Edwards 5520 Horn/Klaxon Repair - Page 1
Forum section: electronics / repair

author: sonnytiger
author_rank: Frequent Contributor
timestamp: November 11, 2017, 04:55:56 pm
content: I got this cool thing in a lot with a bunch of other stuff, and much to my disappointment nothing happened when I applied 24V DC to the power terminals.I started checking a bunch of stuff, bypassing the plug and applying power to the circuit board, I checked resistors transistors and capacitors and the horn itself with everything coming back fine. The worst part is that it draws zero current and I can't find a fuse anywhere. I need help!I will include some pictures.https://imgur.com/gallery/zNmoOI also have a video I will link to.https://youtu.be/AJz-M5TY-50

author: Gregg
author_rank: Super Contributor
timestamp: November 11, 2017, 06:02:44 pm
content: Those Edwards sirens sure are expensive; but they look well built. From my experience with cheaper home alarm sirens; often the voice coil is the first to die. From your pictures, it looks like an orange wire has been pinched rather hard. That large blue cap looks a little dodgy like somebody added it.

author: sonnytiger
author_rank: Frequent Contributor
timestamp: November 11, 2017, 06:23:06 pm
content: I checked that cap and it has the rated capacitance, no break in the orange wire, and the voice coil has a resistance of 6 ohms, a reasonable value.Yeah I imagine it would have been a couple hundred new, it is really nicely made a big reason why I want it to live.Thanks for the suggestions, need more!

author: Armadillo
author_rank: Super Contributor
timestamp: November 11, 2017, 06:29:15 pm
content: Nice Cat in the videoPower up the transformer and then measure "AC voltage" from the secondary side, best without any load [wires disconnected], then you effectively isolate one part of it from the troubleshooting equation.

author: sonnytiger
author_rank: Frequent Contributor
timestamp: November 11, 2017, 09:37:50 pm
content: Yes he likes to make am appearance in most videos.The transformer is an output transformer for the speaker and it's windings measure a reasonable value.

author: Cyberdragon
author_rank: Super Contributor
timestamp: November 11, 2017, 10:40:09 pm
content: Possibly a stupid question, but are you sure it's 24V? The 5520 is sold in several different models based on a letter code. What's the letter code on your unit? Since it didn't go bang, it's probably not the AS model (12V).

author: sonnytiger
author_rank: Frequent Contributor
timestamp: November 12, 2017, 12:48:03 am
content: It's the 24V AC/DC model. I wish it was a simple fix

author: Cyberdragon
author_rank: Super Contributor
timestamp: November 12, 2017, 01:07:09 am
content: Well, if you checked all the components, the only thing left is a bad solder joint or a wire with a break in it.

author: sonnytiger
author_rank: Frequent Contributor
timestamp: November 12, 2017, 04:54:11 pm
content: I tested all the wires and inspected all the solder joints, everything checks out. I suppose I should test all the resistors now? Running out of optionsEdit: I believe I have found the problem, there is chunky resistor in series with the input that is measuring ~2.5 M ohm when it should be 1 ohm. Score.

author: sonnytiger
author_rank: Frequent Contributor
timestamp: November 12, 2017, 05:20:51 pm
content: Yep that fixed it, 50 m of 18 awg sufficed as a 1 ohm resistor for testing. Thanks for all the suggestions guys.Have a good one!