[mythtv-users] I think my HRHR Prime died...

Daryl McDonald darylangela at gmail.com
Fri Sep 4 12:50:29 UTC 2015


On Fri, Sep 4, 2015 at 8:43 AM, Richard Shaw <hobbes1069 at gmail.com> wrote:

> On Thu, Sep 3, 2015 at 11:07 PM, Stephen Villano <
> stephen.p.villano at gmail.com> wrote:
>
>> OK, let's preface this with, I am a certified electronics technician.
>>
>> OK, a VOM, pretty much *any* VOM will be fooled by ripple.
>> DC power in ancient and familiar for me days of analog circuitry, had
>> mains frequency hum. Most failed to notice, those that did got extra
>> filter caps and occasionally, a massive inductor coil in a pi circuit.
>>
>> Today, we're in the digital age. A 5 volt supply supplies, with luck,
>> 5 volts. What is of import is, sampling rate of the VOM, which is why
>> I previously mentioned an oscilloscope.
>> One can end up with 2.5 volts *real* DC and a full five volts of
>> spikes that result in no useful supply to a logic circuit.
>> At 2.5 volts or so, logic goes into an indeterminate state, which
>> means getting confused,senile and eventually locked of destructive,
>> depending upon the logic usage.
>> I've personally witnessed many hard drive physical failures, courtesy
>> of a lousy 12 volt supply that measured fine with a cheap VOM, but
>> looked like pure DC spikes on an oscilloscope . Later, better VOM's
>> had RMS, which was *really* revealing, as there is no sine wave in DC.
>>
>> Hence, my suggestion at first to try a new power supply.
>> No need for detailed comprehension of two years and change of
>> electronics school, no 40 years of experience and no requirement of
>> more advanced electronic diagnostic equipment that you'd also have a
>> massive learning curve to learn how to utilize.
>> Based upon my experience and many, many, many other users of the HDHR
>> Prime, swap out the power supply.
>> If you're as proficient as I am, replace the defective filter
>> capacitors. I've done that, via measures that'd give my fire marshal a
>> stroke, but the caps got replaced.
>> Assuming that you also own an ESR meter, to find the defective capacitors.
>> Mine is aging, when it fails, I'll go straight to replacement.
>> The cost isn't worthy of the benefit.
>
>
> Thanks for the explanation! I don't have a fancy Fluke meter but it's a
> half-way decent Extech True RMS meter. When reading VAC (in mV mode) it
> shows 0, as well as if I try Hz, but I'm not sure what the input to the
> meter is supposed to look like for cycles...
>
> Thanks,
> Richard
>
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Does it not make sense that you have already spent ten time the cost of a
replacement wallwart in time and effort reading and writing this thread?
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