Hurricane Harvey Flooded Circuit Board Repairs Ideas???

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rockhtown

Joined Sep 24, 2019
1
Hello,

we have about 300 analog cordless telephones that have everything working on them except the ring when calling the phone. I am thinking it is a small component that needs to be replaced or it is corrosion that is blocking the connection. I am hoping someone can help me figure out where on this phone the defect is coming from. We tested the ringer and it works but when you call the phone it wont ring. All other features work just fine. If it is a component you see that needs to be replaced let me know a site it can be purchased if known. See photos
Thanks so much.
 

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dl324

Joined Mar 30, 2015
9,122
Welcome to AAC!

Trace the ring signal on a phone that should be ringing and determine where it's getting blocked.
 

shortbus

Joined Sep 30, 2009
7,073
Can you take a speaker or what ever is used to make the sound, from a good phone and connect it to a bad one? Doing that would maybe narrow the problem to the speaker or the total circuit.
 

AnalogKid

Joined Aug 1, 2013
8,140
Conductive crud left behind by evaporated flood water could be invisible underneath SMT components and cause various problems. But I don't think the problems would be identical across 300 units. Still, there are other ways this could happen.

If the ringer is a piezo element, then crud left behind by evaporated flood water could alter its characteristics enough to no resonate. Or, the crud is acting as a medium-impedance path and upsetting the driving circuit.

I agree with shortbus - first, find a known-good ringer/speaker/whatever on a known good board, and swap it with the ringer on a bad board. Does the bad board now ring? Does the good board now not ring?

ak
 
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