[pvrusb2] Ability to fully reset a PVRUSB2 Device

[isely at isely.net]

On Sat, 16 Mar 2019, Gary Buhrmaster wrote:

> On Sat, Mar 16, 2019 at 4:06 PM Diego Rivera <diego.rivera.cr at gmail.com> wrote:
> >  Every so often one of the devices ceases to function and just "dies".
> 
> It has been a long long time since I touched one of
> those, but I would always look at the root causes
> of the hangs first.....
> 
> The two most common issues with the HVR-1950
> that I ran into is that it can overheat (and hang)
> and the power supply can be going bad (and the
> device hangs).

I didn't consider the heat aspect in his original question because he 
said it had been working for a while just fine and only now is starting 
to experience trouble.  Heat won't do that - unless of course he moved 
the hardware into an environment which causes it to run hotter now.

The power supply going bad is certainly plausible though.  One thing I 
have learned over the years of dealing with digital hardware is 
(capacitor plague excepted) always to first suspect the power supply.  
What's more a power supply can slowly drift out of spec over time, at 
least the crappier ones.  I had this issue with some early Silicon Dust 
devices.  Eventually it drifts far enough to cause the device being 
powered to because sporadically unstable, ultimately leading to a 
complete failure.  Frequently just replacing the power brick with a 
compatible substitute will do the trick (as it did with that Silicon 
Dust device).  Digital circuits themselves can't really "drift", but 
analog power supplies can, and do.


> 
> For the first, I found avoiding stacking them (which
> I had been doing) was sufficient to avoid overheating
> (although your location may vary and you may need
> active airflow), and for the second, I replaced the
> power adapter.  FWIW, I don't think any of the
> power adapters that I ever got from Hauppauge
> were of good quality, and I usually just replaced them
> pro-actively with a high quality switching supply
> (at the time I had a local source of delta branded
> oem switching supplies that were dirt cheap and
> new in box).  Note that you typically can't just use
> a VOM on the adapter to test, you have to put the
> adapter under load and look at the ripple.  Usually
> just easier to replace the power supply.

I've never heard of any anecdotes of the HVR-1950 devices getting into 
heat trouble when stacked, but definitely that was the case with the 
earlier generation PVR-USB2 devices.

And yes, if it is voltage drift you have to measure that voltage when it 
is powering the device not open-circuit.  Switching power supplies 
(which is everything I have ever seen from Hauppauge) can be affected by 
severe load conditions, and "no load at all" is actually such a severe 
state...


> 
> And none of this was actually in response to
> the question you asked...

Well maybe not for disentangling the driver when the hardware fails but 
obviously if he can stop the failures from happening at all that's a 
pretty good outcome.

  -Mike

-- 

Mike Isely
isely @ isely (dot) net
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