Hi all: My 15-yr old Toshiba 27" crt television has recently developed a
problem which is that approx 15 minutes after being turned on, the picture
bows inward on the left and right sides. Then, after a few more minutes,
the picture resolves and returns to normal and remains perfect for the
remaining time the tv is on. If the symptom described above means the crt
is wearing out, so be it, the set will soon be history. However, I'm
wondering whether some other, replaceable part, might be going bad and
causing the temporarily distorted picture.
Would appreciate any suggestions re. probable cause(s) of symptom described
above. Am basically novice, but handy and with soldering skills, and have
done a few simple tv repairs in the past. Thanks for your replies!
See if the problem can be influenced by vibration. Smack the set on it's
side to see if you can influence it. If so turn the lights out and look
inside the vents. See if you can see small sparks that could be a bad
solder joint. Because the problem comes and goes it may very well be a bad
solder joint or connection. Be safe. If you don't know of the dangers
involved then stay away from the repair.
Bowing in of the sides of the picture has nothing to do with the crt ,
it is the deflection yoke (coils) at the base of the tube that move
the beam from one side to the other and top to bottom. Have you
tried running the set with the back loose enough to greatly lower the
internal temperature, and see what effect that has.
On 01/16/2011 10:05 PM, hr(bob) firstname.lastname@example.org wrote:
The real answer, sadly (it offends me to say this) that it's likely not
*worth* repairing, as you can likely get an equivalent size widescreen
1080i flat screen that won't require a DTV converter box for $300 or less.
replace "roosters" with "cox" to reply.
Yes, but don't give the impression that replacing the yoke will solve
this, because he might go do it, even though yokes are expensive. I
think it more likely it is the circuit that powers the yoke.
Maybe, but this is a "repair" group. Some of us live to repair.
STill, what I would do at my stage is nothing, and figure a few
minutes of distorted picture is nothing, and I'd watch it the way it
is until it got intolerably worse, or I got a free tv somewhere.
When I was eager to repair tvs, I might have tried looking for swollen
nd broken capactitrs, or signs of burned parts, but otoh by 15 years
ago, everything may have been in an integrated circuit.
OP, whatever you do rememeber that the picture tube holds thousands of
volts, even after the set is turned off and unplugged. The picture
tube is one big capacitor. I've always deeply avoided the thick red
wire that goes to the picture tube, and I've always avoided the whole
surface of the picture tube also. Especially if it is dust covered.
Maybe dust conducts elecricity, for all I know. (It has 15 to 20
thousand volts when running, maybe more for a picture tube as big as
The yoke also has a couple thousand volts on some leads, but only when
the tv is on IIUC. YOu can always use a voltmeter to check on that,
but not so much the picture tube, whose voltage tends to be hidden
under a big rubber wafer at one the picture tube end. There used to
be a metal cage at the other end, for the tech's safety, but those
went away 20 or 30? years ago to save weight. It's also hard without
a lot of experience, more than I have, to fix these things without a
schematic, and they are about 30 dollars last I looked, years ago.
It stinks, doesn't it?
Yeah, it's only *worth* repairing if that's what gets you off, but
then you become that weird TV guy whose house is stacked with old sets
awaiting repair, and your hair is sticking straight out from one too
many encounters with the high-voltage on the CRT.
The state of affairs is such that the low failure rate and low cost to
manufacture "durable" goods these days, that it's cheaper to replace
the few that fail with new units than it is to staff and stock a
On Mon, 17 Jan 2011 13:05:08 -0800 (PST), email@example.com
That would be me. Once in college I ended up with an electric
percolator, but only the main piece. By the time I bought the pipe in
the middle and the basket and its lid, and maybe the pot's lid and
glass middle, and the cord, it cost more than a new coffee pot, even
I wouldn't do exactly that again, but I've never regretted it. And I
don't even drink coffee.
Since a little after vacuum tubes went out, there's not much you can
do unless you have some electronics skills or want to learn them.
Back in 1980 a buddy gave me my first color TV, but it had no color.
There was a repair shop and I took it there after the mechanical
tuner screwed up. That guy fixed the tuner and replaced the "color
chip" for $75. Good deal, since a TV like that was about $300.
Now you can a much better CRT TV for $50-100 at a thrift shop.
I've got a perfectly working 27" Magnavox in one room my wife paid
$30 bucks for, and a 30" Bell-Howell in another room that my son
picked up for $100 at a place called Cash Converters around here.
Not a pawn shop, but you they'll pay for used working electronics and
Add $10 for a universal remote and you're set.
