"Gareth Magennis"

Mark, I have seen lots of these TDA powered speakers, mostly studio
monitors, with the "conductive glue" problem.

At the risk of repeating myself, have a good look at the PCB, particularly
between the pins of the TDA ICs. If there is any kind of chemical
coating, yellow or black, then this really is very likely to be your
problem.
It starts off as component adhesive, but over time melts and runs
everywhere, eventually becoming brittle and conductive, causing erratic
and illogical behaviour.

** The yellow glue problem is at least 30 years old.

Roland " Cube " series amps had problems with it and they were made in
Japan.

VCRs had problems it in spades as do many SMPS too.

Class D amps used in high end line array boxes made by dB Technologies have
it splashed about.

The stuff does NOT melt and move around, it simply goes dark with heat and
time and becomes conductive and corrosive to copper and tin.

Long as it has no contact with metal, it hardly matters.

Now, the colossally stupid Chinese spread it about on PCBs like jam on
toast.

They have the exact same philosophy on these matters as Alfred E. Neuman.

http://mikophoto.net/wordpress/wp-co...-E.-Neuman.jpg




.... Phil