got a television from a neighbor. she told me it works "sometimes"
so i brought it home and pluged it in.. it worked just fine.
now after a few minutes white lines started appearing horizontially across the verry top of the screen.. after a day or so.. it just wont turn on anymore..

does this sound like it might be something that a noobie could fix if he knew what to look for? or what might be the culprit component? :scratch2:

So, place a photo of the set showing the entire front with the screen showing what you describe. Take the back off if you have the ability to do so and post a pick showing the full back/interior area. Write the model number with the posted pics. Somebody here may recognize the problem and give you a clue or tell you what to do. The other way to most certainly repair it is to search the correct category for info that most certainly is here that will let you know everything that is needed to do.
If you send me a round trip ticket and wine and dine me very well I can personally sit with you and even hold your hand if you like to help you click your mouse on all here that will solve your problem.

Brand, model number, does it have tubes or is it solid state?

Sounds like a vertical failure of some sort, pictures would be a great help. Probably a cap or possibly a transistor if the set is new enough to have them, which it sounds like it is by your description.

thanks for the attention to my problem..
ok i took some photos.. and gathered some information.
on the front it says Signature2000.. than on the back the model number is GRD15141
manufactured june 1990. service number is GRD15141f01

i powered it up in attempt to photo the white lines but it nolonger does that.. instead there is a really bright light thats streaches across the very center of the screen horizontally. as if the whole picture was squeezed together. audio is working fine tho.
im working on linking the pictures so you can see fullsize photos.

http://img836.imageshack.us/i/sany1263.jpg/
http://img638.imageshack.us/i/sany1267.jpg/
http://img693.imageshack.us/i/sany1268t.jpg/
http://img822.imageshack.us/i/sany1270.jpg/
http://img251.imageshack.us/i/sany1271.jpg/
http://img828.imageshack.us/i/sany1274.jpg/

My vote would be for a bad cap in the vertical circuit. Don't run it for long as-is unless you can turn the brightness down (which you probably can't without accessing the menu.)

Search the circuit board for the vertical section and look, you might get lucky and see obvious signs of a faulty cap (leakage/corrosion around the base, a bulging top) otherwise you might have to just replace all the electrolytic caps in that circuit. Not a huge ordeal once the board is pulled. You can get those parts at RadioSchlock, though there are cheaper/better places. If it blew a transistor, though, you have a problem out of my league!

ok i noticed here. that in photo3.. one of the smaller caps have what looks like a brownish orange spot below it..
i will replace it tomorrow when it is less risky of getting shocked because i just had it plugged in..

i will remove the board as much as possible.. to reveal the underside. and check for broken solder connections while replacing that cap.. also.. should i try and locate a schmatic and see if there are any fuzeistors or picofuzes. and test them?

thanks verymuch for the reply bgadow..
now is it possible for me to completely remove the board.. by that specifically i mean the really fat red wire?

You need to discharge the high voltage first. Here is my favorite method of doing it: Get a large screwdriver and a wire with alligator clips. Connect one end securely to the metal shaft of the driver and the other end securely to something grounded on the set-there will be some sort of spring that makes contact with the outside of the picture tube and it will have a small wire connected to it, probably running somewhere on the chassis. Hook the other alligator clip to that spring or that wire. There might be a metal frame for that chassis which will work, too. Now, with one arm behind your back, and your hand off the screwdriver shaft, poke the tip of the screwdriver under the "suction cup" HV connector on the picture tube. When you make contact with the connection you should hear a "snap" from the HV discharging. Do it a couple times. Then you can grasp the rubber cup and pull the connector off the tube. Usually you have to squeeze it and wiggle it around some. Before you put it back on there, I would discharge the HV again. They can build up a charge just sitting there.

The HV wouldn't kill you; but you sure wouldn't like the experience!

Looks like a Thomson made set - CTC157-166 possibly. If so, all of the 500-series caps should be checked/replaced. C4505, a 220uf/35v is a common culprit, as is C4502. Both would be marked C505 / C502, as they leave the prefix off most board markings. The one with the leakage in the photo would be a safe start!

Cheers

hehe awesome.. thats simple enough..
i wasent sure if it was ok to remove the suction thinggy.. thought there might of have been gas or something inside there.
now putting it back in should be simple too right? just squeeze it and set it in?

Looks like a Thomson made set - CTC157-166 possibly. If so, all of the 500-series caps should be checked/replaced. C4505, a 220uf/35v is a common culprit, as is C4502. Both would be marked C505 / C502, as they leave the prefix off most board markings. The one with the leakage in the photo would be a safe start!

Cheers

Awesome! i will replace all i can as soon as i can, hopefully tomorrow.
is it wise to try it after replacing them?

