How to Measure SCR Polarity with a Multimeter
1,Polarity discrimination
T1 pole and G pole discrimination: with a multimeter Rx10 block were measured between the poles of the positive and negative resistance, if you find that the two poles between the positive and negative resistance are very small (about 150ll or so), the two poles are T1 and G pole. Then the multimeter set 'f-Rx1 block, rotate the measurement of the two poles, the reverse resistance, the measured resistance value of the smaller once the black pen connected to the T1 pole, the other for the control pole C, the remaining foot T2 pole. To} bi-directional SCR is MAC97A6 / M329 model, measured with MF47F multimeter. If the resistance value measured with Rx100 block is different (in the 500ll or so), should be noted. If the measurement of high-power SCR data will be different, small current can not be triggered, the multimeter also need to add (series) voltage can be carried out.
2, to identify good and bad and conductivity
Can be placed in the multimeter Rxlk block, measuring T1 and T2, G and T1 resistance between, if the resistance is very small, indicating that the SCR has broken down. If the measured G and T2 pole positive and negative resistance are very large (normal should be in the hundreds of ohms or so). That is, it has been broken.
Discriminate the SCR's ability to conduct, the black pen of the multimeter can be connected to the T1 pole, the red pen connected to the T2 pole. With a dry cell as a trigger power (can also be used as another multimeter Rx1 instead), then the needle is conduction, dry cell is still conduction, this is to identify the T1 to T2 of the conductive parts can be. The principle is very simple, the positive pole of the battery connected to T1, the negative pole of the G false dry cell to form a trigger voltage, the current path: from dry cell 10-T1 a G thousand batteries, the formation of the current path was triggered, then the multimeter is also used as a power supply, the negative pen within the + - T1 - T2 a positive pen Within a, the formation of T1 to T2 pathway.
T2 to T1 conduction performance and this polarity is reversed, the town with the same method of discrimination.
Experience shows that different models of SCRs used in different stops of the multimeter, the measured resistance is not the same. For example, it is not easy to find a smaller resistance value with Rx100 block, change to Rx10 block will be easy to find. Thyristor model is not the same, the measured resistance value is different, for example, in the measurement of unidirectional SCR MCR100, with the multimeter resistance range Rx1-R×1k block rotation measurement can only appear a smaller resistance value (without the second larger resistance value); Fork, such as, in the measurement of unidirectional SCR FD315M, with the positive and negative pens in turn, with Rx100 or RXlk piggyback measurement, with the Rx100 or RXlk piggyback measurement. RXlk piggyback measurement when there are two resistance values, but it is not easy to find which is smaller, if the Rx1 or Rx10 block measurement is easier to find smaller resistance values, with the black pen to determine the G-pole, the red pen to determine the K-pole is easy to find, so do not be rigidly applied.
