Distinguishing manufacturer's PCB wash from user spillage?

[n cook]

I'm repairing a 16 channel Mackie 1604 mixing desk.
On a large area of one pcb there is a distinctive scum pattern where a
liquid has dried leaving a dried bubble lattice pattern. I somehow doubt it
could be due to in-service drinks spill, due to where this patterning is,
but is there a way of distinguishing deliberate at-manufacture from in-use ?

 

[Dave Plowman (News)]

I'm repairing a 16 channel Mackie 1604 mixing desk. On a large area of
one pcb there is a distinctive scum pattern where a liquid has dried
leaving a dried bubble lattice pattern. I somehow doubt it could be due
to in-service drinks spill, due to where this patterning is, but is
there a way of distinguishing deliberate at-manufacture from in-use ?

Never underestimate the ability of a sound man to spill drinks absolutely
anywhere. ;-)

 

[Phil]

I'm repairing a 16 channel Mackie 1604 mixing desk.
On a large area of one pcb there is a distinctive scum pattern where a
liquid has dried leaving a dried bubble lattice pattern. I somehow doubt it
could be due to in-service drinks spill, due to where this patterning is,
but is there a way of distinguishing deliberate at-manufacture from in-use ?

Check the obvious - look at the enclosure, there'll be traces....

 

[n cook]

Check the obvious - look at the enclosure, there'll be traces....

No trace on the casing, but I'm surprised this horrible looking mess would
pass final QC or would the appearance have worsened or perhaps only becaome
apparent, over time.

It started with the other pitfall, USA equipment (120 V in very tiny
letters) with a nice Euro socket, used in the UK so inviting a UK standard
mains lead.
About 90 off SM plus 2 SIP 4560 dual amps , 6 off SM 2901 quad comp and
nothing else in the way of ICs strangely.