M.Kireev
Today's televisions have stagnant pulse generators whose advantages, similar to those of transformers, are well described in the literature. The body of life is functionally composed of the primary and secondary lancets (Fig. 1).
The power switch VT1 is either located in the vicinity of a transistor or technologically placed on the chip of a PWM controller microcircuit.
Most often, with such signs of malfunction, such as the front panel LED lighting up for 1...5 s and going off, the clanging and whistling sound continued for 1...5 s and the TV is turned off, it is impossible to reliably determine the function tsionalny vuzol, scho vyyshov in harmony TV However, in practice, repairs can be confirmed with great certainty that similar external signs appear in the way of the next nodes of the TV:
primary lancers were provided with life (PWM controller, switch transistor, edge rectifier, filter capacitor, damping lancer, etc.);
secondary lantsyugs dzherel life (viperative and dry LEDs, capacitors of secondary filters, elements in the avantage dzherel okremikh voltage and so on);
Lanzjugi life of the output cascade small rosette(The rectifier and filter were powered by a small-bore +95...140 V, a small-bore output transistor, a small transformer, etc.).
Let's take a look at the methodology for identifying malfunctions in the primary and secondary lancets of impulse life-giving engines. There is a sound of malfunction in the device, which may include the most common signs of malfunction, which can be identified from a thorough inspection of the installation. With particular respect, we look at the number of traces of burnout on the cases of power transistors and microcircuits, the integrity of the cases of oxide capacitors, and the number of traces of wear of high-pressure low-resistance stories that serve as jet-interchange elements, and the place of “cold” soldering of the main heat-visual elements. Sometimes, visually, based on the indicated signs, you can determine the nature of the malfunction.
If a visual inspection does not yield any results, proceed to the next stage of searching for a malfunction. Here you should do a little preparation for the robot, and then: or solder the jumpers J1, J2, J3 of the flow paths drukovanoy payment In order to go through the outputs of the life-saving device, since there are no such ones, carefully cut the flow conductors in such a way that before the life-saving device exits, you can separately connect and Some of these can be used in various frying lamps, and in the laboratory for the life of the main components of the TV. (Fig. 2).
The external appearance of the living dzherel is shown in Fig. 4.
At first glance, it is enough to connect the signal to one straight line, for example, to live the output cascade of a small flare, in order to verify this lance as a whole, but this is not the case. If you want a pulse generator in this case, it will firmly request, otherwise there is a possibility of missing defects in rectifier diodes and capacitors of low-voltage rectifier filters. This happened, for example, during the repair of the Vityaz 51TTs-420D TV. TB without getting wet, prote when the generator is turned on, the life cycle is fixed with the pressure on the generator +135 V in a stable manner. The defect was present in the capacitor of the filter +12 and was not detected during operation without interference.
Before turning on the life-saving device, it is important to check all direct currents in the second and first lanyards for damage or breakdown, as well as oxide capacitors, which are necessary to check their parameters in life of televisions oxide capacitors often breaks down electrolyte vicates .
Most of today's televisions have in their storage pulsed life-saving engines, power cascades of some kind, either on permanent transistors or on specialized microcircuits. If the life-giving device has a voltage transistor in its storage, then before turning on the life-giving device, it is at least necessary to check the integrity of its transitions using an additional ohmmeter for the presence of breakage and short shimmer. Possible replacements for power transistors are presented in the table. 1.
Since all the components, as well as the power transistor, are in good condition, the device can be stuck in the middle. If the pulse generator oscillates due to the PWM controller being stuck, then due to the impossibility of checking the microcircuits using an additional ohmmeter, it must be turned on in moderation and the voltages at the pins of the PWM controller are reduced. The presence of one or more voltages with the same other parts clearly indicates a faulty microcircuit that requires replacement. Vrahovuchi, that on some basic circuit diagrams of TVs, the PWM controller of the decals looks like a “black screen” (for example, “Kolon CTK-9742”) or it looks like a bunch of functional units (“Grundic CUC 4510”), table. 2
Presents the voltage values at the pins of the most frequently used PWM controllers in television equipment. Voltage values may vary by ±10% from those indicated.
