Ask about the voltage regulator test question

kal9623287

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12V voltage regulator, SOD323 package,
measured with a multimeter
Forward voltage: Vf=0.64V (positive to negative)
Reverse voltage: Vf1=0.25V
Can this voltage regulator still be used?

maychang

[Can this voltage regulator tube still be used?]

It is obviously damaged and cannot be used anymore.

A forward measurement of 0.64V is normal, but a reverse measurement of 0.25V is abnormal.

Gen_X

maychang posted on 2023-8-11 09:41 [Can I ask if this voltage regulator tube can still be used?] It is obviously damaged and can no longer be used. 0.64V measured in the forward direction is normal, and 0.25V measured in the reverse direction is abnormal...

The multimeter cannot measure the reverse direction! Or the meter has a weak response

chunyang

No matter what kind of multimeter you use, the 12V Zener tube cannot be reversely broken down, which means the Zener tube is broken.

shuangchafeng

12V Zener diode, reverse voltage: Vf1=0.25V, this Zener diode cannot be used.

led2015

According to this measurement result, the Zener diode may be damaged and unsuitable for normal use. You may need to replace it with a new one to ensure the normal voltage regulation function of the circuit.

kal9623287

led2015 posted on 2023-8-12 13:30 According to this measurement result, the voltage regulator tube may be damaged and not suitable for normal use. You can replace it with a new voltage regulator tube to ensure the normal voltage regulation function of the circuit...

Under normal circumstances, how big should the forward voltage be from positive to negative?
How big should the reverse voltage be?

maychang

kal9623287 posted on 2023-8-15 15:07 Under normal circumstances, how big should the forward voltage be from positive to negative? How big is the reverse voltage?

[Under normal circumstances, how big should the forward voltage be from positive to negative? ]

Under normal circumstances, the forward voltage drop of the Zener diode is the same as the forward voltage drop of an ordinary diode, which is about 0.7V.

maychang

kal9623287 posted on 2023-8-15 15:07 Under normal circumstances, how big should the forward voltage be from positive to negative? How big is the reverse voltage?

[How big is the reverse voltage? ]

The internal battery of a general digital multimeter cannot measure the reverse voltage of a voltage regulator tube. The voltage of some special voltage regulator tubes can be as low as 2.7V, which can be measured by some models of digital multimeters.

maychang

kal9623287 posted on 2023-8-15 15:07 Under normal circumstances, how big should the forward voltage be from positive to negative? How big is the reverse voltage?

You have already stated in your first post that it is a 12V voltage regulator. The breakdown voltage of a 12V voltage regulator should be around 12V. This voltage cannot be measured by any multimeter.

lanhua

"Measured with a multimeter, forward voltage: Vf=0.64V (positive to negative pole), reverse voltage: Vf1=0.25V"

I wonder how you measured it?

kal9623287

lanhua posted on 2023-9-17 22:25 "Measured with a multimeter, forward voltage: Vf=0.64V (positive to negative pole), reverse voltage: Vf1=0.25V" I wonder how you measured it?

Measured with a multimeter

lanhua

kal9623287 posted on 2023-9-18 13:11 Measured with a three-meter

Which measuring position of the multimeter should I use? Can you draw a diagram? A picture will tell the truth.

beyond_笑谈

Is the voltage of the Zener diode measured with the diode position of the multimeter when it is not working? Or is it measured when it is working?

kal9623287

beyond_笑谈Published on 2024-6-17 19:35 Is the voltage of the Zener diode measured with the diode position of the multimeter when it is not working? Or is it measured when it is working?

How can I measure the voltage value when there is no power?

beyond_笑谈

kal9623287 posted on 2024-6-20 08:22 How can I measure the voltage value when there is no power or work?

Set the multimeter to the diode measurement position and measure the PN junction voltage drop of the diode. A rough method to measure whether the diode/transistor/mosfet/IGBT is damaged when the power is off

风太大了

It must be scrapped, there is no unidirectional conductivity

kal9623287

The wind is too strong. Posted on 2024-7-8 11:15 It must be scrapped. It has no unidirectional conductivity.

How do you judge?

风太大了

The voltage regulator tube is damaged and there is no unidirectional conductivity of the diode