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Repairing Cordless Phone

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I'm using a Panasonic Phone. I used an ordinary/un authorised for it . The adaptor by fault, somehow have the output as reverse of Mains voltage (AC) so the system is not working now. I think only the transmitter is gone. I'm not sure about what inside is burnt. Please tell me the possibility of repairing this system. Also tell me what wrong could have happened. And how to check for falls inside the system.
 

DerStrom8

Super Moderator
Yeah, it's a bit hard to follow, but I think I get the gist.

When you say "I used an ordinary/un authorized for it", I assume you left out the word "adapter".

Some adapters are set up with different polarity on the tip--the outside is usually negative and the center positive, but that is not always the case. Sometimes it's reversed, and if you connect the wrong one to the device, depending on the internal circuitry, it can cause serious problems. This is why you NEVER mix adapters, and make sure the one you're using has the same polarity and voltage output as what the device needs. Don't ever assume that just because the adapter fits that it'll be okay to use. This is rarely the case.

To answer your question, I doubt there's really much you can do to fix it. Open it up and see if there's anything obvious, but chances are you won't be able to find everything that's been destroyed. I'd suggest you just buy a new one, and DON'T plug it in with the wrong adapter!

Regards,
Matt
 
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Yeah, it's a bit hard to follow, but I think I get the gist.

When you say "I used an ordinary/un authorized for it", I assume you left out the word "adapter".

Some adapters are set up with different polarity on the tip--the outside is usually negative and the center positive, but that is not always the case. Sometimes it's reversed, and if you connect the wrong one to the device, depending on the internal circuitry, it can cause serious problems. This is why you NEVER mix adapters, and make sure the one you're using has the same polarity and voltage output as what the device needs. Don't ever assume that just because the adapter fits that it'll be okay to use. This is rarely the case.

To answer your question, I doubt there's really much you can do to fix it. Open it up and see if there's anything obvious, but chances are you won't be able to find everything that's been destroyed. I'd suggest you just buy a new one, and DON'T plug it in with the wrong adapter!

Regards,
Matt
Hi DerStrom, I used a proper polarity adapter, but it was a different make. Everything was alright and i used it for few months. But, all of i sudden the device stopped working. I felt that the adapter was gone, so i checked the output voltage. While doing so, i felt the shock and my multimeter revealed it through readings. The polarity of the mains voltage was reverse to that of the normal 5V polarity. I tried with another wall wart and found the device/transmitter not working.

I think all the ICs and those stuffs inside could have been damaged. I think i have no way to fix it myself. Yet, i want to know how these technicians find the faults or solve these type of issues.
 

alec_t

Well-Known Member
Most Helpful Member
so i checked the output voltage. While doing so, i felt the shock
So the adapter had failed with mains voltage getting through to the output. At least you are still alive to tell the tale, but the phone will have died a horrible death :).
i want to know how these technicians find the faults or solve these type of issues
They wouldn't bother. The cost of labour to fix it would be much more than the cost of a new phone.
 

dr pepper

Well-Known Member
Most Helpful Member
See if it has a protection diode on the dc input, usually accross the supply, if its gone short the phone will have no power, if thats ok then look at the voltage reg if it has one, if thats ok then maybe its a bin job.

Edit: you want to know how a technician would know it had been reverse polaritied, well after powering up if the polarity diode was short that'd be a sure sign, or if the volatge reg was toast thats another indicator, if neither of those 2 show then its a little more difficult to be sure, esp with a cordless phone as these tend to be sinsitive to things like lightening strikes, the repair shop I worked at had loads of them come in every time there was storm.
 
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