 sufficient energy is transferred and the B1 supply; High voltage, etc.. is active. • If the 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.
Page 52 TELEVISION SWITCHING OPERATION REFRESH • In practical use, we need to restart the IC earlier than the AC In pre-determined time • Apply 2.0V pulse to pin1 • During the negative edge, the IC will refresh (reset) and turns on again. Refresh Ocp/ G en.
Page 53 •When the transistor is off the ramp voltage will disappear because of the internal oscillator. •After a pre-determined time, the FET 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.
Page 55 IC921 Error Amp: Monitors B1 Line Voltage This is the basic circuit configuration and use for all JVC Power Supplies. While some Power Supplies may omit or add circuits, the general function of all JVC Power Supplies are the same.
Page 56 TELEVISION SWITCH CIRCUIT REVIEW We will quickly go through the operation of a Switching Supply...
TELEVISION SWITCH CIRCUIT REVIEW BRIDGE RECTIFIER AC In The AC line Voltage is converted to DC by the Bridge and Capacitor. STR- F6514/5 Ocp/...
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 TELEVISION SWITCH CIRCUIT REVIEW APPLIED DC A C In O VP Raw DC flows through the G N D T S D transformer to the Switching Device. VC C O SC D R V When the FET is turned On, it will allow current flow to ground.
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 TELEVISION SWITCH CIRCUIT REVIEW RAMPING VOLTAGE A C In O VP G N D T SD V C C O SC D R V •Start-up Voltage applied to IC turns On FET, allowing current through Inductor. ST R- F6514/5 O cp/ •Current Flow allows the Inductor to charge and a Ramp Voltage to Build at IC.
Page 62 The Start-up DC is applied to the ICs Pin4 from the Bridge Rectifier through the Resistor 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.
TELEVISION SWITCH CIRCUIT REVIEW RAMP VOLTAGE FEEDBACK AC In •The ramp voltage is applied to pin1.  STR- F6514/5 Ocp/...
Page 64 • When the Inductor is charged, it is necessary to turn Off the FET to allow 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.
Page 65 TELEVISION SWITCH CIRCUIT REVIEW RUN-DC AC In 1STB13 •Transformer discharges into the Secondary when FET shuts off. •DC Voltage supplying the Switching IC STR- becomes insufficient. F6514/5 Ocp/ • Run-DC provided to IC from the Transformers Secondary. •Run-DC maintains the ICs stable operation...
Page 66 •As the Transformer discharges, the Secondary Windings develop secondary voltages •The DC Voltage supplying 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.
Page 67 TELEVISION SWITCH CIRCUIT REVIEW STANDBY OPERATION On-tim e PHC DC AC In O n-tim e 1STB13 •Micon powered by Standby Voltage from Transformer secondary •Micon turns on the Photo 1STB13 Coupler ST R- F6514/5 Ocp/ •Photo Coupler adds DC shortening IC On time •TV is now in Standby Mode •Regulated DC added to RunDC...
Page 68 • TV Micon is powered by the Transformers Secondary Voltages. • The Micon Turns on the Photo Coupler. • The Photo Coupler adds additional DC to the Switching IC’s feedback reducing its On Time. • The TV is now in Standby Mode. •...
Page 69 TELEVISION SWITCH CIRCUIT REVIEW POWER ON Relay • Power ON command received by Micon AC In • Micon turns off Photo Coupler and turns on Main Power Relay and circuits • Error Amp monitors B1 1STB13 and controls Switching IC off time.
Page 70 • When power is turned on the CPU turns off the Photo Coupler and turns on the relay for the main Power Circuits (B1 Voltage). • Turning off the Photo Coupler means there is no control over the output • The Error Amp is activated and Monitors the B1 supply. •...
Page 71 TELEVISION POWER FACTOR CIRCUIT •Used in Some HDILA models. •Power demand of TV circuits cause AC line current spikes. •AC spikes affect rectified AC Line Without Power Factor Circuit...
Page 72 • Some HDILA TV Power Supplies utilized a Power Factor Circuit (PFC). • The High current demand of the Ballast PWB and Circuit exceeded the ability of the Standard Bridge Rectifier/Capacitor 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.
Page 73 TELEVISION POWER FACTOR OPERATION Transformer Secondary Current •PFC controls FET ON/OFF Operation •Eliminates AC Line Spikes •Smooth Power Output...
Page 74 TELEVISION •The PFC IC controls the Power FET. •The FET increases Power output 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 TELEVISION POWER FACTOR IC MC33262D-X...
Page 76 Pin Explanation 1. Monitors B1 Line and provide Voltage Feedback to IC 2. Compensation to 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.
Page 77 TELEVISION FUNCTION CHECK PROCEDURE The following will explain steps that will allow the Powering Up of the Power Supply in a Stand Alone 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.
Page 78 TELEVISION FUNCTION CHECK PROCEDURE INSPECT UNIT UNINSERTED CONNECTOR PARTIALLY INSERTED CONNECTOR DAMAGED CHASSIS...
Page 79 •Before and After performing any 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 TELEVISION FUNCTION CHECK PROCEDURE REQUIREMENTS FOR POWER ON AC line Voltage Standby Voltage Circuit function Power On Signal from Micon 4. In some models, Main AC line voltage switch must be closed...
Page 81 Provided all circuits function within a Power Supply, there are only (3 or 4) requirements for the Power Supply to function AC Line input voltage: This voltage will be rectified and provide the DC for the Switching Circuits. Standby Voltage: This voltage is needed to power the Micon. Power On signal from Micon: The micon receives the Power on signal from the Remote or Front Panel.
Page 82 TELEVISION FUNCTION CHECK PROCEDURE PROCEDURE STEPS OF PROCEDURE • Remove PWB from TV HD-52G786 • Inspect PWB SRP-9022A-M2 PWB • Ensure Main Power Switch is Closed Reference YA293 Schematic • Plug unit into AC line • Test Standby Circuits • Simulate Micon “Power On”...
Page 83 Pictured are the (2) example PWBs that will be used in this procedure This is a quick and simple procedure that can be used to quickly test the circuits operation. Ensure you have properly inspected the PWB for Shorted, Open, Damaged or Missing components. The Steps of the Procedure are as follow: Remove PWB from