Any Television Engineers Here?

[Daffy D]

Hi

Some time ago the TV started showing a few horizontal lines at the bottom of the screen. A gentle thump would fix it. Over time the lines increased in number with the force of the thumps increasing proportionately till now we sometimes can hardly get a watchable picture at all.

According to This WebSite the problem is with the Vertical IC and the solution is to re-solder the circuit board's connections.

Sounds simple enough would be no problem for me as in a former life my hobby was constructing electronic projects but I have never needed to mess with the inside of a television set before.

So I was just wondering if there are any TV engineers out there who could offer any usefully hints and confirm that this fix would solve my problem.

On This Page it shows "How to Discharge the CRT without killing yourself" which looks straight forward enough if a little hairy Do I really deed to discharge the CRT if I'm only going to be working on the solder joints of the board?

With the school holidays and all these rainy days there is not much for the kids to do so I don't want to "fix" the TV only to make it not work at all.

I would never be forgiven so any useful hints and advice most welcome.

[paulfr]

Please .... Do not attempt to do this yourself

There is very high voltage in there which is lethal.

Kilovolts. And the line 220vac can do you in.

Even with power off, the caps may retain charge

And this suggestion of re-soldering the IC is a shot in the dark

educated guess since there are several other possible reasons for this behavior.

If you can find a knowledgeable fellow, good for you.

Otherwise go to a repair place and pay for the man to

come to your condo/apt with tools and parts.

JMHO as a degreed MSEE.

Good luck

[Spoonman]

Daffy, where are you located ?

I have a 68cm Samsung TV here that works perfectly but has a cracked case though when it was knocked off its stand onto the floor. I stopped using it as I purchased an LCD.

It's yours (free) for the kids to watch if you want it, Iam located in Pattaya.

[ETatBKK]

Daffy, before I can give use any useful hints, I have to give you a SAFETY WARMING !

the CRT is charged with very high voltage EVEN it is UNPLUG, as well as some components on the board ( it is not a 12V motherboard ). even TV engineer needs special tools to deal with this thing !

please put down your screw driver and it is time designing some creative games for your kids !

[Crossy]

A TV is indeed potentially lethal, but just a modicum of common sense will ensure you remain safe.

I spent my earlier years fixing ex-rental TVs to sell, some of the early valve (tube) colour sets really were lethal! Had a fair few wallops, invariably running the beast with the lid off.

Unplug the set and leave it off for 24 hours. The final anode could still bite, but you're going nowhere near, it's (the rubber sucker thing on the tube).

Pop the back off and look for dry joints, re-solder any that look iffy. Avoid poking your fingers about in there, chances are everything is safely discharged but why take the risk.

Replace the back and test. Do NOT operate the set with the back off, here be dragons!

If you can't get at the solder side of the board without removing the anode connector (rubber sucker) then put the back on again and take it to your local telly repair man.

[Daffy D]

Thanks everyone for your comments all appreciated.

"paulfr" - Thanks for your concern. I am aware of the potential danger of messing with the insides of a TV but there is always the the satisfaction of doing a job yourself. I am reluctant to take the set to a repair man as he would probably keep it for several weeks and then say "No good No fix" but as you suggest if I can find someone to come to the house, that would be worth considering.

"Spoonman" - Thanks for your kind offer. A 26" would be nice, even with the cracks but I'm located some miles North of Bangkok and don't have a car so unfortunately can't take you up on the offer.

"ETatBKK" - Your safety warning noted. If I do go ahead with this I do plan to leave the set unplugged for a day as I believe the CRT does discharge over time so if I do poke the wrong bit hopefully it won't be lethal.

Creative games for kids easy to say but not so easy being creative all day every day for about a month, guess I don't have that much creativity in me.

"Crossy" - As usual you come through with some positive encouraging comments. Yes I had planned to have the set unplugged for a day or so before working on it and intend to be careful only touching things with plastic handled screwdriver. And yes if it looks too impossible will get a man in to have a go.

Two negative to one positive comment - Got to think about this for a couple of days.

[Nisa]

Thanks everyone for your comments all appreciated.

"paulfr" - Thanks for your concern. I am aware of the potential danger of messing with the insides of a TV but there is always the the satisfaction of doing a job yourself. I am reluctant to take the set to a repair man as he would probably keep it for several weeks and then say "No good No fix" but as you suggest if I can find someone to come to the house, that would be worth considering.

"Spoonman" - Thanks for your kind offer. A 26" would be nice, even with the cracks but I'm located some miles North of Bangkok and don't have a car so unfortunately can't take you up on the offer.

"ETatBKK" - Your safety warning noted. If I do go ahead with this I do plan to leave the set unplugged for a day as I believe the CRT does discharge over time so if I do poke the wrong bit hopefully it won't be lethal.

