Advice 1: How to check the optocoupler

The failure of PCP often leads to a complete loss of efficiency of the switching power supply, switch, loads, or other device where it is installed. To ensure that the cause of failure was precisely this element, and that the newly installed device is serviceable, it is necessary to conduct a simple test.
How to check the optocoupler
You will need
  • - soldering iron, solder and neutral flux;
  • - multimeter;
  • - power source;
  • - resistors.
Instruction
1
If the optocoupler, the serviceability of which is questioned, is soldered to the motherboard, you must disable the power to discharge her the electrolytic capacitors, and then desoldering the optocoupler, remembering how it was soldered.
2
Optocouplers have different emitters (incandescent lamps, neon lamps, LEDs, light emitting capacitors) and different radiation sensors (photoresistors, photodiodes, phototransistors, photothyristors, porosimetry). They also differ in the Pinout. It is therefore necessary to find data on the type and Pinout of the coupler in either the reference or measurements, or in the scheme of the device where it was installed. Often deciphering the Pinout of the opto-coupler applied directly to the cost of this device.If the unit is modern, you can almost certainly be sure that the emitter is a led.
3
If the light receiver is a photodiode, it connect multimeter, to measure DC voltage to 200 millivolts. In all other cases, the receiving element of the optocoupler will turn on in the correct orientation, in a chain consisting of a DC voltage of a few volts, the resistor is calculated so that the current through the radiation detector is not exceeded, and multimeter, to measure current at the appropriate limit.
4
Now enter the emitter of the optocoupler to work. To turn of the led pass through it in straight polarity DC current equal to the rated. The incandescent lamp apply rated voltage. Neon lamp or light-emitting capacitor, taking care connect to the network through a resistor of 500 kω to 1 Mω and a capacity of at least 0.5 watts.
5
The detector must react to the inclusion of the emitter an abrupt change in regime. Now try multiple times to turn off and turn on the emitter. The photothyristor and the photoresistor will remain open and after removing the control action up to disconnect their supply. Other types of photodetectors will respond to each change of the control signal.If the optocoupler has an open optical channel, be sure to change the reaction of the radiation receiver due to the overlapping of this channel.
6
Making a conclusion about the state of the optocoupler, the experimental setup unplug and disassemble. Then solder the optocoupler back to charge or replace to another. We will continue repairing the device, which includes the optocoupler.

Advice 2: How to check capacitor for proper

The ignition system of the engine is one of the main systems of the car. Thanks to the car factory and we can move on the road. In our country there are still plenty of vehicles that have a contact ignition. The condenser is one of its elements. Usually it does not fail, but drivers should always be prepared. Checking and changing it in a way that does not cause any difficulties.
How to check capacitor for proper
You will need
  • - ohmmeter;
  • - crank (curve starter);
  • - portable lamp
Instruction
1
Take the device ohmmeter. Output capacitor connect with his body, his discharge. One probe of the ohmmeter, connect the tip wire, the second to the case (instrument switch in the upper limit of measurement). With proper capacitor arrow is sharply deflected in the direction of "0" and then gradually return to the symbol "∞". If you change the polarity, the arrow will further deviate to a "zero." The faulty capacitor and replace.
2
Disconnect the wire from the ignition coil wire and condenser from the clip of the circuit breaker. Take a portable lamp, it will give the opportunity to test the breaking down of the condenser to the vehicle body. Connect it to the terminal breaker. Turn on the ignition. The capacitor is considered to be faulty if the lamp will light up. It is used to reduce the erosion of the breaker contacts and increase the secondary voltage. Connect the capacitor in parallel. When opened, at a time when the gap is at a minimum value, a spark, with the result that it accumulates charge. For each ignition system has its own condenser. Its capacity is usually located within the boundaries of 0,17—0,35 UF. For the contact system of the car VAZ, its value is 0,20—0,25 mkF. In the case of deviations in the capacitance of the capacitor decreases to the secondary voltage. When charging or discharge of the capacitor does not exceed 5 kV.
3
Disconnect the black wire coming from the ignition coil from the clip circuit breaker, disconnect the wire to the condenser from the breaker. Turn on the ignition. Make between touch. The capacitor will be faulty in the event of a spark. The following method - charge its high-voltage current from the ignition coil, then secure it to the vehicle body. If there is spark discharge between the ground wire and capacitor with an audible click, then it works. If spark is not observed, it means the capacitor is broken.
4
Disconnect the condenser. Take the winding handle and start to turn the crankshaft of the internal combustion engine. Remove the ignition distributor cap and turn the ignition on. A malfunction of the capacitor is excessive sparking of the contacts of the interrupter at this time. The appearance of too weak of a spark between the casing and the Central high-voltage wire, and with a fairly strong arcing of the contact breaker, the condenser is defective and requires replacement.
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