How to repair TPI - from personal experience. Switching Power Supply For Screwdriver - Power supplies (switched) - Power supplies Winding data of the transformer tpi 4 3
A schematic diagram of a self-made switching power supply with an output voltage of +14V and a current sufficient to power a screwdriver is described.
A screwdriver or cordless drill is a very handy tool, but there is also a significant drawback, with active use, the battery discharges very quickly - in a few tens of minutes, and it takes hours to charge.
Even having a spare battery doesn't help. A good way out when working indoors with a working 220V power supply would be an external source to power the screwdriver from the mains, which could be used instead of a battery.
But, unfortunately, specialized sources for powering screwdrivers from the mains are not commercially produced (only chargers for batteries that cannot be used as a mains source due to insufficient output current, but only as a charger).
In the literature and the Internet, there are proposals to use car chargers based on a power transformer, as well as power supplies from personal computers and for halogen lighting lamps, as a power source for a screwdriver with a rated voltage of 13V.
All these are probably good options, but without claiming originality, I propose to make a special power supply yourself. Moreover, on the basis of the circuit I have given, you can make a power supply for another purpose.
circuit diagram
The circuit is partially borrowed from L.1, or rather, the idea itself, to make an unstabilized switching power supply according to the blocking generator circuit based on the TV power supply transformer.
Rice. 1. Scheme of a simple switching power supply for a screwdriver, made on a KT872 transistor.
The voltage from the network is supplied to the bridge on the diodes VD1-VD4. A constant voltage of about 300V is released on the capacitor C1. This voltage is fed by a pulse generator on a transistor VT1 with a transformer T1 at the output.
The VT1 circuit is a typical blocking oscillator. In the collector circuit of the transistor, the primary winding of the transformer T1 (1-19) is turned on. It receives a voltage of 300V from the output of the rectifier on diodes VD1-VD4.
To start the blocking generator and ensure its stable operation, a bias voltage is supplied to the base of the transistor VT1 from the circuit R1-R2-R3-VD6. The positive feedback necessary for the operation of the blocking generator is provided by one of the secondary coils of the pulse transformer T1 (7-11).
The alternating voltage from it through the capacitor C4 enters the base circuit of the transistor. Diodes VD6 and VD9 are used to generate pulses based on the transistor.
Diode VD5, together with the circuit C3-R6, limits the positive voltage surges at the collector of the transistor to the value of the supply voltage. The VD8 diode together with the R5-R4-C2 circuit limits the negative voltage surges at the collector of the transistor VT1. The secondary voltage 14V (at idle 15V, under full load 11V) is taken from the winding 14-18.
It is rectified by the VD7 diode and smoothed by the capacitor C5. The operating mode is set by the tuning resistor R3. By adjusting it, you can not only achieve reliable operation of the power supply, but adjust the output voltage within certain limits.
Details and construction
Transistor VT1 must be installed on the radiator. You can use a radiator from the MP-403 power supply or any other similar one.
Pulse transformer T1 - ready-made TPI-8-1 from the MP-403 power supply module of a domestic color TV type 3-USCT or 4-USCT. These TVs some time ago went for disassembly or were thrown away altogether. Yes, and TPI-8-1 transformers are on sale.
In the diagram, the numbers of the outputs of the transformer windings are shown according to the markings on it and on the schematic diagram of the MP-403 power supply module.
The TPI-8-1 transformer also has other secondary windings, so you can get another 14V using the 16-20 winding (or 28V by connecting 16-20 and 14-18 in series), 18V from the 12-8 winding, 29V from the 12-winding 10 and 125V from winding 12-6.
Thus, it is possible to obtain a power source for powering any electronic device, for example, a ULF with a preliminary stage.
The second figure shows how rectifiers can be made on the secondary windings of the TPI-8-1 transformer. These windings can be used for individual rectifiers, or they can be connected in series to get more voltage. In addition, within certain limits, secondary voltages can be adjusted by changing the number of turns of the primary winding 1-19 using its taps for this.
Rice. 2. Scheme of rectifiers on the secondary windings of the TPI-8-1 transformer.
However, the matter is limited to this, because rewinding the TPI-8-1 transformer is a rather thankless job. Its core is tightly glued, and when you try to separate it, it breaks at all where you expect.
So in general, any voltage from this block will not work, except with the help of a secondary step-down stabilizer.
The KD202 diode can be replaced by any more modern rectifier diode with a forward current of at least 10A. As a radiator for the VT1 transistor, you can use the radiator of the key transistor available on the board of the MP-403 module, having slightly altered it.
