Changing PC monitor capacitors…..question !
July 31st, 2016
I’d like to change the capacitors in my LG monitor cuz they’re dead.
The question is: does the actual size/dimensions of the capacitors matter(as long as they fit inside the case and they have the exact same specs like uF, V, �C) ?!?
I need capacitors with dimensions(hight x diameter) 20x10mm but I found only 23x10mm.
Is there a problem if I use taller capacitors(as long as they fit inside the case) ?!?
Thanks.
No, The size doesn’t matter. And for the record, They only have to match on
the UF/Voltage (But higher voltage is fine too as long the UF matches, Capacitors
don’t dictate the voltage, They only store it) Anyways, Have you ever
done any soldering work before? What kind of soldering iron/equipment do you have?
To be honest, If you have no prior experience, You might damage the circuit
board if your not careful enough! Also, Make sure you put em in with the correct polarity!
You can bend legs of the capacitors, personally I wouldn’t bother replacing them. A new monitor is a good idea, if you don’t discharge them safely, you will get a nasty shock.
A new monitor will cost him much more money than repairing his current!
Capacitors in most cases discharge themselves once the device has been disconnected
from power for a while, But yeah, It’d be a good idea to discharge em first just to be on the safe side. This can be done quite easily by shorting the capacitor legs together with either a multimeter
test lead or a small flat screwdriver (Using one that has a rubber or plastic handle is highly recommend!) but that’s only idle for low-voltage capacitors, For high-voltage ones, Using a resistor would be better.
Yeah, I’m pretty handy with the soldering iron, I’m kinda n00b when it comes to electronics….
5 capacitors are ~5$ so it’s way cheaper than buying a new monitor.
And even if I don’t succeed, at least I tried.
PS:
Actually, I managed to change them but I just wanted to know about the dimensions as I wasn’t sure.
I needed:
– 3x 1000uF 25v 105�C 20x10mm
– 2x 1000uF 16v 105�C 20x10mm
And the only capacitors I managed to find at the local store(not having to wait for eBay/online store shipping):
– 3x 1000uF 25v 105�C 20x10mm
– 2x 1000uF 16v 85�C 20x10mm
These were the only ones in my size range(dimensions), all the other were too big.
So I just replaced them with what I found now in store and, in the future, if the monitor brakes down again(cuz of the 85�C), I’ll replace the capacitors with the right ones(I’m placing an order on eBay right now).
Thanks for the info guys and for the tip on discharging the capacitors before replacing them….which I haven’t done but they were dead already.
just make sure they dont get to 85�C
Yeah, I'm pretty handy with the soldering iron, I'm kinda n00b when it comes to electronics.... The 85C/105C matters a lot!. some capacitors get hotter than 85C, hence the need for 105C caps. things like being near components which get hot, and internal power dissipation, caused by non steady DC or needing to carry AC at a high current increase the power dissipation inside the cap, and raise it’s temperature. a switching power supply, since it’s converting a voltage to high frequency AC then to a chopped DC voltage at a high frequency, puts a strain on caps, that raises the temperature. also, some of those caps NEED to be low ESR caps, look on Google for the part number. standard electrolytic caps will simply act as an open circuit in an SMPS, because they have high ESR. they will manifest itself as a lower than normal DC voltage, as the high frequency won’t be properly filtered out.
5 capacitors are ~5$ so it's way cheaper than buying a new monitor.
And even if I don't succeed, at least I tried.
PS:
Actually, I managed to change them but I just wanted to know about the dimensions as I wasn't sure.
I needed:
- 3x 1000uF 25v 105�C 20x10mm
- 2x 1000uF 16v 105�C 20x10mm
And the only capacitors I managed to find at the local store(not having to wait for eBay/online store shipping):
- 3x 1000uF 25v 105�C 20x10mm
- 2x 1000uF 16v 85�C 20x10mm
These were the only ones in my size range(dimensions), all the other were too big.
So I just replaced them with what I found now in store and, in the future, if the monitor brakes down again(cuz of the 85�C), I'll replace the capacitors with the right ones(I'm placing an order on eBay right now).
Thanks for the info guys and for the tip on discharging the capacitors before replacing them....which I haven't done but they were dead already.
