Hisense Plasma TPW4218P Power Board Principle and Maintenance (Samsung V3 Screen Power Supply) - Home Appliance Repair

Since Hisense launched the TPW4218P series of plasma color TVs in 2005, it has conquered a large number of consumers with its excellent images and sounds. Social ownership is huge. As time goes by, this series of products gradually enters the maintenance period. Since everyone is familiar with the motherboard and AV board on plasma color TVs, we will not introduce them here. The following mainly introduces the working principle and troubleshooting of common faults of the Samsung V3 screen plasma power supply used in this series of models.

1. Incoming line anti-interference circuit and VSB (standby 5V) voltage forming circuit.

After AC220V enters through socket CN8001, it enters the overvoltage protection composed of SA8001, R8005, C8004, C8096, L8002, RA8001, R8004, C8003, C8008 and C8006 through F8001 circuit and preamplifier anti-interference circuit. The AC voltage after filtering out the interference signal is divided into two channels, one channel is sent to the next-level anti-interference circuit composed of L8003 and other components, and the other channel is rectified and filtered by F8002, D8007, C8017 to form an unstable 300V DC voltage. This voltage is added to pin 5 of IC8003 (TOP223PN) through winding 2/1 of T8001. IC8003 enters working status. The VSB (+5V) voltage is formed from the rectification and filtering (D8014, C8018) of the secondary winding of T8001, which supplies power to the motherboard CPU. This voltage is also isolated by D8015 to generate F/B-VCC voltage to power the voltage stabilizing part of the subsequent circuit. At the same time, the VSB voltage passes through R8035 to make LED8003 light up (green). The signal induced by another set of windings of T8001 is rectified and filtered by D8006 and C8016 to form a voltage of 18V, which is applied to the emitter of Q8012, and Q8012 is in a cut-off state.

2. Generation of the 5V and 3.3V voltages required by the logic board.

After we issue the second power-on command, the RELAY signal changes from high level to low level. At this time, Q8009 is turned on, and Q8013 is also turned on with saturation. Q8013 The collector goes low. All the way is sent to HIC8002 as a PS-ON detection signal. After the other channel is isolated by the optical coupling (IC8005), the base of Q8012 changes to low level through R8058, Q8012 saturates to pass, and outputs a controlled 18V voltage. This voltage is stabilized by IC8009 (7815A) to generate a 15V PFC-VCC voltage to power the PFC membrane module HIC8001. The other channel is sent to the emitter of Q8010 to be ordered. At the same time, the decrease in the collector voltage of Q8013 also causes Q8004 and Q8006 to be saturated and turned on, relay RLY8001 is closed, and LED8002 lights up (green). AC220V is sent to D8003 through the secondary and tertiary line anti-interference circuit composed of C8006, C8007, L8003, RLY8001, R8009, R8010, C8001, C8009, L8004, C8002, C8010 and C8005, and a pulsating DC current of 100H2 is obtained, which is added to the PFC circuit. At this time, R8037, R8038, R8039 and R8044, R8045 provide detection signals for the PFC membrane block HIC8001. The PFC circuit starts to work and outputs the PFC-OK signal and RELAY-ON signal. The PFC-OK signal turns on the Q8010, generating a controlled DC-VCC signal to power the circuits on the secondary power board and the main power board, and then passing through Q8011 to generate a 17V VCC-S voltage, which switches the VS part and the VA part. Integrated circuit power supply. After the RELAY-ON signal is isolated by the optical coupling IC8002, Q8005 and Q8008 are saturated and turned on, RLY8002 is closed, and R8009 and R8010 are short-circuited, which reduces the power consumption of the whole machine. At the same time, LED8001 is lit. The PFC circuit is fully in working condition. Outputs a PFC voltage of approximately 400V.

The PFC voltage is divided into three channels, and one channel is sent to the auxiliary power board through socket CN8009 to generate a 32V tuning voltage and a 12V audio amplifier voltage. The second PFC voltage is added to the drain of Q8016 after passing through F8003. The third PFC voltage is added to pin 1 of IC8023 through the 16/11 windings of F8003 and T8005. At this time, the VCC-S voltage generated by Q8011 is also added to pin 3 of IC8023. IC8023 enters normal working state. The secondary winding of T8005 is rectified by D8040 and filtered by C8059 to generate a VA voltage of 70V. Used for power supply of X board. The other channel is divided into three channels after being rectified and filtered by D8042 and C8063. After passing through the voltage stabilizing film block IC8022, a VCC voltage of 15V is generated. The second path generates a D3V3 voltage of 3.3V after DC/DC conversion by (IC8024). The third path generates 5V D5VL voltage after DC/DC conversion through (IC8026). D3V3 and D5VL are mainly used to power logic boards and small signal power supplies for other boards.