After checking all the parameters of the pulse generator during the hour of work on the installation kit, you can connect the generator to other nodes of the TV by updating the remote jumpers. However, before this, it is necessary to note that there are no malfunctions in the lanyards of life and elements that went out of order, for example, short circuits or breakage of transistors at the node of the small flange, and the zener diode included in the lanyard of the life like a cascade of small sparks, how to fight In some TV models, there is still a possibility of repeated failure of the elements of the pulse generator. Possible options replacement of imported stabilizer diodes with domestic ones is indicated in the table. 3.
When replacing a zener diode, it may be necessary to select the required unit based on the stabilization voltage value. Although, in most cases, the TV begins to operate immediately after the faulty power supply is renewed, by connecting a laboratory device, similar to the author’s version, it allows you to monitor the hidden functioning of the node And in the TV, if it is impossible to quickly update the standard device, the vitality and strum of the skin node of the TV will be - any unit can be used to indicate the presence of a defect, and the application of an electronic device in any channel of the laboratory life cycle device can be directly indicated to the unit to remove defective elements.
Consider how it follows from the practice of repair that if there is a malfunction in the pulse generator and other parts of the TV, then the device, after being turned on, begins to operate normally, and it will be easily repaired Vav 20...30 khv, then the repair can be carried out successfully.
A little trick. After replacing the key transistor in the primary power supply unit or the PWM microcircuits, remove the lock before the first turn on. Instead, connect a 60 W 220 Volt roasting lamp. When turned on at first, the lamp must burn brightly, and then stay on. This is a demonstration of reference work B.P. If the lamp constantly glows brightly or does not burn out, then the repair will need to be continued. This trick allows you to save the key transistor from the reference station, like B.P. faulty. (Krilov P.V.)
Literature
1. V.S. Moin. Stabilized transistor converters. M.: Vishcha School, 1986.
[email protected]
Secrets of the telemaster
B. KISELEVICH, Khatanga village, Krasnoyarsk region
Radio, 1998 rіk, No. 4
So, the title of “three-transistor” power supply is due to the wider pulse generator of life, which has been the case in many CRT models. TV-PHILIPS- 2021, AKAI - ST-1407, AKAI - 2107, SHERION, CROWN - STA/5176, ELEKTA - CTR-1498EMK, RECOR and many others.
Dzherel life scheme
As a butt, let’s look at the same dzherel that is vikorized on the CROWN TV – CTV5176.
The voltage of the 220 voltage through the life filter goes to the rectifier BR601, C601 - C604 and to the demagnetization loop L2001. The collector of the key transistor Q604 is rectified to pass through the winding 1-5 of the pulse transformer T601.
On transistor Q604 there is a blocking generator - the voltage of the positive gate connection is taken from windings 7 - 8 of the transformer. The frequency of pulses generated by the blocking generator, which is the hour that transistor Q604 is in the saturated state, is determined by the functioning of the pulse width modulator (PWM).
Before the base of transistor Q604 is connected, capacitor C607 is charged every hour when the transistor is closed with a voltage pulse from winding 7 - 8 of the transformer through diode D604. When transistors Q602, Q603 are activated, the PWM capacitor C607 is connected to the saturated transistor Q604, the discharge flow of the capacitor, flowing through the transistors and resistor R616, quickly closes the transistor Q604. The bias voltage of transistor Q604 is supplied through resistors R603, R604. Lance C610R617 interconnects the pulses on the collector of transistor Q604, protecting it from breakdown.
