JVC I'Art AV-27MF36 Power Supply Training Download Page 34

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• Repeating ON/OFF

switching generates
Secondary Voltages

• IC function drains the

ICs Power Supply and
it becomes too low

TELEVISION

The IC could Shut OFF due to insufficient Supply Voltage

SWITCHING DEVICE

SECONDARY VOLTAGES

Reference Schematic 52004 Main PWB for Schematic Details.

Summary of Contents for I'Art AV-27MF36

Page 1: ...JVC Television Power Supply Training ...

Page 2: ...ent Click Here to read more This eBook will show you how to test the electronic component correctly and accurately Some of you may say that I don t need this eBook because it is too simple Do you know that in fact there is lots of testing electronic components secrets I have learned from this guide Do you know how to test a TRIAC correctly and accurately If you answer no then I guess you have to g...

Page 3: ...peration of Switching supplies Details about the regulator IC Operation of the Power Supply Modes The operation of the Power Factor Circuit Troubleshooting procedures useful in diagnosing defective components Some failures and their symptoms TELEVISION ...

Page 4: ...dentification Service Manual Supplements Switching Power Supply Power Supply Components Basic Switching Switching Device Switching Operation Switching Review Power Factor circuit Troubleshooting techniques TELEVISION ...

Page 5: ...TELEVISION MODEL IDENTIFICATION ...

Page 6: ...the Main Difference List of the Service Manual or the Service Manual Supplements For example YA319 is the service manual but YA319B would be a revision The Example shows that the AV 32MF36 has 4 versions The example shows the Z Version of this model The Model Number listed at the top of the model label will always be the same for all versions The TV Model Version is usually shown to the right of t...

Page 7: ...r from those of the AV 48P776 H service manual For details other than those described in this manual please refer to the AV 48P776 H service manual No YA318 2005 11 No YA318B 2006 6 Supplements show Corrections Additions and Differences that may have occurred during the production of a TV Model Service Manual Supplement Original Service Manual ...

Page 8: ...sure you have all Service Documents for a model prior to servicing The Original Manual will only show the original Service Information for a model but Service Manual Supplements may list information that is important to the service of a model Ensure that you use the Model and Model Version when looking for documents on ISee to ensure you are getting the correct information ...

Page 9: ...SWITCHING POWER SUPPLY TELEVISION LIVE ISOLATED When troubleshooting it is necessary to use the respective ground of the device you are measuring Taken from Schematic 52004 Main PWB ...

Page 10: ...live Those on the right side are isolated When troubleshooting it is NECESSARY to use the respective ground Live or Isolated of the device you are measuring Additional components located along the dotted line ensure circuit isolation while passing all Power or Control signals These components are the Relay Switching Transformer Photocoupler and the Capacitors that are used to connect the Live and ...

Page 11: ...nd C903 Line Filter 4 D901 and C907 Main rectifier 5 IC911 Switching Regulator 6 D911 R911 R930 and C914 Startup 7 T921 Switching Transformer 8 R912 R913 and R914 Current Feedback 9 R915 and D912 Run DC 10 D917 and D914 Refresh 11 D945 RY951 Main Relay 12 Q951 Main Relay Drive 13 IC921 Error Amp Schematic 52004 Main PWB ...

Page 12: ...7 Main rectifier Provides rectified DC to Switching Regulator and Switching Transformer 5 IC911 Switching Regulator Regulates Switching Voltages out of Transformer 6 D911 R911 R930 and C914 Startup Provides Startup DC for Switching Regulator until Transformer conduction begins 7 T921 Switching Transformer Provides voltages to all circuits 8 R912 R913 and R914 Current Feedback Provides current feed...

Page 13: ...NDUCTOR CHARGING 1 Switch SW1 off 2 Apply a DC to the inductor as shown 3 Turn SW1 on and the Current rises slowly 4 The Inductor charges to its maximum 5 After charging is complete the current stays constant TELEVISION ...

Page 14: ...stor The current ramps up and Reaches maximum and stays constant When the current does not change any more the inductor is fully charged Capacitors and inductors behave similarly but opposite Capacitors can hold the charge but inductors can not It has to be discharged If there is no path to discharge it will make eddy current through the coil and produce heat The basic of Switching power supply is...

