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- Phil Allison
May 17, 2017, 4:18 am
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Re: Ping Trevor Wilson
** New Sanyo STK083Gs are now installed and working fine.
The old, blown modules were an STK080G and an STK084G - the latter having i
ts white markings obliterated. I cut them both open for a look revealing al
l the chips inside. The output devices in the 080G are puny, similar to TIP
34s while the ones in the 084s are larger, more like 2N3055 ones.
But this is not the problem.
The problem is that there is simply NO current limiting at all - making the
modules fail instantly if there is a short on the speaker line.
ALSO there is a thin, phenolic PCB *between* the thick copper headers used
for the output devices and the alloy heatsink on the back of each module. T
he temperature drop across this would be many times that of the usual mica
or silicone insulators.
PLUS there are no emitter ballast resistors employed at all - making the ou
tput stage prone to thermal runaway.
I intend to write a stern warning to the owner to be VERY careful with the
speaker wiring from this unit and to NEVER use 4 ohm speakers.
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