3. Generation of other voltages in the whole machine.

After the logic board is powered by D3V3 and D5VL, the internal CPU enters the working state and sends corresponding signals to the Y driver board, maintenance board, and X board. At this time, the indicator LED2000 on the logic board flashes. At the same time, a high level (3.3V) VS-ON signal is returned to the power board. The high-level VS-ON signal causes Q8023 to saturate and conduct, and through the isolation of the photocoupler IC8017, pin 4 of HIC8003 becomes low level, and HIC8003 enters the working state. Output the positive driving signal from pin 15 to put Q8019, Q8020 and Q8016 into working state. The negative driving signal output from pin 9 puts Q8021, Q8022, and Q8018 into normal working status. At this time, the resonant switch circuit composed of Q8016, Q8018, C8031, and T8002 works normally. The secondary winding is processed by D8021, D8022, D8029, D8030 bridge rectification and HIC8004, L8005, C8032, C8033 filtering to generate a VS voltage of 160V-185V, which supplies power to the Y drive board of the plasma screen. At the same time, the VS voltage is divided into three channels.
One channel is sent to pin 5 of T8003 through F8004, and then output from pin 3 to pin 2 of IC8012 after passing through the internal winding of T8003. The starting voltage is filtered by R8094, C8041, and C8042 at the same time and then added to pin 3 of IC8012. The switching power supply composed of IC8012 and T8003 works normally. From the secondary D8023, C8034 rectifier and filter, the VSET voltage of 135-165V is obtained. The other path is rectified by D8032, filtered by C8037, and isolated by D8033 to form the F/B-VCC voltage.

The second path is added to pin 2 of IC8019 through the 6/3 winding of F8004|T8004. The starting voltage is filtered by RC8116, C8057 and C8054 and then added to pin 3 of IC8019. After negative rectification and filtering by the secondary D8034 and C8052, the VSCAN voltage of -70V is obtained. The other channel supplies power to the voltage stabilizing circuit after being rectified and filtered by D8039 and C8055.

The third path is added to pin 1 of IC8027 through the 5/3 winding of F8005 and T8006. The starting voltage is filtered by R8131, C8075 and C8076 and then added to pin 3 of IC8027. The switching power supply composed of IC8027 and T8006 enters normal working state. The secondary D8044 and C8071 rectify and filter to obtain a VE voltage of 125V-155V, which supplies power to the maintenance board. The other path is rectified and filtered by D8049 and C8077 to provide voltage for the voltage stabilizing part.

4. The whole machine voltage stabilizing circuit

The voltage stabilizing circuit of this machine is relatively simple. The resistor samples the sample and sends it to the control pin of the precision voltage regulator TL431. Then, through the isolation of the optical coupler, the secondary circuit voltage conversion information is sent to the power adjustment pin of the switching power supply. Thereby controlling the output of the secondary voltage and achieving a stable output of the secondary voltage. For example, the VSB voltage stabilizing part: the VSB voltage after rectification and filtering by D8014 and C8018 is added to the voltage stabilizing circuit in two ways, and one way is added to the voltage stabilizing output pin of IC8006 (TL431) through R8049 and the diode inside the photocoupler IC8004. The other channel divides the pressure through R8055 and R8061/VR8002, and then adds it to the control pin of IC8006 through R8060. When VSB drops: (VSB↓) → [Control pin of IC8006 (TL431) ↓] → [Regulated voltage output of IC8006 (TL431) ↑] → [The third pin of optical coupling ↓] → [4 of IC8003 (TOP223PN) Pin ↓] →IC8003 internal output duty cycle ↑ →VSB↑. When the VSB voltage rises: VSB↑→[IC8006 (TL431) control pin↑] →[IC8006 (TL431) regulated output↓] →[Optical coupling third pin↑] →[IC8003 (TOP223PN) 4 Pin ↑] → IC8003 internal output duty cycle ↓→VSB↓. In this way, VSB voltage stabilization is achieved. The other parts all use TL431 plus optical coupling, but the controlled ICs are different, so I won’t analyze them one by one here.

5. Protection circuit

The protection circuit of this machine is mainly played by HIC8002. Each set of output voltages will be sent to HIC8002 for detection. When one of the voltages is abnormal. Pin FA1L1 of HIC8002 will output a high level to saturate and conduct the thyristor Q8017, LED8004 (red) will be lit, and after isolation by the photocoupler IC8017, the base voltage of Q8006 will be 0V, and Q8006 will be cut off. RLY8001 trips, causing the PFC power supply of the subsequent stage to be disconnected. All subsequent circuits of the PFC stop working. At the same time, pin 27 of HIC8002 also outputs a low-level PANEL-POWER signal to cut off Q8015, and Q8011 is cut off through the isolation of optical coupling IC8018. Disconnect the power supply to the VS and VA part switching power supply integrated circuits. Make the switching power supply integrated circuits of the VA and VS parts exit the working state.

