smps high pitch click sound once on load

[elor]

i dont have many experience in fixing smps
and would appreciate any kind of lead from you guys
this power supply belongs to my tec controlled camera and supply 12v ,-12v ,5v ,tec and thermistor
it fails under load of the camera making high pitch click noise once
there is another section that connects to the tec deriver (pid-1500 by wavelength electronics with a window comparator ltc1042) 
adding couple of pictures

[kosomsk]

Shalom Change shorted part & try to load repaired psu 

[wasyoungonce]

Look there is not a lot in it.  A main switching fet, a TL431 and anther transistor on the hot and rectifier.  You should be able to check these with a multimeter but be aware the fet will be in series with the primary hot so you may back measure thru the winding. There is a small Tantalum C2 and diode and diode D3 and resistor R2.  Check these especially tantalum's...maybe change on speck.  These usually form an oscillator cct that drives the FET and chops the rectified "tank" voltage on the coil hot side.  The opto feeds back from the cold side.  Oh there is glue or something around R2 can you clean away.

Check the cold side diodes wit ha multimeter again these will be across windings but they will have differing readings one way compared to the other on diode test or low ohms.  Might be also regulators on this side...cannot see  them in the pics.

Also check the electros on the cold side rails.  More than likely the fault is "bad caps"....electros that the ESR has gone high which loads the secondary down causing feedback to turn off the oscillator.   Bad electros in a switchmode is a common fault.  They only way to test them is to use an esr meter or replace on spec with low esr new caps.

If the PSU is older....i'd be doing this as a matter of course.  Oh by the way what camera is it....a TEC cooled astro camera?

[elor]

sure its an old swir camera 320x240
i think ill try to reverse engineer it as i need it to run from dc anyhow
ill try to update this post as i go

12 pin hirose plug

1 -- gnd
2 -- (-12v)
3 -- gnd
4 -- 12v
5 -- gnd
6 -- 5v
7 -- tec +
8 -- tec -
9 -- thermistor -
10 -- thermistor +
11 -- nc
12 -- nc

my bom so far:

lm2937et -- 5v
lm2940ct -- 12v
lm2940t -- tec power ~7v
ptn78000a -- (-12v)
htc-1500/pid-1500
ltc1042
caps, res etc as needed

[kosomsk]

Easier to take the Chines  DC/AC inverterer and use the camera according to the scheme 12V->DC/AC( to ~220)->Camera's PSU.