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TROUBLESHOOTING 

continued

If there is no video on the CRT, check for a video waveform at
TP12.

If video is present at TP12:

Refer to the “Video” section of this Troubleshooting guide.

If there is no 

 at TP12:

Check the voltages, waveforms, and components associated
with IF Module 

 and AGC Mute Transistor 

A defective AGC circuit can cause an overloaded picture, excessive
snow or loss of audio and video.

See the AGC Voltage Chart for AGC voltages with signal.

AGC Voltage Chart

IF201

pm 1 

SYNC

If there is no vertical or horizontal sync:

Check the voltages, waveforms, and components associated
with Y Buffer Transistor (4301).

If there is no vertical sync:

Check the voltages, waveforms, and components associated
with pins 38, and 44 of Y/C/J 

 

 

 1 Transistor

 

 2 Transitor 

 and 

 3 Transistor

If there is no horizontal sync:

Check the voltages, waveforms, and components associated
with pins 41, and 45 of 

VIDEO

Inject a signal at 

 and check for video on the CRT

If video is present:

Refer to the 

 section of this 

 guide.

If there is no video on the CRT, check for a video waveform at pin 6
of Comb Filter (CM1301).

If video is missing at pm 6 of CM1301:

Check the voltages, waveforms, and components associated
with Buffer Transistors 

 

 and AV-Switch IC

 and CM1301.

If video is present at pin 6 of CM1301, check for a video waveform
at the emitter of Y Amp Transistor (4305).

If the video is missing:

Check the voltages, waveforms, and components associated
with 4305, Buffer Transistor 

 and Y Switch IC 

If the waveform is present at the emitter of 

Check the voltages, waveforms, and components associated
with pins 

 and   of Y/C/J 

 

 Buffer

Transistors 

 

 

 Gamma Comp 1 Transistor 

 

and Equalizer Transistor 

 

 Y Clamp Transistor 

 

and Gamma Comp 2 Transistor 

If brightness is inadequate or 

 be 

Check the voltages, waveforms, and components associated
with pin   of 

Check for a chroma waveform at pm   of Y/C/J IC 

If the waveform is missing:

Check the voltages, waveforms, and components associated
with Buffer Transistor 

 C-Switch IC 

 and pin 4

of Comb Filter (CM1301).

If chroma waveform is present at pin   of 

 1, cheek for the 

er waveforms at pins 

 of 

If these waveforms are missing:

Check the voltages, waveforms, and components associated
with pins 

 thru 25 of 

Check the 

 oscillator at pin 7 of 

If the proper wavforms are present at pins 

 of 

Refer to the “Raster” section of this Troubleshooting guide.

RASTER

Check the CRT and CRT voltages. Cheek the voltages, waveforms,
and components associated with Buffer Transistor 

 SW 1

Transistor 

 and SW 2 Transistor (4712).

If there is no Red:

Cheek the voltages, waveforms, and components associated
with pin 20 of Y/C/J IC 

 Red Output Transistor 

Video Amp Transistor 

 and Red 

 Det Transistors

 16).

If there is no Green:

Check the voltages, waveforms, and components associated
with pin 22 of 

 Green Output Transistor 

 Video

Amp Transistor 

 and Green 

 Det Transistors (4706,

 15).

If there is no Blue:

Check the voltages, waveforms, and components associated
with pm 24 of 

 Blue Output Transistor 

 Video

Amp Transistor 

 and Blue 

 Det Transistors 

 14).

If the raster has a keystone shape:

Check the Deflection Yoke 

Summary of Contents for KV-27EXR25

Page 1: ... 7 CBoard 9 PIP Adjustments 6 Placement Chart 5 Safety Precautions 1 Safety Related Adjustments 6 Schematics CRT 2 Control D A Converter 2 MTS Decoder 3 PIP 4 Power Supply 4 Television 2 Terminal Guides and Notes 7 Test Equipment 1 Troubleshooting 1 Tuner Terminal Guide 6 Tuner Voltage Chart 6 For Supplier Address See PHOTOFACT Annual Index SONY Model W 27EXR25 Chassis SCC D50F A Complete coverage...

