"Gareth Magennis" wrote in
:



"Phil Allison" wrote in message
...

** I had hoped that the dreaded Yellow Glue peril had gone away - but
it is still with us.

Most of you will have seen it holding parts down to PCBs on Asian
made equipment and many of those will have seen what happens if the
parts involved get hot.

The example on my bench is the SMPS from an Alesis powered monitor (
M1 Active, Chinese made) ) which has blown up big time because of the
damn Yellow Glue used to secure a ferrite toroidal coil. All the
glue used had gone brown or back ( ie carbonised ) on this coil and
arced across nearby tracks taking out the main switching MOSFET, its
drive IC and associated transistors, high speed diodes and even the
AC bridge rectifier diodes.

The toroidal coil had to be un-wound, cleaned up and re-wound. The
same glue was attacking parts elsewhere on the board too ( it
corrodes copper) and had to be laboriously scraped off.

Are the dickheads who squirt this horrible goop all over PCBs NEVER
going to wake up ??



..... Phil


the manufacturers probably don't get the products back(due to their age)
for failure analysis,and thus are unaware it happens.
No "closed-loop action process".

OR,it's planned "obsolesence".
or both. ;-)




I had an M1 with exactly the same problem. Conductive gak all over
the place, very messy, but fortunately didn't blow anything up.



Gareth.





--
Jim Yanik
jyanik
at
localnet
dot com