Wall-wart Repair

Friday, July 4, 2014

Wall-wart Repair

Yes, I know it's a waste of time and I could have bought a new one for the price of a couple of cups of coffee - but it was very satisfying.

We have one audio device at our house which has become a major part of how we enjoy television.  It's portable and depends on an occasional re-charge using a 5V wall-wart.

These things fail - and re-charging becomes a problem.  We have had failures in two modes:  as the result of a lightning strike and because the cable failed. 

It was pretty obvious that the lightning strike victim was toast as it was blown to bits.  The other failure took us a while to notice as the LED charge indicator is not readily visible in normal use.  We finally figured out that the charging was intermittent and a few simple experiments identified the culprit as the cable.

We ordered a new one and it occurred to me that if I could repair the broken one, we could have a spare.

I know that even if I value my time at half the minimum wage, I would be wasting money in trying the repair, but I like to fix things.  To quote my friend and co-worker Murel:

Use it up

wear it out

make it do -

or do without.

The first thing was to open it up (and make sure it wasn't toast).  The tools I used are in the first photo and the 'technique' (if you will allow me to characterize hitting something with a hammer as a 'technique') is in the second.  This was easier than expected:

Inside was what appeared to be a fairly nice regulator - and as you can see below, it was still working! 
 



 

I note here that I did not try to reuse the cable.  I have the advantage of being near a Goodwill Computer Store and cables with the appropriate connector are about 50 cents - in the USB to mini-DIN style.




Here I have re-connected the new cable.  What might appear to be a solder blob at the end of the cable is actually a bit of aluminum foil shielding that I finished removing after I noticed it in the photo:



 

Then I glued it back together.  You can see the unused USB cable end which I used when I mixed the epoxy.

Sure enough, about a week after I got the 'spare' working, we had another failure.  The spare will allow us to continue until we can visit someplace large enough to buy another replacement.

20-20 hindsight:  I should have bought a longer cable - and I should have bought more than one while I was there!

cln - Nick
WB5BKL