Page 15: ...charging turn SW1 off 1 What happens to the charge in the inductor It will be lost as heat 2 Can we use this energy If so how 3 Can we control this charging If so how This can be applied in the Switching Power supply BASIC SWITCHING INDUCTOR DISCHARGING ...

Page 16: ... When the current flow to the Fully Charged Inductor is interrupted by closing SW1 the stored energy is released as Heat This stored energy is utilized in the Switching Power Supply ...

Page 17: ...RGY If there is a secondary winding during the off time energy will be transferred into the secondary In other words Transformer charges during ON time Discharges during OFF time BASIC SWITCHING TRANSFORMER OPERATION ...

Page 18: ...core of the inductor discharges into the secondary 3 Since we are interested in DC output the addition of the Diode and Capacitor at the secondary will allow for the energy to be stored in the Capacitor This stored energy is our Secondary DC voltage 4 If the switch is turned off prior to fully charging the inductor the transferred energy will be less This shows that by controlling the Switch s on ...

Page 19: ...imary ON and OFF will result in Secondary Voltage 3 Controlling the ON OFF timing of the Switching Device will result in a Regulated Secondary Voltage Switching power supply regulation is achieved by controlling the switching device s ON OFF timing TELEVISION BASIC SWITCHING SUMMARY ...

Page 20: ...SWITCHING DEVICE STR Fxxxx IC Very reliable construction All in one package Protection circuits Minimum pins 5 pins GND 5 4 VCC S D Ocp FB OVP TSD OSC DRV STR F6xxxx 2 3 1 TELEVISION ...

Page 21: ...ons we called it SW1 On the Schematics previously outlined it is the Regulator It has the actual ON OFF switch a Power FET control circuits and protection circuits The Internal Circuits of the other Switching Devices used by JVC may vary but the operation of the Device is the basically the same for them all ...

Page 22: ...GND OCP FB DRV T S D Latch OVP Pre Reg Q1 Ref1 Ref2 5 Osc 1 3 2 S D 4 0 7V Applied to Pin 1 will turn OFF the FET FET will turn on after pre determined time Applying a 2 0V pulse to Pin 1 refreshes the IC prior to pre determined time TELEVISION ...

Page 23: ...ween pin2 and pin3 of the IC If 0 7V is applied at pin 1 the FET turns OFF Due to the internal timing circuit the FET will start again after a pre determined time If we wants to turn ON the IC prior to the internally decided time we can apply a 2VDC to pin1 This means we can turn ON the FET and turn OFF the FET at any time we want ...

Page 24: ...Start Up V IN GND OCP FB DRV T S D Latch OVP Pre Reg Q1 Ref1 Ref2 5 Osc 1 3 2 S D 4 TELEVISION SWITCHING DEVICE Internal ...

Page 25: ...DC after a pre determined time it will come on OCP FB This is the control input to override the oscillator s timing By applying a 0 7V to this input we can turn OFF the internal circuit and FET By applying a 2 0V pulse we can turn it back ON TSD Thermal Shut Down This is for the thermal protection When the IC overheats this circuit turns off the IC and latches it We have to unplug the power to res...

Page 26: ...the Start up voltage IC starts conduction The Switching FET turns ON Now it can switch the RAW DC through the Transistor if it is connected TELEVISION SWITCHING DEVICE Turn ON D901 C914 D911 R911 R930 D901 Reference Schematic 52004 Main PWB for Schematic Details ...

Page 27: ...s circuit turns the IC and FET ON If the IC was open and AC current was allowed to flow no current would flow through the IC This would cause C914 to overcharge and explode For this reason If you find a defective Switching Regulator IC replace the Capacitor Similarly if you find exploded Capacitor replace the IC Reference Schematic 52004 Main PWB for Schematic Details ...

Page 28: ... charges it A proportional voltage develops at the source resistor Turning the FET off will cause the switching action TELEVISION T921 C907 R912 R913 SWITCHING DEVICE TRANSFORMER CHARGING Reference Schematic 52004 Main PWB for Schematic Details ...

