LCD Monitor problem

[Arfa Daily]

Doesn't it have to do with higher stray inductance (more inductance, less
high-frequency shunt capability)? SMD parts are usually the only usable
kind
of part in sensitive equipment, like PWM amplifiers.

That's certainly a possibility. The servo data strippers and loops, are
quite sensitive bits of circuitry in CD players, and these caps are glued
straight on the end of pins on the servo processor chip, so they may well be
decouplers or timing caps.

Arfa

 

[Wiebe Cazemier]

That's certainly a possibility. The servo data strippers and loops, are
quite sensitive bits of circuitry in CD players, and these caps are glued
straight on the end of pins on the servo processor chip, so they may well be
decouplers or timing caps.

Arfa

I would hope that all timing is done with a clock pulse, based on a crystal.
Caps used for timings yield very unstable circuits, at least where high
frequencies are concerned, such as FM transmitters.

 

[Arfa Daily]

I would hope that all timing is done with a clock pulse, based on a
crystal.
Caps used for timings yield very unstable circuits, at least where high
frequencies are concerned, such as FM transmitters.

Yes, but this is not an FM transmitter ... The servo processor chips used in
CD players are a hybrid mix of digital and analogue circuitry. There are
analogue servo loops to control focus, tracking, disc rotational speed and
laser output power, as well as accurately defined reference voltages for
such things as the data slicer, and temperature tracking and compensation.
In common with most hybrid loops, although they may be controlled digitally,
with a clock derived from a crystal source as you surmise (and hope!), they
will still have analogue filtering in the loop feedback, formed from C and
R. If the time constant of these is not correct within a relatively small
range - as may be the case if the filter capacitor is no longer to spec -
then failure of the servo loop to lock reliably, is the likely outcome.

Arfa