For the life of the supporter postynogo strum on transistor Q601 Voltage change windings 9 - 10 are rectified by diode D603 and charge capacitor C606. The voltage on the emitter of transistor Q601 is stabilized by a parametric stabilizer on elements D601, R609, and the voltage on the base of transistor R006 is taken from the vibrating resistor. The voltage remains on the winding 9 - 10 of the transformer, then the output voltage of the living unit is + 110 and +12 V. Voltage on resistor R608 - the collector voltage of transistor Q601 serves as a voltage supply and provides the moment of PWM opening on transistors Q6. By means of a resistor VR601 the output voltage is set to + 110 St.
From the resistor R605, through the lance C605R611, a saw-like voltage is supplied to the base of the transistor O602 of the PWM former. It receives voltage from the collector of transistor Q601. It is important that the remaining PWM opens up earlier or later, depending on the moment the transistor Q604 opens. Transistors Q602, Q603 are analogous to a trinistor. The principle of this action is similar to that of the trinistor in the pulse life module MPZ-3.
With an increase in voltage or a change in voltage, the voltage on windings 9 - 10 of transformer T601 increases. As a result, transistors Q602, Q603 open earlier, closing more early hour output transistor Q604 Tim itself changes the energy that is stored in the transformer T601, which compensates for the increase in voltage.
With a reduced voltage, the voltage will be lower on windings 9 - 10 of the T601 transformer. At the collector of transistor Q601, the switching voltage changes. The PWM opens at a later hour, and the amount of energy transmitted to the secondary lancet increases, compensating for the change in voltage.
The secondary rectifiers of the block are connected using a single-phase forward circuit. Winding 4 - 2 transformers and elements D606, C612, L601 create a +12 V voltage source, which is used for the operation of the remote control system and other low-precision lancets. Winding 4 - 3 and elements D607, L602 are included at the +110 V voltage source to live the small-scale output stage.
On transistors Q608, Q606, Q605, the energy supply is switched on and the output cascade of the small plug is turned on. The TV itself is turned on or off by the remote control system and switched to operating or standby mode. In the draft mode, transistor Q606 is closed and the voltage +110 does not go to the output stage of the small flare. On some TV models, the relay is blocked.
For repairs, remove the board of the unit from the TV body and place it so that there is easy access to the elements. In parallel, capacitor C604 is connected to a resistor with a support of 220 kOhm and a voltage of 0.5 W. The capacitor will be discharged through this device after the TV is turned off. One of the dermal elements L601, L602, D608, C617 is used. In this case, the TV set will be constantly connected to the living unit. In parallel with the C615 capacitor, connect a 220 and 25 W roasting lamp, which is equivalent to the heating of the living unit.
After repairs, before connecting the living unit to the TV's lanyards, it is imperative to check the output transistor of the small plug and the secondary lanyards of the small transformer. Voltage is often taken from the secondary windings of the remaining winding, straightened and smoothed to energize the nodes of the TV. One of the reasons why the life block is going well may be the Lancsugs.
When adding transistors using the replacement method, the results were consistent with their characteristics indicated in the table. 1.
Transistors 2SC1815Y can be replaced with KT3102B, 2SB774T with KT3107B, and 2SD820, BU11F with KT872A. The rest should be secured to the heat dissipation area with an insulating gasket. Diody can be replaced with KD209B, KD226A, KD226B.
Most typical malfunction of this module This means “output from separation” through a change in capacity (or an increase in EPS) of electrolytic capacitors. Moreover, the reason for this unacceptability is not the fact that the parts are stuck together: the main problem lies in the fact that the daily pulse generators operate at high frequencies (15 kHz or even higher ...), and the primary electrical circuits are simply not adequate at such high frequencies and in U The robotic process starts to heat up.
Since the filter capacitor (behind the C606 circuit) copes even less with its obligations, the C607 operates in an even more important mode (it has to pass high-frequency pulses through itself).
Therefore, when repairing this ІІП track, in the obligatory order, firstly turn on the capacitors, and repair the unit is carried out with the connection of the row igniter, which has become necessary as a heating lamp with a intensity of 60...100 W.
Note: the main part of the material is from Radio magazine, 1998, No. 4
Hello everyone!
