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Samsung 27" TV doesn't work.

M

Malissa Baldwin

Jan 1, 1970
0
George said:
Someone gave me a Samsung 27" TV, Model TXL2791F. When I tried to turn
it on it did nothing. No indication of power at all. I opened it up and
checked the fuses. All good.

You didn't say that you plugged it in, asshole, maybe you should try
doing that.
I got a copy of the schematics, and did a little circuit tracing.
There's a component called a flyback transformer, which is connected to
a component called a high voltage tripler, which is connected to the CRT
high voltage anode. There's a picture of it at
http://www.wehaveparts.com/index.cgi?product=&pid=1553&cart_id=
1146478751 . The picture says it's a flyback transformer, but according
to the schematic it's the tripler. The schematic just shows a box. No
internal wiring.

The thick wire shown in the picture goes to the CRT anode, the thin wire
goes to a ground, and the hole is for a thick wire from the flyback.
That's the wire that the cable company sends the picture to the tube.
When I pull the ground off, I can turn the TV on with the switch as well
as the remote. After removing the ground, when I plug it in I hear the
slight crackling/humming sound that means the set is powering up, and a
red LED comes on that means the set is powered up but off. When I press
the ON switch or the remote, the LED turns green, and I get a tone that
means I need to set up the time, channels, etc. I get no picture, of
course, because there's no voltage to the CRT, but everything else seems
to indicate that the TV is starting to power up normally.

If there is no voltage to the CRT, then how the **** would you know
that the time and channels need to be set up.
When the ground wire is connected, presing the switch or the remote gets no
reaction at all.

That's probably because the ground wire is connected to the switch,
stupid.
No, my question. Would this indicate a problem with the tripler? Or the
flyback? What's a good way to test? I am familiar with radio and
computer repair, but I've never worked with televisions, and I don't
have any high voltage test equipment. Thanks for the help.
Well then, you're fucked.
Oh, and I'm aware that the voltages in a TV can kill me, so I take
proper safety precautions, so no need to remind me. Thanks for the
thought, though.

**** it and just throw it away and buy a Protron.
 
R

Rick Brandt

Jan 1, 1970
0
George said:
Maybe, but not for lack of a working TV. I have three.

One of the more common (totally dead) failures I see is a cracked circuit board
which interrupts some of the circuit traces. This is common in the area of the
flyback due to its weight. If the set is dropped or otherwise subjected to
sufficient G-forces the weight of the flyback causes enough board flex to crack
it. Sometimes these are easy to see, sometimes finding all of them can be a
real tough nut.
 
G

George Jetson

Jan 1, 1970
0
I'll ignore everything else you wrote, except this. I think you really
don't know this.

If there is no voltage to the CRT, then how the **** would you know
that the time and channels need to be set up.

Remember what I said? "I get a TONE that means I need to set up the time,
channels, etc." A tone. As in sound. Sounds don't go through the CRT, you
feeble minded bitch.
 
C

CptDondo

Jan 1, 1970
0
Malissa said:
You didn't say that you plugged it in, asshole, maybe you should try
doing that.
That's the wire that the cable company sends the picture to the tube.


If there is no voltage to the CRT, then how the **** would you know
that the time and channels need to be set up.

That's probably because the ground wire is connected to the switch,
stupid.
Well then, you're fucked.


**** it and just throw it away and buy a Protron.

Take a shit, have an orgasm, do what it takes, but lose that attitude.
 
G

George Jetson

Jan 1, 1970
0
One of the more common (totally dead) failures I see is a cracked
circuit board which interrupts some of the circuit traces. This is
common in the area of the flyback due to its weight. If the set is
dropped or otherwise subjected to sufficient G-forces the weight of
the flyback causes enough board flex to crack it. Sometimes these are
easy to see, sometimes finding all of them can be a real tough nut.

The set is only a few years old, and the flyback is relatively light. I
also looked at the circuit card and didn't see any marks or cracks at
all. And to be honest, I'm not sure it's the flyback. There's a
component called a High Voltage Tripler that sits between the flyback
and the CRT. When I take the tripler out of the circuit the set powers
up and goes through a short diagnostic. With the tripler in it does
nothing at all.

On the schematic the tripler is just a box, with an input, output, and
ground. If the triler is some kind of step up transformer, wouldn't the
resistance across the input and output be infinity? I measured it at a
little over a hundred ohms. Would that indicate a shorted tripler?
That's what I suspect, but I don't know exactly how the tripler is set
up. Any advice?
 
R

Rick Brandt

Jan 1, 1970
0
George said:
The set is only a few years old, and the flyback is relatively light.
I also looked at the circuit card and didn't see any marks or cracks
at all. And to be honest, I'm not sure it's the flyback. There's a
component called a High Voltage Tripler that sits between the flyback
and the CRT. When I take the tripler out of the circuit the set powers
up and goes through a short diagnostic. With the tripler in it does
nothing at all.

On the schematic the tripler is just a box, with an input, output, and
ground. If the triler is some kind of step up transformer, wouldn't
the resistance across the input and output be infinity? I measured it
at a little over a hundred ohms. Would that indicate a shorted
tripler? That's what I suspect, but I don't know exactly how the
tripler is set up. Any advice?