Page 29: ...mer is allowed to charge Raw DC is passed through the primary of a transformer to the IC pin 3 The Voltage passed through the FET connects to a source resistor on pin2 to ground As the Transformer charges a proportional voltage will build on the Source Resistor R914 ...

Page 30: ...D OCP FB DRV T S D Latch OVP Pre Reg Q1 Ref1 Ref2 5 Osc 1 3 2 S D 4 TELEVISION Do you remember this Applying 0 7V to Pin 1 will turn OFF the FET FET will turn on after pre determined time SWITCHING DEVICE Turn Off 1 2 ...

Page 31: ...If 0 7V is applied at pin 1 the FET turns OFF Due to the internal timing circuit the FET will start again after a pre determined time ...

Page 32: ...witching action TELEVISION SWITCHING DEVICE Turn Off 2 2 R914 C913 Ramping Voltage builds here and is feed back to pin1 If this feedback Resistor Capacitor opens up the IC will never be turned off The transformer and the IC will overheat and shutdown occurs Reference Schematic 52004 Main PWB for Schematic Details ...

Page 33: ...rmer is charged 0 7V builds at the Capacitor C913 We use this ramping voltage at pin2 to turn off the IC When the inductor primary charges Current increase through the source resistors It causes a ramp voltage at pin2 and is applied to pin If this feedback Resistor Capacitor opens up the IC will never be turned off The transformer and the IC will overheat and shutdown occurs ...

Page 34: ...econdary Voltages IC function drains the ICs Power Supply and it becomes too low TELEVISION The IC could Shut OFF due to insufficient Supply Voltage SWITCHING DEVICE SECONDARY VOLTAGES Reference Schematic 52004 Main PWB for Schematic Details ...

Page 35: ...This action causes the transformer to charge and discharge generating generates Secondary Voltages The IC s startup voltage is through a high value resistor When the IC functions it drains current through pin4 and the supply is insufficient and cannot continue to supply voltage to the IC The IC could Shut OFF due to insufficient Supply Voltage We want the IC to be permanently on and turn ON OFF th...

Page 36: ...the start up DC with Run DC IC Power Supply becomes stable Transformer fully Charges Discharges TELEVISION D912 R915 SWITCHING DEVICE SUPPLEMENT POWER RUN DC Reference Schematic 52004 Main PWB for Schematic Details ...

Page 37: ... voltage an additional DC is supplemented using a Resistor and Diode This is known as Run DC circuit Now that the supply is steady and running We have secondary voltages The Transformer charges fully and discharges into secondary ...

Page 38: ... 2 POWER ON Switching Circuits ONLY supply Power after TV Power is ON Standby Voltage for Micon is supplied from DC Voltage tapped directly from incoming AC line Reference Schematic 52004 Main PWB for Schematic Details Reference Schematic YA321 Power and Def PWB for Schematic Details There are 2 general types of circuit configurations used in JVC Power Supplies ...

Page 39: ...w B1 Voltage flow when the TV is turned ON Reference Schematic YA321 Power and Def PWB for Schematic Details TYPE 2 POWER ON Switching circuits supply Power after TV Power is ON Standby Voltage for Micon is supplied from DC Voltage tapped directly from incoming AC line In the example shown the Standby VCC is supplied by T951 D954 D957 and C951 The Micon turns ON RY951 this allows AC Voltage to flo...

Page 40: ... In Standby Mode very few devices are functional They need only very little charge We must reduce energy transfer TELEVISION SWITCHING OPERATION STANDYBY MODE ...

Page 41: ...ce CPU power is also provided from the transformer s output we can not turn off the regulator In order to minimize the Power consumption we control the energy transfer by reducing the charging and discharging time Refer to the schematic and follow the standby supply for the CPU It is generated from the STB13V ...

Page 42: ...normal mode the on time is the transformer s charging time In standby mode additional DC added to the ramp This reduces ramping time TELEVISION SWITCHING OPERATION STANDBY MODE GRAPHIC Standby OFF ON Turn off by Feedback Turn on by Refresh Turn on by Oscillator ...

