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Posted: 4/17/2014 6:17:20 PM EDT
I acquired an NEC Accusync PV40 LCD TV/monitor for free.
It works for a bit then after about 7-10 minutes, the picture goes black but I still have sound. I took the back off to look for the obvious bad capacitors but didnt really see anything. Anyone have any ideas besides toss it? Thanks |
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[#1]
When it goes black shine a flashlight on it, if you can see your content/picture then your problem is with the backlight.
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[#2]
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[#3]
If you turn it off and then back on again does it immediately work for another 7-10 minutes? Or does it have to be off for awhile before it can work again?
If it has to be off for awhile before it'll work again it is likely related to heat, you can test this by running it for awhile with the back/covers off and have a fan on it. If it works for awhile like this I'd say it's still likely that it could be a capacitor, they can be bad without outward signs sometimes, and heat can change their operating characteristics when they're failing. This forum is a good source for info on capacitor replacement and general repairs, the guys on there really know their stuff. |
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[#4]
Quoted: If you turn it off and then back on again does it immediately work for another 7-10 minutes? Or does it have to be off for awhile before it can work again? If it has to be off for awhile before it'll work again it is likely related to heat, you can test this by running it for awhile with the back/covers off and have a fan on it. If it works for awhile like this I'd say it's still likely that it could be a capacitor, they can be bad without outward signs sometimes, and heat can change their operating characteristics when they're failing. This forum is a good source for info on capacitor replacement and general repairs, the guys on there really know their stuff. View Quote I can turn it right back on and it will do it all over again. Off to look at your link Thanks! |
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[#5]
There are about 10 dozen things to do in a circuit before looking for random capacitors to replace. I have no idea how this business of opening a radio or television and simply swapping capacitors got started, but it ought to stop, it puts folks about 10 steps closer to becoming Democrats.
I think I'll go out and change all the oxygen sensors in my cars. That ought to fix something. |
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[#6]
Quoted: There are about 10 dozen things to do in a circuit before looking for random capacitors to replace. I have no idea how this business of opening a radio or television and simply swapping capacitors got started, but it ought to stop, it puts folks about 10 steps closer to becoming Democrats. I think I'll go out and change all the oxygen sensors in my cars. That ought to fix something. View Quote |
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[#7]
Quoted:
There are about 10 dozen things to do in a circuit before looking for random capacitors to replace. I have no idea how this business of opening a radio or television and simply swapping capacitors got started, but it ought to stop, it puts folks about 10 steps closer to becoming Democrats. I think I'll go out and change all the oxygen sensors in my cars. That ought to fix something. View Quote Because it works a lot of the time? Especially if there is visible damage or if they're a brand known to have produced bad caps in the past. |
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[#8]
Quoted:
There are about 10 dozen things to do in a circuit before looking for random capacitors to replace. I have no idea how this business of opening a radio or television and simply swapping capacitors got started, but it ought to stop, it puts folks about 10 steps closer to becoming Democrats. I think I'll go out and change all the oxygen sensors in my cars. That ought to fix something. View Quote There was a big run of defective electrolytic capacitors a few years ago. They showed up in all kinds of stuff and failed quite often. This is where the "capacitor craze" most likely came from, so it's not totally unwarranted for people to look there first. |
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[#9]
Paul.
You need to talk to Paul. He's a mod here and a guru TV man with expertise in such matters. Send him a PM and he will help you out. |
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[#10]
More than likely you are having thermal issues with a chip. Does this happen to all of your video outputs??
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[#11]
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[#12]
Quoted:
I dont have anything to plug into it. Just a digital TV converter View Quote View All Quotes View All Quotes Quoted:
Quoted:
More than likely you are having thermal issues with a chip. Does this happen to all of your video outputs?? Just a digital TV converter My bad I've been a drinkin, I meant to type IN-puts. |
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[#13]
Quoted: My bad I've been a drinkin, I meant to type IN-puts. View Quote View All Quotes View All Quotes Quoted: Quoted: Quoted: More than likely you are having thermal issues with a chip. Does this happen to all of your video outputs?? Just a digital TV converter My bad I've been a drinkin, I meant to type IN-puts. |
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[#16]
I ask this because some of these TV's will have a asic chip in line between your main processor and the HDMI or DVI inputs. A/V and component don't require such so this can help you narrow down where to look.
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[#17]
BTW if this was a capacitor issue it would knock out everything on the input in use, so the fact that you have sound is an indicator that it's going to be a chip.
Sorry I had to edit my gibberish. |
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[#18]
Also because you can't turn the TV off normally makes me lean heavily towards the processor but there is still potential that something else could be drawing current away from it causing it to react sluggishly or not at all when you hit the power button..
