TV repair anyone?

[Hatz]

I've been having problems with one of my TVs........It was working great until a little while ago.

I would see the picture and audio just fine but then the picture would turn into a thin horizontal line on the screen. Then I could beat on the side of the box until the picture would come back on but then the next time I turn on the TV I would have to do it again.

Now its at the point where beating on it doesnt even help. I still get audio just fine.....but video is just a thin line.

Anyone know anything about TVs? Im sure Im on the wrong forums for this kind of stuff but it is offtopic.........hehe. Thanks everyone

Hatz

[Roundabout]

You didn't mention what brand/model it is, but from my experience (as a Sony tech) this is caused by an intermittent solder connection. Could be just a loose wire, but probably bad soldering. Certain Sony models were famous (KV-27XBR10, KV-32XBR10, etc.) for this problem. It happens in other models and brands too. This usually happens around output transistors that get hot. Over time, heat from these components causes the solder to expand and contract, eventually making the connection intermittent, which is why you can bang on the set and make it go in and out. If you are comfortable with opening the set up, and you are able to access the bottom of the main board where the components are soldered, you can do what I did to find intermittents. BTW: the set has to be on when you do this. Use common sense and don't put your hands on the connctions while the set is on, unless you like getting zapped Pull the PCB up to where you can access it (before plugging the set in), making sure it doesn't touch anything else inside the set. Then turn it on. I used a toothbrush (not scientific, but effective) to tap on the board while watching to see if it would start working. Use the back of the brush first, tapping around carefully, and if you find it turns on again, use the bristles to isolate which connection is bad. Sometimes it's hard to see, because there is very little clearance where the lead wire of the component comes through the board and is soldered. It might move around a fraction of a millimeter. If you can find this broken solder connection, you can go out to Radio Shack and get a soldering iron for 5 bucks and resolder the connection yourself. I literally fixed hundreds of Sony products this way - might be low tech, but I located more problems this way than using thousands of dollars worth of O-scopes, meters, frequency counters, etc.

[Hatz]

Thanks for advice Roundabout.............my model is a JVC C-20CL5.

I know this isnt a great tv but its a just a TV for my room which is good enough just to watch TV before I sleep at night.......also helps when im messin around on the comp.

I have opened the case up and everything before but havent tried the technique you told me about. Let me clarify to understand exactly what you meant.


There is a main board in the box. Find the bottom of it and tap on it with a toothbrush or what not while the machine is on to see when it comes back on or not. Then when I find where it comes back on I should see a loose solder connection there. Just resolder and it should work?

Anything else I need to know would be greatly appreciated. Thanks very much.

Hatz

[Solarjetman]

I know absolutely nothing about how to preform TV repair, but I do know there is some dangerous stuff in there even if the TV is unplugged. There are capacitors in there that hold electricity for some time after unplugging it, and the cathode-ray tube is in a vacuum making a potential implosion if you break the seal.

If you want to fix this yourself. Be super careful. But best of luck to you.

[pixel]

Sorry, I don't want to be a wet one here, but I think it is effectively gone.

I had an old TV (like 9 years) and this started happening. I tried adjusting things inside, but still it went the way of the dodo.

I even asked around if it was possible to be fixed and everyone I asked told me there wasn't any use in trying to fix it.

Roundabout probably knows what he's talking about, so hope that works for you but if it doesn't, I'd say get rid of it.

[The village idiot]

Roundabout is right. But be careful!

[MOVIEGEEK]

I would UNPLUG the set,open up the back and clean everything with a can of comp. air and then visually inspect for loose wires/solders or broken/melted components.If that doesn't help have a pro look at it,at most it will cost $65 for an estimate.If it's going to cost more than $200USD to repair buy a new one.

[Hatz]

Thanks everyone. I appreciate everyone helping me out and looking out for me. I'm gonna try a little bit later today to visually look at it and then possibly plug it in...........I'm usually good with mechanics and stuff but there is something about a TV that worries me.

Then again my birthday is coming up in 13 days so maybe I should just ask for a new tv.....

Thanks again everyone. I'll let you know how it goes.