Page 43: ... Ramp By this time the transformer would normally be fully charged In standby we don t need the transformer to charge fully this means reducing the ICs on time This is done by raising the Ramp s base or adding DC to it The new ON Time will be the time it takes to ramp up to 0 7V from the additional DC ...

Page 44: ...tional DC is applied from IC s supply using a Photo Coupler The Photo Coupler must be turned On in Standby Mode and turned Off in Normal Mode TELEVISION SWITCHING OPERATION ADDITIONAL DC USING PHOTO COUPLER ...

Page 45: ...he ICs Supply Voltage using the Photo Coupler The CPU s outputs a High turning the Photo Coupler on The Photo Coupler supplies additional FeedBack DC to pin1 As we already saw in the chart this must be added in standby and must be removed in normal mode ...

Page 46: ...TSD OSC DRV STR F6514 5 2 3 1 AC In REG 5V CPU 1STB13 TELEVISION SWITCHING OPERATION SUPPLEMENT POWER RUN DC During Standby Mode the Run DC may be insufficient to keep Switching IC ON IC Power is supplemented by Regulated Voltage ...

Page 47: ...ed When this happens the IC could turn off due to the insufficient Run DC Voltage that is being supplied For this reason a regulated DC voltage from a higher tap is used to supplement the RUN DC This voltage must be regulated otherwise in normal operation the voltage will be too high and will destroy the IC This circuit is not used in all models ...

Page 48: ...VP TSD OSC DRV STR F6514 5 2 3 1 AC In REG 1STB13 5V CPU Relay 1STB13 TELEVISION SWITCHING OPERATION PHOTO COUPLER DURING POWER ON At Power On Micon outputs LOW Photo coupler is inactive On Time is normal B1 relay is turned On ...

Page 49: ...low This signal through some inverters turns on the relay and supplies power to Main Power output At the same time the Micon turns off the Photo Coupler The control circuits for the Photo Coupler and their operation may vary slightly in some models ...

Page 50: ...monitors B1 Controls Photo Coupler to Reduce on time if B1 exceeds spec GND 5 4 VCC S D Ocp FB OVP TSD OSC DRV STR F6514 5 2 3 1 AC In REG 1STB13 5V CPU Relay B1 Error Amp TELEVISION SWITCHING OPERATION ERROR AMP ...

Page 51: ... B1 Supply is more than required it must be reduced By controlling the ON OFF timing of the supply the B1 Supply voltage can be controlled This is done with the use of an Error Amp The Error Amp monitors the B1 Supply and Activates the Photo Coupler feedback as needed to reduce the ON time of the Switching Supply ...

Page 52: ...r than the pre determined time Apply 2 0V pulse to pin1 During the negative edge the IC will refresh reset and turns on again GND 5 4 VCC S D Ocp FB OVP TSD OSC DRV 2 3 1 AC In Turn off signal Refresh Gen From Tx TELEVISION SWITCHING OPERATION REFRESH ...

Page 53: ...ET will turn on again In case of additional power requirements by the TV circuits instead of waiting for the internal Timing generator to turn on the IC we can refresh the IC By raising pin1 above 2 0V and dropping it back to zero on the negative edge the IC resets again and starts conduction This is known as the Refresh Circuit ...

Page 54: ... Main rectifier 5 IC911 Switching Regulator 6 D911 R911 R930 and C914 Startup 7 T921 Switching Transformer 8 R912 R913 and R914 Current Feedback 9 R915 and D912 Run DC 10 D917 and D914 Refresh 11 D945 RY951 Main Relay 12 Q951 Main Relay Drive 13 IC921 Error Amp Schematic 52004 Main PWB SWITCH CIRCUIT REVIEW POWER SUPPLY COMPONENTS ...

Page 55: ...4 Startup Provides Startup DC for Switching Regulator until Transformer conduction begins 7 T921 Switching Transformer Provides voltages to all circuits 8 R912 R913 and R914 Current Feedback Provides current feedback to Switching IC to stop conduction 9 R915 and D912 Run DC Provides additional DC to Switching IC 10 D917 and D914 Refresh Provide Refresh voltage to Restart IC Regulation 11 D945 RY95...

