View Single Post
  #25   Report Post  
Posted to sci.electronics.repair
Jeff Layman[_2_] Jeff Layman[_2_] is offline
external usenet poster
 
Posts: 1,212
Default Kill-a-Watt surprises

N_Cook wrote:

I bought a set-top box (UK Freeview) and thought to myself
"hang on a bit the box is as warm with green LED on as on red standby"
I measured consumed watts in both states and standby is 80 percent of the
on state. I put in a hard on/off switch , data held in EEProm or whatever
and no difference in function except programme info pages takes a couple
of minutes to gather


What is meant by "standby"? You may think you know (as I thought I did,
too), but it isn't that simple. See he
http://arstechnica.com/gadgets/news/...75-of-time.ars

It's not just Sony. I queried Panasonic about the regular clicking from my
LCD TV, even when it was in "Standby" mode, and also the less-than-green
readings I was getting from a power meter attached to it (15w in standby,
and 30w when it clicked. I do not know what the power factor of the TV is,
so do not know how these figures correlate with Panasonic's stated standby
consumption of 0.3w, but they don't seem very different from those reported
with the Sony). This was their reply:

"In response, I would advise that first please ensure the SETUP menu option
for “auto search in standby” is switched off. (this is in the “System
Update” SETUP menu option.

Turning off this option will also stop intermittent clicking from the TV
that are caused as the internal PSU relays are turned on to allow the
Freeview decoder to work for software updating.

2.) Please note that the set takes approximately 2 minutes for all the PSU
relays to click off and so the power will only read 0.5W after this time.

3.) Ensure that the power meter used can read the power factor of the unit
required to calculate AC power and is using this to calculate power.

4.) Ensure the meter is capable of accurately reading 0.5W; many meters
cannot go this low. Please refer to the meter’s specification."

That reply was open and very helpful, but (a) "auto search in standby" is
the default condition (b) there is no mention of this in the manual (c) I
still do not know how often the TV goes into auto search mode, for how long,
and what the actual power consumption is in this mode.

I have now taken to switching off at the plug when the TV is not in use.
Info on the DTG pages let me know when to leave the TV in standby/autosearch
for an update.

It makes me wonder just how accurate many other low consumption "standby"
figures are.

--
Jeff