I'm pretty sure the vertical IC is toast. The IC dies when the caps dry out. The caps cause the lines on the top of the picture. When the IC dies it causes just the white line across the screen.
Changing the caps near the IC and the IC usually bring that set back to life! That set can provide a great picture once fixed and set up properly.

ok so if i replace the caps, and it doesnt fix it.. i should then replace the IC..
does the IC look like a transistor? (small black thing with 3 leads on it?)
it would probably be nearby right?

im going to look for a schmatic now..

ok i replaced the cap..
it still does the same thing..
ok there is a big heatsink near that cap has u4501 VERT engraved on it..
the black chip thinggy cliped onto it is labled. LA7831. than below that 51105 than below that.. 01a 0b4 (thats all on the chip)

im guessing that is the vertical IC>>??

should i just buy something labled la7831.. or can sombody find me a link to a site selling one?

if interested.. the cap i replaced was the one leaking.. a 100uf 20v. i replaced it with a 100v 50v
the old one was flat on the top, but the bottom was buldging and leaking orangeish brown stuff

i seem to be finding that part on websites but only for sayno and philips televisions.. does that make a difference?
i found this on mouser. they seem to have something called cross reference part.

http://www.mouser.com/Search/Refine.aspx?Keyword=LA7831
is that like a compatiable replacement?

Yup. looks like a CTC167 to me. I had a floor model CTC167 that was bought from steinbergs before they went out of business.

I had to change darn near 80% of all the caps before it sprung back to life. out of those 80%, maybe about 50% had crud/leakage around the pins. Then the tube wore out and i junked it.

It started as vertical foldover that would go away after a slow period. then eventually to collapse, and loss of HV.

Yup. looks like a CTC167 to me. I had a floor model CTC167 that was bought from steinbergs before they went out of business.

I had to change darn near 80% of all the caps before it sprung back to life. out of those 80%, maybe about 50% had crud/leakage around the pins. Then the tube wore out and i junked it.

It started as vertical foldover that would go away after a slow period. then eventually to collapse, and loss of HV.

thanks for this info i will replace all of the other caps soon

if your going to use this TV as a daily watcher, it might be worth just recapping it as if you were doing a 50s era TV.

its getting old. caps dont last forever.

anybody kno where i should buy the proper IC?>

The vertical IC is mounted on the U-shaped heatsink closest to the CRT - picture 1271.jpg shows it to the right. The part number is on the chip, and starts with LA.... the whole six letters and numbers are the part number, something like LA7830, LA7838 or the like. Do a Google Shopping search to find a replacement - the LA7830 (which I think it might be) is only a couple of bucks from some dealers.

Cheers,

ok so im planning on ordering this tonight
http://www.bdent.com/ProductDetails.asp?ProductCode=LA7831&CartID=1

although google search didnt come up with this site.. most of the other sites had a minimum purchase i had to spend.. something like $50.
this one is a $12 minimum.. the IC is only $7.23 so i will order the caps needed at the same time to make up the difference..

is it important at all or could it benifit from a good cleaning?

ok i have all the caps and the IC..
now i noticed something new now..
on the main board near the powersupply area i see a circular disc about the thickness of a nickel but the legnth of a dime, that is disconnected on each end just kinda hanging out..
almost like a ceramic cap with no shell on it..
its grey and has 100-01a a170 1 written on it..

following the traces that connect to it. i can see it connects to a relay (i think) and a empty terminal marked degauss
i can see that its not used (i think) unless you are degaussing the television..
should i just solder it back in place and leave it alone?

any idea what this part is? should i just try and solder it back together or does it need to be replaced?

oh wait it actually runs into the ground wire attached to the springs that go around the outisde of the tv..
think when i discharged the television maybe it poped that component?

crap.. i replaced the IC., and most of the caps and still have the same exact problem..
it still has the thin line across the middle..

anything else i should check guys?

btw i put alittle drop of solder on each end of that component that came loose and reattached it.

When the original IC shorted, it likely took out a small value resistor and possibly the B+ diode that provides B+ to the IC. This voltage source comes from the flyback transformer.

