Repair and disassembly guides for Uniden phones.

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Why when I want to make a call the telephone line stops?

After a ligthing storm, when I want to make a call the telephone line works, but when telephone is calling, the telephone line is off and I can't use any other device.

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Hi, What have you got connected to the telephone line? Do you have the incoming telephone line (from the street) connected into an ADSL2+ splitter with one output going to a modem router for your internet service and the other output going to the phone? If not what do you mean by 'can't use any other device'?

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Thanks for attending. I have got connected several telephone devices each one with an ADSL splitter. When I plug the Uniden phone, the telephone line is off, and then is when I can't use any of the other devices. So, I have to unplug the Uniden phone, and with this action the telephone line Works again. I think the Uniden phone suffered damage during the lighting storm. It is posible to fix the device?

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The lightning storm may have shorted out your phone. Lightning can cause strong transient voltages on phone lines, and these may cause electronic components in modern phones to fail. Often, electronic components fail short-circuit. The bottom line is, when you plug in a phone with this type of damage, the line effectively goes dead.

Ironically, it is not unlikely that the failed component is the transient protector. These are components that protect the phone's electronics from excessive voltages. When the voltage on the phone line rises above a certain threshold, this component behaves as a short circuit and dissipates the transient thereby protecting the phone's circuitry. Once the transient is gone, the component should then return to its passive state just sitting there waiting until another transient comes along. But sometimes the transient is strong enough to destroy the transient protector, which will then remain in its short-circuited state having valiantly sacrificed itself in order to do its job. If the phone does indeed have a transient protector (not all phones do) chances are that this is what happened, and it's an easy repair. Just removing the failed transient protector will get your phone working again, but replacing it is better - if you leave it out the next lightning strike might destroy your phone.

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Thanks. Very useful response. After this, I disassembled the device, but now I don't know where is transient protector, in order to remove it and replace it. It will be posible that you can show where is it placed? Tanks again.

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@Fernand Perez: if you are not really practical in electronics repair, you should enlist the help of someone who is. For this repair, you'd need at least a multimeter and a soldering iron.

First you'd need to check if my guess is correct: connect the multimeter directly across the line terminals of the phone to see whether they are indeed shorted. If so, you can proceed to try and locate the offending part.

If you can, post detailed pics of the phone's innards.

Depending on the way your phone is built, you'd look for a part that presents as a small black plastic cylindrical object, about 1/4" long, 0.1" dia with two leads sticking out, connected directly across the line terminals. In modern surface-mount electronics the part may look like a small rectangular black box of about the same dimensions.

When you locate such a part, use the multimeter to check if it is indeed connected across the line. If so, you use the soldering iron to carefully remove the part, and then check if the line is still shorted.

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Fernand Peretz will be eternally grateful.
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