Trafo secondaries suddenly...die?

[sethinspain]

Hey everyone,

In the middle of a DIY pre (green pre ::thumbs up:: ) and I'm testing voltages with my 15-0-15 trafo to make sure the PSU is ready to plug into the pre.

I have been testing it for a bit working with the voltages for a couple weeks when suddenly, as of last night, I switch it on and I read 0 volts across the secondary pins.

Across the primary pins I read 227v (Spain) like I should, but secondaries read 0.  I tested continuity between the secondary pins (3 & 4, 1 & 2) and I read 0 ohms, so I don't think the trafo is busted.  I've got the mains running through a switch to a fuse before the trafo - switched out the fuse just for good measure.  I have NO idea what to do. 

The trafo works but reads no volts, yet I read input voltage on the primary side, what gives?!

Any help would be much appreciated.  So close yet so far.... :-\

Seth

:: EDIT ::

Tested secondary voltages on pins 5 & 6, 7 & 8.  Primaries are pins 1 & 2, 3 & 4.  Link to trafo and datasheet are here as well as 2 posts down:

http://www.mouser.com/ProductDetail/Triad-Magnetics/FP30-400/?qs=71qcunE5gONSODXqnt1RVw%3d%3d

 

[12volts]

Is your meter OK? Use a Led and resistor to check your circuit board has power.

Frank B.

 

[sethinspain]

I assume the meter is good because it measures the AC fine, but it's nothing special.  Cheapo meter to get started with (7 euros).  I changed the batteries as well just to find out.  How do I use a LED and resistor to check power on the board (I'm a newbie)?  Solder the resistor to the LED and touch it around?  Any specific value of resistor?

Thanks for the help Frank!

Seth

 

[s2udio]

The trafo works but reads no volts,

??

Sorry thats not a logical statement ?


Whats the primary read ,open circuit or low ohms, ?
Many trafos have a thermal fuse in the primary windings which go OC on prolonged overcurrent use

 

[sethinspain]

The primaries read 0/low ohms between pins 1 & 2, and pins 3 & 4.  Secondaries as well ( pin 5 & 6, 7 & 8).

Here's the trafo page on mouser with the datasheet available.

http://www.mouser.com/ProductDetail/Triad-Magnetics/FP30-400/?qs=71qcunE5gONSODXqnt1RVw%3d%3d

I would be surprised as to how I could have exposed it to too high of current for too long.  I have only hooked up the PSU and only a few times did I hook up the pre as well to test voltages on the IC's.  However, I never tried to measure current, and the PSU is reading -25 instead of -15 which is what it SHOULD read (this was what I was testing to see if I had fixed it or not).

Thanks again for your help!
Seth