101–110 of 128 posts
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Huh. I have a Dell monitor that suddenly started showing these kind of smeared stripes instead of a proper picture. Took it apart, looked carefully at all the capacitors and other components on both boards, but none looked bad. Disconnecting and reconnecting the ribbon that goes to the LCD panel made no difference whatsoever. What could it possibly be?
does a bad capacitor always show damage visibly?
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I am old. I did not even open the link until you mentioned it was an LCD. I was thinking: "Why would you repair a CRT?"
Comes up fairly often as a nostalgia thing for old Macs, Kaypros, Compaqs, arcade games, and so on.
I feel old; I came here for a guide to repair a "VGA monitor" and instead got a flat panel.
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Aye I remember bringing back a lot of dead monitors, TV's and even a cheap Pentium 4 motherboard by swapping caps. A place I worked at had a bunch of 19" Optiquest LCD monitors which ALL eventually died from a single bad cap on the power supply board. I fixed every one of those monitors, think it cost less than $10 to order the caps from digikey.
How do you figure out which ones are bad?
I've repaired several TVs and monitors, LED lamps, etc. just by replacing bad capacitors, and in a few cases some diodes too, so it's worth trying especially on electronics that would otherwise be thrown away. If you see a TV/monitor going off randomly or a LED lamp starts flashing, pretty sure there are one or more defective capacitors in there. Defective capacitors are a common plague in modern electronics, and the…
I've got several broken electronics that I'd love to try to repair someday, but they don't have any screws and they are obscure enough to not have any tear-down guides to tell me if a heat gun would help. Cutting them open could just leave them unappealing to use, and thus I wasted my time.
In short, get in there are see what happens. Sometimes you will destroy something, but right now it is landfill material so you didn't lose anything. sometimes it is an easy fix.
I feel old; I came here for a guide to repair a "VGA monitor" and instead got a flat panel.
LCD monitors only used VGA because customers didn't know enough to demand DVI. A pixel array is inherently digital, so it makes no sense to put DAC/ADC in the path.
Really, it was more that we didn't have DVI outputs.
Its the smartest way to break the chicken-egg situation -- for many (I'd wager the majority) the advantage of a flat panel at first was more about space saving then picture quality.
Earlier quoted context omitted.
Aye I remember bringing back a lot of dead monitors, TV's and even a cheap Pentium 4 motherboard by swapping caps. A place I worked at had a bunch of 19" Optiquest LCD monitors which ALL eventually died from a single bad cap on the power supply board. I fixed every one of those monitors, think it cost less than $10 to order the caps from digikey.
How do you figure out which ones are bad?
Leakage (ie, when a capacitor exhibits resistive properties by conducting current also when fully charged) can be measured easily by using an analog tester or a digital one plus a few parts, while the ESR (equivalent series resistance) measurement would need a proper instrument called ESR meter. The ESR is an unwanted static series resistance the capacitor would exhibit no matter the frequency it works at, it increases with aging and it's independent from the capacitive reactance which it's related to the frequency. Therefore, the lower the ESR, the better quality or condition is the capacitor.
However, you can just ignore the 2nd sentence if repairing a device would require just a bunch of capacitors; quality ones aren't that pricey, and if you find a bulged one, it is often advised to replace all capacitors employed in the same stage anyway. Some in fact can degrade without showing any visible hints of their condition.
Here are some links that might turn out useful.
http://www.elecrealm.com/down/class/
http://www.mattmillman.com/info/lcd/rovatools/
https://github.com/ghent360/RTD-2660-Programmer/
https://sites.google.com/site/lcd4hobby/home
https://www.codeforge.com/article/258602
I've repaired several TVs and monitors, LED lamps, etc. just by replacing bad capacitors, and in a few cases some diodes too, so it's worth trying especially on electronics that would otherwise be thrown away. If you see a TV/monitor going off randomly or a LED lamp starts flashing, pretty sure there are one or more defective capacitors in there. Defective capacitors are a common plague in modern electronics, and the…
Low ESR only matters for PWM filtering capacitors, such as those found in monitor backlight drivers and some switching power supplies’ secondary circuits. It is not necessary to use such capacitors on the primary side, i.e. when the large capacitor nearest to the mains input dies, just replace it with a normal electrolytic capacitor that matches or exceeds the original’s voltage rating and closely matches its capacit…