[mythtv-users] HD-PVR power supply (wall wart) gone bad
mythtv at cox.net
Sun Dec 16 01:06:13 UTC 2018
On 12/3/18 8:37 AM, Allen Edwards wrote:
> I will repeat, you will almost certainly burn out your device if you
> power it from +12 volts. I just looked at your cable and it looks
> fine. Therefore I would ask why do you think the old supply is bad?
> Did you use a voltmeter or an oscilloscope to test it. If so, you
> should be able to test the output of your cable. If you didn't test it,
> and given you want to put +12 into a +5 device, I would guess you did
> not test it, perhaps it is the PVR that is bad and not the power supply.
> The other possibility, mentioned already, is that there are ground
> problems. The wall wart is almost certainly not grounding your PVR as
> the supply from the computer is. If your PVR is grounded on a ground of
> different potential than where the computer is grounded that could cause
> problems. Plug them both into the same outlet and see if that helps.
No worries, I never planned to use the +12V because it seemed like a
mistake that someone on the list said to use it.
I had a bad power supply and a "good" one, I just wanted to fabricate a
cable so when my next supply went bad I would be ready. I'm already on
my 4th so it's probably a matter of time. Currently I'm using my "new"
wall wart power supply since my newly fabricated cable isn't working so
I did test the new cable after I soldiered it. Some interesting readings:
Old wall wart reading at 1/2 inch from the brick: 5.14 V
New wall wart reading at the barrel connector: 5.09 V
Newly fabricated cable that uses PC power supply (at the barrel
connector): 5.04 V
I suspect it may be a current/amperage issue and am hoping to make time
to move to a different connector on the PC power supply.
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