Repairing LCD TV - Westinghouse LTV-32W3

[Ecnerwal]

It's an LCD, which means it's more than likely a low voltage device.
Doesn't take much more than 12V tops to run them.

And 800V (or so) running the lamps so that you can see the picture on
the 12V screen...before you go getting all comfortable poking around in
there.

 

[T]

And 800V (or so) running the lamps so that you can see the picture on
the 12V screen...before you go getting all comfortable poking around in
there.

Is it really 800V? If so what does my laptop use to step the voltage up
to that level?

There are low voltage fluorescents out there. I know, I have one in my
toolkit and it runs on 4.5V.

 

[James Sweet]

Is it really 800V? If so what does my laptop use to step the voltage up
to that level?

There are low voltage fluorescents out there. I know, I have one in my
toolkit and it runs on 4.5V.

Fluorescents are discharge lamps, the smallest in the world require
somewhere around 50V to draw an arc through the low pressure argon/mercury
fill. Cold cathode lamps used in LCD monitors require a higher voltage,
usually 500-1500V run with a 2-4KV ignition pulse. Any fluorescent
application with a low voltage power source uses an electronic inverter to
provide the required voltage and regulate lamp power.

 

[Alan]

Is it really 800V? If so what does my laptop use to step the voltage up
to that level?

Voltage converters.

There are low voltage fluorescents out there. I know, I have one in my
toolkit and it runs on 4.5V.

It uses 4.5 volts input to the voltage converter. A fluorescent
requires enough voltage to create an arc in the mercury vapor.


Alan

 

[Franc Zabkar]

here electonic parts with metal case removed:
http://www.evkosystems.kgbinternet.com/evkosystems/tv/IMG_0017.JPG

I have no experience with LCD TVS (only LCD monitors), but I'm
wondering what is inside the tuner/IF can that warrants a heatsink for
this module? And why do the other chips require such massive heatsinks
when I see nothing of that kind in LCD monitors or digital STBs?

- Franc Zabkar

 

[zalek]

I am trying repaire my LCD TV Westinghouse LTV-32W3. I purchased it 1
1/2 year ago - it worked OK for about 1 year. After warranty expired
it works OK for about hour, after 1 hour the following symptoms
appeared:http://www.evkosystems.kgbinternet.com/evkosystems/tv/Bad-TV-2-1.wmv
The TV on the left is a good one, on the right Westinghouse LTV-32W3

I come to conclusion that some parts in the TV are getting too hot. To
test my theory I removed TV's back cover to allow better air
circulation - now TV is working without problem. What I want to do is
to install small fan to make a better cooling.
I am not a TV technician, so here are my questions:

electronics parts that are getting hot are enclosed in a metal case:
http://www.evkosystems.kgbinternet.com/evkosystems/tv/IMG_0014.JPG
here electonic parts with metal case removed: http://www.evkosystems.kgbinternet.com/evkosystems/tv/IMG_0017.JPG
I guess the metal case is to prevent electromagnetic transmition - can
I make more holes in a metal case without causing electromagnetic
interferrence?

I plan to put inside a small fan, similar to one used in computers -
can you recommend one?
Can you recommend simply converter from 110 AC to 5V(?) DC to power
this fan?

Thanks,

Zalek

Thanks for all replies. This week I got very thin fan that can be
attached to a metal sheet that covers the circuit board that I think
is overheated. Here is PowerPoint (3mb) as it looks like on my TV:
http://www.evkosystems.kgbinternet.com/tv/Westinghous-tv.pps
The fan is very quiet.
Now I have a problem - how to connect this fan to electricity. I have
a small power supply 5V, but if is difficult to find 110V AC after a
power-on switch. I see many open points on a circuit board, but even
it shows 5V, I am afraid to connect to a fan. What do you suggest?

Thanks,

Zalek

 

[Tony Hwang]

Thanks for all replies. This week I got very thin fan that can be
attached to a metal sheet that covers the circuit board that I think
is overheated. Here is PowerPoint (3mb) as it looks like on my TV:
http://www.evkosystems.kgbinternet.com/tv/Westinghous-tv.pps
The fan is very quiet.
Now I have a problem - how to connect this fan to electricity. I have
a small power supply 5V, but if is difficult to find 110V AC after a
power-on switch. I see many open points on a circuit board, but even
it shows 5V, I am afraid to connect to a fan. What do you suggest?

