On Sat, 07 Jan 2012 15:33:54 -0700, you wrote:

>Good day to all.
>
>I was looking for some cheap mains-powered mini-USB and micro-USB=20
>(5V) power supplies a few months back and purchased some from=20
>eBay.  They've been sitting on the shelf until a few weeks ago.
>
>Upon going to use one of these units for the first time, something=20
>odd caught my eye.  Although the input voltage rating is 100V - 240=20
>Vac, the output voltage was shown as 4.5-9.5 Vdc @ 800mA.  This=20
>seemed odd but I didn't really pay much attention to it.
>
>I ran one of the micro-USB supplies on the cute little Gabotronics=20
>micro-sized DSO / MSO units that I purchased a while back.  Seemed to=20
>work OK for that purpose.
>
>When I went to go play with the Gabotronics unit again, the power=20
>supply was dead.  I didn't have another unit with a micro-USB plug on=20
>it, so I opened the unit up with an eye towards fixing it.
>
>But - I'm not going to bother.
>
>This thing is total piece of excrement.
>
>One each power and small-signal transistors in the front end - and NO=20
>feedback voltage regulation (!!).  It really looks as if this thing=20
>was designed to supply about 4.5V with 100Vac at the input, rising to=20
>about 5V with 120Vac input and getting all the way to about 9.5V with=20
>240Vac input.
>
>In other words, its a fixed ratio power supply with absolutely NO=20
>regulation whatsoever.
>
>Failure was input fusible resistor open and power transistor=20
>shorted.  Didn't even bother to see if the small-signal transistor is OK.
>
>I'll use these things as a source of micro and mini USB power cables=20
>but I'm not going to trust the power supplies to power anything that=20
>I want to keep.
>
>Just thought that I'd put the word out to keep an eye out for these=20
>things.  I can see someone who lives in a 230Vac part of the world=20
>being bit rather badly by the 9V or so output when they were=20
>expecting 5V.  Talk about "Ouch!" !!
>
>dwayne


Sounds similar to this one I took apart recently, except mine had only ONE =
transistor!

http://www.youtube.com/watch?v=3DT88ej64aXUM

--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.