Can Tantalum caps be used to replace electrolytic caps

[archerbob]

Assuming the same polarity, Farads, same or higher voltage... is there any reasons to not use Tantalum caps?

[Unimportant]

Depends on the application. What's it for?

[ShredBird]

Difference in material, geometry and construction generally effects the frequency response and/or leakage properties of the capacitor.  Some capacitors are better as filtering caps for this reason, but if you're using them for their capacitance rating at DC they are interchangeable.

[mariushm]

Tantalum is often mined in war countries, so that's bad.

Tantalum capacitors also have problems with over voltage, they can blow up or burn all of the sudden, with real nice flames.

The ESR is typically higher than ceramic capacitors and even some polymer capacitors. They are lower ESR than electrolytic capacitors (if the capacitor volume is relatively small) but modern polymers and ceramic caps are often better these days.

 

[NelizMastr]

3 hours ago, mariushm said:

 

Tantalum capacitors also have problems with over voltage, they can blow up or burn all of the sudden, with real nice flames.

That's why they're known as Tantrum capacitors.

[archerbob]

I've got an old Dell 2209WA that has horizontal lines across the screen accompanied with cap squeal... so I am looking to see if I can identify and replace all the electrolytic caps.

 

There are 25 of them and I've identified 20 of them.  The other 5 I cant read yet due to white hard epoxy covering the numbers and not knowing how to read the numbers on the top of 3 solid caps.

 

The solid caps have the numbers

027

330

16

 

and the last 1 has

 

023

47

35

 

I presume the 2nd line is the uF and the 3rd line is the volts, but am having trouble finding a definitive guide that explains how to read the values printed on top of these solid caps.  Anyone know how to remove the white epoxy without damaging the PCB?

[mariushm]

If the board looks like in the picture below, then the capacitors you need to replace are most likely the ones I circled. Those have the potential to cause instability or issues.

The ones in yellow circle are bulk capacitors for power supply, like 24v , 12v, 5v these if they're dying can cause monitor to turn off and on randomly or go in standby etc etc

The ones in blue circle are most likely used by the display controller (the one that takes hdmi / dvi / vga and converts that to digital signals that go through that flat connector to the lcd panel)... faulty capacitors there could cause horizontal lines but it seems a bit unlikely.

Yeah, you got the values right ... it's 330uF 16v and 47uF 35v. 

The voltage rating is basically the maximum the capacitor can handle, it doesn't mean that's the voltage going through the circuit. You can often replace existing capacitors with capacitors rated for higher voltage (if the ones rated for same voltage are too expensive or not stocked) as long as you're careful not to change the specifications too much.

If those 330uF 16v capacitors look like the ones in my picture (different than regular electrolytic capacitors with their black sleeve), those are polymer capacitors and are unlikely to be bad. 

You can replace these capacitors with LOW ESR electrolytic capacitors, you can't just use any capacitor.

 

You have Panasonic FM and FR, Nichicon HM, HN, HW,  United Chemi Con KY, KZG , Rubycon ZLG, ZLH, YXG ...

 

I've preselected these series that would work fine for you in this link : https://www.digikey.com/short/ptfjvc

You'll see prices for 5pcs if you click on link but you can change that...  you can order just one if you want to, i just specified 5 so that when you sort by price, you won't get price for 1000pcs as a first result.

If you're in US, Digikey is a good place to buy from.

 

You can then simply select the capacitance you want and the voltage rating (select the exact one and the one higher), then sort by price and whatever you pick will 95% sure it will be fine for you. May want to check distance between leads but that's not critical.

 

 

[archerbob]

17 hours ago, mariushm said:

If the board looks like in the picture below, then the capacitors you need to replace are most likely the ones I circled. Those have the potential to cause instability or issues.

The ones in yellow circle are bulk capacitors for power supply, like 24v , 12v, 5v these if they're dying can cause monitor to turn off and on randomly or go in standby etc etc

The ones in blue circle are most likely used by the display controller (the one that takes hdmi / dvi / vga and converts that to digital signals that go through that flat connector to the lcd panel)... faulty capacitors there could cause horizontal lines but it seems a bit unlikely.