Let us take a look at this statistic LCD TV living unit Samsung BN44-00192A , which is available in devices with screen diagonals of 26 and 32 inches. We will also look at the typical malfunctions of this module.
All components of this life block distributed on one board. The external appearance of the payment for the presentation of the little one:
Life module diagram BN44-00192A can be found on this site.
This module is functionally divided into a number of nodes:
- Power Factor Correction (PFC) or tension coefficient corrector (KKM);
- Dzherelo tavern “chergoviy”;
- Dzherelo tavern “Robitnik”.
Let's take a look at the skin vuzol okremo.
Tension coefficient corrector
This product absorbs a harmonious storage stream at the input lancus, which is created by rectifying diodes in conjunction with the electrolytic capacitor of the filter of the intermediate rectifier of the pulse lifer (IIP). These harmonious warehouses negatively affect the electrical supply, therefore everyday equipment They are required to equip their products with PFC devices. Depending on tension, these devices can be active or passive. The block of life BN44-00192A, which we see, has an active PFC device.
Here the PFC is turned on by commutating the voltage M_Vcc on the 8th pin of the ICP801S controller simultaneously with the working life switch. If the active PFC mode is not turned on, the remaining +311V voltage from the diode bridge passes through the DP801 diode to the filter capacitor. To filter out harmonics at low voltages, it is entirely necessary to install input filters. Vlasne, with filters and passive PFCs.
Dzherelo tavern "chergoviy"
Chergovo's device is based on a gate valve circuit, which is controlled by an ICB801S PWM controller. The transformation, which operates at a fixed frequency of 55...67 kHz, produces a stabilized voltage of 5.2V at the output and can increase the voltage to 0.6A. This voltage ensures the life of the control processor in the draft mode, the life of the PWM microcircuits of the main engine, as well as the life of the PFC in the operating mode. From there, switch to the TV operating mode by forming a voltage of 5.2 with the help of a transistor switch QB802. The live voltage M_Vcc, in this case, should be supplied to the PWM controllers ICP801S and ICM801. At the same time, PFC and the main life source are launched.
Dzherelo zhivlennya “worker”
The robotic life-saving device is implemented using a forward-moving switching circuit, which is similar to the overhead bridge circuit. Dana Dzherelo The output form is a stabilized voltage:
24V (inverter power supply), 13V, 12V and 5.3V for food lane.
Typical faults
Now let's look at the most popular defects in the life block.
These can be seen:
The material of this article is intended not only for owners of already rare televisions who want to renew their usefulness, but also for those who want to develop their circuitry, design and principle robots of impulse life units. Once you have mastered the material of this article, you can easily work out any scheme and principle of operation of pulsed living units for consumer equipment, be it a TV, laptop or office equipment. So let's get started...
The TVs of the Radyansky production plant, the third generation of ZUSTST, had pulsed life units - MP (life module).
Pulse life blocks, depending on the TV model, have been analyzed and divided into three modifications – MP-1, MP-2 and MP-3-3. The life modules are assembled behind the same electrical circuit and are separated by the type of pulse transformer and the voltage rating of the capacitor C27 at the output of the rectifier filter (different circuit principle).
Functional diagram and principle of operation of the pulse block of the TV ZUSTST
Small 1. Functional diagram pulse block ZUSTST TV life:
1 - hemstone viper; 2 - formulate launch impulses; 3 - pulse generator transistor; 4 - control cascade; 5 - stabilization device; 6 - device zakhistu; 7 - pulse transformer for the TV housing unit 3st; 8 – viper; 9 - navantazhennya
At the earliest possible moment, device 2 will generate a pulse, which is generated by the transistor of pulse generator 3. In this case, a saw-tooth flow continues to flow through the winding of the pulse transformer with circuits 19, 1, which increases linearly. At the same time, energy accumulates in the magnetic field of the transformer core, the value of which is determined by the hour the transistor of the pulse generator is open. The secondary winding (windings 6, 12) of the pulse transformer is wound and connected in such a way that during the period of accumulation of magnetic energy, a negative potential is applied to the anode of the VD diode and the voltage is closed. After about an hour, control cascade 4 closes the transistor of the pulse generator. Since the flow in the winding of transformer 7 cannot change spontaneously through the accumulated magnetic energy, the EPC is due to the self-induction of the turning sign. The VD diode opens up, and the flow of the secondary winding (pins 6, 12) increases sharply. In this way, since in the beginning period the magnetic field was connected to the stream, which flowed through winding 1, 19, then it is now created by the stream of winding 6, 12. If all the energy accumulated during the hour of the closed state of key 3, it goes to the vantage point , then the second winding reaches a zero value.