Shcheglov V. N. RK-02-18.
Literature:
1. Kompanenko L. - A simple switching voltage converter for a TV PSU. R-2008-03.
I’ll also bring in my (partially borrowed from a cooler specialist in this matter, I think he won’t be offended) a nickel into this piggy bank.Before disassembling, it is not harmful to measure the inductance of the quality factor of the windings, and it is even better to take these data from a live sample so that there is something to compare with after repair.
On sticking - a hair dryer does not always help in the case of large cores. I used for sticking first a small laboratory tile, then a flat heating element from
an electric kettle (there is even a thermal switch at 150 degrees, but you can turn on and select the temperature for reinsurance through LATR). Be sure to put it tightly pressing the free part of the ferrite (if the side of the gluing, then after grinding the influx of glue) to the cold surface of the heater and only then turn it on.
When disassembling, the main thing is patience - I pulled harder and those problems are superfluous.
As for the cores, there were almost no problems with disassembly and reassembly, except for GRUNDIGs and PANASONICs. In hryundels (filled with TPI compound in old TVs), the main problems are precisely connected with the cores, more precisely with their cracking. It is not possible to put another core of suitable size there due to the fact that the operating frequency of these TPIs is 3-5 times higher and low-frequency cores do not live in them. Saves in this case the use of cores from large FBT. Full reproduction requires a live sample from the same product to compare performance. (if it is very hard to restore - there is)
(Please do not ask questions about the cost and feasibility of these works, but the fact remains that such hybrids work.)
With some Panas, the trick is in very small gaps, and this is where the preliminary measurement of the inductance helps.
I do not advise gluing with superglue because it had several repetitions due to cracking of the glue line. Kneading a drop of epoxy is of course vain but more reliable, and after gluing it is good to compress the joint (for example, by applying a constant voltage to the winding, it will pull it off and even slightly warm it up).
About a pot of boiling water - I confirm for the case with FBT (it was necessary to tear out the cores from 30 dead flies) it works fine, I did not mock at TPI in this way, which I had to rewind.
At the moment, everything that was rewound (by me, and in especially severe cases by the mentioned specialist N. Novopashin) works. There were even successful results in rewinding line transformers (with an external multiplier) from fairly ancient industrial monitors, but there the secret of success is in the vacuum impregnation of the windings (by the way, Nikolai impregnates almost all rewound trances except for outright consumer goods) and unfortunately this is not treated on the knee.
The device mentioned by Rematik recently checked the BB trance of the backlight from the Mercedes dashboard - it showed everything OK on a deliberately broken trance, although the DIEMEN device also deceived on it - the trance made its way only at a rather high voltage, which actually allowed it to be measured at low.
Pulse power transformers (TPI) are used in pulse power supply devices for household and office equipment with intermediate conversion of the mains voltage of 127 or 220 V at a frequency of 50 Hz into rectangular pulses with a repetition rate of up to 30 kHz, made in the form of modules or power supplies: PSU, MP-1, MP-2, MP-Z, MP-403, etc. The modules have the same circuit and differ only in the type of pulse transformer used and the rating of one of the capacitors at the filter output, which is determined by the features of the model in which they are used.
Powerful TPI transformers for switching power supplies are used for decoupling and transferring energy to secondary circuits. Energy storage in these transformers is undesirable. When designing such transformers, as a first step, it is necessary to determine the range of oscillations of the magnetic induction of the DW in the steady state. The transformer must be designed to operate at the largest possible value of the DV, which allows you to have a smaller number of turns in the magnetizing winding, increase the rated power and reduce the leakage inductance. In practice, the value of the DV can be limited either by the saturation induction of the core B s or losses in the magnetic circuit of the transformer.
In most full-bridge, half-bridge, and full-wave (balanced) mid-point circuits, the transformer is energized symmetrically. In this case, the value of the magnetic induction changes symmetrically with respect to the zero of the magnetization characteristic, which makes it possible to have a theoretical maximum value of the DV equal to twice the value of the saturation induction Bs. In most single-ended circuits, such as those used in single-ended converters, the magnetic induction fluctuates completely within the first quadrant of the magnetizing characteristic from remanent induction Br to saturation induction Bs, limiting the theoretical maximum DV to (Bs - BR). This means that if the DW is not limited by losses in the magnetic circuit (usually at frequencies below 50 ... 100 kHz), single-ended circuits will require a large transformer for the same output power.