When there is an overcurrent in a certain channel, causing the stability of Q8001 and Q8002 to increase, after the TC8001 on the same heat sink detects this abnormal overheating situation, the Q8024 is cut off through the isolation of the photocoupler IC8018, and the collector of Q8024 becomes high voltage. level, the "K" pole of Q8017 becomes high level through the isolation of D8035, and the thyristor Q8017 is turned on. Like the previous one, LED8004 lights up and the whole machine enters the protection state.

As we all know, plasma screens have strict requirements on the supply timing of voltage, and the sequence of establishing each voltage has strict requirements. But this can be ignored for maintenance purposes. We only need to know the conditions that trigger the generation of each voltage. For Samsung V3 screen power supply, when we repair it, we only need to observe the indicator light on the power board and the indicator light on the logic board to roughly determine which voltage causes the circuit problem: after plugging in the power, LED8003 will light up. Bright. If it does not light up, it means there is a problem with the power supply of the whole machine or the VSB forming circuit. After the power-on command is issued, LED8002 lights up. If it does not light up, directly check whether the RELAY signal is sent to the motherboard normally. Then LED8001 lights up. If it does not light up, check whether AC220 is fed into the PFC circuit or whether the PFC circuit is working normally. When LED8001 lights up, the indicator light LED2000 on the logic board will flash accordingly. If it does not light up, it means that D5VL and D3V3 are not formed properly. After LED2000 lights up, each group of voltages on the power board should be output normally. If not, check the VS voltage forming circuit and VSET, VSCAN, and VE voltage forming circuits. For the convenience of panel removal and maintenance. This power supply provides multiple sets of sockets that can be shorted to simulate or disconnect certain parts of the circuit. For example: J8005, when it is shorted, it can simulate the motherboard sending back a power-on signal. J8004, when disconnected, can remove the protection detected by TV8001. J8003, when it is disconnected, PANEL-POWER protection starts and the whole machine enters the protection state. J8002, when it is shorted, it can simulate the VS-ON signal returned after the logic board works normally. J8001, after disconnecting it, the power supply of PFC and subsequent circuits is disconnected, which can easily determine whether the VSB part or the PFC part of the circuit is short-circuited. In order to make maintenance easier for everyone. Attached are the measured voltmeters of each major IC.

Actual measurement data:


1. The TPW4218P plasma color TV has no light after it is turned on for the second time, and will shut down for protection after a while.

After disassembling the phone, I found that it has a Samsung plasma V3 screen. In order to determine the fault location, first self-check the plasma screen, and the result is dull. During normal self-check, the screen should be a uniform white grating. It means the plasma screen component is defective. During the self-test, it was found that LED8001, LED8002, and LED8003 were all on. There is no voltage when measuring VS, VSCAN, VSET, VE, etc. Visually, the indicator light on the logic board turns on and goes off after a while. It means that the logic board also needs electricity to work. Check that the VS-ON control signal sent by the logic board is normal. It stands to reason that the output voltages of the power board should be normal. When the VA was measured, it was found that the voltage exceeded 90V when the power was turned on, and slowly dropped to OV after burning. Normally, the voltage should be 70V. It indicates that the VA circuit is poorly regulated. Observing the circuit carefully, we found that the VA voltage stabilizing part is composed of optical coupling IC8025 and three-terminal precision voltage stabilizing block (IC8029) TL431, peripheral resistors R8129, R8133, R8134, R8135R8138, R8142 and capacitors C8074, C8079 and C8070. Measure the voltage sent from the VA part to R8134. The positive terminal voltage of the diode in the photometric coupling is -0.24V. According to the normal circuit, there should be a positive voltage here. It is estimated that this is abnormal. Check the resistor R8129 supplied to the optical coupler. There is no positive voltage at both ends. It means there is a problem with the F/B-VCC forming circuit. After inspection, R8129 is connected to the VSB (+5V) rectified by D8014 through D8015, and the indicator light of the local power supply is on, indicating that VSB has voltage. Measured VSB is 5.2V. Good guess. Check that the negative terminal of D8015 is not short-circuited to ground, and detect that D8015 is open circuit while on the road. After replacing it with a new IN4148, the fault is eliminated.

