I'm working on a keypad controller for a garage door opener. My experience is simply as an enthusiast. The signal diode in the middle of the picture (between the BJT and the capacitor), I think is bad. With one end off the board, there is no voltage in either direction through the diode. The weird thing is I cannot find ANYTHING on the internet about this diode. I am 100% sure of these markings. The only markings are BR 52 48. I cant even find any information about the diode much less where to get one. Mouser has a 1N5248BTR Zener, but I don't know enough to know if the "1N" and "T" makes a difference or not, nor if what I think is a signal diode is actually a zener. I would sure appreciate some guidance on what this is or where to get one.

 

Look here: https://datasheet.datasheetarchive.com/originals/scans/Scans-064/DSA2IH00159917.pdf

It's a 1N5248B, a Zener diode.

 

Its an 18V Zener, so to test -

http://www.learningaboutelectronics.com/Articles/How-to-test-a-zener-diode


Regards, Dana.

 

Thank you for the comments. The diode shows +- 8 ohms in both directions. The data sheet is very helpful. Thanks.