Creative games for kids easy to say but not so easy being creative all day every day for about a month, guess I don't have that much creativity in me.

"Crossy" - As usual you come through with some positive encouraging comments. Yes I had planned to have the set unplugged for a day or so before working on it and intend to be careful only touching things with plastic handled screwdriver. And yes if it looks too impossible will get a man in to have a go.

Two negative to one positive comment - Got to think about this for a couple of days.

Capacitors in your TV can hold a charge for days or more. If you don't know how or are not fully comfortable discharging the main capacitor then you have absolutely no business playing around with a soldering iron in your TV. Your reasons for wanting to do this on your own are idiotic compared to the potential risk you are putting yourself in. I feel for your loved ones.

With Thai labor so cheap and so many TV Repair shops and people available to work on sets why in the hell would you think it smart to do yourself with absolutely no experience working on a TV? Why would your logic tell you that the problem is so common and easy to fix that you can easily get the answer on the internet but that it will take weeks for an experienced TV technician to determine it can't be fixed? It almost sounds like you are looking for trouble ... forget about the safety issue and just think about wanting to get your TV repaired properly.

Edit: Have you looked at the price of the old CRT style TVs? They are dirt cheap new and barely nothing to free used.

[Litlos]

Well you have had a ll the safety warnings and most of them are sound advice. Basically after 24 hours the set will be safe to look at as the capacitors will be discharged, even if there is some residual charge, it will be a surprise rather than lethal, if the set is a few years old then 2 hours is probably sufficient for the capacitors to discharge to a reasonaably low level.

Anyway to the advice part on actually getting it fixed. Step one make yourself an earth strap, there are commercially available ones but a piece of wire attached to a metal watch band then connected to a good earth will serve to discharge your static electricity and prevent further problems. Approximately 50% of electronic problems are push in/on connectors, this includes cable plugs and IC into sockets. As the problem has previously responded to mechanical input (the thump) then it may well be a mechanical type problem of a push on connectoin. So step two is to give all the connectors a wriggle and look for signs of corrosion which is generally a whiteish powder. If possible loosen each connector one at a time and visually check, the action of removing and replacing the connectors quite often solves the problem and is technically referred to as "reseating" the connector. The big cable that runs to the rear of the CRT and the electronics obviously associated with this (large components and wiring) leave well alone as this is where the dragons live, and is probably not the cause of your problems. If the IC's are in plug in connectors then you could try an IC remover/replacer, or a small screwdriver at either end to gently lever them up and reseat. If you can see obvious dry solder joits (whiteish looking) and have a decent soldering iron for electronics then if you are feeling game you could try resoldering. Be aware that most soldering irons are not earthed and can actually put a nice spike into components whilst doing the job.

Any doubts or lack of confidence at any point, reinstate the rear cover and call for a tech. Said tech will do exactly the opposite of what I have just suggested and fix it anyway. A lot of Thai people do not have a car so there must be visiting techs or the ability to get the local Somtaeow driver to take set to tech.

Cheers

[tutsiwarrior]

in these cases with a CRT problem is it usually the case that a connection needs re-soldering rather than having to replace the CRT? I've got a relatively new Sharp, about 3 years old hardly ever used except when I'm at home to watch videos and the picture went wonky (that is, no picture) not long ago...I figure that if the tube had to be replaced then there ain't no use in tryin' to fix it...

also...next to impossible tryin' to find a TV repairman in a small town and you can totally forget a Sharp repairman leaving the BKK city limits...

[Daffy D]

I'm Alive! Alive! Alive!

I survived fixing my own TV - Yippee! - Got to get the T-Shirt

What a lot of fuss over a relatively simple job. I only posted on here to get some hints or tips from anyone who knew something and all you guys did was make me paranoid. Nearly stopped me from getting on with the job at all.

So, only 4 screws holding the cover and there I was in the dragons lair. Rigged up a screwdriver with a wire to earth to the chassis, didn't have any rubber gloves so put on a heavy duty gardening glove, put on flip flops to insulate me from the tiled floor and standing well back started to poke about under the rubber thingy to discharge the CRT.

Nothing! No Bang no Whoop! not even a small electric click - nothing. Checked the end of the screwdriver and crocodile clip with meter to check the rig actually worked. It did, so poked about again under the rubber thingy still no Wizz Bang so guess having the set unplugged overnight did the trick.

It was all pretty mucky and dusty in there so first got an old pain brush to clean everything up then started to unplug various wires so I could slide out the main board.

Before unplugging anything I took a photo and identified the various connections with marker pen. I also bundled the unplugged cables together to make sure I found them all again. Unplugged as many cables as necessary to turn the main board upside down so I could work on the solder joints. Luckily the CTR cable was long enough so did not have to disconnect that.

