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Cobra 25 LTD : Dead Channel LED after attempted replacement.

Posted: Friday 20th Feb 2009, 15:48
by fsjonsey
Radio Make and Model: Cobra 25 LTD Classic
Test gear available: Multimeter, VTVM, Heathkit Oscilloscope
Symptoms:
I attempted to replace the channel display LED in a Cobra 25 that had a few blown segments to the stock LED. After replacement, the channel LED no longer lights. A few segments of the second display digit now light intermittently. I installed the display with the part number facing down, as the original was. Is it possible that it is installed upside down? This radio was built in 2005. Any help would be greatly appreciated.

Re: Cobra 25 LTD : Dead Channel LED after attempted replacement.

Posted: Monday 23rd Feb 2009, 7:09
by The Defpom
Have a look fr a decimal indicator on the displays, and see f that will tell you if they are both the same way up, the part marking is not always on the same edge.

If you have a multimeter with a diode test function you can use that to probe the pins, and you will see that it makes some segments light up when you go between the common pin and the segment pin, you can use that to compare the displays, the test leads should be the same way around for both displays, otherwise you could have a common anode vs common cathode type.

Re: Cobra 25 LTD : Dead Channel LED after attempted replacement.

Posted: Monday 23rd Feb 2009, 10:54
by fsjonsey
Thanks Defpom, I appreciate the help. I'll check the display segments tonight.