Hatz

[Roundabout]

Hey Guys, Don't get too worried about voltages, etc. If you exercise a little common sense (don't stick your hands on the High Voltage wire) and use a little caution, you don't have anything to worry about. Just make sure no metal touches when you have the board out. Make sure it's at least somewhat stable when you are tapping on the board, so it doesn't slide around and short out. What have you got to lose? It doesn't work anyway.
Most of the capacitors are lower voltage in modern sets anyway - not very likely you could get shocked after the power is off. Hell, I've been shocked thousand of times, didn't kill me (yeah, I know what you're thinking - "YET" ).
And like I said, if you use a little caution, you have nothing to worry about. Just be careful. Solarjetman, yes, you are right, the CRT could implode - if you are hamfisted and slam something into it. It won't break if you touch it. It has to be hit pretty hard to break. If it were to be broken in the rear, what happens is not so dangerous than if it's broken by the front glass. I've broken hundreds of them, purposely, old CRT's that had to be disposed of. I'd just tap them at the very back and snap off the tip of the tube - and air rushes into it very fast, but it doesn't implode. I dropped one into a dumpster once on it's face - and it did implode sending glass everywhere. Didn't do that again!
Hatz, if the set isn't that old, you may want to try the repair. Yes, try tapping on the bottom of the board and see if it comes back on or not. If you can isolate the area where you are tapping and use the toothbrush bristles to rub over the board in the area where you think the intermittent is, you may be able to find exactly which connection is intermittent. Then turn the power off and unplug the set and get a magnifying glass and see if you can find the exact connection that is broken. If you know what an output transistor looks like, it would be a good place to start. It usually has three fairly thick flat legs coming through the board, and usually would be screwed to a heat sink or a metal part of the chassis. The transistor itself has a metal tab with a screw through it, and a small square chunk of plastic resin and three leads coming out the bottom. The only reason I suggest looking at these components, is because of the problems Sony had with broken connections on Vertical and Horizontal output transistors. Logic tells you that anything that gets hot, then cools, then heats up again hundreds of times will eventually break the solder connection. That's a very good percentage of the failure in TV's, and it's shame to throw it out just because of a bad solder connection. And that's probably all that's wrong with yours, since you could bang on it and it would come back on. Of course, we can't be 100% sure, but why not try?

[g_shocker182]

Hell, I've been shocked thousand of times

ahh the g_shocker at work...

[stiltman]

Hell, I've been shocked thousand of times

ahh the g_shocker at work...

I was thinkin it's more like when you're a kid and putting your tongue on a 9 volt battery....
It stings, but you can't stop doing it

[g_shocker182]

I once accidentaly stuck my finger in an switch outlet (that was open) and missed the switch (to turn off a light) and got shocked. Talk about electrical sensations...

[gmatov]

I don't know how big or how new the TV is, but maybe better you get the parents to go to Circuit City and buy an Apex 20" for 100 bucks. If it's a bedroom TV, that's plenty big enough, and cheaper than a repaired TV.

And, if you do get it repaired or looked at, most modern shops have a repair history on most models, and will tell you that it will probably fail again, soon, with a related problem.

[Roundabout]

Well, I'd recommend that too, if the set is over a couple of years old - it doesn't make any sense to have it repaired at a shop. Sony charged a flat rate for labor ($129.00) and obviously, that wasn't worth it for older sets. That's why I recommended trying to fix it at home. If it's a decent set and you like it, why not try to fix it? If you can't, hell, throw it away! I wouldn't pay either, at those prices. New sets are so cheap now, it's not cost effective to pay someone to fix it. I think eventually PC's will be the same story. Everything will be on one board, not interchangeable - you just throw it away. When Fry's is selling new PC's for as low as $199.00, who's gonna pay to have it fixed? That's the biggest reason why I'm not working as a tech anymore. No one wants to pay to get something fixed. In 25 years, we've gone from almost everything being repairable, to everything being thrown away when it fails. Only problem is where to dump all this trash. At least we're getting away from CRT's with all their lead and phosphor, to LCD's - which I suppose won't be as polluting when they all start getting dumped. :P

[gmatov]

Roundabout,

You're right. I have talked to the people selling used monitors for, maybe , 25 to 50 bucks. Almost everyone had a cold joint that had separated, a good smack got it going till the next time, then slap it again, actually a sign of a cold, or broken solder joint.. And, without good eyes, and a good glass, hard to find.

Really, most often not worth fixing, unless you have a lot of spare time and like a challenge.

[Roundabout]

gmatov,
Yeah, except in my job I HAD to fix intermittents. That's the most hated word in a Tech's vocabulary - intermittent. It seemed after a while that every repair I saw had the word "intermittent" in the complaint. It's not just my imagination, over the years, that reliability got worse. A lot of things with SMD's (surface mount devices) would develop problems, especially if the item was something portable. Especially cordless phones. So many had intermittent problems that after a while I was ready to throw them against the wall. Try finding an intermittent connection on a PCB with 240-pin flat pack IC's and see how long you can stand it! Know what I used to do? I would literally resolder every connection on the board by using a heat shrink gun ( like a super high powered hair dryer, output 700 Degrees + ). I'd just heat up the whole friggin' board until the solder on every component melted enough to make contact again. Like my other method, with the toothbrush, not very scientific, but very effective. This is just some of what I did to speed things up a little. The other option was to change the whole PCB with a new one, but most of the time the new boards didn't work, fresh from the factory. So much for QC...
Anyway, finding an intermittent on a TV PCB is much easier, as the components are larger, the board is not nearly as dense, making the intermittent relatively easy to find. For me, at least. If Hatz has a little technical skill, he should be able to find it.