I've got perfectly good 18" and 21" CRT monitors that I paid good
money for sitting idle because I got flat screen replacements as
gifts. Kinda pissed me off but I couldn't say anything.
Wouldn't look right. Waste of money to me.
Probably be a waste of money for you to get that fixed.
I've got a 27" CRT TV in my bedroom that I was sure needed replacement
about a year ago when it would go blank.
Smacked it a few times and it hasn't acted up in months.
If you can find the problem and repair it yourself, it may be worth it. If
you have to pay for repair, it is not worth investing much in a 15 year old
set. There are some amazing prices on 42" sets now and the picture quality
for HD is a huge step up.
When my old CRT got fried after a power surge, I was happy to buy a new set.
After 6 months, I'm still amazed at the picture quality with HD.
I'll bet it is a bad capacitor, fixed hundreds of video game monitors
with similar symptoms. Most of the time we don't even test the caps,
look for parts of the circuit board that look like they run hot, then
replace all caps in that area. Also replace all caps rated for 100
volts or higher, they go bad much more often. Also if you know your way
around a monitor, be sure to change the caps in the vertical and
horizontal circuitry. For newbies in the video game monitor repairs,
lot's of people put together a list of all the common caps that fail on
that particular model and sell you a bag of caps and a picture showing
what goes where. The "cap kits" will fix several problems at once,
including problems you didn't notice yet but are about to go.
Actually my TV is doing the same as yours but it stays that way. When
it quits I'll probably take a look inside, but chances are I'll toss it
and get a new one instead of fixing mine. TV's have a lot more
components than cheap video game monitors and aren't as easy to fix (not
for me anyway).
OH, no way is that a sign of a bad CRT, and no way is the yoke itself
bad, just the circuitry that powers the yoke.
You beat me to the bad capacitors. 15 years is a darn good life for
consumer grade electrolytic capacitors. I had a customer who's Viewsonic
LCD monitor on his server/office computer died after a year.
I thought it a shame to toss a nice monitor so a little Google search
turned up a common problem with an electrolytic in the power circuit
on the main circuit board. The store had a problem with recurring power
surges and even though there is good surge protection on the computer
system, what can get past the surge arresters will damage some
components. I believe it was a 100uf 16volt electrolytic and when
looking at the circuit board I noticed lands on the board for a parallel
capacitor. I installed two 47uf 35volt caps and there have
been no more problems with the monitor.
Google might work. I fixed a couple of DTV converter boxes by googling
the problem and found a cap that failed in all of them. Likewise
replacing caps is a common problem in switching supplies (Mac supplies
in particular) although that is not the issue here. Claire is close to
having this nailed, the symptoms are almost classic.
Capacitors have gotten a lot smaller for the same ratings, I suppose
it's not to be unexpected that they would fail more often. The digital
stuff in particular as switching supplies are hard on them.
Not sure how long modern HV sections hold a charge, but some caution
should be exercised.
The store had a problem with recurring power
I just reread his post and I've seen the same symptoms caused by cold
solder joints. After a warm up the device starts working correctly but
it will GRONK if you jar or slap it hard. I used to repair a lot of two
way radio gear and when I finished repairing a problem, I would smack
the unit against my carpet covered work bench much to the consternation
of the other techs in the shop. I explained to them that the radio was
going to get a lot rougher treatment in the field. I've also seen a lot
of very strange thermal intermittent malfunctions.
It's the bowing part that lead me to think cap, but you are right that
healing like that is not really a cap thing. I've got a friend who still
fixes TVs, though mostly it's all flat panel stuff now. I'll ask if I
get a chance...
After a warm up the device starts working correctly but
It's better to know sooner than later. Toward the end of my repair
"career" I was mostly fixing giant car amps. Nothing I could do to them
could come close to the abuse they would get later! Oh, the abuse!
I've also seen a lot
I've used more than my share of freon tracking them down. Or not
tracking them down!
I got a call a little while ago from the customer who had the Viewsonic
monitor quit because of a bad electrolytic, an identical monitor on
another workstation just did the same thing. I have to pick it up today
and repair it.
Repair? In our town we get an 18 inch monitor for 79.00 on sale. What is
your hourly rate? Mine is 250.00 plus T&L minimum 2 hours.
My hobby is fixing tube gears specially guitar amps for poor local
musicians. No chaege for them. Just I let them buy necessary parts.
Good for you. But, you wouldn't have many customers fixing consumer
electronics at that price.
For a reasonable price, putting a Viewsonic Flat Panel back in service
is worth it. Neither is it junk, nor is it worth sinking $500 in.
Myself, I don't have to charge $250/hr to feel like I have self
worth. Just how big is your hwang, Tony?
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