In voltage-fed circuits (which include all step-down regulator circuits), according to Faraday's law, the value of DV is determined by the volt-second product of the primary winding. In steady state, the product "volt-second" on the primary winding is set at a constant level. The range of fluctuations of magnetic induction is thus also constant.
However, with the normal duty cycle control method used by most switching regulator ICs, at start-up and during a sudden increase in load current, the DV value can reach twice the steady-state value. Therefore, to prevent the core from saturating during transients, the steady-state DV should be less than half the theoretical maximum However, if a microcircuit is used that allows you to control the value of the volt-second product (circuits with input voltage perturbation tracking), then the maximum value of the volt-second product is fixed at a level slightly higher than the steady-state one. allows you to increase the DV value and improve the performance of the transformer.
The value of the saturation induction B s for most ferrites for strong magnetic fields of the 2500NMS type exceeds 0.3 T. In push-pull voltage-fed circuits, the magnitude of the increment in the induction of the DV is usually limited to a value of 0.3 T. With an increase in the excitation frequency to 50 kHz, the losses in the magnetic circuit approach the losses in the wires. An increase in losses in the magnetic circuit at frequencies above 50 kHz leads to a decrease in the DV value.
In single-cycle circuits without fixing the product "volt-second" for cores with (Bs - Br) equal to 0.2 T, and taking into account transients, the steady value of the DV is limited to only 0.1 T. Losses in the magnetic circuit at a frequency of 50 kHz will be insignificant due to the small range of fluctuations in magnetic induction. In circuits with a fixed value of the “volt-second” product, the DV value can take values up to 0.2 T, which makes it possible to significantly reduce the overall dimensions of the pulse transformer.
In current-fed power supply circuits (boost converters and current-controlled coupled-coil buck regulators), the DV value is determined by the volt-second product of the secondary at a fixed output voltage. Because the output volt-second product is independent of changes in input voltage, current-fed circuits can operate at close to the theoretical maximum DV (ignoring core losses) without having to limit the value of the volt-second product. .
At frequencies above 50 . 100 kHz, the LW value is usually limited by losses in the magnetic core.
The second step in the design of high-power transformers for switching power supplies is to make the right choice of the type of core that will not saturate for a given volt-second product and provide acceptable losses in the magnetic circuit and windings. For this, an iterative calculation process can be used, however, the formulas below ( 3 1) and (3 2) allow you to calculate the approximate value of the product of the areas of the core S o S c (the product of the core window area S o and the cross-sectional area of the magnetic circuit S c) Formula (3 1) is applied when the DV value is limited by saturation, and the formula ( 3.2) - when the DV value is limited by losses in the magnetic circuit, in doubtful cases, both values are calculated and the largest of the tables of reference data for various cores is used, the type of core is selected for which the product S o S c exceeds the calculated value.
Where
Рin \u003d Pout / l \u003d (output power / efficiency);
K - coefficient taking into account the degree of use of the core window, the area of the primary winding and the design factor (see Table 3 1); fp - operating frequency of the transformer 
For most ferrites for strong magnetic fields, the hysteresis coefficient is K k \u003d 4 10 5, and the eddy current loss coefficient is K w \u003d 4 10 10.
In formulas (3.1) and (3.2) it is assumed that the windings occupy 40% of the area of the core window, the ratio between the areas of the primary and secondary windings corresponds to the same current density in both windings, equal to 420 A/cm2, and that the total losses in the magnetic circuit and windings lead to a temperature difference in the heating zone by 30 ° C during natural cooling.
As a third step in the design of high-power transformers for switching power supplies, it is necessary to calculate the windings of the impulse transformer.
In table. 3.2 shows unified power supply transformers of the TPI type used in television receivers. 
The winding data of transformers of the TPI type, operating in switching power supplies for stationary and portable television receivers, are given in Table 3. 3 Schematic diagrams of TPI transformers are shown in Fig. 3. 1
The end of the table. 2.2 Number w IV IVa IV6 IV6 IV6 V VI Winding Name Positive feedback Rectifiers 125, 24, 18 V Rectifier 15 V Rectifier 12 V Pins 11 6-12 including: 6-10 10-4 4-8 8-12 14 -18 16-20 Number of turns 16 74 54 7 5 12 10 10 Wire grade PEVTL-0.355 ZZIM PEVTL-0.355 PEVTL-0.355 in four wires The same Resistance, Ohm 0.2 1.2 0.9 0.2 0.2 0.2 0.2 0.2 Note. Transformers TPI-3, TPI 4 2, TPI-4-3, TPI-5 are made on the M300NMS Sh12Kh20Kh15 magnetic circuit with an air gap of 1.3 mm in the middle rod, the TPI-8-1 transformer - on the M300NMS-2 Sh12Kh20Kh21 closed magnetic circuit with air a gap of 1.37 mm in the middle rod of any electrical alterations, but at the same time the connector X2 of the MP-4-6 module must be shifted to the left by one contact (its second contact becomes, as it were, the first contact) or when connecting the MP-44-3 instead of MP-3, the fourth contact of the X2 connector becomes, as it were, the first contact.
