Tip 1: How to check the optocoupler

Failure optocoupler often leads to complete loss of efficiency switching power supply, load switch or other device where it is installed.To make sure that the cause of the fault was precisely this element, as well as the fact that the newly installed device is working properly, it is necessary to conduct a simple test.
you need
  • - soldering iron, solder, flux and neutral;
  • - multimeter;
  • - power supply;
  • - resistors.
Guide
1
If optocoupler, serviceability is in question, is soldered to the board, you must disable the power, discharge the electrolytic capacitors on it and then vypayat optocoupler, remembering how she had been soldered.
2
Optocouplers have different emitters (incandescent, neon lights, LEDs, light emitting capacitors) and various radiation detectors (photoresistors, photodiodes, phototransistors, fototiristory, Phototriac).Also they are different pinout.Therefore, you must find the data on the type and pinout optocouplers or reference or datasheet, or in the scheme
of the device, where it was installed.Often transcript optocoupler pinout applied directly to the board of pribora.Esli modern instrument, you can almost certainly be sure that it is the emitter LED.
3
If the radiation detector is a photodiode, it is connected to the meter running in the measurement mode DC voltage to 200 mV.In all other cases, the receiving element optocoupler switch with the correct polarity in the chain, consisting of a DC voltage of a few volts, resistor, designed so that the current through the radiation receiver did not exceed the permissible and the meter operating in the current mode at the appropriate limit.
4
Now enter the optocoupler emitter in operation.To turn the LED pass through it in the straight polarity DC current equal to the nominal.In an incandescent lamp post nominal voltage.Neon lamps or light emitting capacitor careful, connect to a network through a resistor of 500 ohms to 1 MW and a capacity of not less than 0.5 watts.
5
photodetector must react to the inclusion of a sharp change in the regime of the radiator.Now try a few times off and on the transmitter.Photothyristors and LDR will remain open, and after removal of exposure up to the shutdown of the power.Other types of photodetectors will react to every change in control signala.Esli optocoupler has an open optical channel, be sure to change the response of the radiation detector in the ceiling of the channel.
6
Having concluded state optocoupler, the experimental setup unplug and disassemble.Then solder optocoupler back to charge or replace the other.Continue to repair the device, which includes an optocoupler.

Tip 2: How to check the optocoupler

Opto or optocoupler consists of a transmitter and a photodetector, separated by a layer of air or a transparent insulating material.They are not connected electrically, allowing you to use the device for electrical isolation of chains.
Guide
1
To connect optocoupler photodetector measuring circuit in accordance with its type.If the receiver is a photoelectric cell, use an ordinary ohmmeter, and the polarity is unimportant.When used as a microammeter photodiode receiver without the power supply (positive to the anode).If the signal is received by the phototransistor structure npn, connect the circuit of the resistor 2 kiloomah, batteries 3 volts and milliamp, and, plus the battery, connect to the collector of the transistor.If phototransistor has pnp structure, the battery change polarity reversed.To check fotodinistora make a chain of batteries at 3 V and bulb 6 V, 20 mA, plus connecting it to the anode dynistor.
2
Most optocoupler emitter is a LED bulb.In her post incandescent bulb rated voltage in either polarity.You can also apply an alternating voltage, the current value is equal to the operating voltage of the lamp.If the emitter is an LED turn ON the voltage across the resistor 3 to 1 k (plus the anode).
3
Opto OK, if you turn on the transmitter changes the meter reading, and when it is disconnected readings are the same as before switching.The exception is dinistornaya optocoupler: after turning off the radiator fotodinistor will open.To close it, briefly turn off the power measurement circuit.
4
Making sure that the optocoupler is OK, check the insulation resistance.Disassemble the measuring circuit, then switch the ohmmeter on the most sensitive limit.Connect the test leads between the input and output circuit optocouplers in all combinations of the conclusions and in both polarities.Do not touch the probe with your fingers - electric shocks will not occur, but the readings may be distorted.In all cases, the device should show infinity.
Note
not exceed the currents and voltages at the transmitter and receiver, as well as the tension between them.Do not work under stress.
Helpful Hint
Optocouplers open channel operate only when between transmitter and receiver is nothing.They are used as sensors.

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