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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
Posted to sci.electronics.repair
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Can you take a look? (help diagnose problem on TV ...) toss or repair?
Hello,
I have a 27-inch Toshiba tv (Model 27A41 - http://www.cs.oberlin.edu/~esmail/tv.jpg) that is only 4 years old and already failing. I was hoping someone could give me an idea what the problem might be, and if it's worth even bothering hauling this behemoth to be fixed. Or alternatively, how long this tv might last in its current state. I get different bands of colors "bowing in" from the sides, where I seem to be loosing one of the RGB channels. There are no magnetic sources etc nearby. Here is a pic of what the tv looks like when it displays a blue only menus screen for my vcr. http://www.cs.oberlin.edu/~esmail/tv_problem.jpg In addition to the color problem, I sometimes also get some flicker accompanied by some crackling sound as if a contact is being connected/disconnected. Every once in a while (very rare) the tv flips back to being normal for a few seconds, but generally the messed up colors are permanent. The flickering/buzzing sound happens somewhat rarely too but not as rare as getting a normal pic. Here are two video clips showing the tv in action: http://www.cs.oberlin.edu/~esmail/tv_problem.avi http://www.cs.oberlin.edu/~esmail/tv_problem2.avi Any ideas? Thanks, Esmail |
#2
Posted to sci.electronics.repair
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Can you take a look? (help diagnose problem on TV ...) toss or repair?
Esmail Bonakdarian wrote: Hello, I have a 27-inch Toshiba tv (Model 27A41 - http://www.cs.oberlin.edu/~esmail/tv.jpg) that is only 4 years old and already failing. I was hoping someone could give me an idea what the problem might be, and if it's worth even bothering hauling this behemoth to be fixed. Or alternatively, how long this tv might last in its current state. I get different bands of colors "bowing in" from the sides, where I seem to be loosing one of the RGB channels. There are no magnetic sources etc nearby. Here is a pic of what the tv looks like when it displays a blue only menus screen for my vcr. http://www.cs.oberlin.edu/~esmail/tv_problem.jpg In addition to the color problem, I sometimes also get some flicker accompanied by some crackling sound as if a contact is being connected/disconnected. Every once in a while (very rare) the tv flips back to being normal for a few seconds, but generally the messed up colors are permanent. The flickering/buzzing sound happens somewhat rarely too but not as rare as getting a normal pic. Here are two video clips showing the tv in action: http://www.cs.oberlin.edu/~esmail/tv_problem.avi http://www.cs.oberlin.edu/~esmail/tv_problem2.avi Any ideas? Thanks, Esmail The problem you're showing wouldn't be that expensive to reapair by an honest, qualified tech. If it ended up being what I think it is, I wouldn't charge more than 40 bucks to take care of it. Call around. Don't toss it just because you don't know what's wrong with it. www.techdata-kicksass.net |
#3
Posted to sci.electronics.repair
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Can you take a look? (help diagnose problem on TV ...) toss orrepair?
The problem you're showing wouldn't be that expensive to reapair by an honest, qualified tech. If it ended up being what I think it is, I wouldn't charge more than 40 bucks to take care of it. Call around. Don't toss it just because you don't know what's wrong with it. Hi, tossing stuff is really something I'd rather not do. Can you give me an idea of what you think is wrong with it? That way I can at least mention this when I call around. I'd gladly pay that amount to have it fixed. The closest authorized place is about half an hour down the interstate (I live in a tiny town w/ no local repair place), and said it might take them 3 or 4 weeks to get to it. I only have one tv so that seems long. Should I take it to best buy? Thanks, Esmail |
#4
Posted to sci.electronics.repair
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Can you take a look? (help diagnose problem on TV ...) toss or repair?
"Esmail Bonakdarian" wrote in message news:KSWgg.4497$Id2.1713@trnddc03... The problem you're showing wouldn't be that expensive to reapair by an honest, qualified tech. If it ended up being what I think it is, I wouldn't charge more than 40 bucks to take care of it. Call around. Don't toss it just because you don't know what's wrong with it. Hi, tossing stuff is really something I'd rather not do. Can you give me an idea of what you think is wrong with it? That way I can at least mention this when I call around. I'd gladly pay that amount to have it fixed. The closest authorized place is about half an hour down the interstate (I live in a tiny town w/ no local repair place), and said it might take them 3 or 4 weeks to get to it. I only have one tv so that seems long. Should I take it to best buy? Thanks, Esmail The fault is either convergence or colour purity, the CRT has a "shadow mask" behind the phosphor coated glass face plate the R, G, & B electron beams have to be accurately aimed at the tiny holes in the shadow mask so they only strike the correct colour phosphor dot (or stripe). There are two possibilities: the first is the degauss posistor in or near the mains input circuitry, this demagnetises the shadowmask each time the set is switched on, a faulty posistor can give weird colour distortions but is usually more random in appearance than the division into R, G & B shown in your photo. More likely is the static convergence and purity rings on the CRT neck between the scan coils and the CRT base board, these rings are usually moulded plastic with a magnetic filler and are usually mounted on a ring-lock assembly which can (in rare cases) work loose and allow the rings to move. The back most spigots on the assembly are the ring-lock cam, if this is not loose then either the rings have been previously tampered with and re tightened or the assembly has been subjected to a strong external magnetic field, if the rings are loose they may have moved so realignment shouldn't be too difficult. If you can get hold of a service manual and borrow a test pattern generator the realignment procedure is really quite straightforward matter of following the steps described in the manual.. |
#5
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Can you take a look? (help diagnose problem on TV ...) toss or repair?
