You better check for loose connection or cold solder joint,Unfortunately,
the solder connection alone is often used to make both the electronic
as well as the mechanical connections. Solder is made up of 60% lead
and 40% tin, so it can not be expected to do the mechanical job for
long. Designing larger circuit board traces does help to increase the
surface area as well as strengthen the pad and the trace leading to it.
To minimize stress to the soldered connections, physically heavy
components — as well as all frequently used switches and connectors —
should first be mechanically secured to the PCB.
Figure 1
has been magnified and enhanced to show four solder pads that have
potentially cold joints. Counter-clockwise from lower right, the
initial problem isn't so easy to spot, just a slightly "grey" or
frosted joint, with each counter-clockwise joint getting progressively
worse. This is what ultimately happens when a little pressure is
applied over and over again via both mechanical stress and repeated
heating and cooling cycles. This would be the case in any studio and
especially on the road. Once in this state, the connector could easily
be removed from the circuit board with little effort, without
soldering. Sometimes the solder connection holds up, but the junction
of the PCB trace and the PCB pad will break.