[mythtv-users] HDPVR problems - power supply again?

[Stephen Worthington]

On Tue, 13 Aug 2019 20:39:24 -0700, you wrote:


>>   Has anyone ever hooked up an ammeter to see what the HDPVR actually
>> draws?  I
>> wonder if it is close to the 2 AMP rating of the PS, so just stresses it
>> out,
>> causing earlier failures.
>>
>
>I had the same thought last time mine crapped out. Instead of doing the
>science as you propose, I replaced with an over capacity wall wart (3-4A I
>think) and that's the one that just failed.
>
>I don't know enough about PS electronics to say if anything other than
>over-drawing current could stress the PS.
>
>It also makes me worry about getting power from the USB of the Myth box.
>It's one thing to kill a $15 wall wart and another to kill a $100 PC power
>supply.

PC power supplies are usually very robust, and typically are running
well below their rated capacity.  If you buy expensive ones, they
usually have a list of the protections they provide (over voltage,
over current and so on).  USB ports have limits in their circuits to
prevent anything from drawing too much power - that is part of the USB
standard.  So the real problem with using a PC power supply only comes
if you connect the HDPVR to a standard power connector (ether Molex or
SATA) and do not have any current limiting in the connection you use
(such as a properly rated fuse or circuit breaker).  The PC power
supply can then supply a great many amps into the HDPVR, and if the
HDPVR has a fault that draws huge current, that can cause a fire.