[gmatov]

Roundabout,

I feel your pain. Thousands of surface mount components, little solderballs, how DO you heat them, hi-freq probably won't work,as it would with a liquid adhesive, woodworking style..

And, if a "sesame seed" is bonded well at one end, why would you assume that the other end isn't. Hey, it's firmly attached, no? But, not electrically. So a tech busts his balls to salvage a 50 buck board, hey, that's what we pay you for. Company doesn't give you a pat on the back.

Solder joint lets loose on a half cent component, 200 buck board, or thousand buck TV, whatever, is kaput. And the guys out here who set up a TV shop are lost, not skilled enough to find such problems,as you said, scopes don't work if the signal doesn't get far enough to be analyzed.

My sympathy to all you who have to do this stuff. Has to be boring as hell, as well.

[Roundabout]

gmatov,
Too bad all customers aren't as understanding as you are. Half the time someone complains about intermittent problems, they don't even understand how the unit works. And we couldn't tell them "RTFM" - that's taboo. So more handholding, explaining how it works, don't move your 5 disk CD player while disks are inside, don't drop your $150.00 cordless phone and expect it to keep working, on and on.
To resolder flat pack IC's, you float some rosin on the leads, then melt solder across all pins at the same time, and the rosin keep the solder from bridging between pins and shorting out. It's a technique you have to learn. But if any solder isn't perfect, it's almost impossible to see on a flat pack SMD IC.
Of course, there's a repair quota, and if you don't fix X amount of units a day, you have a problem. Doesn't encourage quality repairs, they don't care. I felt bad for customers that were being charged for repairs on products that the company knew damn well were defectively designed. The techs get it from both sides - management demanding faster turnaround time, customers demanding you find the problem, pronto. It's just not possible to have high quality and high output at the same time. I went round and round with management about the quality issue, they didn't want to hear it.
Sony products have definitely declined in quality over the years. Of course, they have to compete, but they give up a lot of customer goodwill and perception of quality in the process. How many times I must have heard "but it's a Sony!!" - sorry, their quality is no better than any other brand. Whatever brand premium you're paying is probably not worth it, with the possible exception of TV's.
Enough for this rant. You get the idea. If you want to hear more, ask me - I've got enough horror stories to write a book, after 16 years of this abuse, I'd had enough.
Thanks again for the sympathy - and listening to this rant

[gmatov]

I can only say again, my sympathy.

Damned wonder anything works. Anyone ever watches those little documentaries, showing Intel's phenomenal machines plugging and placing discrete components,and a finished product coming out the other end of the machine, would be amazed to know how many don't work, or need to go to the repair station, just as they would be surprised to know how many cars need to be properly finished after they reach the end of the assembly line and don't fire up.

[Hatz]

hehe.......sorry to dig up the past Roundabout......hehehe. Didnt mean to bring the pain back.

I appreciate your help very much as well as everyone elses. Things got a bit hectic today so I didnt have time to look at the TV.......I got as far as opening the case up thats about it. I will go into more depth tomorrow........if worse comes to worse I might just take some digital pictures and you can tell me where to look. I think I have a good idea though. You are very thurough.


Of course I will pay the 65.00/an hour repair fee

[Roundabout]

Hatz,
Yeah, I'm curious what you might find in there. You'd be surprised how many TV's have roaches inside...warm and cozy.
Let us know what you find. Like I said, there's nothing to lose trying, as long as you are careful you won't get hurt. If all else fails, you can always throw it away :P

[Hatz]

Well Roundabout.....Didnt find any roaches :P :P

However I started tapping with a piece of plastic but I am somewhat confused now because no matter where I tap on the main board (the big one, not sure what they call it), the screen will flicker. So either its just one spot or alot of spots.

In fact it doesnt matter if I tap on top of the board where all the capacitors and stuff are or the bottom of the board. It flickers everywhere.

Any suggestions? I would rather fix it myself instead of buying a new tv but I may just have to.

Once again thanks for your help.

Hatz

[Roundabout]

Hatz,
When you say "it flickers" do you mean that the screen appears, or is it a horizonal line on the screen like before? Does it fill out, even for a second, or looks like it could? If it's that intermittent, you probably will need to use the bristles of the brush and just "brush it" like you brush your teeth, all over the board. First do it lightly, then increase the pressure and do it again until something happens. Just rub back and forth, trying to cover all areas of the board. Hopefully, you will find a point where the screen will flicker when you rub across it. Try not to vibrate or shake the board when doing this, so you don't get false positives. Try lightly tapping on the wires going from the board to other components (use the brush for this too, so there's no shock danger). It could be a connector on the top side of the main board is loose. With the power off, AND the set unplugged, check all connectors and make sure none are loose. Pull them out, even, and plug them back in.
Unfortunately, I have to go out shopping with the wife right now and can't answer for a while. I'll come back later and check on whatever you've found.

