Hi,

I've got a 120V switching power supply that produces 12 and 5 Vdc outputs
that I've been using for the last couple of years to power a digital piano
after the original quit.  It is salvaged out of an old piece of equipment
somewhere.  The 12 V goes to the piano and the 5V goes to an LED to tell me
the main power supply is on.  It stays on all the time and the piano has
it's own power switch.

I noticed the other day that the LED was pulsing and the supply was making a
clicking sound at the same time of the pulses, at about 3 Hz.    The 12 V
supply output was fluctuating wildly with no load.  When I loaded the supply
with 200 mA current everything settled down with 11.5 V output and the LED
stopped pulsing.  I don't remember that the supply was doing this pulsating
under no-load originally when I started using it 2-3 years ago.  It's got me
concerned that something is not working right.

Could this be a sign that the power supply is starting to break down?  Is
the clicking sound from the transformer?

Suggestions?

Gordon Williams



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