Thanks,

Zalek

Hi,
From the board find a source for 5V or 12V DC depending on fan voltage.
You can include an in-line pico fuse if you wish. Thought about drilling
whole bunch of holes at the bottom/top of cover to increase the air flow?

 

[zalek]

Hi,
From the board find a source for 5V or 12V DC depending on fan voltage.
You can include an in-line pico fuse if you wish. Thought about drilling
whole bunch of holes at the bottom/top of cover to increase the air flow?

Yes - I thought about drilling more holes. Here are the fan specs:

# Specifications: Model: EC4007M05CA,
# Voltage VDC: 5;
# Current AMP: 0.15,
# Input Watts: 0.75,
# Fan Speed: 4500,
# AirFlow CFM: 4.81,
# Pressure MMH2O: 2.38,
# Noise dBA: <25.
# Ball-Bearing.
# CE Approved.
# Power Connection: 3-Pin PC power connector.
# Dimension: 40 x 40 x 7mm

Do you think connecting fan to the board will not take to much power?
My problem is how to find source of 5V on the board? To take voltmeter
and to look for a 5V? Are there any standards how to mark power
connectors on the board?

Thanks,

Zalek

Zalek

 

[jakdedert]

Yes - I thought about drilling more holes. Here are the fan specs:

# Specifications: Model: EC4007M05CA,
# Voltage VDC: 5;
# Current AMP: 0.15,
# Input Watts: 0.75,
# Fan Speed: 4500,
# AirFlow CFM: 4.81,
# Pressure MMH2O: 2.38,
# Noise dBA: <25.
# Ball-Bearing.
# CE Approved.
# Power Connection: 3-Pin PC power connector.
# Dimension: 40 x 40 x 7mm

Do you think connecting fan to the board will not take to much power?
My problem is how to find source of 5V on the board? To take voltmeter
and to look for a 5V? Are there any standards how to mark power
connectors on the board?

Thanks,

Zalek

Zalek

Unlikely to use too much power. If you look at that plastic connector
between boards, there's probably power available right there. If you
cut to 1/2" pieces of stiff paper clip, you can likely force each down
into the +12v and ground lines that are likely located there. Then bend
the protruding ends to match the pin spacing on the fan connector. Be
sure to observe polarity.

All that said, I'd closely examine the convective air currents naturally
occurring in the set when in operation; then locate the fan to enhance
them. That will likely put your fan much higher up on the panel than
the site you've chosen. Otherwise, you could actually impede the
airflow, rather than increase it. Convection will always induce air
currents. If you put your fan in opposition to them, stagnation occurs.

jak

 

[Tony Hwang]

Yes - I thought about drilling more holes. Here are the fan specs:

# Specifications: Model: EC4007M05CA,
# Voltage VDC: 5;
# Current AMP: 0.15,
# Input Watts: 0.75,
# Fan Speed: 4500,
# AirFlow CFM: 4.81,
# Pressure MMH2O: 2.38,
# Noise dBA: <25.
# Ball-Bearing.
# CE Approved.
# Power Connection: 3-Pin PC power connector.
# Dimension: 40 x 40 x 7mm

Do you think connecting fan to the board will not take to much power?
My problem is how to find source of 5V on the board? To take voltmeter
and to look for a 5V? Are there any standards how to mark power
connectors on the board?

Thanks,

Zalek

Zalek

Hi,
I don't think so. It draws only 150mA. You can slow the fan speed down
with voltage drop resistor in series as well. Or if you install variable
resistor you can set the fan at a speed you need. 1/4 or 1/2 Watt
resistor will do.

 

[T]

[email protected]>, [email protected]
says...

Yes - I thought about drilling more holes. Here are the fan specs:

# Specifications: Model: EC4007M05CA,
# Voltage VDC: 5;
# Current AMP: 0.15,
# Input Watts: 0.75,
# Fan Speed: 4500,
# AirFlow CFM: 4.81,
# Pressure MMH2O: 2.38,
# Noise dBA: <25.
# Ball-Bearing.
# CE Approved.
# Power Connection: 3-Pin PC power connector.
# Dimension: 40 x 40 x 7mm

Do you think connecting fan to the board will not take to much power?
My problem is how to find source of 5V on the board? To take voltmeter
and to look for a 5V? Are there any standards how to mark power
connectors on the board?

Thanks,

Zalek

Zalek

It'll take a whole 3/4W at 5V. That isn't much.