From the pointed butt, you can proceed without any effort, so that by regulating the voltage of the open-state transistor in the pulse generator, you can remove the amount of energy that comes from the generator. This regulation is carried out by an additional control cascade 4 of the voltage signal on the windings 7, 13 of the pulse transformer. The turn-off signal at the ends of the winding is proportional to the voltage at the vantage point 9.
If the voltage is required to change for some reason, then the voltage that is found in the stabilization devices will also change 5. In the stabilization device, through the control cascade, the transistor of the pulse generator is closed. from above. This increases the hour that passes through winding 1, 19 of the current flow, and consequently increases the amount of energy that is transferred to the generator.
The moment of turning on of transistor 3 is determined by a stabilization device, and the signal coming from windings 13, 7 is analyzed, which allows you to automatically adjust the average value of the output constant voltage.
The stagnation of the pulse transformer makes it possible to eliminate differences in the amplitude of the voltage in the windings and reduces the galvanic connection between the lanyards of the secondary rectifiers and the live electrical circuit. Cascade 4 determines the range of pulses created by the generator and, if necessary, turns it on. The generator switches on when the voltage changes below 150 V and the compressed voltage decreases to 20 W, when the stabilization cascade ceases to function. If the stabilization cascade is not working, the pulse generator is unquenched, which can lead to the development of new large pulses and the output of the transistor of the pulse generator.
Principle diagram of the pulse block of the TV ZUSTST
Let's take a look at the principle diagram of the MP-3-3 life module and the principle of operation.
Small 2 Principle diagram pulse unit for TV life ZUSTST, module MP-3-3
This warehouse includes a low-voltage rectifier (VD4 - VD7 diodes), a starting pulse generator (VT3), a pulse generator (VT4), a stabilization device (VT1), a protection device (VT2), a pulse transformer T1 for the life cycle unit 3 rectifiers on diodes VD VD15 with a voltage stabilizer (VT5 – VT7).
Pulse generator behind a blocking generator circuit with collector-base connections on transistor VT4. Turning off the TV constant voltage From the output of the low-voltage rectifier filter (capacitors C16 C19 and C20), through winding 19 1 of transformer T1, go to the collector of transistor VT4. One hour voltage limit from the diode VD7 through capacitors C11, C10 and resistor R11 charges capacitor C7, and also goes to the base of transistor VT2, which is not used in the protection device of the life module reduced voltage boundaries. When the voltage on capacitor C7 is applied between the emitter and base 1 of unijunction transistor VT3, reaches value 3, transistor VT3 opens. Discharge of the capacitor C7 occurs: the emitter-base junction of 1 transistor VT3, the emitter junction of transistor VT4, connected in parallel, resistors R14 and R16, capacitor C7.
The discharge stream of capacitor C7 turns on transistor VT4 for an hour of 10 - 15 μs, sufficient for the flow of the collector circuit to rise to 3...4 A. The flow of the collector stream of transistor VT4 through the magnetization winding 19, 1 is accompanied by accumulation energy in magnetic. After the discharge of capacitor C7 is completed, transistor VT4 closes. The connection of the collector flow in the coils of transformer T1 produces EPC self-induction, which creates a positive voltage on pins 6, 8, 10, 5 and 7 of transformer T1. In this case, a stream flows through the passages of the one-way rectifiers at the second rectifiers (VD12 - VD15).
