Keywords: coil inter-turn short circuit tester
Instructions
When the tester is loaded, the number of AC voltmeter is about 1V. A square pulse that is 5VPP with an oscilloscope is measured, and the frequency of RP is adjusted, and the frequency of square wave pulses can be varied in a range of 12.5 to 25 kHz.
When testing, the two outputs J1, J2 of the tester are respectively connected to both ends of the test coil, respectively. The inductance L of the test coil forms a series circuit in the output coupling capacitor C5. Adjust the RP, when the frequency of the output square wave pulse is equal to the inherent frequency of the LC series circuit, the number of volttries is the largest. If the amount of inductance of the test coil is large (as the "FBT" primary coil of the color TV is 3.26MH), the number of voltmeter is up to 30 V (not necessarily a valid value) when the inductance of the color TV "FBT" primary coil is 3.26Mh. If the oscilloscope measures the two ends of the coil is 80 Vpp, a sine wave having a period is 80 μs (frequency of 12.5 kHz). If the amount of inductance of the test coil is small (such as 0.427MH of the secondary coil of the transformer), the maximum number of voltmeter is 16V, and the oscilloscope is measured to be 35Vpp. Sine wave of 30 μs per cycle.
When the tape is shorted, the Q value of the coil is largely lowered, and the number of calculation meter is greatly reduced.
1. Output transformer (FBT) detection
(1) Independent Test: "FBT" to be tested from the board, for the "FBT" of the color TV or color display, the two output "FBT" primary windings (+ B end and " C-terminal). If the "FBT" of black and white televisions, the rushing capacitor and damping diode connection is adjusted, the RP is adjusted to the maximum number of voltmeters. "FBT" without turntable, the number of voltmeter is generally between 20V ~ 30V, wore 1 on the magnetic core of "FBT", and the two ends are made into one turn, which is 1 short circuit ring. Dianspei UO of time the voltage meter fell to about 2V.
"FBT", UL / UO>8 without turntable short circuit, "FBT" in the interior, UL is greatly reduced, UL / UO<3, the more severe short circuit, the smaller the value of UL. Since the "FBT" of "FBT" without turntable short circuit is much different from the number of "FBT" voltmeter of the turns. This tester can accurately determine whether "FBT" exists between turns.
(2) When the road detection: "FBT" is installed on the board, since the primary windings are connected to the peripheral components, the deflection coil plug and the imaging tubular tail plate can be unplugged, and the effect of the peripheral device on the measurement results can be reduced. At the time of the road detection, the number of voltmeter is generally greater than 15V, but the UL is very small, it is possible to cause short circuits of peripheral components. It also needs to be independently detected from the board on the board to prevent accidents.
2. Switch transformer detection
(1) Independent Test: Deep the switch transformer from the circuit board, the output of the tester, the primary winding (300V terminal, and C terminal) of the switching transformer, adjust the RP to make UL maximum, different models of switching transformers, voltage meter of the voltage meter Between 20V to 30V, the UO is approximately 3V, UL / UO>6 on the coil. There is a short-circuit switching transformer in the interior, and the value of UL is small, the smaller the value of the UL between the turns, the smaller the UL. When waling 1 短 路 环, the number of voltmeter is lowered, UL / UO<2.
(2) On the road detection: Due to the influence of the primary windings connected to the peripheral components of each of the secondary windings, the UL value measured by different movements differs greatly. In order to reduce the error, it is possible to use a suctioner to make the tin of the primary winding, or use the needle to separate the pin to the board and then detect it. If the measured UL is small, it is possible to cause the peripheral components. It also needs independent detection.
3. Row drive the detection of transformers
Push the transformer is welded from the board. The output of the tester pushes the secondary winding of the transformer, and the RP is adjusted to push the UT, no turntable short-circuit rows, and the number of voltmeter is generally around 16V. UO is generally around 2V when wearing a short road ring. UL / u>6. The row of turns is pushing the transformer. When the value of UL is much smaller, the number of voltmeter is lowered, and the closing the turns is severe, the smaller the value of the UL.
The row of the magnetic core is used to push the transformer, and the ul and uoes are small, and this tester cannot be used to detect the determination.
4. Detection of routing coil
The plug of the deflection coil is taken from the board, and the output of the tester is connected to the input of the deflection coil, and the RP is adjusted to maximize UL. The UL of the routing coil without turntable short circuit is generally around 22V. If the measured UL is smaller, the two windings of the row deflection coil can be separated, respectively, the UL values are detected, and the routing coil of the turntable short circuit is detected, and the two UL values are approximately equal, if the two are large, There is a short-haired short circuit in the row deflection coil. We can further remove the row deflection coil from the developing tube, close to the line deflection coil to do a short-circuit ring, detect UO, no turntable routing coil, UO is generally around 16V. Since loofacer, there is a row of row of row of row of row of rowless row of row, and there is a short-circuit route, which is short-circuited between the rows of row of row of row of row, and there is a short-circuit line UL / UO.
three. Description of the test results
For different inductance coils, the UL and UO dispersibility measured by the turnt between the line turns are different due to the different coupling degrees between the L, Q and the windings. For row output transformers, switching transformers and row push transformers, inductance coils, high Q values, high and coils, are simply accurately determined whether the windings are short-circuited in the winding between UL / UO>6. . For row deflection coils, a loosely coupled inductive coil is used, and there is no turntable short circuit, and there is a row of routing coils of the turns to short circuit UL / UO. 1881.1.2. As long as you pay attention to accumulation of experience in usual inspection, it is also possible to more accurately determine whether the tested coil is present.
Since the inductor coil can be detected independently or in the case where the road machine is not energized, it is used to measure whether the inductive coil is present in the turret, which is not only simple and accurate.
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