In message , ian field
writes The fault is either convergence or colour purity, It's not convergence. More likely is the static convergence and purity rings on the CRT neck between the scan coils and the CRT base board, these rings are usually moulded plastic with a magnetic filler and are usually mounted on a The fault is almost definitely not related to the purity/convergence rings as it's intermittent/changing, the crackling noise gives it away as a problem with the degauss circuit, either a dry joint on one leg of the posistor or coil connector, a faulty posistor or degauss coil. I'd replace the posistor first and re-solder all associated connections. If you can get hold of a service manual and borrow a test pattern generator the realignment procedure is really quite straightforward matter of following the steps described in the manual.. If you mess about with the rings to try and fix a fault, you'll definitely need a test pattern generator and a lot of patience. -- Clint Sharp |
#6
Posted to sci.electronics.repair
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Can you take a look? (help diagnose problem on TV ...) toss orrepair?
Hi Ian,
ian field wrote: If you can get hold of a service manual and borrow a test pattern generator the realignment procedure is really quite straightforward matter of following the steps described in the manual.. Well, that's out of my comfort zone/area of expertise, but if I am understanding you correctly, you concur with the previous poster in that this seems like a fairly trivial repair and shouldn't cost too much? Once again, I would rather not have to toss this thing out if a fairly simple (and cheap) repair can take care of it. Thanks, Esmail |
#7
Posted to sci.electronics.repair
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Can you take a look? (help diagnose problem on TV ...) toss or repair?
"Clint Sharp" wrote in message ... In message , ian field writes The fault is either convergence or colour purity, It's not convergence. More likely is the static convergence and purity rings on the CRT neck between the scan coils and the CRT base board, these rings are usually moulded plastic with a magnetic filler and are usually mounted on a The fault is almost definitely not related to the purity/convergence rings as it's intermittent/changing, the crackling noise gives it away as a problem with the degauss circuit, either a dry joint on one leg of the posistor or coil connector, a faulty posistor or degauss coil. I'd replace the posistor first and re-solder all associated connections. If you can get hold of a service manual and borrow a test pattern generator the realignment procedure is really quite straightforward matter of following the steps described in the manual.. If you mess about with the rings to try and fix a fault, you'll definitely need a test pattern generator and a lot of patience. -- Clint Sharp That's certainly possible, and dry joints around the degauss posistor (or its relay if it has one) are not at all unlikely now so many manufacturers are using lead-free solder - it seems to almost fall apart after only a couple of years!!! |
#8
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Can you take a look? (help diagnose problem on TV ...) toss or repair?
On Mon, 05 Jun 2006 14:47:40 GMT, "ian field"
There are two possibilities: the first is the degauss posistor in or near the mains input circuitry, this demagnetises the shadowmask each time the set is switched on, a faulty posistor can give weird colour distortions but is usually more random in appearance than the division into R, G & B shown in your photo. More likely is the static convergence and purity rings on the CRT neck between the scan coils and the CRT base board, these rings are usually moulded plastic with a magnetic filler and are usually mounted on a ring-lock assembly which can (in rare cases) work loose and allow the rings to move. The back most spigots on the assembly are the ring-lock cam, if this is not loose then either the rings have been previously tampered with and re tightened or the assembly has been subjected to a strong external magnetic field, if the rings are loose they may have moved so realignment shouldn't be too difficult. I vote for #1. It can't be the purity adjustment because he said it "flips" back to normal sometimes. Purity rings don't adjust themselves. A bad connection in the degaussing circuit could return to normal occasionally. Andy Cuffe |
#9
Posted to sci.electronics.repair
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Can you take a look? (help diagnose problem on TV ...) toss orrepair?
Hi,
So the consensus is that this is a fairly trivial thing to repair with a bill well under $100 ? I realize it's hard to diagnose something based on a video & jpg posted on the web, but if everyone's guess is right. So, it's best to go for the repair, if I'm drawing the right conclusions on the above posts, yes? Esmail |
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