Yeah, you got the values right ... it's 330uF 16v and 47uF 35v. 

The voltage rating is basically the maximum the capacitor can handle, it doesn't mean that's the voltage going through the circuit. You can often replace existing capacitors with capacitors rated for higher voltage (if the ones rated for same voltage are too expensive or not stocked) as long as you're careful not to change the specifications too much.

If those 330uF 16v capacitors look like the ones in my picture (different than regular electrolytic capacitors with their black sleeve), those are polymer capacitors and are unlikely to be bad. 

You can replace these capacitors with LOW ESR electrolytic capacitors, you can't just use any capacitor.

 

You have Panasonic FM and FR, Nichicon HM, HN, HW,  United Chemi Con KY, KZG , Rubycon ZLG, ZLH, YXG ...

 

I've preselected these series that would work fine for you in this link : https://www.digikey.com/short/ptfjvc

You'll see prices for 5pcs if you click on link but you can change that...  you can order just one if you want to, i just specified 5 so that when you sort by price, you won't get price for 1000pcs as a first result.

If you're in US, Digikey is a good place to buy from.

 

You can then simply select the capacitance you want and the voltage rating (select the exact one and the one higher), then sort by price and whatever you pick will 95% sure it will be fine for you. May want to check distance between leads but that's not critical.

 

 

Yes that looks exactly like my PCB, all the electrolytic caps look pristine except for the one you've circled in the brightest yellow it has like coffee stained all around itself on the PCB, other than that it's pristine too.

 

I am in Australia, a business named Jaycar has most of the caps but I don't know what brand they are... they possibly seem to be generic.  I've read elsewhere that Panasonic and Rubycon are the way to go, but am having trouble finding places to order from that don't required some ridiculous amount of postage.

 

I just had a look at those caps in the blue circle, they are two black and 3 maroon colored caps.

Black are:

4.7uF 16V

100uF 16V

 

Maroon are

47uF 50V

 

The cap in the yellowist circle is a 100uF 16V maroon colored cap that is bigger than it's black twin in the blue circle, the caps are all of the su'scon brand.

 

All of the larger caps you circled in the dirty yellow circles are of SAMXON brand.

 

If I focus on those 6 caps on the digikey website it comes to $2.89 for the caps and $24 for the postage... I think I'll have a look around and see if I can get them somewhere else

[mariushm]

I think Farnell / Element 14 has decent shipping in Australia, and they stock these brands and series  in your country

Here's links:

 

all leaded electrolytic capacitors: https://au.element14.com/c/passive-components/capacitors/aluminium-electrolytic-capacitors/leaded-aluminium-electrolytic-capacitors

 

filtered series and brands :  long link

 

Yeah, you can replace those 4.7uF 16v capacitors with 4.7uF caps with higher voltage rating, like 25,35,50v ... will work.

 

Su'scon capacitors are susceptible to heat, but those small ones aren't so sensitive. Samxon is also a sort of decent brand.

 

I suspect replacing the capacitors won't give you much improvements, but if you can get the shipping low, it would be worth trying.

 

[archerbob]

I've been looking at that element14 website but their catalog is super slow, delivery is $12.95 for less than $3 worth of caps

 

Jaycar sell the SAMXON caps for a dollar each on ebay or as little as 35 cents each on their actual website, with $9 postage.

[Tim B]

Hi, thought I'd chip in here. The main high voltage reservoir capacitor could have gone bad, causing extra overall stress. And would make the PSU whine loudly. I recently fixed and old Acer AL1619W. The high voltage cap had failed completely.

[archerbob]

I don't hear the whine all the time, just when the horizontal lines appear across the screen... intermittently.  I've put this project on hold for awhile until I have time to arrange getting the capacitors.  Other family commitments have come up, I'm sure you all know how it is.

 

My first hurdle was just getting to the capacitors as some of the screws were already stripped and I had to get help from a cousin to cut slots in the screws with his angle grinder.

 

Thanks all for your help thus far!