          1. Check that Speaker's plug is seated properly.
          2. Check that the "Speakers" are turned ON & "Fixed Level Mode"is OFF
          3. Check that Balance is Centered.
          4. Check if there is audio present at Audio Output Jacks to isolate problem.


  EEPROM Error           Does set turn               Check 9V regulator Q11603.
code indicates Audio        ON?            NO         Check U11601 Bus lines
      Problem.                 YES
                                                             Pins 9,10 .


                           Wide Band
                         Audio present at
                         Pin 17 U11601 ? NO
                                                   Check C11601, Pin 6 U12101
                              YES




                          U11601 Pin 39,
                            40 Audio
                                           NO
                           ABSENT ?
                               YES




                 Check menu items again. Send
                    Volume Up Command.

                           U11601 Pin 22
                            Vcc~ 9.4V ?    NO          Check Q11603
                               YES




                          U11601 Pin 12, 13,
                           17, 39, 40 Bias NO          Replace U11601
                           Voltage~ 4.1V ?
                               YES




                          U11601 Pin 12,
                            13, Audio      NO         Replace U11601
                            Present ?
                               YES



                        Go To Next Page

                                                Page 7-18                  Return To Main Flow Chart
CTC203
TROUBLESHOOTING

               Genearl Audio Troubleshooting (continued)

              Set Volume To Max


                  U11601 Pins 7, 8             U11601 Pins 1, 8
                  Audio Present?     NO          Bias ~4.1V? NO          Replace U11601
                        YES                            YES



                                                   Components
                                                    on U11601            Replace with correct
                                                   Pins 1-4,7, 8   NO
                                                                            components
                                                     Correct?
                                                       YES



                                               Replace U11601


                                                 U11602 Pin 8
                  U11602 Pins 1, 7              ~+8V and Pin 4           Troubleshoot Power
                                     NO                            NO
                  Audio Present?                   ~ -8V ?                    Supplies
                        YES                            YES




                                                   Components
                                                    on U11602            Replace with correct
                                                                   NO
                                                     Correct?               components
                                                       YES



                                               Replace U11602

                   U11900/11901                    +16V Supply
                    Pin 2 Audio                                          Troubleshoot Power
                                     NO             present ?      NO
                     Present?                                                 Supplies
                        YES                            YES




                                                   U11900/11901
                                                      Pin 3             Check Q11901, C11909,
                                                                   NO
                                                      >7V ?                 U13101 Pin 2
                                                       YES



                                                   U11900/11901
                                                    Pin 4 Audio
                                             YES      Present      NO   Replace U11900/11901
                                                   ( 71mVrms )?
            Check Connector J11901


                                          Page 7-19                     Return To Main Flow Chart
CTC203
TROUBLESHOOTING

                        Audio Troubleshooting (Distortion)

       Use a standard 1kHz or 3kHz Sine Wave as an input to the Audio System.

       Scope Audio at HiFi or Speaker Outputs (whichever is failing) to determine
         if distortion is visible. Move back along Audio signal path to determine
       where distortion begins. If point of origin cannot be determined check the
                                        things below.


      Check for electrolytics installed backwards or solder shorts around U11601.
      Anything that can cause shorts or improper bias on the IC pins. Check for
                         open traces or missing jumper wires.


      Check values of R11704/11706. Excessive gain in Expanded Stereo can cause
       Loop IN (U11601 Pins 41,41) to be overdriven. This can cause distortion in
                                      All Modes.

       Check voltages on Vcc pins at the Audio ICs as well as the power network
          that supplies power to the audio circuit for proper voltage levels.


      Check that the Pins of all Audio ICs are soldered properly. Unsoldered pins
             can cause overheating and shutdown in the output devices.

       If Speaker output is distorted but HiFi outputs are not then the problem is
                      probably in the U11900/11901 circuit area.


         Check that coupling capacitors are loaded properly. Check for shorts
        around U11900/U11901 and that the devices are not partially MUTED.



                                 No Stereo Seperation

       Problems with stereo seperation are mostly due to wrong, missing or back-
       ward parts around U11601. Specifically C11605, C11610 and other parts
       connected to pins 16, 18, 23, 24, 28, 29, 30 and 34. this can cause failure of
                                 one of the alignments.




                                         Page 7-20                       Return To Main Flow Chart
CTC203
TROUBLESHOOTING

                    Audio Troubleshooting (No Stereo)
        Tune to a channel with known good strereo. Set SOUND PROCESSOR
          mode to STEREO. Insure set is working with Mono audio signal.

                                                     U11601 not locked to strereo pilot or pilot
                      Set OSD says                  level to low. Check components at pins 14,
                       STEREO?             NO
                                                      15, & 16 for correct values and proper
                            YES                                    installation.


                      Stereo signal
                     @ U11601 Pins
                                           NO       Replace U11601
                     23, 24, 31&32?
                            YES

                                                   Use Chipper Check to view Stereo alignment
                     U11601 Pins                   values. Values near one end of the alignment
                     39,40 Stereo                  range may indicate wrong or missing compo-
                                           NO
                       Present?                      nents. Noisy or improperly aligned SIF or
                          YES                       poorly aligned stereo alingment. Attempt to
                                                                      realign.
                      U11601 Pins
                    14,15,16,19,28,29,30            Check components at dbx pins for correct
                        &34 bias           NO       values and proper installation. If compo-
                         correct?                      nents are correct Replace U11601
                          YES




                    U11601 Pins 7,
                    8 stereo signal
                    both channels?
                                           NO             Replace U11601
                          YES



                     U11602 Pins 1
                       & 7stereo
                      signal both          NO             Replace U11602
                       channels?
                          YES



                     U11900/11901
                     Pin 2, stereo
                      signal both          NO           Replace device without signal
                       channels?
                          YES




             Check connector J11901, P11901
                     and speakers


                                            Page 7-21                      Return To Main Flow Chart
CTC203
TROUBLESHOOTING

                  Audio Troubleshooting (Sound Logic)

           Tune to a channel with strong MONO signal. Connect a DC
                        voltmeter to cathode of CR11503.




                      Voltmeter
                                                 Check components around U11501 for
                    reading ~4V ?     NO
                                               correct values and proper installation. In-
                                               sure that there is a strong WBAudio Signal
                         YES                                at U11601 Pin 17.


                  Remove Audio input

                       Voltmeter              Check +12V and -12V supplies. Check for
                    reading <100mV    NO      missing parts, wrong values or solder prob-
                           ?
                                                        lems. Replace U11501
                         YES




                    U13101 Pin 37
                    Voltage same as            Check components in Sound logic line be-
                                      NO
                     @ CR11503 ?                 tween U13101 pin 37 and CR11503
                         YES



                   Sound Logic OK




                                       Page 7-22                    Return To Main Flow Chart



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