Testing Silicon Rectifier Diode - Page 1
Forum section: electronics / beginners

author: mr.fabe
author_rank: Regular Contributor
timestamp: November 05, 2019, 06:24:14 pm
content: How do you test a silicon rectifier diode such as this GS1MF ? Besides a resistance check for open/close, do you test at rated voltage or at a lower voltage level with low current?Thanks in advance.

author: Wimberleytech
author_rank: Super Contributor
timestamp: November 05, 2019, 08:52:58 pm
content: Depends on the purpose. If I just wanted to know if it were good or bad, I would test forward and reverse to confirm that it was rectifying. You can do that with most any modern DMM. If I wanted to characterize it, I would put it on a curve tracer and test it against datasheet values, which would mean running it up to rated voltage.

author: mr.fabe
author_rank: Regular Contributor
timestamp: November 06, 2019, 12:07:37 am
content: For normal diodes, the DMM diode test would work but it does not work with the HV type rectifier diodes. A curve tracer would work if I had one that can generate 1kV. Can anyone recommend other methods to test these diodes?

author: Wimberleytech
author_rank: Super Contributor
timestamp: November 06, 2019, 12:31:06 am
content: Quote from: mr.fabe on November 06, 2019, 12:07:37 amOh, I see...the cutin voltage is 1.1 volts...yeah DMM may not recognize that.

author: magic
author_rank: Super Contributor
timestamp: November 06, 2019, 07:10:17 am
content: A DMM will measure 1.1V just fine, but you need to use volts mode and apply the test current externally from other sourceA DMM wouldn't test the diode to its full rated 1A anyway.As for reverse voltage, you just need some source of 1kV, no way around it. Somebody recently did a thread on testing diodes with a megger. If not, a voltage multiplier may give you 1kV.

author: Wimberleytech
author_rank: Super Contributor
timestamp: November 06, 2019, 01:54:01 pm
content: Quote from: magic on November 06, 2019, 07:10:17 amOf course...I was referring to the diode test mode common on modern DMMs. I checked my Fluke 87V...it tests a blue led just fine. Presents an open circuit voltage around 7 volts

author: Kirill V.
author_rank: Regular Contributor
timestamp: November 06, 2019, 05:46:29 pm
content: Quote from: mr.fabe on November 05, 2019, 06:24:14 pmI'm sorry, but this is the first time I've heard of such parameters. Maybe I'm behind the times?Direct voltage drop and breakdown voltage are usually measured...Measuring the reverse breakdown voltage is best done with some kind of current source and voltmeter parallel to the diode. In this case, this is a non-trivial task, but the current source can be replaced with a high voltage source and a resistor to limit the value of current through the test diode.

author: mr.fabe
author_rank: Regular Contributor
timestamp: November 06, 2019, 07:58:46 pm
content: Quote from: Kirill V. on November 06, 2019, 05:46:29 pmMy mistake. I stated "open/close" incorrectly and confused the issue. Resistance check as a test that you can perform with normal diodes. The point is that the normal DMM diode tests failed with HV diodes. I am aware of testing at rated voltage but sought an alternative method to test at a lower voltage to determine if a HV diode is operating properly.

author: Kirill V.
author_rank: Regular Contributor
timestamp: November 07, 2019, 02:01:57 pm
content: The matter is that semiconductors and ohmic contacts have resistance and too create voltage drop which is added to 0,7 volts of voltage drop at pn junction. As far as I know, HV diodes has more high resistance of semiconductor that another diodes. Therefore, the voltage drop on the diode you are interested in is 1.1 volts at a current of 1 amp, but the voltage drop at pn junction is 0.7 volts approximately, and everything else is ohmic losses. At low direct currents this voltage will not exceed 0.7 volts and can be measured with a DMM.There are diodes that can not afford a DMMThis is HV diode array. Now I uses amperemeter and voltmeter for testing. Direct current 8 mA, drop voltage 18,6 VThese are diodes that cannot be measured with a conventional DMM. In datasheet says that maximum drop voltage equal 25 V at 10 mA current, therefore they passed the test:)

author: mr.fabe
author_rank: Regular Contributor
timestamp: November 08, 2019, 02:28:39 am
content: Thank you all for your input!