Ok, I kinda got it.
About the voltage….I guess it would be ok to use 1000uF 35V instead of the 1000uF 25V, right ?
Is this better than using the recommended 1000uF 25V ?
It’s not better in any way (nor worse), Just compatible!
Again, Capacitors only store the voltage they get and don’t actually dictate it!
Using a higher voltage capacitor will not make the device use more power and won’t
put it at risk either. A 35V capacitor will be able to sustain 25V just fine and as long as
the capacitance value (uF) is the same, It’s all good. I was simply pointing out that a higher voltage capacitor can be used in cases where you can’t find a replacement with the exact same one (Or if you just happen to have some compatible capacitors laying around )
Great, thanks for the input guys.
One final question……how can one check some capacitors to see if they have the specs that the seller posted(thinking about all the eBay knock-offs) ?!
I think your being a bit too paranoid about this. Capacitors are very cheap to make and
surely the seller could earn a few extra bucks for each one he sells. They’re not really fake-worthy.
But there could be bad batches sometimes. Anyways, There are 3 ways to test a capacitor:
1. Live testing with a DMM while it’s connected to a circuit board which is powered up.
Set the multimeter to DCV with a higher level than your gonna be testing.
I.E 20V if the capacitor is of lower volts. Then attach the probes into the legs
of the capacitor from the opposite side of the board (Unless the capacitor is laying sideways instead of standing, Then you could do it from the same side) Do keep in mind however that the charge of the capacitor depends on what it’s getting, So
you are not guaranteed to get 16V out of a 16V capacitor for example. Also, You should be very careful while doing this as you might get electric shock if you accidentally put your hands/fingers in the wrong place!
2. Using a DMM to charge em, Set it to resistance (2M/2000K)
and attach the probes into the legs of the capacitor, If your not getting any reading, Then try
a lower resistance level. If your still not getting any reading (or it only goes up to 0.1) then that would mean the capacitor is defective! With a good capacitor, It’d gradually go up. Anyways, After a few seconds have past, Remove the probes and switch the operating mode to DCV (20V would do, It’s only gonna charge it slightly) and then quickly reattach the probes.
You should now see the charge it holds gradually go down.
3. Using a digital capacitance meter:
https://www.youtube.com/watch?v=TFa6JfVu3B4
Important Note: Always use the correct polarity!
Or in simpler terms, The black probe should always go into the minus.
Great, thanks for the input guys. you mean counterfeit capacitors. search google for the brand.. if it’s a bad brand, google will list it. years ago, a partial capacitor formula was stolen, and sold. the problem was, it didn’t include the stabilizer. so the manufacturers that used that formula made many thousands of capacitors that had seriously reduced lifetime. the cases bulging being one indicator. there’s always someone trying to save a few cents. many major manufacturers used those bad caps because they are a tiny bit cheaper!. and they had to repair those products they used them in too..
One final question......how can one check some capacitors to see if they have the specs that the seller posted(thinking about all the eBay knock-offs) ?!
Yeah, I was thinking about the possible knock-offs of those good brands(Panasonic, Chemicon, Rubycon, Nichicon….) that could be rated for less than 1000uf or 20V or 105�C but sold as 1000uf/20V/105�C.
Isn’t there a risk of messing up your broken Tv/Monitor even ore by using these knock-offs ?
They will just burst and leak electrolyte, maybe a bang.
Capacitors were never designed to dissipate heat.
Not as bad as a MOSFET catching on fire.
They will just burst and leak electrolyte, maybe a bang.well, a bit , up to the rated temperature that is. an SMPS will make the capacitors a bit hot because of the rapidly rising and falling DC voltage an SMPS generates ahead of the filter caps. also, if AC is passed through a cap, it will generate heat within the cap also.. capacitors rated for AC have a maximum current rating listed. the main concern if a counterfeit cap is used, is leakage of electrolyte, explosion, and greatly diminished lifetime. the capacitance, voltage rating, and temperature rating is most likely right on. what is missing is the stabilizer for the electrolyte, which is the cause for the problems mentioned.
Capacitors were never designed to dissipate heat.
Not as bad as a MOSFET catching on fire.