P
Phil Bowser
Have two of these on the bench with same problem... blown STA505 output
ICs (surface-mounted...pretty cheesy....) and driver IC's. Power supplies
are so poorly designed on these units, they destroy themselves immediately
if you try to run them with the amp board unplugged (insufficient load).
More nasty is that after replacing all output ICs and drivers (all smd!)
They short again immediately whether or not there are speakers connected at
turn-on. I am now thinking that the power supplies are responsible for an
over-voltage condition at turn-on, and am working on a way to test the
supply under load without the amp board connected, and also a way to supply
the amp board slowly with a variable DC supply to the output ICs to
determine why exactly these turds are the fastest and most efficient
voltage-to-smoke converters I've ever seen!
(And I used to work on the Pioneers with their built-in 'blow drive"
feature that was supposed to be designed to blow the main fuse in the event
of a power supply problem, because those units lacked a relay...what it in
fact did was short everything, THEN blow the fuse...real piece of
engineering marvel they were........looks like RCA has followed suit)
ICs (surface-mounted...pretty cheesy....) and driver IC's. Power supplies
are so poorly designed on these units, they destroy themselves immediately
if you try to run them with the amp board unplugged (insufficient load).
More nasty is that after replacing all output ICs and drivers (all smd!)
They short again immediately whether or not there are speakers connected at
turn-on. I am now thinking that the power supplies are responsible for an
over-voltage condition at turn-on, and am working on a way to test the
supply under load without the amp board connected, and also a way to supply
the amp board slowly with a variable DC supply to the output ICs to
determine why exactly these turds are the fastest and most efficient
voltage-to-smoke converters I've ever seen!
(And I used to work on the Pioneers with their built-in 'blow drive"
feature that was supposed to be designed to blow the main fuse in the event
of a power supply problem, because those units lacked a relay...what it in
fact did was short everything, THEN blow the fuse...real piece of
engineering marvel they were........looks like RCA has followed suit)
