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resistance short ckted but only in one direction (multimeter)? is this possible?

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haroon_tech

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hi,
i done programmer ckt(made it on GP board) ..in that ckt one end of resistance and zener diode's negative terminal are shorted and given to controller and positive terminal of zener is grounded, other end of resistance going to db9's pin4 ....
while testing the resistance with multimeter....i got resistance is shorted(it is beaping(sound)) ,
then if change polarity of multimeter probes again i tested , this time resistance is not shorted(means it is not beaping)..............is this normal ..............or resistance is gone(short ckt).......


this testing is done after giving power supply..........
 

It is possible, because when you change the polarity of the zener diode, the current becomes flowing through the diode and acts like a short circuit for your resistance. Therefore no resistance is detected by the multimeter. In fact, you can use this property to test diodes.
 

DMMs force a current and measure a voltage. They assume zero external
current is flowing. Evidently this is not the in-circuit, powered case.
 

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