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[#20]
My Samsung shit the bed(was kinda doing the same thing, then stopped working completely), the first thing to notice the LED in the front. Mine was a solid red and then cut out completely when the TV cut on(normal conditions). It started flashing when on, then when the TV broke the picture wouldn't come on but that LED would flash.
That flashing was a out of tolerance PS voltage. 2 Caps later and my TV worked fine. The Caps are easy to spot when they go bad. |
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[#23]
Quoted:
My Samsung shit the bed(was kinda doing the same thing, then stopped working completely), the first thing to notice the LED in the front. Mine was a solid red and then cut out completely when the TV cut on(normal conditions). It started flashing when on, then when the TV broke the picture wouldn't come on but that LED would flash. That flashing was a out of tolerance PS voltage. 2 Caps later and my TV worked fine. The Caps are easy to spot when they go bad. View Quote Not always. Most of the ones I have found had no indications of being puffed or any smoke residue. Sometimes you just have to break out a multimeter and trace that sumbitch down. |
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[#24]
Quoted:
That methodology is due in large part to shenanigans like this: http://usr.audioasylum.com/images/5/52135/FakeChinesecaps.jpg If a tv or flat computer monitor made between 2003-2008 starts acting funny (ie, suddenly has to warm up before it comes on,) or, hell, any consumer electronic product made during that time period (like a motherboard that started throwing intermittent memory errors) started acting up, the most efficient troubleshooting step was--at one time--to open it up and look for exploded or distended capacitors. I've had two capacitors pop--quite audibly--while using equipment from that timeframe. View Quote View All Quotes View All Quotes Quoted:
Quoted:
There are about 10 dozen things to do in a circuit before looking for random capacitors to replace. I have no idea how this business of opening a radio or television and simply swapping capacitors got started, but it ought to stop, it puts folks about 10 steps closer to becoming Democrats. I think I'll go out and change all the oxygen sensors in my cars. That ought to fix something. That methodology is due in large part to shenanigans like this: http://usr.audioasylum.com/images/5/52135/FakeChinesecaps.jpg If a tv or flat computer monitor made between 2003-2008 starts acting funny (ie, suddenly has to warm up before it comes on,) or, hell, any consumer electronic product made during that time period (like a motherboard that started throwing intermittent memory errors) started acting up, the most efficient troubleshooting step was--at one time--to open it up and look for exploded or distended capacitors. I've had two capacitors pop--quite audibly--while using equipment from that timeframe. Yep, some Chinese companies have put there asses out of business for shit like that. Luckily that helps drive some of my business. |
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[#25]
Quoted:
Not always. Most of the ones I have found had no indications of being puffed or any smoke residue. Sometimes you just have to break out a multimeter and trace that sumbitch down. View Quote View All Quotes View All Quotes Quoted:
Quoted:
My Samsung shit the bed(was kinda doing the same thing, then stopped working completely), the first thing to notice the LED in the front. Mine was a solid red and then cut out completely when the TV cut on(normal conditions). It started flashing when on, then when the TV broke the picture wouldn't come on but that LED would flash. That flashing was a out of tolerance PS voltage. 2 Caps later and my TV worked fine. The Caps are easy to spot when they go bad. Not always. Most of the ones I have found had no indications of being puffed or any smoke residue. Sometimes you just have to break out a multimeter and trace that sumbitch down. The caps in mine had the tops that pop out when they go. If I had scats I woulda did all that,, |
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[#26]
Quoted:
The caps in mine had the tops that pop out when they go. If I had scats I woulda did all that,, View Quote View All Quotes View All Quotes Quoted:
Quoted:
Quoted:
My Samsung shit the bed(was kinda doing the same thing, then stopped working completely), the first thing to notice the LED in the front. Mine was a solid red and then cut out completely when the TV cut on(normal conditions). It started flashing when on, then when the TV broke the picture wouldn't come on but that LED would flash. That flashing was a out of tolerance PS voltage. 2 Caps later and my TV worked fine. The Caps are easy to spot when they go bad. Not always. Most of the ones I have found had no indications of being puffed or any smoke residue. Sometimes you just have to break out a multimeter and trace that sumbitch down. The caps in mine had the tops that pop out when they go. If I had scats I woulda did all that,, Even the caps that are designed to "pop" can give a man a run for his money. Sometimes the frequency can fluctuate through them while the voltage is still ok. Or they pop in the opposite direction where the bottom will swell and the top will have a slight indention or just stay flat. |
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[#27]
Quoted:
There are about 10 dozen things to do in a circuit before looking for random capacitors to replace. I have no idea how this business of opening a radio or television and simply swapping capacitors got started, but it ought to stop, it puts folks about 10 steps closer to becoming Democrats. I think I'll go out and change all the oxygen sensors in my cars. That ought to fix something. View Quote I've fixed a Samsung monitor and an LG TV by replacing bad capacitors, so it can work. I did do some research before I opened either one of them up and found that bad capacitors where a know issue in each case. |
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[#28]
But I'm glad you were able to spot and fix the problem with your TV, Ironknife.