Page 56: ...SWITCH CIRCUIT REVIEW TELEVISION We will quickly go through the operation of a Switching Supply ...

Page 57: ...GND 5 4 VCC S D Ocp FB OVP TSD OSC DRV STR F6514 5 2 3 1 AC In TELEVISION The AC line Voltage is converted to DC by the Bridge and Capacitor SWITCH CIRCUIT REVIEW BRIDGE RECTIFIER ...

Page 58: ...The circuit begins with the AC Input Line Filters not shown Bridge Rectifier and the Filter Capacitor The Bridge Rectifier converts the AC input into a DC output The DC output is stored by the Capacitor ...

Page 59: ...D Ocp FB OVP TSD OSC DRV STR F6514 5 2 3 1 AC In Raw DC flows through the transformer to the Switching Device When the FET is turned On it will allow current flow to ground TELEVISION SWITCH CIRCUIT REVIEW APPLIED DC ...

Page 60: ... DC voltage flows through the Transformer to the to FET When the Switching Device is turned ON the FET will close When the FET closes it will allow the DC voltage to be ground through the Resistor ...

Page 61: ...SC DRV STR F6514 5 2 3 1 AC In Start up Voltage applied to IC turns On FET allowing current through Inductor Current Flow allows the Inductor to charge and a Ramp Voltage to Build at IC TELEVISION SWITCH CIRCUIT REVIEW RAMPING VOLTAGE ...

Page 62: ...and Diode Powering up the IC turns On the FET allowing the DC voltage from the Transformer to pass through the FET The current flowing through the Transformer allows the inductor to charge At the same time the Inductor is charging a Ramp Voltage builds up at the Feedback of the Switching IC ...

Page 63: ...5 4 VCC S D Ocp FB OVP TSD OSC DRV STR F6514 5 2 3 1 AC In The ramp voltage is applied to pin1 When the ramp voltage reaches 0 7V the FET will shut off TELEVISION SWITCH CIRCUIT REVIEW RAMP VOLTAGE FEEDBACK ...

Page 64: ...llow the Inductor s stored energy to be released The Feedback of the Ramping Voltage through the Resistor connecting pins 2 and 1 will turn OFF the FET when the ramping voltage reaches 0 7V removing the 0 7 V will allow the IC to resume conduction in a pre determined time ...

Page 65: ... 1STB13 TELEVISION Transformer discharges into the Secondary when FET shuts off DC Voltage supplying the Switching IC becomes insufficient Run DC provided to IC from the Transformers Secondary Run DC maintains the ICs stable operation SWITCH CIRCUIT REVIEW RUN DC ...

Page 66: ...g the Switching IC becomes insufficient As the Capacitor discharges the Switching IC requires additional voltage to maintain stable operation Additional Run DC is provided to the Switching IC from the Transformers Secondary This Voltage maintains the ICs continuous operation and the Circuit becomes stable ...

Page 67: ...om Transformer secondary Micon turns on the Photo Coupler Photo Coupler adds DC shortening IC On time TV is now in Standby Mode Regulated DC added to RunDC GND 5 4 VCC S D Ocp FB OVP TSD OSC DRV STR F6514 5 2 3 1 AC In REG 1STB13 5V CPU 1STB13 SWITCH CIRCUIT REVIEW STANDBY OPERATION ...

Page 68: ...l DC to the Switching IC s feedback reducing its On Time The TV is now in Standby Mode Since the on time is reduced all voltages from Transformer are reduced including the Run DC that helps power the Switching IC Regulated DC is added from a higher Transformer winding to ensure the IC does not shut when the TV is in Standby Mode ...

Page 69: ...eived by Micon Micon turns off Photo Coupler and turns on Main Power Relay and circuits Error Amp monitors B1 and controls Switching IC off time Refresh Circuit added in case TV circuits require additional power Refresh circuit allows Switching IC to be turned On whenever needed by applying 2V pulse to IC SWITCH CIRCUIT REVIEW POWER ON ...

