Gareth Magennis wrote in message
...

"N_Cook" wrote in message
...
2 of this make and type? on power amp heatsink with no other markings
other
than moulded numbers on the black housing, so unlikely to indicate temp
etc.
One marked 23 is n/o , to activate fan but seems rather high click over
temp
(soldering iron activation), temp not actually measured yet.
The other is n/c marked 14, overall cutout
Anyone know how to decode these mould marks assuming they do relate to
temp/type or any other ideas?




IME, thermal switches on Power Amps tend to be around the 60 / 90
ballpark.
i.e. 60degrees C switches on the cooling fan, 90 degrees C shuts down the
amp. Its not an exact science.
Whatever you think is appropriate safety vs reliability probably is.

take your pick:

http://uk.farnell.com/jsp/search/res...Ntk=gensearch_
001&Ntt=thermal+cutout&Ntx=&isGoback=false



Gareth.




If I was designing amps ~ I would only use normaly closed switches as
failure mode is usually o/c or high impedance plus each of these use 2 pairs
of connectors in line back to solder points I would choose fails safe mode.
Fan one tested higher than I would have thought but as usually only used at
low power , will leave unchanged
Fan one cuts in at 68 degree C and out at 45 degree, checked up and down
twice for reduced "hysteresis"
overall cutout one goes o/c at 90 C and s/c at 60 C


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/