When there is a positive voltage on winders 5, 7 of transformer T1, capacitors C14 and C6 are charged in parallel in the anode and electrode lanyards of the ceramic thyristor VS1 and C2 in the emitter-base lanjug of transistor VT1.
Capacitor C6 is charged by a lancet: terminal 5 of transformer T1, diode VD11, resistor R19, capacitor C6, diode VD9, terminal 3 of transformer. Capacitor C14 is charged by a lancet: output 5 of transformer T1, diode VD8, capacitor C14, output 3 of transformer. Capacitor C2 is charged by a lancet: terminal 7 of transformer T1, resistor R13, diode VD2, capacitor C2, terminal 13 of the transformer.
The same happens when the VT4 transistor of the blocking generator is switched on and switched on. Moreover, a number of such impairing voltages are sufficient to charge the capacitors in the secondary lancets. Once the charging of these capacitors is completed between the windings of the blocking generator, connected to the collector (base 1, 19) and to the base (base 3, 5) of transistor VT4, the action begins to be positive Gateway link. When the blocking generator switches to auto-coupling mode, the VT4 transistor automatically opens and closes at the same frequency.
In the open state of the transistor VT4, the collector stream flows from the plus of the electrolytic capacitor C16 through the winding of the transformer T1 with connections 19, 1, the collector and emitter junctions of the transistor VT4, in parallel with the inclusion of resistors R14, R16 to the minus . Through the presence of lancus inductance, the rise of the collector stream follows a saw-like law.
To turn off the output from the fret of transistor VT4 by reversing the supports of resistors R14 and R16, it is selected in such a way that when the collector flow reaches a value of 3.5 A, a voltage drop is created across them, sufficient for thyristor VS1. When the thyristor is activated, capacitor C14 is discharged through the terminal junction of transistor VT4, in parallel with resistors R14 and R16, and thyristor VS1 is activated. The discharge line of capacitor C14 emerges from the base line of transistor VT4, which leads to its initial closing.
Further processes in the operation of the blocking generator are indicated by the thyristor VS1, which allows you to regulate the rate of rise of the saw-like flow and thus the amount of energy that is stored in the core of the transform ator.
The life module can be operated in stabilization and short circuit modes.
The stabilization mode is indicated by the operation of the UPT (steady-state booster), selected on transistor VT1 and thyristor VS1.
With a voltage of 220 Volts, if the output voltages of the secondary life circuits reach the nominal value, the voltage on the winding of transformer T1 (voltages 7, 13) increases to the value at which the voltage at the base of the transistor VT1 is constant, wherever walk through the debtor Rl - R3 more negative , below the territory where it is transmitted throughout. Transistor VT1 is opened with a lance: terminal 7 of transformer, R13, VD2, VD1, etheric and collector junctions of transistor VT1, R6, core electrode of thyristor VS1, R14, R16, terminal 13 of transformer. This strum, the subsumable strum of the ceramic electrode of the thyristor VS1, opens it at the moment when the output voltage of the module reaches the nominal value, which increases the rise of the collector strum.
By changing the voltage on the basis of the transistor VT1 with the adjusting resistor R2, you can adjust the voltage on the resistor R10 and, therefore, change the moment of opening of the thyristor VS1 and the voltage of the open state of the transistor VT4, thereby setting the output and voltage to the life block.
When the voltage changes (or the voltage of the circuit increases), the voltage on pins 7, 13 of transformer T1 increases. When this occurs, the negative voltage at the base of the emitter of transistor VT1 increases, resulting in an increase in the collector flow and a drop in voltage across resistor R10. This causes the thyristor VS1 to open up earlier and the transistor VT4 to close. Tim himself changes the tension that appears in the vanguard.