Page 70: ...d Monitors the B1 supply The Error Amp uses the Photo Coupler to control the Switching IC s Off times In case of additional power requirements by the TV circuits instead of waiting for the internal Timing generator to turn ON the Switching IC we can refresh the IC The Refresh circuit is added and works by raising pin1 above 2 0V and dropping it back to zero On the negative edge the IC will reset a...

Page 71: ...POWER FACTOR CIRCUIT AC Line Without Power Factor Circuit TELEVISION Used in Some HDILA models Power demand of TV circuits cause AC line current spikes AC spikes affect rectified DC ...

Page 72: ...itor combination to deliver the power As the AC would rise the Capacitors ability to supply power diminished causing the Ballast Circuit to Pull Power from the AC supply The charge discharge of these circuits happens quickly causing AC line Current spikes during these Peak Power Demand periods As shown in the figure this causes AC voltage dips and affects the Rectified B1 Voltage ...

Page 73: ... PFC controls FET ON OFF Operation Eliminates AC Line Spikes Smooth Power Output TELEVISION POWER FACTOR OPERATION Transformer Secondary Current ...

Page 74: ...ut during spikes The PFC IC monitors the incoming DC to the Transformer and Outgoing DC from the Transformer As the Transformer Charges the PFC IC turns the FET ON When the Transformer is fully Charged and begins to discharge into it s secondary the PFC IC turns the FET OFF ...

Page 75: ...MC33262D X TELEVISION POWER FACTOR IC ...

Page 76: ...o allow IC to compensate for Temperature changes during operation 3 Samples Bridge Rectifier Output Turns FET OFF when Bridge Rectifier goes to 0 0VDC 4 Monitors FET current 5 Switches FET ON when Transformers Secondary Current Reaches 0 0VDC 6 IC Ground 7 Controls FET operation 8 IC VCC ...

Page 77: ...ne condition using 2 AA Batteries This means that no other PWBs should be connected to the unit during the test Stand Alone power on of the units allows a technician to test the Power Supply without the effects of other PWBs possibly isolating the trouble These steps must be carefully followed to prevent damage to PWB or injury to self ...

Page 78: ...FUNCTION CHECK PROCEDURE INSPECT UNIT TELEVISION PARTIALLY INSERTED CONNECTOR UNINSERTED CONNECTOR DAMAGED CHASSIS ...

Page 79: ...ny troubleshooting it is necessary to visually inspect the TV to ensure all connectors are properly inserted and there are no additional damaged or broken parts These items may act as clues to help determine the cause of TV symptoms ...

Page 80: ...N CHECK PROCEDURE REQUIREMENTS FOR POWER ON TELEVISION 1 AC line Voltage 2 Standby Voltage Circuit function 3 Power On Signal from Micon 4 In some models Main AC line voltage switch must be closed 1 2 4 3 3 OR ...

Page 81: ...wer on signal from the Remote or Front Panel It will then send the Power On Signal to the Power Supply circuits This always turns on a relay that activates the Main Power Circuits 4 Main AC line voltage switch must be closed In some units primarily HDILA models there is a switch that controls the AC line voltage In HDILA models this switch is the Temperature Sensor that is mounted above the lamp I...

Page 82: ...2 PWB Reference YA318 Schematic HD 52G786 SRP 9022A M2 PWB Reference YA293 Schematic STEPS OF PROCEDURE Remove PWB from TV Inspect PWB Ensure Main Power Switch is Closed Plug unit into AC line Test Standby Circuits Simulate Micon Power On signal Check Switching Circuits ...

Page 83: ...eps of the Procedure are as follow 1 Remove PWB from Television 2 Inspect PWB for Shorted Open Damaged or Missing components 3 Ensure Main Power Switch is Closed Shorted to allow AC in circuit 4 Plug unit into AC line to provide voltage to Standby VCC circuits 5 Test Standby Circuits and Check Standby Operation of Switching Circuits 6 Simulate or Activate Micon Power On signal to activate Main Pow...

