Samsung CSR5987 Page 8 Service Bulletin Download

Page: 8 / 22

Disclaimer: This information is provided “as is” without warranty of any kind

either expressed or implied, including, but not limited to, the implied
warranties of merchantability and fitness for a particular purpose.

REV 11-1

SUBJECT: Vertical Circuit Modification

BACKGROUND: The vertical output IC301 has been changed from a TDA4866
to a TDA8351. The circuit change was made with serial numbers higher than
A95025160. The circuit change was made due to the failure of IC301 in some
cases during power up.

SOLUTION: The circuitry around IC301 was changed to meet the specifications
of the TDA8351.

PARTS LIST:

SN. A9524002821 TO A9538025160

SN. A9538026160 TO ?

Location No.

Part No.

Description

Part No.

Description

C306

NONE

1218204707

C-CERAMIC
47PF, 50V

R310

NONE

1412104229

R-CARBON
4.2K, 1/6W

R303

1413401021

R-CARBON

1413402214

R-CARBON

1K, 1/4W

220, 1/4W

R304

1414201R01

R-CARBON

1433601R0B

R-CARBON

1, 1/2W

1, 1W

R307

141420R508

R-CARBON

1433601R0B

R-CARBON

0.5, 1/2W

1, 1W

IC301

2332290235

IC, TDA4866

2332190339

IC, TDA8351

SERVICE BULLETIN

PRODUCT: Computer Monitor

BULLETIN: Monitor 95-006
MODEL: Samtron SC-428PS

Summary of Contents for CSR5987

Page 1: ...anufacturer PARTS LIST Location No 15 Toshiba CRT 15 Samsung CRT CRT M36KUT23XX02 M36KUK35XX02 CODE NO 897 250125AA CODE NO 897 250134AA C447 CAP MPPF 400V 304J CAP MPPF 400V 274J CODE NO 916 656300TJAX CODE NO 916 656270TJAX C442 CAP MPPF 400V 274J CAP MPPF 400V 224J CODE NO 916 656270TJAX CODE NO 01518 343 224 R324 NONE REF CF 1 2W 5 470 ohm CODE NO 911 134707FF R639 REF MO 3W 5 4 7 ohm REF MO 3...

Page 2: ...UBJECT CRT Substitution BACKGROUND Samsung is supplying three different CRT manufacturers with the CMG7377L monitor Parts differ in the heater high voltage and deflection circuits as well as the degaussing coil rating SOLUTION The parts that differ from each other are listed in the parts list below PARTS LIST See the back of this cover page SERVICE BULLETIN PRODUCT Computer Monitor BULLETIN Monito...

Page 3: ...REF FUSIBLE 2 2 CODE 911 611807LA CODE 911 811807LA CODE 2008 000002 T504 TRANS FOCUS 100 650T TRANS FOCUS 100 600T TRANS FOCUS 100 850T CODE 923 480157GA CODE 923 480167HA CODE BH26 30018A R215 REF CF 3 9K 5 1 6W REF CF 3 9K 5 1 6W R CAR 2 2K 1 6W CODE 911 143907YA CODE 911 143907YA CODE 911 142207QJAL C428 CAP MPP 250V 104J CAP MPP 250V 104J C MPP 250V 274J CODE 916 656100QJAL CODE 916 656100QJA...

Page 4: ...10 1 SUBJECT CRT Substitution BACKGROUND Samsung is manufacturing the CMB5477L with three different manufacturer s CRTs Each type of CRT has parts that differ in the heater brightness and the deflection circuits SOLUTION The parts that differ from each other are listed in the parts list below PARTS LIST See the back of this cover page SERVICE BULLETIN PRODUCT Computer Monitor BULLETIN Monitor 95 0...

Page 5: ...507LFXA R631 R M OXIDE 3 9 3W R M OXIDE 3 9 3W R M OXIDE 1 5 3W CODE 911 313907LF CODE 911 313907LF CODE 911 311507LFXA R307 R CAR 470 1 2W R CAR 470 1 2W R CAR 330 1 2W CODE 911 134707FF CODE 911 134707FF CODE 911 133307FF C461 C M P P 1 6KV 552 J C M P P 1 6KV 552 J C M P P 1 6KV 502 J CODE 916 944550YJAX CODE 916 944550YJAX CODE 916 354560YJAX R472 R M OXIDE 180 2W R M OXIDE 180 2W R M OXIDE 75...

Page 6: ...mbers after A9538025160 use a different IC301 TDA8351 These are not interchangable without making various circuit changes to meet the specifications of the new IC301 SOLUTION The counter measure to keep the original IC301 TDA4866 from failing is done by improving the grounding on the monitor Two ground lugs and two additional ground wires have been added See the attached page for mounting procedur...

Page 7: ...ng Procedure Add a ground lug to point A and point D as in the figure shown below Take the 200mm wires and route them through the holes labeled E and F in the main pcb as in the diagram below The holes are located next to the IC301 heatsink Solder the 200mm wires to the heatsink solder connection located nearest to the routed wire hole The other end of the 200mm wires are to be soldered to the CRT...