2. There was no light after the TPW4218P plasma color TV was turned on for the second time. After a while, it

was shut down for protection and disassembled, and it was found that the TV was a Samsung plasma V3 screen. In order to determine the fault location, first self-check the plasma screen. The result is a dim purple grating. During normal self-check, the screen should be a uniform white grating. It means that the plasma screen component is defective and has nothing to do with the motherboard and AV board. I suspect the power board or maintenance board is defective. During the self-test, LED8001, LED8002, and LED8003 all light up, and LED2000 on the logic board also lights up. Measure the VS, VSC, and other voltages and they are all normal, but the VE voltage is 0V. The VE voltage is abnormal. Check that VE is short-circuited to ground while on the road. Unplug the CN8002 socket to check. Keep the VE load on the board not short-circuited to ground, and the VE on the power board is not short-circuited. If there is a short circuit to ground, carefully search the components on the VE. Only D8044 and C8071 (resistors generally do not cause short circuits) may cause short circuits. After disconnecting C8071, there is still a short circuit, indicating that D8044 is damaged. Replace it with a new RU3C and the fault is eliminated.

3. The indicator light of the TPW4218P [Samsung V3] screen plasma color TV is on. After the second power-on, the light turns yellow and then the whole machine becomes dark. After a while, the protection shuts down.

After disassembling the machine and observing, it was found that the indicator light LED8003 was on. After the machine was turned on for the second time, both LED8002 and LED8001 were on, and the relay made a closing sound. But the screen does not light up. After a while, the red LED8004 lights up and the whole machine shuts down for protection. In order to facilitate maintenance, the whole machine was self-checked and it was determined that the on-screen component was defective. The voltage supply sequence of this machine is as follows: After plugging in the power supply, the switch circuit composed of T8001 on the power supply board works, VSB (+5V) is generated, and provides working voltage to the CPU on the motherboard. The CPU enters the working state and issues a standby command. At the same time, green LED8003 lights up. When we issue the boot command, the CPU sends a low-level RELAY signal to the power board. At this time, relays RLY8001 and RLY8002 are engaged, and the PFC circuit composed of L8001 and peripheral circuits works, generating a PFC boost of about 400V. voltage, at the same time, the green indicator lights LED8002 and LED8001 light up one after another. The switching circuit composed of T8005, IC8023 and peripheral circuits generates VA (+70V) voltage, VCC (+15V), D3V3 (3.3V) and D5VL (+5V). Among them, D3V3 and D5VL are sent to the logic board, and the circuit on the logic board enters the working state (LED2000 will flash at this time) and sends back the logically normal VS-ON (high level) signal to the power board. The VS-ON signal causes the VS voltage generating circuit composed of T8002 and peripheral circuits to enter the working state and output an adjustable VS voltage of 160V~185V. This voltage forms VSE voltage through T8003 and peripheral circuits, and this voltage forms VSC voltage through T8004 and peripheral circuits. , this voltage forms the VE voltage through T8006 and peripheral circuits. The generated voltages are sent to various components on the screen, and the components on the screen are powered to work, causing the plasma screen to be lit. If any of the voltages generated above are abnormal or overcurrent, and are detected by the CPU on the power board, the CPU will issue instructions to put the power supply into standby mode and light up the red LED 8004 at the same time.

After the machine is turned on for the second time, the relay makes a closing sound and LED8001/LED8002 lights up, indicating that the motherboard is working normally and has issued a power-on command. Observe that the indicator light LED2000 on the logic board does not light up, indicating that the logic board does not receive the working voltage or is not working properly. Test D3V3 at F2000 and it is normal. Measure D5VL at F2001, 1.34V, which is abnormal. Disconnect the power supply connector of the logic board and measure the voltage of the D5VL test point on the power board. It is 1.34V. It is still abnormal. Check the resistance to ground and no abnormality is found. Measuring pin 1 of D5VL's DC/DC converter IC8026 is 17.5V, indicating that the power supply to the front stage has arrived and should be normal. After debugging the VR8009 adjustable resistor, the voltage gradually dropped from 4.2V to 1.34V when turned on. Abnormal. Check the external resistors R8143, R8145, D8050, C8099, etc. No abnormality is found. After replacing IC8026 (LM2576T-ADJ), the D5VL voltage output is normal, and the VE, VSE and other voltages are also generated normally. After connecting all the lines, it returns to normal status. , the whole machine returns to normal. (D5VL and D3V3 are both produced by LM2576T-ADJ. The only difference is that their external resistor values ​​are different)