With a decrease in voltage, the voltage on the winding of transformer T1 and the base potential of transistor VT1 in relation to the emitter decrease less. Now, through the change in voltage generated by the collector string of transistor VT1 on resistor R10, thyristor VS1 opens at a later hour and the amount of energy that is transferred from the second lance increases. An important role in the protection of transistor VT4 is played by the cascade on transistor VT2. When the voltage changes below 150, the voltage on the winding of the transformer T1 with connections 7, 13 is insufficient to open the transistor VT1. When the device does not provide stabilization and protection, the VT4 transistor becomes uncoated and it becomes possible for it to go out of tune through the permissible limits of voltage, temperature, and current of the transistor. To prevent the output from the fret of transistor VT4, it is necessary to block the blocking generator. For this purpose, switch on the transistor VT2 in such a way that a constant voltage is supplied to its base from the conductor R18, R4, and to the base there is a pulsating voltage with a frequency of 50 Hz, the amplitude of which is stabilized by the stabilizer VD3. When the voltage changes, the voltage at the voltage level of transistor VT2 changes. Since the voltage on the emitter is stabilized, changing the voltage on the base causes the transistor to open up. Through the closed transistor VT2, trapezoidal-shaped pulses from diode VD7 go to the ceramic electrode of the thyristor, turning it on for an hour, which indicates the trivality of the trapezoidal pulse. This is to bring the blocking generator into operation.
The short-circuit mode is responsible for the appearance of a short circuit in many secondary life-saving devices. The start-up of the life block in this case is carried out by pulses that are triggered by the start-up device selected on the transistor VT3, and the turn-off is carried out by the additional thyristor VS1 along the maximum flow of the collector of the transistor VT4. After the end of the triggering pulse, the device is not awakened, since all the energy is spent in the short-circuited circuit.
After removing the short circuit, the module enters the stabilization mode.
Pulse voltage rectifiers, connected to the secondary winding of transformer T1, are collected in a single-phase forward circuit.
The rectifier on the VD12 diode produces a voltage of 130 to support small-scale circuits. Smoothing of the voltage pulsation is effected by the electrolytic capacitor C27. Resistor R22 recognizes the possibility of a significant voltage shift at the output of the rectifier when the voltage is turned on.
On the VD13 diode, the rectifier voltage is 28, used to liven up the TV's frame distribution. Voltage filtering is ensured by capacitor C28 and inductor L2.
15 V voltage supply for power supply audio frequency collections on VD15 diodes and SZO capacitors.
Voltage 12, vicorized in the color module (MC), radio channel module (MRK) and frame distribution module (MK), is created directly on the VD14 diode and capacitor C29. At the output of this switching rectifier there is a stabilizer that compensates for the voltage collected on the transistors. This warehouse includes a regulating transistor VT5, a booster transistor VT6 and a curing transistor VT7. The voltage from the output of the stabilizer goes through the connector R26, R27 to the base of the transistor VT7. Change resistor R27 is used to set the output voltage. In the equalizer of transistor VT7, the voltage at the output of the stabilizer is equal to the reference voltage at the zener diode VD16. The voltage from the VT7 collector goes through the booster on the VT6 transistor to the base of the VT5 transistor, which is connected in series to the rectified string. This leads to a change in the internal support, which is due to the fact that the voltage output increases or changes, either increases or decreases. Capacitor C31 protects the stabilizer from alarm. Through resistor R23, voltage is supplied to the base of transistor VT7; it must be opened when turned on and renewed after a short circuit. Throttle L3 and capacitor C32 are an additional filter at the stabilizer output.
Capacitors C22 - C26 are shunted into direct diodes to change the transients transmitted by pulse rectifiers into the electrical circuit.
Mesh filter for ZUSTST housing unit
The PFP life filter board has been added to electrical lines through connection X17 (A12), switch S1 in the TV control unit and monitors FU1 and FU2.
As border guards, fuses of the TVP-19 type are used, the characteristics of which ensure the most reliable protection of TV receivers in the event of malfunctions, the lower ones of the PM type.
The purpose of the filter is .
On the life filter board there are elements of the secondary filter (C1, C2, SZ, throttle L1) (a diagram similar to the principle).