Didn't read the whole thread, have you ohm'd out the yoke?

ohm'd out the yoke??

thanks much for the replys.
ok so most likley i need to replace those components..
i know how to check resistors.. but how do i check a diode, or should i just follow the trace from the b+ to a diode?

now without a schmatic.. is there a way i can find out what kind of diode it is or would any more beefy diode work in place?

im going to take it back apart now and take a closer look

ok so with it open just visually i think i might of have found the bad components..
i labled the points of interest as 1,2,3 1 is a resistor that looks strangely dark on one end, and 2 is the cap that was leaking that i have replaced already. and 3 is what looks like a very dirty diode..

uh oh. i found another cap while staring at this that is leaking pretty good..
i hope this doesent mean i need to buy another vertical IC now??
:tears:

btw i cleaned off that dirty diode and it looks the same as the others.. it was just covered in cap juice.


why do all these caps leak out the bottom instead of buldge at the top like i usually find them?

ok so i found the bad resistor, and learned how to test diodes,, (sorta) the website explained, as i understood it, that you should get a reading in one direction but not in the other direction..
it didnt clarify weather a bad one would be open both ways, or weather impendence would rise or drop when you are dealing with a bad one....
im looking in my box o parts for another resistor to replace this one..
by looking at it very carefully it looks like the colors are black-black-gold-gold
now it cant start with black and it also has a tiny bit of brown near the edge of the black also on one side it looks like the 2nd ring might of have been a white or grey..
if grey 1.8ohms if white 1.9ohms
is one of these gambles safer than the other?
or does it need to be exact??

ok i found a resistor at a really really close resistance.. if not the exact..
the color code is brown-grey-gold-gold.. so 1.8ohms

WHOOOOO ok its working again. now just to be safe before i put this tv in fulltime use...
i am going to do more recapping.. sofar there has been 3 caps leaking blackish stuff from there bottoms.

also about that resistor i installed..
im pretty confident the origional resistor colors were either
brown-white-gold gold (1.9) or
Brown-grey-gold gold.. (1.8)
the difference is .1ohms..

how important is it that it is EXACTIALLY the same resistance??
what i put in there is a Brown-Grey-gold-gold (1.8ohm)

is it mostlikley the Vertical IC would run hotter than normal?
or maybe that the screen might not streach to be the full vertical size?

It should not make any difference. That resistor is only there for safety reasons. It is designed to open, should an excessive load take place on the B+ line feeding the vertical output circuit.

I've seen several of these sets where the caps would leak and eat the foil off the PC board. RCA and Mitsubishi must have been getting their caps from the same supplier. No, wait, I think the caps in Mitsubishi sets were much worse.

Wow good to know.. reason being in the areas where the caps were leaking there are tiny black bubble like formations forming on the foil underside the board..
think i should maybe run a wire from point to point bridging those traces affected??

also thanks a whole lot Radiotvnut, and also the other people who helped me before.
im happy to get this tv in our livingroom.
our current tv is a little 17"
its hard to see whats going on in some movies and also play on a split screen in videogames...

this tv is a 26" so its great compared to the other..

i think the thing that i like the most about this little project. is that i learned alot..
this is the first project where i actually found caps leaking from the bottom instead of the caps buldging at the tops..
also i didnt know about the leaking caps eating away at the traces..
(btw the leaking caps were all 105c Nichicon) each was a different uf rating, first one was a 100uf 25v, second was a 220uf 35v and third was a 470uf 16v

does anybody know why some caps leak at the bottom and some buldge?
is one related to heat over time, and the other high voltage for too long or something like that?

well if you want to keep the set running, and if its sentimental to you in any way to make it worthwhile, i would replace ALL electrolytics.

you may want to google "capacitor plague". It will explain a lot about the drooling capacitors.
Also, do keep an eye on your soldering iron tip. Usually the oil left by the caps on the board will eat the tip rapidly!
The :thumbsdn:worst I ever saw for electrolytic problems were Mitsubishi 36 inchers. The would have two and three inch areas of foil turning black when some of their caps drooled.

I've noticed how manufacturers like to put capacitors close to heat sinks and nice warm wirewound resistors. Often, they just get cooked and fail.

I have a 1991 Sony 27" that used to eat the big regulator IC regularly, about once a year or so. It got so bad, that I now keep a spare IC when I buy them in stock for this set.

The last time I did the repair, I installed a 3" box fan that blows air across the IC and its heat sink. It's a 220 volt fan running on 120 volts, so it runs really quiet. I dont notice any noise from the set. It's been almost 3 years, and the IC is happy.

well ive come to learn that engineers dont give a hoot. They just engineer the crap. they dont have to worry about fixing it.

if they had to fix what they engineered, the electronics world would be 180 of what it is today.

Example: if you ever have to service a 5 disc CD changer trayload mechanism from Panasonic, such as the SA-PM19 or SA-pm29, or SA-PM33, etc etc etc... DONT.. BE WARNED.

I tore it apart and retimed it 3 times already, and still the timing isnt correct and jams at the trays. There are timing marks and holes all over the thing, but the service assembly manual being in broken English does NOT help matters any at all.

well its almostly completely recapped, i recapped all the ones near heatsinks and most of the other ones, i left some of them alone because of the locations,..
i had to adjust the brightness, i must of have bumped it when working on it.
this set has a great picture.