Well any time you take a component out of the circuit and get more functionality
than when it is in place that is pretty good evidence that you are in the right
area, but the real problem might be downstream of the tripler and removing it
from the circuit might also be taking other things out of the circuit that are
the real problem.

That's what sucks about trying to fix this stuff as a consumer. At the shop
they would try the tripler and if that wasn't it they could grab any of a
hundred other parts at their disposal and try them. Ordering your first best
guess on-line, waiting for it to arrive, and then trying it only to find that it
doesn't fix the problem is a hell of a way to make progress. Short of seeing
parts that are visibly damaged it really is a crap-shoot.
 
G

George Jetson

Jan 1, 1970
0
Well any time you take a component out of the circuit and get more
functionality than when it is in place that is pretty good evidence
that you are in the right area, but the real problem might be
downstream of the tripler and removing it from the circuit might also
be taking other things out of the circuit that are the real problem.

That's what sucks about trying to fix this stuff as a consumer. At
the shop they would try the tripler and if that wasn't it they could
grab any of a hundred other parts at their disposal and try them.
Ordering your first best guess on-line, waiting for it to arrive, and
then trying it only to find that it doesn't fix the problem is a hell
of a way to make progress. Short of seeing parts that are visibly
damaged it really is a crap-shoot.
If I knew what was inside the tripler I could test it. I have a
schematic of the flyback, but I would have to unsolder it to test, and
I'm trying to avoid that. If I can test the tripler and it turns out
bad, I can avoid unsoldering the flyback.
 
K

Ken Weitzel

Jan 1, 1970
0
George said:
If I knew what was inside the tripler I could test it. I have a
schematic of the flyback, but I would have to unsolder it to test, and
I'm trying to avoid that. If I can test the tripler and it turns out
bad, I can avoid unsoldering the flyback.


Hi..

http://tpub.com/neets/book7/27m.htm

Ken
 
A

anonymous

Jan 1, 1970
0
uh, george, are you sure that is not a voltage divider?
 
G

George Jetson

Jan 1, 1970
0
uh, george, are you sure that is not a voltage divider?

Positive. It's called a "High Voltage Tripler" on the schematic, and a
picture I found on the internet calls it a tripler.
 
A

anonymous

Jan 1, 1970
0
george I have not messed with consumer stuff very much, but I believe
the so-called triplers in TV sets disappeared quite some time ago. That
thar critter appears to me to be an integrated high voltage
transformer, (aka flyback transformer, aka FBT) The part/sub-part
(whatever) you are calling a tripler is, I believe, actually a divider
network. Note the 2 variable resistors, screen and focus. I doubt it is
bad.

Anyways, reflow any poor solder, especially in high heat areas and the
FBT pins themselves. Check any small value fusible resistors in the FBT
secondary side ckts. Look for white, ceramic heat-sink-bodied resistors
near the FBT, 1 ohm or so in value, about 1-2 watts in physical size,
(cant remember the actual ratings.) Check them with an ohmmeter. You
may have to desolder/lift one end to measure properly.

Chances are good it is either that or the FBT its self, as pointed out
earlier.

If you get the crackle of static when trying to power on, it sounds
like the HV is coming up, then going right back down again. One of the
fbt derived low voltages is fed back <i>somewhere</i>, but the fuse
resistor is open. That could be a cheap easy fix that you may be able
to locate without too much extensive troubleshooting skills or
equipment, do not overlook that possibilty.
 
A

anonymous

Jan 1, 1970
0
hey there will also be somma them thar rectum-fliers in series with the
fbt sec. & them thar fusible resistors, be sure to check them too.
 
B

b

Jan 1, 1970
0
first things first. have you performed the test with the HOT removed
and a 60-100watt bulb across c-e? have you measured the b+? without
these simple tests you could be wasting time or money on the tripler or
whatever. post results.

..B
 
G

George Jetson

Jan 1, 1970
0
george I have not messed with consumer stuff very much, but I believe
the so-called triplers in TV sets disappeared quite some time ago. That
thar critter appears to me to be an integrated high voltage
transformer, (aka flyback transformer, aka FBT) The part/sub-part
(whatever) you are calling a tripler is, I believe, actually a divider
network. Note the 2 variable resistors, screen and focus. I doubt it is
bad.
The flyback transformer is soldered to the circuit board. There's another
part screwed to a plastic bracket connected to the flyback by a thick
cable. According to the schematic it's a tripler.
 
A

anonymous

Jan 1, 1970
0
George said:
The flyback transformer is soldered to the circuit board. There's another
part screwed to a plastic bracket connected to the flyback by a thick
cable. According to the schematic it's a tripler.

sounds like you got it all under control there sparky.
good luck.
 
M

mm

Jan 1, 1970
0
My point is that if you're not convinced of my knowledge of proper safety
precautions, then don't offer any troubleshooting advice.

I got your point.

You don't seem to have gotten mine. I'll offer advice based on
whether I want to or not, not based on your particular desires.

Other people read this list. Not just you.


If you are inclined to email me
for some reason, remove NOPSAM :)
 
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