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Troubleshooting: Why the normally closed and normally open pin in my relay is shorted internally?

Paul Saha

Jul 7, 2016
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Jul 7, 2016
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Did I do anything wrong with the relay or is it a manufacturing defect?
I have detected this through multi-meter and it shows internal connectivity between the pins.
 

Harald Kapp

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Nov 17, 2011
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Both possibilities exist.
You'll have to open the relay and inspect the contacts to find out why they are shorted.

Does the short dissappear when you knock hard against the relay body?
Are you sure to measure between the right pins?
 

Minder

Apr 24, 2015
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Another is if the relay has been used and the N.O. has welded to the common, this then shorts all three contacts.
M.
edit: make that N.O.
 
Last edited:

hevans1944

Hop - AC8NS
Jun 21, 2012
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The N.O and N.C. contacts are normally physically separated by an air-gap with the movable common contact in between. To have continuity between a pair of N.O. and N.C. contacts requires that both the N.O. contact and the N.C. contact be "welded" to the common contact across the air gap! That condition is likely to be fairly obvious upon inspection of the relay, and there is probably no way to "fix" it. However, I suspect you are not measuring what you think you are measuring. Try measuring again with another relay of the same type and report back here with the results. Also, a model number and a pin-out of the suspect relay would help us identify what appears to be wrong. Show us these and explain which pins you are using to measure continuity between.
 
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