Page 84: ...FUNCTION CHECK PROCEDURE INSPECT PWB TELEVISION BROKEN SHORTED MISSING COMPONENT NOT FULLY INSERTED ...

Page 85: ...ubleshooting steps it is necessary to visually inspect PWBs Failure to Inspect PWB for these Items could result in further damaging the PWB Catching these items prior to troubleshooting can prevent wasted troubleshooting efforts ...

Page 86: ...D 52G786 SRP 9022A M2 PWB Reference YA293 Schematic FUNCTION CHECK PROCEDURE PROVIDE AC AND CHECK STANDBY VCC TELEVISION 1 Short CN90SE 2 Plug in AC cord 3 Check for Standby VCC at IC9141 1 Plug in AC cord 2 Check for Standby VCC at IC922 Short CN90SE IC922 ...

Page 87: ...ctional begin at the incoming AC Line Voltage and check all voltages supplying the Standby VCC circuit SSR 9001A M2 PWB The Standby VCC for the SSR 9001A M2 PWB is created by the Switching Circuits If the Standby VCC circuit is not functional troubleshoot the Power line from the Transformer supplying this voltage In this case it is the 28V line Remember In Standby Mode the Power Supply voltage is ...

Page 88: ...001A M2 PWB Reference YA318 Schematic CHECK CIRCUITS 1 F905 Surge Protection 2 D901 and C907 Main rectifier 3 IC911 Switching Regulator 4 D911 R911 and C914 Startup 5 T921 Switching Transformer 6 R923 C903 and R920 Current Feedback 7 FR915 and D912 Run DC 8 PC921 Photo Coupler ...

Page 89: ... Standby Voltage Source is a good sign that the other circuits are functional It is still necessary to fully power up the Supply to ensure it is fully functional as some components may fail under a higher load voltage The SRP 9022A M2 PWB does not utilize a Switching Circuit during Standby Mode Therefore these circuits cannot be tested in this PWB ...

Page 90: ...Reference YA293 Schematic HD 52G786 AV 48P776 H AV 48P776 H 1 Apply 3VDC to CN90G pin3 MAIN_POW use pin2 GND2 as Ground 2 Check all Supply Voltages 3 Check Switching Circuits Function 1 Apply 3VDC Pulse to CN9003 pin12 B1_POW and CN001 pin12 RELAY use CN003 pin15 as Ground 2 Check all Supply Voltages 3 Check Switching Circuits Function ...

Page 91: ...cified The AA batteries will provide a 3VDC to the Main Power Relay and other circuits necessary to turn on the Power Supply Test all output voltages of the Supply If the supply does not activate ensure the 3V source is connected properly then troubleshoot the Switching Circuits Any external Power Supply may be used to provide the 3VDC turn on voltage ...

Page 92: ...ROCEDURE ORDER OF FUNCTION CHECK 1 Surge Protection 2 Main rectifier 3 Switching Transformer 4 Switching IC 5 Startup 6 Photo Coupler 7 Run DC 8 Error Amp 9 Secondary Voltages 10 Current Feedback 11 Main Relay 12 Main Relay Drive ...

Page 93: ...eshooting procedures in the sections that will follow to aid in testing the specific circuit The SSR 9001A M2 PWBs Switching Circuits Operate in Standby Mode therefore it is possible test many of these circuits by only applying AC line voltage Although Standby Mode will not provide full Output Voltage from the Transformer Secondary B1 Power On at the correct Voltage is a good sign that the PWB has...

Page 94: ...FUNCTION CHECK PROCEDURE BATTERY TESTING DEVICE TELEVISION _ _ _ _ ...

Page 95: ...teries in series with the positive of one battery connect to the negative of the other When connecting wires to the batteries it is wise to use 2 different colors to represent positive and negative to prevent later confusion Always measure the voltage to ensure you have a proper connection between the batteries and they are outputting the correct voltage ...

Page 96: ...LESHOOTING TELEVISION The following goes over procedures that will allow the testing of specific circuits of the Power Supply These steps must be carefully followed to prevent damage to PWB or injury to self ...