Page 8: ...ilure of IC301 in some cases during power up SOLUTION The circuitry around IC301 was changed to meet the specifications of the TDA8351 PARTS LIST SN A9524002821 TO A9538025160 SN A9538026160 TO Location No Part No Description Part No Description C306 NONE NONE 1218204707 C CERAMIC 47PF 50V R310 NONE NONE 1412104229 R CARBON 4 2K 1 6W R303 1413401021 R CARBON 1413402214 R CARBON 1K 1 4W 220 1 4W R3...

Page 9: ...tes first when power is first applied to the monitor This will affect the horizontal circuit and cause a surge which in turn will cause Q403 and Q408 to short SOLUTION Insert a IN4937 diode into location D300 and substitute R401 33 ohm 1 2W with a 220 uH coil PARTS LIST Original Parts New Parts Location Parts Code Description Parts Code Description R401 911 123307FF R Carbon 33 1 2w 925 001001AN C...

Page 10: ...rst when power is first applied to the monitor This will affect the horizontal circuit and cause a surge which in turn will cause Q403 and Q408 to short SOLUTION Insert a IN4937 diode into location D300 and substitute R401 33 ohm 1 2W with a 220 uH coil PARTS LIST Original Parts New Parts Location Parts Code Description Parts Code Description R401 911 123307FF R Carbon 33 1 2w 925 001001AN Coil 22...

Page 11: ...peration Q415 is designed in the circuit to cut off horizontal drive to the base of Q404 This is achieved by turning Q415 on in the Suspend mode In normal operation Q415 is turned off There is a delay in turning Q415 off by approximately 15 ms This will cause an abnormal pulse at the base of Q404 causing damage to the transistor SOLUTION The base current limiting resistance to Q415 has been change...

Page 12: ...itor BULLETIN MON 97 002 MODEL CMH7379L SUBJECT To prevent whistling sound from occurring BACKGROUND A whistling sound is created from harmonic noise generated between T402 L402 and the main PCB near the Flyback Transformer SOLUTION Add a piece of rubber to insulate the main PCB solder side from the bottom metal shield See Illustration below showing the section of the PCB where the rubber will be ...

Page 13: ...ransistor Quality BACKGROUND The horizontal output for the CQB4147 has been changed as of May 1 1997 The BU2508DF which had been used prior to this date has been failing intermittently due to a current surge from the 166 volt B line The current surge is caused mainly from the DPMS off mode recovery SOLUTION The circuit has been improved by using a 2SC5149 which has a higher hfe than the originally...

Page 14: ...e vertical positioning circuit The failure is caused by a current surge during power up and from the monitor recovering from an extended period in the DPMS Suspend mode SOLUTION Replace Q302 Q303 and R327 with different ratings Production went under these changes as of February 1 1997 Observe the pin configuration when replacing Q302 PARTS LIST ORIGINAL NEW Location No Part No Description Part No ...

Page 15: ...ROUND Q407 fails due to a transient pulse and current when mode switching from DOS to Windows This occurs with a Matrox video card installed in the computer SOLUTION Add a sub PCB assembly as in figures 1 and 2 and a snubbing circuit for the horizontal output as in figure 3 PARTS LIST ORIGINAL NEW Location No Part No Description Part No Description NA NA NA BH92 50106J SUB PCB ASSEMBLY NA NA NA BH...

Page 16: ...Figure 1 Top View of the Main Board ...

Page 17: ...Figure 2 Bottom View of the Main Board ...

Page 18: ...Figure 3 Snubbing Circuits ...

Page 19: ...d in the x ray protection and the high voltage adjustment circuits SOLUTION When replacing a flyback transformer refer to the parts list below The resistance values should be changed accordingly If the resistance values are different from the flyback transformers listed below intermittent no raster or shutdown conditions will exist Refer back to the original parts list and schematic located in the...

Page 20: ... zenor diode between pin 13 of IC101 and ground cathode to pin 13 and anode to ground Replace jumper wire JP104 with a 100 ohm watt resistor The resistor will act as a delay and improve the R G B surge absorbers discharge effect Replace the 300V spark gaps at each of the Red Green and Blue cathodes of the CRT with 200V surge absorbers PARTS LIST ORIGINAL NEW Location No Part No Description Part No...

Page 21: ...ODUCT Computer Monitor BULLETIN MON 97 009 MODEL CMB5477L SUBJECT Video Pre amp IC101 LM1207 Failure BACKGROUND IC101 becomes damaged from arcing within the CRT during electronic discharge SOLUTION Add a 300V spark gap in between the G1 grid of the CRT and ground This will aid in reducing the discharge effect from the CRT PARTS LIST ORIGINAL NEW Location No Part No Description Part No Description ...

Page 22: ...QA4147 CQB4147 SUBJECT No Raster BACKGROUND D618 which is the rectifier diode for the 166V line burns due to a reverse peak voltage that occurs when power is turned off SOLUTION A snubbing capacitor must be added in parallel with D618 in order to prevent this from occurring This capacitor should be added to all CQB and CQA chassis as a preventative maintenance PARTS LIST ORIGINAL NEW Location No P...

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