[The village idiot]

This might be a really simple but long way of doing things.... Get a soldering iron, and heat EVERY joint until the solder is liquid. Then move on to the next. Only problem is that if you heat a few things too much, they will stop working. On the old Sony's and RCA's they would use a metal rivet to pass power from one side of the board to the other. The rivets would expand and contract until they were loose. There was no solder on the early units, so you might look for those. With the cover off, they may never get warm enough to expand and lose contact. Also look for large solder "blobs" that seem to do nothing. They may be used to do the same job as the rivets.

[Hatz]

Well, I believe I have found the general location but its towards the front of the screen more. Everything was going good.......until i was brushing that spot and my forearm touched the board where the tube is at.


MY LORD did that scare me. Now I got a nice little series of solder points on my arm. I got shocked by 5 of them....hehehe. See Picture.



Well now I'm a little timid to get back in there but I think I will eventually. Maybe after dinner. It didnt hurt at all, just a nice wake up call. Doesnt hurt as bad as working on lawn mowers (summer job) and accidentally hitting the spark plug with your hand........that throws you back a bit.


Hatz

[Roundabout]

Hatz, I TOLD you to be careful! Jeez, you'll go frying yourself then I have to feel guilty..
Sorry it took so long to get back to you. Was out all night at Kohl's (tip: don't ever let wife into this store). Meanwhile, you're out electrocuting yourself. BE CAREFUL!
So, what did you find? Were you able to isolate any bad connections with the brush? Did the screen ever fill out completly? Sometimes it can be really difficult to isolate, if it's very sensitive to even the slightest movement. Like Village Idiot said, you could just try resoldering everything in the general area where you suspect the bad connection is. See what fun it is to be a Tech?
I'm curious if you got anywhere with it yet. Bring me up to date.

[Hatz]

Roundabout:

I havent exactly found the exact location but I have narrowed it down quite a bit...........the only thing is, the part of the board I would have to solder is in the front. So that means I am going to either have to pull the board or some how take the other half of that bottom cover off.

I only have one class tomorrow so I will probably dick around with it then.
Thanks again.

Hatz

[Roundabout]

Hatz,

Ha! Now the fun begins. Just when you think you've found the problem for sure, it'll be somewhere else. Welcome to the world of electronics repair !
OF COURSEyou'll have to take the board out...it's called Murphy's Law. I hope it isn't designed like Sony crap, when you take the board out, you have to disconnect everything...and when you disconnect everything you can't troubleshoot. I had an entire box of homemade extension cables for 100 different models that were designed like this. You can't imagine how many product designers I cursed every day.
You still didn't mention if it started working or not, or at least seemed like it could. Did you ever see a picture on the screen when you were tapping on the MCB? Hopefully you're getting closer.

[Hatz]

Well the reason I think I found the right spot is when i push the toothbrush back towards the front where my hands cant reach.....the screen stays on permanently. I can let go of the toothbrush and just let it sit there and the video will stay full screen just like a new TV.

Do you think this is the right spot?? Its my best guess.

Of course I am going to have to pull the whole board out. I just knew you were going to say that.......hehehe.


Hatz

[gmatov]

Hatz,

Have you looked at the area you think you have isolated with a pretty good magnifying glass? You seem to have it down to a few square inches. Look closely.

I think Roundabout will agree you will see what looks like either a "crack" in the joint itself, or the same where the solder joint may have broken from the board.

Solder is an alloy of tin, lead, and maybe antimony. Tin and lead are very ductile metals, very soft., therefore you would tkink it can't crack.

A "cold joint", however, results in something closer to zinc, crystalline, easily cracked. Must be reheated to above melting, else it won't bond to the leads properly, which may also be what your problem is, an improperly bonded lead.

Again, needs reheated to rebond, with flux, actually resin core solder, not acid core, as the acid core will do more damage than what was the original problem.

Go to the Shack and buy a small tube, probably an ounce and 5 or 6 feet of wire, a buck or two. They don't sell plumber's solder, so you're safe there.

Get a good light and a good glass. I think you'll find it. You have gotten all the help in the world from Roundabout.

Are you sure you can't see the bad joint from where you have the board? You should see it from the top as well as from the bottom. Also, if you use a low light area, you may actually be able to see some very faint sparks when you use the brush.

Good luck, again. Really hope you fix it. Nothing more satisfying than to do something like this.

George