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#41
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polarity of power cord - gateway fpd1520
"zirath" wrote in message news:RrcMj.2161$vz2.1500@trndny05... Arfa Daily wrote: The fact that the light stays green, is a good sign. What you next need to do, is to shine a strong desklamp or hand flashlamp at the screen at an angle, after it has gone back to black. If you can then see an image on the screen, that indicates that the backlamp tubes are not staying alight. This could well be because either the inverter is faulty, or that a worn tube is making the inverter shut down. Either is quite a common fault condition. Arfa I was able to see the image on the screen - but the monitor remained black the whole time (it didn't go back to black). (I shined a bright light on the monitor at an angle). OK. Well that tells us that the whole monitor part is working, and the failure is in the LCD screen backlighting circuit. It is generally a bit fiddly, but it is repairable if you are that way inclined. Unless you are able (or want to) just throw it back where you got it from. Arfa I'm into trying to repair it. Is there info somewhere on how to do it? Thanks for your help. If the screen comes apart easily, start by examining the backlight tubes. Be careful when extracting them as they are quite fragile. If any are badly blackened at the ends, suspect them. It's hard to test the inverter, without having known good tubes to connect to it. If you have a 'scope, you can get a good idea by looking to see if you have waveform at the primaries of each of the tube high voltage drive transformers. If you do get a momentary burst that then disappears, this could be because the inverter is detecting a bad tube, and shutting down. You might see the tubes initially flash up, and you might see one not do so. You can disconnect the tubes one at a time, and see if that keeps the inverter running, and if it does, you can cross connect the tubes to the opposite inverter outputs, to prove the drive electronics. Inverters and tubes are available from a number of sources. See, for instance, http://www.lcdparts.net/ccfl.aspx http://www.ergpower.com/pdf30/cross.pdf http://www.ergpower.com/ Arfa One thing I started wondering about after you were saying it could be a problem with the adapter-- The picture of the original adapter that came with the monitor says the plug is supposed to be 6.5mm o.d. 4.4mm i.d. and 9.5mm long. (Thanks to Michael Terrell - http://www.lcdpayless.com/productpag...productId=237). The measurements of the plug that came with the adapter I got (from ebay) are : 5.5x2.5 / 9.5mm. Could this be the problem? As long as the plug is 'making' ok to the centre pin, it shouldn't be a problem. However, the way round that you have described it sounds wrong. If the original was looking for a plug with an id of 4.4mm, (which is *very* big for this type of plug) that would suggest that the monitor has a 'thick' pin, which I'm surprised that your replacement at just 2.5mm, will fit over. 2.5mm is a pretty 'standard' size. However, if you can see an image with an external light shone at the screen, that says that the plug *is* making ok, and the whole monitor is working, less the backlights. So no, I don't think that will be the problem. Arfa |
#42
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polarity of power cord - gateway fpd1520
Arfa Daily wrote:
The fact that the light stays green, is a good sign. What you next need to do, is to shine a strong desklamp or hand flashlamp at the screen at an angle, after it has gone back to black. If you can then see an image on the screen, that indicates that the backlamp tubes are not staying alight. This could well be because either the inverter is faulty, or that a worn tube is making the inverter shut down. Either is quite a common fault condition. Arfa I was able to see the image on the screen - but the monitor remained black the whole time (it didn't go back to black). (I shined a bright light on the monitor at an angle). OK. Well that tells us that the whole monitor part is working, and the failure is in the LCD screen backlighting circuit. It is generally a bit fiddly, but it is repairable if you are that way inclined. Unless you are able (or want to) just throw it back where you got it from. Arfa I'm into trying to repair it. Is there info somewhere on how to do it? Thanks for your help. If the screen comes apart easily, start by examining the backlight tubes. Be careful when extracting them as they are quite fragile. If any are badly blackened at the ends, suspect them. It's hard to test the inverter, without having known good tubes to connect to it. If you have a 'scope, you can get a good idea by looking to see if you have waveform at the primaries of each of the tube high voltage drive transformers. If you do get a momentary burst that then disappears, this could be because the inverter is detecting a bad tube, and shutting down. You might see the tubes initially flash up, and you might see one not do so. You can disconnect the tubes one at a time, and see if that keeps the inverter running, and if it does, you can cross connect the tubes to the opposite inverter outputs, to prove the drive electronics. Inverters and tubes are available from a number of sources. See, for instance, http://www.lcdparts.net/ccfl.aspx http://www.ergpower.com/pdf30/cross.pdf http://www.ergpower.com/ Arfa I was able to disassemble the front and back panels. Is the inverter the part that has the power button and various setting buttons? I was able to disconnect this part. I didn't see the lcd tubes. The lcdparts.net site didn't have this model of gateway listed and the instructions for getting to the tubes for the gateway models they had didn't match. |
#43
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polarity of power cord - gateway fpd1520
"zirath" wrote in message news:2hGMj.5445$eg2.332@trndny06... Arfa Daily wrote: The fact that the light stays green, is a good sign. What you next need to do, is to shine a strong desklamp or hand flashlamp at the screen at an angle, after it has gone back to black. If you can then see an image on the screen, that indicates that the backlamp tubes are not staying alight. This could well be because either the inverter is faulty, or that a worn tube is making the inverter shut down. Either is quite a common fault condition. Arfa I was able to see the image on the screen - but the monitor remained black the whole time (it didn't go back to black). (I shined a bright light on the monitor at an angle). OK. Well that tells us that the whole monitor part is working, and the failure is in the LCD screen backlighting circuit. It is generally a bit fiddly, but it is repairable if you are that way inclined. Unless you are able (or want to) just throw it back where you got it from. Arfa I'm into trying to repair it. Is there info somewhere on how to do it? Thanks for your help. If the screen comes apart easily, start by examining the backlight tubes. Be careful when extracting them as they are quite fragile. If any are badly blackened at the ends, suspect them. It's hard to test the inverter, without having known good tubes to connect to it. If you have a 'scope, you can get a good idea by looking to see if you have waveform at the primaries of each of the tube high voltage drive transformers. If you do get a momentary burst that then disappears, this could be because the inverter is detecting a bad tube, and shutting down. You might see the tubes initially flash up, and you might see one not do so. You can disconnect the tubes one at a time, and see if that keeps the inverter running, and if it does, you can cross connect the tubes to the opposite inverter outputs, to prove the drive electronics. Inverters and tubes are available from a number of sources. See, for instance, http://www.lcdparts.net/ccfl.aspx http://www.ergpower.com/pdf30/cross.pdf http://www.ergpower.com/ Arfa I was able to disassemble the front and back panels. Is the inverter the part that has the power button and various setting buttons? I was able to disconnect this part. I didn't see the lcd tubes. The lcdparts.net site didn't have this model of gateway listed and the instructions for getting to the tubes for the gateway models they had didn't match. The inverter board is usually long and thin, and has a multipin plug going to somewhere around its middle, and thickish high voltage wires coming out of each end to go to the backlight tube connections at either side of the screen. I seem to recall that there are pictures of inverter boards on at least one of those sites. they all look pretty much alike generally, if not in detail. Each backlight tube will have two of these high voltage wires at either end, that will go back to connectors located at the inverter board ends. Arfa |
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