Page 97: ...ING SWITCHING IC TELEVISION Check VCC Check Ramp Voltage at Feedback Pin Check for DC voltage at FET input Check that FET is not shorted to GND Always Replace IC and Capacitor together STR G9626 STR F6167 STR X6737 ...

Page 98: ...Check for the Ramping Voltage at the Feedback Pin This voltage will vary between models but 7VDC is the average measurement Some PWBs have shown 1 4VDC at this pin Check for DC voltage at FET input It should be the same as the Input to the Transformer and is usually about 170VDC Check that the FET is not shorted to GND Ensure the Power Supply is Off before making this measurement Always Replace th...

Page 99: ...N Power On and check IC supply Usually a Diode Resistor and Capacitor connected directly to the AC and bypassing the Main Bridge Rectifier Desoldered components to isolate StartUp supply if needed Always Replace Capacitor and IC together Reference YA318 Schematic ...

Page 100: ...ge to the IC Check the Diode Resistor and Capacitor that make up this circuit for opens or shorts This circuit is connected to the Photo Coupler circuit so it may be necessary to check or desolder these components to eliminate the possibility of them being the trouble Desoldering and Lifting the ICs pin 4 will allow the check of this voltage without the influence of the Switching IC Always Replace...

Page 101: ...R TELEVISION Rectifier Circuits always used to Provide DC Out from AC In Check Incoming AC Check DC Voltage at Capacitor Desolder components after capacitor to isolate Bridge from shorting YA389 Schematic YA293 Schematic AC AC AC AC DC DC ...

Page 102: ...le by the TV circuits Begin troubleshooting this Device by first checking the incoming AC line voltage then checking the DC voltage at the Capacitor It may be necessary to desolder components to eliminate them as a possible cause of problems If so desolder the components after the Capacitor ...

Page 103: ...TROUBLESHOOTING RELAY FUNCTION CHECK TELEVISION Use this circuit to test the Relay Follow Steps to assist ...

Page 104: ... continuity short at relay contacts Relay Short Adjust voltage to 0V and check that relay deactivates Check for open at relay contacts Relay Open Procedure Complete Troubleshoot Components No No No Yes Yes Yes It is possible that the Relay contacts may wear or the supply circuits to the relay may not function Use this circuit to test the relays function Follow the Steps to assist in troubleshootin...

Page 105: ...TROUBLESHOOTING REGULATOR CHECK TELEVISION Use this circuit to test the Regulators Follow Steps to assist ...

Page 106: ...tput pin 2 less than 5 7 VDC Observe current readings on the Power Supplies current meter Less than 0 75 Amp IC functioning Properly No Yes No No No Yes Yes Yes TELEVISION The Circuit may be used to test the Voltage Regulators used in the Power Supply The voltages shown apply to a 5V regulator If a larger regulator is being tested follow these rules 1 Positive On input Negative to GND 2 Begin by i...

Page 107: ...e GND Isolated GND Connect the DC supply so that it will replace the voltage that normally would supply the voltage Photo Coupler TROUBLESHOOTING FEEDBACK PHOTO COUPLER TELEVISION Reference YA293 Schematic ...

Page 108: ...own When the Photo Coupler becomes operational you will see the voltage at the emitter of the Photo Coupler Transistor rise from 0 to approximately 5V When checking this circuit using the FUNCTION CHECK PROCEDURE you will notice a 1V difference between the Photo Coupler Transistors pins ...

Page 109: ...by supplied by Switching Circuits measure the supply voltage to this circuit Many times other PWBs have failed in the TV shorting the supply line for the Standby Voltage Ensure the Circuit Protectors have not blown on this supply line B1 VOLTAGE HIGH LOW SECONDARY VOLTAGES Leaky Error Amps may can cause High B1 voltages Check voltages at error amp If it is excessive then change The Zener Diode on ...

Page 110: ...ent Click Here to read more This eBook will show you how to test the electronic component correctly and accurately Some of you may say that I don t need this eBook because it is too simple Do you know that in fact there is lots of testing electronic components secrets I have learned from this guide Do you know how to test a TRIAC correctly and accurately If you answer no then I guess you have to g...

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