N Cook wrote in message
...
Only 2.5 Kg weight and 10x6x 2.5 inches, 70W, probably made 2005
Probably yet another victim of Chinese made lead-free junk solder assembly
as it loses one channel intermittently.
Anyone familiar with these sort of tiny compact units ? any pitfalls ?as
its
the first of this type of miniature kit I've dealt with.
Not possible to play around with it without disassembling as, all wrapped
inside one another.
Marked all the bits of celluloid and sub-assemblies before disassembling.
No obvious solder problems or wobbly bits under illuminated mag glass.
The power board with 2 fans is confusing because what looks like 2 channel
power amp farthest from the mains inlet filter chokes is a very
distributed
SMPS, split into 2, especially with a thermistor on a vaned heatsink with
a
7 pin TO220 device either side, that look like TDA... monolithic audio o/p
blocks.
But those devices are TOP249YN smps drivers.
The compact lump nearest the mains inlet, that looks like a compact SMPS,
contains 4 TO220 devices , 2 being ST P14NF12FP 120V 14A mosfets and
presumably 2 matching , shrouded unseen, complements , whetever they are -
you'd think it would be easy on the ST site to find this basic info.
Any advice before replugging everything spread out on the bench and then
powering up on Monday with a twiddle stick.
--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/
Running it at 50% mains but as smps I don't suppose it makes much difference
with no load.
Located down to one of the power amps, permanent out rather than
intermittant now, nothing found twizzling. Visually they look the same but
one has a different heatsink. Both have indirect edge connector pairs . It
would be nice to swap them over because the duff one is not very accessible
without making a pair of extenders, but probably not advisable.
With maybe 250KHz on these amps in operation I'm loathe to put a scope
around the mosfets and will try and diagnose cold.
Does anyone know where there is a primer on how to deal with these
new-fangled sort of amps as far as repair/diagnosis is concerned.
Running it at 50% mains but as smps I don't suppose it makes much difference
with no load.
Located down to one of the power amps, permanent out rather than
intermittant now, nothing found twizzling. Visually they look the same but
one has a different heatsink. Both have indirect edge connector pairs . It
would be nice to swap them over because the duff one is not very accessible
without making a pair of extenders, but probably not advisable.
With maybe 250KHz on these amps in operation I'm loathe to put a scope
around the mosfets and will try and diagnose cold.
Does anyone know where there is a primer on how to deal with these
new-fangled sort of amps as far as repair/diagnosis is concerned.
--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/