[mythtv-users] PVR-150 quality problems
Saul A. Peebsen
jaglover at gmail.com
Sun Dec 2 21:52:53 UTC 2012
On Sun, 2 Dec 2012 13:03:26 -0800
Gary Buhrmaster <gary.buhrmaster at gmail.com> wrote:
> On Sun, Dec 2, 2012 at 9:02 AM, George Mari
> <george_mythusers at mari1938.org> wrote:
> ....
> > The PVR-150/25/350/500 are of an age where many of them may be
> > suffering from leaking capacitors.
>
> Not only can (older) caps leak, analogue devices can slowly, over
> time, be impacted by component value changes that are due to
> heat. In the (really) old days, it was not unknown for the old
> analogue TVs to have problems on really hot days as the component
> values changed just enough to be out of range. This was a short term
> issue (open the window, use a fan, etc.). But there are also long
> term value changes due to heat (and the old TVs were really really
> hot with their tubes and PS resistors), and eventually the components
> were always too far out of acceptable ranges. Some PVR-xxx boards
> experience both those short and long term issues, resulting in poor
> lock/decode, since they can end up inside PC cases that are hot, and
> under-ventilated.
>
> To see if it is a heat issue that you might be able to (short term)
> mitigate against, open the case, and use a fan to blow a lot of air
> onto the PVR-xxx board to cool it, and see if the symptoms change.
>
> The likely long term solution is to replace the board, but if you like
> tinkering (and your time is free), testing and replacing all the
> analogue components that are out of spec (including the caps) can be
> interesting.
This was real problem with germanium based components, silicon is much
better.
--
Cheers, Saul
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