Resistor R3 is used to exchange the flow of diodes that are rectified when the TV is turned on. The posistor R1 and resistor R2 are elements for the demagnetization of the kinescope mask.
When diagnosing television devices, identifying a faulty component usually takes more than an hour to replace, especially if the defect is detected by self-exertion, rather than by a professional television technician. It is absolutely logical to entrust the repair to a specialist, who has evidence and great practice of this kind of work, as well as care, skills with a soldering iron and a tester, the necessary technical documentation in the form of principles electrical circuits, you can try to repair your TV at home yourself.
Life block daily TV, Whether it is a plasma panel or an RK, LED TV, it is a pulse generator with a given range of output voltages and a nominal tension, which is applied to the skin of them. The life board can be installed in a nearby block, which is typical for devices with small diagonals, or integrated into a TV chassis and located in the middle of the device.
Characteristic signs of a malfunction of this unit:
- The TV does not stick when you press the button of the edge switch
- The LED in the working mode lights up, but does not switch to the operating mode
- Change the image to look like evil and dark, background by sound
- There is sound, but there is no image, so you can appear in about an hour
- It is necessary to test switching on for normal picture and sound to appear.
Let's take a look at the circuitry of the standard block that causes this type of malfunction on the ViewSonic N3260W TV.
For a complete review of the diagrams, you can open it in a new window and enlarge it or download it to your computer or mobile device
First of all, from where to start, a thorough visual inspection of the payment on the connected device. To do this, the unit must be removed from the TV, disconnected from the connectors, and the high-voltage capacitor at the filter - C1 must be discharged. In units of this series of televisions, the electrolytic capacitors of the filters of the secondary life units often go out of tune. The stink is easily diagnosed by the swollen upper crust. All capacitors, external look Any doubts must be replaced immediately.
Vuzol chergogo mode visconation on IC2 (TEA1532A) and Q4 (04N70BF) with elements of stabilization of the output voltage 5V on the optocoupler IC7 and ceramic zener diode ICS3 EA1. Either the voltage at the output of this node is underestimated, it is measured on capacitors CS22, CS28, tell about this wrong robot. In order to update the circuit design, please note that the greatest impact is on elements IC2, Q7, ZD4 and Q11, R64, R65, R67, which require revisions and replacements at different times of need. The efficiency of the parts is checked by a tester directly on the board of the unit. In this case, doubtful components are soldered together and tested extensively in order to determine the consistency of their components with the circuit elements. The IC2 chip simply delays replacement.
Due to the presence of a 5V voltage at the output of the black-mode circuits, the red LED burns out on the front panel of the TV. Using the remote control or buttons on the front panel of the TV, the life unit must switch to operating mode. This command – Power_ON – seems to have a high potential of close to 5V coming to the 1st output connector CNS1, turning on the keys to QS4 and Q11. In this case, life voltages are supplied to the microcircuits IC3 and IC1, putting them into operating mode. At 8, IC3 is output from the collector Q11, at 12, IC1 is output through key Q9 after starting the PFC circuit. The effectiveness of Power Factor Correction circuits is indirectly indicated by the increase in voltage from 310 to 390 volts across capacitor C1. If the output voltages appear to be 12V and 24V, then the main drive on IC3, Q1, Q2 functions in normal mode. Practice shows the low reliability of the UCC28051 and LD6598D among critical minds, if the filtration of the secondary jets is poor, and their replacement is routine.
As a further indication of the repair of television life units, it should be noted that the weakest link in our warehouse is the filter capacitors, which waste their power and nominal parameters. Sometimes the “capacity” is faulty, which can be seen from a swollen cap, sometimes not. The legacy of bad rectified voltage filtration can be varied: from wastage of the life cycle itself, to deterioration of inverter elements or failure software security memory chips on the motherboard
It is very important to independently examine all the reasons and consequences when repairing the life unit of a current TV, correctly diagnosing it without special tools and accessories. Our pleasure in such situations -