Gave the bottom of the board, where all the solder joints are, a good clean with a scrubbing brush and checked for any obvious problem. It all looked fine but I resolderd the joints of the chips connected to the main heat sinks. These are the ones that get very hot and supposedly cause the problem.

I then checked all connections I could find and reseated them (thanks "Litos") and that was just about it.

Put ever thing back together and switched on. AND NOBODY WAS MORE SURPRISED THAN ME WHEN THE THING ACTUALLY WORKED.

So thanks to all who suppled helpful support and leave you with this extract from one of the sites I looked at:-

Let's face it: High voltages are scary. When someone says "kilovolts", you usually hear "killovolts", right? And if you fire off a quick search on the Web, you find dire warnings everywhere that reinforce your natural fears. The warnings are so numerous and frightening, in fact, that it's easy to believe that a CRT can vaporize humans and entire herds of cattle with a single discharge.

It turns out that most of these warnings are delivered by people with little or no expertise in electronics. Would you accept advice from a gardener about brain surgery, or might you do a little more research?

[Tywais]

I only posted on here to get some hints or tips from anyone who knew something and all you guys did was make me paranoid.

When it comes to high voltage systems, paranoid is good.

It turns out that most of these warnings are delivered by people with little or no expertise in electronics. Would you accept advice from a gardener about brain surgery, or might you do a little more research?

I've repaired hundreds of CRT based TVs over the years and consider myself highly experienced working with high voltage systems. Worked as a repair technician in electronic stores while in college and the local neighborhood electronics handyman. The warnings are quite valid and even with all my experience I still become very cautious entering the lions den. Not that long ago I got a 20kV (20,000 Volt) hit from being a bit too lax going into a high voltage supply to repair it at the university lab. Hope you took your watch and rings off on entering, standard requirement for sparkies.

I will admit I'm impressed with your systematic approach to the safety issue and glad it worked out.

[paulfr]

And if you fire off a quick search on the Web, you find dire warnings everywhere that reinforce your natural fears. The warnings are so numerous and frightening, in fact, that it's easy to believe that a CRT can vaporize humans and entire herds of cattle with a single discharge.

It turns out that most of these warnings are delivered by people with little or no expertise in electronics. Would you accept advice from a gardener about brain surgery, or might you do a little more research?[/color]

Congratulations on your successful repair.

As someone who got across 7Kv once in the lab, I can tell you there are several

ways to die. The zap threw me back about 10 feet out of control. Had

I hit my head on one of the benches I could have bought it that way.

But the real danger is that very little energy is needed to kill you.

Ten milliamps thru the heart is sufficient. And with 10-20Kv around,

there is no problem for nature to overcome the resistance of the skin.

Since we are 85% water the rest is easy.

So not wanting to be a party killer I still have to say you should

not be too cavalier the next time simply because of this success.

As Murphy has instructed all lab prowlers, "If anything can go wrong, it will"

Again, good job and congrats !

[ETatBKK]

ha ha ha . . . Daffy, well done ! and WELCOME BACK ; -)

thanks for sharing your 'high voltage' experience. you are a creative guy, you do have a gut :-)

certainly, you have a beginner's luck too ! hmm . . . think twice in your next adventure !

[Daffy D]

Thank Ya'all.

Got to be honest and say it probably worked more by sheer luck than my fix.

In a former life I would have just chucked the TV and bought a multi-inch flat-screen, but I enjoyed the challenge and have learned something about repairing TV's, mainly not to make a habit of it.

[astral]

Despite the comment about numerous local repair men, I would head for the local

service centre for whatever brand it is.

I have experienced problems with the "local man" who claims the parts are not available.........

whereas the real service centre has had the job done in 24-48 hours.

[paulfr]

Despite the comment about numerous local repair men, I would head for the local

service centre for whatever brand it is.

I have experienced problems with the "local man" who claims the parts are not available.........

whereas the real service centre has had the job done in 24-48 hours.

I think this is an important point regarding all repair, not just for TVs.

Recently had my laptop screen go black with a blinking cursor.

Took it to a local "Computer shop"

He looked at it for a few hours and said he could not repair it.

I suggested a simple hard drive exchange/new hard drive.

He could not do that.

Then took it to Fortune town to a fellow on the 3rd floor

way in the back to the right of the Bangkok Bank.

90 minutes later I had a new HD with upgrade to Windows 7 for

under 2000baht.

[Semper]

Thank Ya'all.

Got to be honest and say it probably worked more by sheer luck than my fix.

In a former life I would have just chucked the TV and bought a multi-inch flat-screen, but I enjoyed the challenge and have learned something about repairing TV's, mainly not to make a habit of it.