Strange problem with a switching regulator

Kike wrote:
> voltage and it was the same voltage (aprox.) like the input voltage
> (Vin=10V, Vout=9.6V).

Please verify that you are using the proper pins.
I can't tell loking at pic1 - it would be easier if you could use 
different wire colors.

Hey Kike,

at least there is one thing that you have to realize
(but maybe there are two of them ...):

Certainly there´s a "little bit" more resistance,
both at the "power"-lines, as at the eventual additional
measurement laces...

(...and - what surely could be the case - the two circuits
could simply be "a little" different... what could be
surprisingly hard to find out).

Please check that thoroughly.

lasag wrote:
> Please verify that you are using the proper pins.

Dear lasag, did you mean a mix-up of two pins
only at the PCB (and right pinning at the BBoard)?

Homo Habilis wrote:
> lasag wrote:
>> Please verify that you are using the proper pins.
>
> Dear lasag, did you mean a mix-up of two pins
> only at the PCB (and right pinning at the BBoard)?
Yep.  Also, I think there is a remark (24V) near the front of the board 
and another (5V) in the depth - which is contrary to OUT-GND-IN (front 
to back) pin order of the regulator if mounted as shown in pic2.

I am unsing the proper pins verify a lot of times...

I figure out that there is a problem with the impedance of the power 
planes:

Pic1 with the yellow board: Z(24V-GND) = 100K. Notice that there is not 
short circuit but the Impedance is very low...
Pic2 without the yellow board and the SW regulator mounted directly on 
the PCB: Z(24V-GND) = 200Ohm.

I guess that there is design failure anyway,  but I would like to know 
if there is anyway to increase the plane impedance to solve this problem 
momentarily and go on with other tests...

thanks in advance.

Kike wrote:
> I am unsing the proper pins verify a lot of times...

I have no other explanation for the reported symptoms(*). Limiting the 
current from the power supply, it should be no problem to mount the 
regulator rotated by 180° - just to be shure.

Without an actual schematic and PCB layout, it is impossible to give you 
any other hint.

(*) variable input resistance by mouning the correct pins either by wire 
or directly would indicate a failure whithin the socket/board soldering.

The SW regulator was mounted in the wrong way on the PCB and there was a 
mess because that....Begginer failure :-( Now it works perfectly :-)

Greetings!!