Hi

I am hoping someone might be able to give me some pointers to look for...

I designed an audio and PSU board for client some time ago. The first two b=
uild batches worked fine but the third build has about a 50% failure rate, =
and I have them all here to try and find a fix :( The failure is SMPSU nois=
e on the audio. The noise mostly disappears if I push on the board with a s=
mall wooden stick on or under one of the regulators, either the LT1617 or t=
he LM2676. Since the first two batches were fine, I am currently assuming t=
hat the PCB or the assembly is at fault in some way but I can not see where=
..

Has anyone had anything similar and found a solution?=20

Thanks

Veronica
 =20
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