If something is going to fail I would prefer it to happen like that so that a lot of time isn't spent tracing it down. |
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[#29]
Quoted:
Even the caps that are designed to "pop" can give a man a run for his money. Sometimes the frequency can fluctuate through them while the voltage is still ok. Or they pop in the opposite direction where the bottom will swell and the top will have a slight indention or just stay flat. View Quote View All Quotes View All Quotes Quoted:
Quoted:
Quoted:
Quoted:
My Samsung shit the bed(was kinda doing the same thing, then stopped working completely), the first thing to notice the LED in the front. Mine was a solid red and then cut out completely when the TV cut on(normal conditions). It started flashing when on, then when the TV broke the picture wouldn't come on but that LED would flash. That flashing was a out of tolerance PS voltage. 2 Caps later and my TV worked fine. The Caps are easy to spot when they go bad. Not always. Most of the ones I have found had no indications of being puffed or any smoke residue. Sometimes you just have to break out a multimeter and trace that sumbitch down. The caps in mine had the tops that pop out when they go. If I had scats I woulda did all that,, Even the caps that are designed to "pop" can give a man a run for his money. Sometimes the frequency can fluctuate through them while the voltage is still ok. Or they pop in the opposite direction where the bottom will swell and the top will have a slight indention or just stay flat. Just saying what happened to me. Frequency change? |
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[#30]
Quoted:
But I'm glad you were able to spot and fix the problem with your TV, Ironknife. If something is going to fail I would prefer it to happen like that so that a lot of time isn't spent tracing it down. View Quote I had no complaints about it,, was right easy,, I don't have scats to the TV so chasing shit down in there woulda been a bitch |
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[#31]
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[#32]
Quoted:
Pull the tubes and take them to the local Sav-On, they have a tube tester. http://www.tuberadios.com/eico660/sign2.jpg View Quote Been a while since I seen tubes |
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[#33]
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[#34]
Replaced 400-500 Teapo brand capacitors at work, they were in IPTV set top boxes. The DVR boxes were the same hardware, with the addition of a hard drive and fan, we only had 3-4 of those boxes go bad due to capacitors, all the rest were the fanless non-dvr boxes. They were failing well before their rated hours at the working temperature, and this would be between 2010-2012, so there are still plenty of bad manufacturers out there.
Also, on these devices depending on the severity of the damage on the capacitors you'd have anything from bad color on screen to no picture, but audio wasn't affected. Saw anything from bulged tops, blown out bottoms, leaking tops and no outside indication at all. Biggest lesson I learned, if you have a bad one, and you see more than one of that brand and part number in use on the board, replace all of them, since they've all been subject to similar conditions. Not necessarily saying it's capacitors though, but in my opinion they're one of the easier and cheaper things to replace. |
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[#35]
Quoted:
"Farads" Sometimes the rate at which the caps charge and discharge can alter while the voltage is right on target. View Quote View All Quotes View All Quotes Quoted:
Quoted:
Frequency change? "Farads" Sometimes the rate at which the caps charge and discharge can alter while the voltage is right on target. Never seen PS caps do that, usually they are there for filters, seen increases in ripple voltage(never a freq change though, usually stays at 60 or 120 hz according to half or full wave rectification) If the cap is part of a freq determining amp(oscillators, band pass or reject filters,Tank circuit, LC circuits or emitter caps) I've seen drifts in frequency and noise generated. Guessing that's what you meant. |
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[#36]
Quoted:
Pull the tubes and take them to the local Sav-On, they have a tube tester. http://www.tuberadios.com/eico660/sign2.jpg View Quote My wife's father had one in his basement, and my wife used to play with it as a kid! |
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[#37]
Stupid question
You test the caps like you would one on like and HVAC unit????? |
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[#38]
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[#39]
Quoted: Not an HVAC guy, how do you test them for that? View Quote View All Quotes View All Quotes Quoted: Quoted: Stupid question You test the caps like you would one on like and HVAC unit????? Not an HVAC guy, how do you test them for that? Still looking for some advice |
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