inexpensive UPS and LCD TV don't like each other

[Steve Stone]

Purchased a 32 inch Panasonic LCD TV.
Also purchased a Tripp Lite OMNI 1000 LCD UPS to handle line switching and
voltage fluctuations bumps from the local power company.

To make a long story short, The TV will not stay powered up when the UPS is
in battery mode yet other gear like VCR , DVD, and stereo receiver have no
troubles, plugged in and running when the TV is dead, the power on LED
slightly flickering.

Swapped in a lower rated APC UPS and the TV has no troubles running on the
UPS on battery.

Tried using the Tripp Lite to run a Compaq PC and 17 inch LG monitor. Worked
fine. Measured output with my Fluke meter shows a steady 117 VAC on battery,
59.9 cycles.

Are new TV sets touchy about power input ? Should I put a scope on the
output and check for waveform issues and harmonics ? Am I expecting too much
from inexpensive $100 gear ?

Steve

 

[Steve Stone]

Have you checked to see if the AC outlets have bonded neutrals? I've

seen quite a few high end electronics that have no sense of humor at
all with having to deal with a floating neutral...

DJ

I have a plug in Ideal circuit tester.
It has three lamps indicating hot, neutral, or ground problems.
When I plug it into the Tripp Lite and press the UPS test button the lights
indicate an open ground.
When I plug it into the APC and press the UPS test button the lights
indicate a normal, good circuit.

 

[Vaughn]

Some of the Tripp Lite's are not sine wave,

Very few (probably none) cheap UPSs will have anything close to a sine wave
output when operating on the battery. That said, usually modern electronics
don't care. Switching power supplies usually tolerate a square wave well.

By the way, startup from cold on a square wave can be another matter
altogether due to the surge from the discharged filter caps. My old 1KW
TrippLite sometimes has trouble starting my computer.

and some (all?) are also over rated in VA vs Watts.

Oh yes! They all assume a crazy power factor and then advertise in VA
rather than watts. To find watts, look in the fine print. It is usually 1/2 of
the advertised VA.

Vaughn

 

[SQLit]

Purchased a 32 inch Panasonic LCD TV.
Also purchased a Tripp Lite OMNI 1000 LCD UPS to handle line switching and
voltage fluctuations bumps from the local power company.

To make a long story short, The TV will not stay powered up when the UPS is
in battery mode yet other gear like VCR , DVD, and stereo receiver have no
troubles, plugged in and running when the TV is dead, the power on LED
slightly flickering.

Swapped in a lower rated APC UPS and the TV has no troubles running on the
UPS on battery.

Tried using the Tripp Lite to run a Compaq PC and 17 inch LG monitor. Worked
fine. Measured output with my Fluke meter shows a steady 117 VAC on battery,
59.9 cycles.

Are new TV sets touchy about power input ? Should I put a scope on the
output and check for waveform issues and harmonics ? Am I expecting too much
from inexpensive $100 gear ?

In a word yes you are expecting to much.
Most inexpensive UPS's are not sine wave some are even modified square wave.
Put the scope on it. See what is being produced by the unit.
All electronic manufactures assume sine wave unless stated otherwise. Then
they do what they will from there.

DJ offered this and I am concerned that he may have mis typed the answer.

Have you checked to see if the AC outlets have bonded neutrals? I've
seen quite a few high end electronics that have no sense of humor at
all with having to deal with a floating neutral...

DJ

Neutrals should be bonded ONCE at the service. Everywhere else the ground,
hot and neutral are separate.

A quick harmonics test is check with your fluke meter. If it reads 60 or
close you do not have any harmonics. Assuming your using something like an
87 to read with. The Fluke is not a harmonics meter but it will read
harmonics. I have used mine and had it show 360 cycles. Divide by 60 and
you have the harmonic. Evens are not usually a problem. The odd ones can
cause problems. The only problem with a 87 is that you can not measure the
amount of the harmonic. And you can only read the biggest/highest one. Then
I pull out the $20K RPM meter for an analysis.

 

[JoeSP]

Purchased a 32 inch Panasonic LCD TV.
Also purchased a Tripp Lite OMNI 1000 LCD UPS to handle line switching and
voltage fluctuations bumps from the local power company.

To make a long story short, The TV will not stay powered up when the UPS
is in battery mode yet other gear like VCR , DVD, and stereo receiver have
no troubles, plugged in and running when the TV is dead, the power on LED
slightly flickering.

Swapped in a lower rated APC UPS and the TV has no troubles running on the
UPS on battery.

Tried using the Tripp Lite to run a Compaq PC and 17 inch LG monitor.
Worked fine. Measured output with my Fluke meter shows a steady 117 VAC on
battery, 59.9 cycles.

Are new TV sets touchy about power input ? Should I put a scope on the
output and check for waveform issues and harmonics ? Am I expecting too
much from inexpensive $100 gear ?

Probably yes.

Chances are, the TV is designed to run on a regular sine wave as provided by
normal household power. Your triplite probably puts out a square wave or a
modified sine wave by switching power on and off, and that works fine for
most devices, but many of the newer ones like your TV probably use a
solid-state power converter. Such a converter reduces the voltage by also
rapidly switching the power on and off. The problem can arise when the
converter switches on at the same time the inverter switches off, too many
times. If too many "hits" coincide with too many "misses," the converter
fails to put out sufficient power for the device and it shuts down.