4. The indicator light of TPW4218P [Samsung V3 screen] plasma color TV does not light up, three no.

If the indicator light does not light up, it means that the motherboard is not receiving power or the CPU on the motherboard is not working properly. Open the back cover and find that the indicator light LED8003 does not light up, indicating that the power supply is poor or the power load is overcurrent. Disconnect the power supply socket to the motherboard and the indicator light. If it still doesn't light up, it means there is something wrong with the VSB voltage forming circuit. With the maintenance experience of the previous case, it will be much easier for us to repair it. First check that fuse F8001 is good. Visual inspection reveals that capacitor C8017 has a bulge. And C8017 happens to be the filter capacitor of the primary part of the VSB voltage forming circuit. It was measured that fuse F8002 was open, rectifier bridge stack D8007 was intact, and no abnormality was found in the circuit resistance of driver block IC8003. After replacing C8017 (450V/33UF0 and F87002 (1A)), the problem still persisted. After replacing IC8003 (TOP223PN), the fault was eliminated.

5. The indicator light of TPW4211PH [Samsung V3 screen] plasma color TV is on, but the relay closing sound cannot be heard after the second power-on. .

The indicator light is on, indicating that the motherboard is powered. The fault may be caused by the motherboard not working properly. If the RELAY signal can change from high level to low level during the power-on test, it means that the motherboard CPU is working normally. In order to determine whether the RELAY signal of the motherboard is sent to the main board. On the power supply board, directly short-circuit J8005, and the visual indicator LED8002/LED8001 still does not light up when the power is turned on. This means that although RELAY has been generated normally, it does not control the pull-in of relays RLY8001 and RLY8002 normally. The fault should be in Q8009/Q8013/Q8004/ On the circuit composed of Q8006/Q8005/Q8008, I checked the quality of the triode on the road and found that Q8009 was not normal. I removed Q8009 (KTN2907A) for inspection and found that the B/C pole was blocked. After replacing it with a good triode, LED8002 and LED8001 lights up and the whole machine returns to normal.

6. The indicator light of the TPW4218P plasma color TV does not light up and the screen is dull.

After disassembling the machine, it is found that the screen is a Samsung plasma V3 screen. In order to determine the fault location, the plasma screen is self-checked. There is no light, and the screen should be a uniform white grating during normal self-test. It means that the plasma screen component is not bright. It means that the switching power supply composed of T8001 and IC8003 is open. , the forward and reverse resistances at C8017 are normal. The forward resistance of the D8007 (S1WBS60) bridge stack is normal, but the AC input pin and the DC negative terminal are short-circuited, indicating that a set of diodes in D8007 is short-circuited after replacing the D8007 bridge stack and F8002. The whole machine returned to normal.

7. The indicator light of Hisense TPW4218P (Samsung V3 screen) turned on after it was turned on. After turning it on for the second time, the light changed but the screen did not light up.

First, self-check the plasma screen and found that the indicator lights LED8003 and LED8002 on the plasma power supply were both on. But LED8001 does not light up. It means that the PFC circuit part or the circuit part composed of Q8005 and Q8008 is abnormal. The voltage at the T-VPFC point after testing is abnormal. It should be 400V when it is normal. Or there is no power supply. Check the secondary and tertiary anti-interference circuits and D8003. It is found that R8010 is open. After replacing R8010, LED8001 still does not light up. It indicates that the positive terminal of IC8002 is in the off state. The membrane module HIC8001 is defective and does not output a high-level RELAY-ON signal. The fault is rectified after replacing the PFC membrane module HIC8001.

8.8. The indicator light of Hisense TPW4211PH [Samsung V3 screen] plasma color TV comes on after it is turned on, and the light changes after it is turned on again. But the screen does not light up.

During the self-test, it was found that LED8001, LED8002 and LED8003 were all on, but LED2000 on the logic board did not light up. It means there may be a problem with D5VL and D3V3. Test D5VL and D3V3 have no voltage, VA also has no voltage. The voltage of the T-VPFC test point is 400V. Detecting the resistor in circuit found that F8003 was open circuit and Q8018 and Q8016 were short circuited. It was visually observed that the BC8054 (1KV/222) capacitor on the secondary HIC8004 of VS burned through a hole. It means that the BC8054 on the component HIC8004 is defective, causing the VS load to increase, causing damage to Q8016 and Q8018. After removing Q8016 and Q8018, check the symmetrical driving transistors Q8019, Q8020, Q8021, and Q8022 on the road. No problem found. To prevent the installed Q8016 and Q8018 from being damaged again. Decided to replace Q8019, Q8020, Q8021, and Q8022 together. After replacing the above damaged components, the fault is eliminated. During subsequent maintenance. I have also encountered damage to Q8016 and Q8018 due to the BC8052 (1KV/222) on the HIC8004 burning a hole.