Posted by Mike S. on 12/21/05 20:21

In article <MKqdnXhvD4DrKjXeRVn-rA@comcast.com>,
Non-entity <none@nowhere.net> wrote:
>Probably a stupid question, but not long ago I bought a Philips PET-1000
>portable DVD player. Nice picture, a few shortcomings. The question is,
>what causes the cabinet to get very warm toward the right side of the unit?
>
>I have two "home" DVD players, one old Sony and one of recent vintage, and
>thinking on it, their cabinets get quite warm. I always figured that it was
>because of the internal power supplies, but the portable has an external AC
>power supply that steps down to 9 vdc. The cabinet on the portable gets far
>warmer in a few places than the small external AC step-down unit.
>
>CD players I've had generated little to no perceptible heat, other than what
>I'd attribute to the internal power supplies. Then to make things a bit
>more puzzling, the DVD drives on my computer seem to get barely warm. What
>creates the heat in the home and portable DVD players? I do realize the
>flourescent tube on the right side of the screen of the portable makes the
>flip-up lid warm, but still not so warm as the chassis makes the bottom part
>of the unit. I've tried to search for answers on the internet and just see
>mentions that "this DVD player generates a lot of heat" but never see what
>component(s) is (are) the culprit(s). No wonder portable DVD players need
>hefty battery packs! I have noticed that when playing a DVD on the computer
>the motor seems to "spin" much faster (sounds like a fan) and the DVD
>probably requires a higher precision, higher power "laser" - but I really
>don't know any of this, just guesses.

It's probably the MPEG decoder chip and digital-to-analog converter
circuits. The MPEG decoding takes a considerable amount of computing
horsepower and that generates heat. On some players you will find heat
sinks attached to those very chips.

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