Re: Can Toshiba tube TV be repaired now days?
- From: "larry moe 'n curly" <larrymoencurly@xxxxxxxxxxx>
- Date: Tue, 10 Jun 2008 09:11:24 -0700 (PDT)
m...@xxxxxxxxxxx wrote:
My brother has a nice 27" tube TV (flat screen) that
has gone bad. The unit is only abt 6 years old.
They were watching it Sat night and the picture shrank
down to one thin horizontal line that stretches across
the screen. In other words. it has no vertical scanning
I think.
He said I could have this TV if I wanted it but I live
in a rural area and no where to take it to have it
fixed!
So.... questions:
1. What is the part that has failed in this set given
its symptoms?
2. Is it worth fixing it? If yes, where can I get the
part and could I install it myself?
This should be a cheap fix if you do it yourself. Look at the
vertical sweep circuitry. The problem could be a bad solder joint or
electrolytic capacitor around the vertical oscillator chip, a high
voltage electrolytic capacitor (probably at least 180 volts) in series
with the vertical yoke (those coils of wires around the rear area of
the CRT) , or the vertical output transistors. There are two of those
transistors, and when one goes bad, so does the other one. In a lot
of TVs the transistors are built into a chip, and that chip may also
contain the rest of the vertical circuitry.
You may be able to find a schematic on the web, especially from
Russian websites (a friend of mine bought a schematic from one for $5,
maybe from http://top.eserviceinfo.com or Radio Locman), or your
library may have Sams (not Sam's) Photofacts, either on paper or
online. It's even possible that Sears.com has the repair manual
online (they do for major appliances).
If you don't know how to solder and desolder, practice on a junk
circuit board. The TV is probably made with one-sided circuit boards,
which are by far the easiest to solder and desolder. Desoldering can
be done with a suction bulb from Radio Shack, but copper desoldering
braid is probably safer because it lessens the chance of overheating
the copper traces and making them come unglued. A 30W iron is good
for soldering single-sided boards, but 40W is better, especially for
desoldering.
If you work on the TV, unplug it first! And don't set it upright on a
soft surface, like a sofa or mattress, because it can easily tip
foward (center of gravity is just 2" behind the front of the screen).
So either place a pillow to catch it, or work on it face-down. Be
careful not to bump or scratch the glass CRT.
Parts prices can vary a lot. Some good sources are MCM Electronics,
MAT Electronics, Dalbani, Premium Parts, and Tritronics, but don't
overlook Sears or even the manufacturer. Generic parts, like
capacitors, can be bought from any electronics supply, but be sure
they're rated for roughly the same capacitance (it may have to be
fairly close for vertical timing capacitors -- I once replaced a 1uF
with a 10uF, and the picture was only 2" tall) and at least as much
voltage as the original. BTW capacitors can't be tested reliably with
just a meter, even a capacitance meter, and bad caps can look
perfectly good. If you're replacing electrolytic caps around the
vertical chip, consider replacing all of them. And don't install any
of them backward!
Even though analog TV is scheduled to go away in Feb. 2009, converter
boxes are only $10-20 if you get a free $40 discount card (limit is
two per person) from DTV2009.gov. I'm using one with a vintage 1976
TV that used to belong to my parents and still works fine (was made in
Japan).
.
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