In table. 2 2 shows the winding data of pulse power transformers.
General view, overall dimensions and layout of the printed circuit board for the installation of pulse power transformers are shown in fig. 2.16.
Rice. 2.16. General view, overall dimensions and layout of the printed circuit board for the installation of pulsed power transformers A feature of the SMPS is that they cannot be turned on without load. In other words, when repairing the MP, it must be connected to a TV set or equivalent loads must be connected to the outputs of the MP. The circuit diagram for connecting load equivalents is shown in fig. 2 17.
The following load equivalents must be installed in the circuit: R1-resistor with a resistance of 20 Ohm ± 5%, with a power of at least 10 W; R2 is a resistor with a resistance of 36 Ohm ± 5%, with a power of at least 15 W; R3 - resistor with a resistance of 82 Ohm ± 5%, with a power of at least 15 W; R4 - RPSh 0.6 A \u003d 1000 Ohm; in amateur radio practice, instead of a rheostat, an electric lighting lamp for 220 V with a power of at least 25 W or 127 V with a power of 40 W is often used; Rice. 2.17. Schematic diagram of connecting load equivalents to the power supply module R5 - a resistor with a resistance of 3.6 ohms, with a power of at least 50 W; C1 - capacitor type K50-35-25 V, 470 uF; C2 - capacitor type K50-35-25 V, 1000 uF; SZ capacitor type K50-35-40 V, 470 uF.
The load currents should be: in the 12 V circuit 1 "o" \u003d 0.6 A; in a 15 V circuit 1nom = 0.4 A (minimum current 0.015 A), maximum 1 A); in a 28 V circuit 1 „OM \u003d 0.35 A; in the circuit 125 ... 135 V 1 „Ohm \u003d 0.4 A (minimum current 0.3 A, maximum 0.5 A).
The switching power supply has circuits connected directly to mains voltage. Therefore, when repairing the MP, it must be connected to the network through an isolation transformer.
The danger zone on the MP board from the printing side is indicated by shading with solid lines.
Replace defective elements in the module only after turning off the TV and discharging oxide capacitors in the filter circuits of the mains rectifier.
MP repair should begin with removing protective covers from it, removing dust and dirt, visually checking for installation defects and radio elements with external damage. 2.6, Possible malfunctions and methods for their elimination The principle of building basic models of 4USCT TVs is the same, the output voltages of secondary switching power supplies are also almost the same and are designed to power the same sections of the TV circuit. Therefore, at its core, the external manifestation of malfunctions, their possible
The Chinese "freaked out" in the power supply of the TECHNOSAT 4050C tuner, which failed. From the factory there was a chip marked 5MO2659R, but in fact - THIS IS INCORRECT MARKING. What kind of microcircuit this is is not known, the one standing there clearly does not fit into this power supply: if it is soldered, then a short circuit of 350 V is obtained.
The board of this power supply has the inscription VIDER22A, which I immediately did not pay attention to. This chip is often used in DVD power supplies. When I noticed this inscription, I thought that everything was decided. But it was not there. To earn this PSU had to sweat a little. Namely: I installed the missing elements - resistors R14: 4.7K, R3: 22 Ohm, diode D6FR207, made one break in the printed wiring, so that R14 was connected only to the optocoupler on one side, and its other output was connected to the cathode of the D6 diode and to the positive terminal of the capacitor C2, and with the fourth terminal of the U1 microcircuit (see photo).
And without disassembling the TPI (transformer), I had to wind the missing winding with a PEL wire of 0.16 fourteen turns (see the figure below):
TPI bottom view
We solder the beginning to the empty terminal 1, which goes to R3 (22 Ohm), and the end - also to the empty terminal, which goes to the minus of the capacitor C1 (47x400V).
Soak the added winding with glue, for example, "Moment". Then you need to solder the VIPER22A chip. Turn on, use.