Can I replace a capacitor with one that is physically smaller?

thor

I have an old crt tv which looks like it is on the verge of giving up the ghost and expiring. When switched on it takes an age to power up properly. It keeps flikering on and off and then does nothing. I have to keep swiching it on an off repeatedly many times before it finally settles down and begins to run properly.
After reading a bit on the Internet it seems it could be a capacitor problem and after opening it up there does seem to be an electrolytic cap looking like it is beginning to dome.
I ordered another cap off ebay with the exact same electrical characteristics but after it arrived in the post I realised that this new capacitor was about half the size of the one which I was going to swap out. I am hoping that someone could tell me if it would be still ok to use this smaller capacitor given that the capacitance and voltage is the same. I am aware that there are other characteristics such as tolerance etc but I don't think they will be too important in this case.
If I can't use it or it does not fix the problem then I will get rid of it and buy a smart tv but as this is a moneysaving site I am keeping my fingers crossed I can get it going again.

espresso

Modern electrolytics are often smaller but in TV sets they often have a higher temperature rating e.g. 105 C. Even if the one that you have bought is not rated at 105C you could still try it to see if it cures the fault and then consider getting a high temp rated one, which should last considerably longer.

thor

I am going to give it a try. It is a longshot as the cap to be replaced only looks slightly dodgy and could well possibly be fine(and may not be the problem anyway) but I don't really have much to lose

chrisw

Dump it and get a free replacement off Freecycle / Freegle.

Nilrem

IIRC with capacitors you can often get away with slightly different physical sizes as sometimes they change/improve the construction depending on brand.

As expresso says most caps in things like TV's and monitors are rated to 105c, but you can often replace them with 80c ones ok as long as you use a good brand, I've had to do it with a pair of LCD monitors because the manufacturer used cheapish ones on an important part of the logic board and they failed just out of warranty.
I used some panasonic 80c ones because I couldn't find 105c ones in small numbers, and so far they've keep them working fine for a year or so.

paddyrg

Physical size shouldn't be a problem if it's technically rated the same and you should observe the polarity of the electrolytic capacitor. Good luck! The worst that'll happen is that you'll still have a knackered telly.

thor

Not only was the newer cap smaller but it was also the one with the higher temp tolerance of 105 degrees compared with the larger one's 80.
Anyway did the swap and it made no difference so I swapped it out with my temporary emergency backup tv which I have kept for a decade in the loft. That is where it will return when I hopefully spot a bargain tv in the coming days. At the moment I have my eyes on a few 32inch smart tvs coming in around the £279 mark. If I see anything similar closer to £250 then I'm going to snap it up.

bluesnake

while there check for dry joints, often found around the power areas. Oh, and make sure yout tv is not plugged in while solering, Switching it off is sometimes just not safe enough.

paddyrg

The other thing to check is if it's the power board, a blown cap may have knocked out the bridge rectifier (4 diodes, cheap, but get the polarity right)