Capacitor check - Making sure I get it right

[MaxAsh]

Hello - new to the forums. I've been doing a lot of reading/learning, and I believe I'm on the right track. Short version: My issue is a Sceptre X20WG-1080P monitor that powers on (LED light flashes) and I hear small click/pop sounds each time it flashes. Eventually the monitor will come on, sometimes after 5-10 mins. From all that I've read, clear capacitor issue. So I popped open the monitor, and sure enough I find 5 capacitors with rounded/bulging tops. My plan is to replace them all. I'm familiar with soldering, but haven't replaced LCD capacitors before. I want to make sure I purchase the correct ones. Here's the info I wrote down, as well as the part numbers I found over on Digikey. My concern is that some of my height measurements don't line up with what they have. Is it okay to purchase a shorter height, as long as the other stats on the capacitor match? Thanks in advance:

(Qty 4) CapXon 1000uF 25V C735 KF 105ºC
22mm (height) 10mm (dia)

(Qty 2) CapXon 1000uF 16V C732 KF 105ºC
22mm (height) 10mm (dia)

I found part number P5544-ND (25V), not 100% sure what to select for the 16V. There's no 22mm, but I found several 20mm. The hours and ripple currents are diff though. Not sure. Assistance would be awesome, thanks!

[mockingbird]

Re: Capacitor check - Making sure I get it right

You should really do a complete replacement, including the small capacitors on the logic board, and the large primary capacitor in the PSU (I have heard that CapXon primaries are somewhat unreliable as well).

The part you chose is inadequate as a replacement because it is a general purpose capacitor.

For 16V 1000uF:
565-1664-ND

For 25V 1000uF:
1189-1245-ND

[MaxAsh]

Re: Capacitor check - Making sure I get it right

With so many going bad on this board, you're probably right about replacing additional caps. I'll look at the data on each one as well. I was confused about one portion of your reply: You said the ones I selected were inadequate because they were general purpose. I looked up the part numbers you suggested, and they also said general purpose under Applications on Digikey. Am I checking the wrong field in the description?

Thanks!

[mockingbird]

Re: Capacitor check - Making sure I get it right

While the big three have really improved their component descriptions (At least in the capacitor sections), they don't get everything right... Off the bat, when I saw NHG I knew it wasn't going to suffice because I'm a little familiar with the series.

I linked you to KZE and ZLJ. I've used them before many times so I know those are both very low ESR and high ripple series. But you have to be smart about it when you shop at Digikey because sometimes one series is far better priced than another.

The way to do it is to select the voltage, capacity, and maximum width in the parametric search and then filter it (Click "in stock" too). Once you have those results, choose "through hole" and then pick all the heights (in mm) up till your maximum height (A taller cap is not always better than its shorter counterpart - often, shorter caps have a superior electrolyte composition). Now filter it once more according to manufacturer. You want Nichicon, Rubycon, and Chemi-Con... Kemet and Vishay have started to get into the game a little more (And I sometimes buy Illinois Capacitor from Newark if the price is good), but you should stick to those three for the time being.

Now sort it by price (Ascending - with the most inexpensive caps first), keeping in mind that you're only interested in products with a minimum quantity of one (Often you'll see obscenely inexpensive caps, only to realize that the nearby column lists them in minimum quantities of 1000). Now go down the list and find the most inexpensive capacitor that suits your needs.

Since we're looking at those three brands, I'll tell you which series you'll most likely get in your results that are suitable:
KZE, ZL, ZLG, ZLH, ZLJ, ZLK, HD, HC, HV

These series might not be as low ESR and not have as high a ripple rating, but they are sometimes suitable, depending on the application:
KY, YXJ, HE

I'm sure there are some series I've missed out, but this is just to help you get started.

And that's how you buy caps.

[MaxAsh]

Re: Capacitor check - Making sure I get it right

Awesome, absolutely awesome, explanation! Many thanks. It helped me find/purchase the additional caps I need to replace them all at once. At these prices, it would be a waste not to spend the mere pennies to get rid of these other junky CapXon caps.

Huge thumbs up and thanks. I'll report back with the results of my efforts!

[momaka]

Re: Capacitor check - Making sure I get it right

Excellent writeup, mockingbird. That's how I usually sort capacitors in Digikey and Mouser as well. As an added step, I also choose only capacitors that have a 105C temperature rating. This removes the general purpose 85C caps.

Speaking of general purpose...

I was confused about one portion of your reply: You said the ones I selected were inadequate because they were general purpose. I looked up the part numbers you suggested, and they also said general purpose under Applications on Digikey. Am I checking the wrong field in the description?

If I remember correctly, Digikey just labels all small leaded capacitors as general purpose. That's quite misleading, though, because as mockingbird pointed out, there are different series of capacitors, and some are better rated than others (hence, they are not all "general purpose") - i.e. lower ESR and higher ripple current. The term "general purpose" we use here on badcaps.net usually means "not suitable for power supply or motherboard use". One way you can actually distinguish general purpose caps from low-ESR caps is by opening the datasheet of the capacitor. If ESR/impedance is not listed anywhere in the datasheet, it's a general purpose capacitor. If it's a low-ESR capacitor, then your replacement capacitor should have preferably the same or lower ESR and the same or higher ripple current specs than the original capacitor you are replacing.