Page 2: ...ken in defeating the high voltage shutdown circuit as this may cause excessive X radiation and damage the CRT TSOO and associated components Monitor the high voltage and troubleshoot HORIZONTAL Determine if the TV is in shutdown Refer to the High Voltage Shutdown section of this Troubleshooting guide If the TV is not in shutdown inject a horizontal signal at the base of the Horizontal Output Trans...

Page 3: ... emitter of 4305 Check the voltages waveforms and components associated with pins 3 4 8 26 and 27 of Y C J IC IC301 Buffer Transistors 43 lO Q3 13 Gamma Comp 1 Transistor 43 15 and Equalizer Transistor 43 14 Y Clamp Transistor 43 17 and Gamma Comp 2 Transistor 4316 If brightness is inadequate or camrot be controll Check the voltages waveforms and components associated with pin 5 of v901 CHROMA Che...

Page 4: ... of PIP Cont IC IC2204 If the waveform is missing Check the voltages wavefotms and components associated with pins 10 thru 13 of IC2104 Vertical Pulse Transistor Q2119 and pins 5 and 36 of Y C J IC IC2103 If waveform is present at pin 23 of IC2204 check for the proper wa veform at pin 61 of IC2204 If waveform is missing Check the voltages waveforms and components associated with pins 1 and 2 of IC...

Page 5: ... Control and pin 12 of IC2103 If chroma waveform is present at pins 20 and 22 of IC2103 check for the proper waveforms at pins 17 and 18 of A D Conv IC IC2206 If the waveforms are missing at pins 17 and 18 of IC2206 Check the voltages waveforms and components associated with R Y Out Transistor Q2103 and B Y Out Transistor 42114 If the waveforms are present at pins 17 and 18 of IC2206 check for the...

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Page 29: ... 4 buttons 3 Make changes on selected adjustment by pressing the 3 and 6 button Saving Adjustments to Memory 1 Adjustments must be saved to memory 2 To save adjustment press the Mute button and then the Enter button Memory Write Confirmation 1 2 3 Disconnect AC plug from outlet Plug set in and enter Service Adjustment Mode Select adjustment and confirm that setting was saved to memory Exiting Serv...

Page 30: ...n oscilloscope to TP47B Adjust Sub Color Con trol RV2 107 so that the PIP portion of the signal is 1 9V p p Tune in a picture on PIP window Adjust Sub Hue Control RV2106 to obtain proper skin tones PIP RGB PICTURE RGBP Tune in a colorbar Pattern Enter Service Adjustment Mode Select RGBP adjustment and adjust level to 00 Set Picture and Brightness to MINIMUM Adjust RGBP for proper colorbars in PIP ...

Page 31: ...ing of pattern Save adjustment to memory VERTICAL COMP VCOM Enter the Service Adjustment Mode Select VCOM and adjust level to 02 Save adjustment to memory CHROMA TRAP CROM Tune in a colorbar pattern Set Color to Maximum and turn NOTCH on Connect an oscilloscope to TP47R On C Board Enter the Ser vice Adjustment Mode Select CROM and adjust level for MINI MUM chroma Save adjustment to memory SUB BRIG...

Page 32: ...f the screen Rotate the Vertical Static Magnets to converge the Red and Blue dots over the Green dots ver tically at the center of the screen NOTE Some versions use a BMC magnet To adjust the BMC magnet slide it in and out to correct for insufficient horizontal static convergence rotate the BMC magnet to correct for insufficient vertical static convergence Tune in a cross hatch pattern and loosen ...

Page 33: ... replac ing the following components IC653 PM501 4608 4607 D531 C545 C627 R570 R591 R627 R628 R675 T500 Preparation Before Confirmation 1 Turn the Power switch on and receive a white signal Set the Picture and Bright controls to Maximum SAFETY RELATED ADJUSTMENTS 2 Confum that the voltage at TP 85 is more than 108V when the set is operating normally with 120VAC supply Hold down Operation Confirmat...

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