Finding a replacement electrolytic capacitor

No matter if you are finding a replacement for a capacitor that has gone bad or finding a cross for one that is obsolete there are a couple steps you can take to make finding a replacement easier.

First things first you need to identify as many of the specifications off the capacitor as you can.

Is the capacitor Through-Hole, Surface mount, or Chassis Mount? Most through hole and chassis mount caps with have a capacitance, voltage, and temp listed right on the part. They may also have a manufacturer name and in some instances particularly chassis mount you may even find a part number.

On surface mount electrolytic caps, it is more common to find a cap that simply lists a capacitance number, a voltage or a voltage code, and a lot number or series number. This can be a bit tricky to identify. Start with the capacitance and see if the other numbers appear to be suggesting voltage or if they appear to be more of a lot/series number.

Note: A V on the top of a surface mount cap may not mean voltage, however may be a voltage code. See more info in the surface mount section below.

Now that we have these specifications we can look at how you can find options on the Digi-Key site under Aluminum Electrolytic Capacitors

Here I am going to look at this through hole cap.
First, I am going to select In-stock as I am looking for a part today. I will also select through Hole and Capacitance as I know these numbers and I don’t want them to deviate. I also know I need a polarized cap and it is a radial leaded cap so I will filter these features as well. Once selected I will hit Apply Filters.

I don’t want to eliminate all my options yet so next I am going to choose voltage. Now my cap is 50V and being general purpose, I am going to choose all options that are 50 volts or more.

I also know my temperature on the cap shows 85°C. Normally I would select a temp and anything higher, however everything available is 85°C or higher already.

I still have many options on this search so I am going to continue to narrow down options. This is a through hole and I want it to go right in my board so I am going to select a 2mm board spacing. If this eliminates all your options there are some ways to bend leads. Look here for details on that.

I still have a few options on this search so I can look to narrow down options more. I will choose 50V and 5mm diameter. Now I am down to a manageable number and can continue to either filter by price, height, or manufacturer and select a replacement capacitor.

Now let’s look at this surface mount capacitor.
Here you can see the markings on this cap are

Looking at the top of this capacitor I can identify that this is a polarized cap by the black mark. I also suspect that it is a 220uF cap, the V is a voltage code, and the HB is a series. The 17Y4 appears to be a lot code. Let’s look through the filters and see if we have something that matches.

I again will go to the Aluminum Electrolytic Caps Section and this time I will choose surface mount, polarized, and 220uF and see what I have available.

Luckily on this cap the HB is a series and I can identify the marking with a data sheet. Here is a clip.
image image
Now I know this is a 220 uF and the V is calling out a 35V

With this information and a limited number of option in this series I can identify this cap as part number PCE4808CT-ND.

Now say I was not able to identify the exact cap. Using this post, I would try to identify the markings on the cap. SMT Electrolytic Capacitor with no Voltage Rating

Now on all the examples I see V is = 35V. So now I can look at my options for 220uF, 35V, Polarized, Surface Mount, and I am going to look for an in-stock option. Then click apply filters.

Note here I have 176 options. If this was lower I could also look at options that are higher voltage.

Now you will have to do a little measuring as the next step to finding a replacement if you have not positively identified the cap is to measure the cap. We can look at the dimension, seated height, and most importantly surface mount land size to ensure it will fit your board.

Once I have verified the physical dimension I will then generally choose the highest temp available if I don’t know the temp rating of the capacitor. Then you can narrow your list again by price, manufacturer, and lifetime @temp if needed.

We also have a quick video guide that shows the website navigation once you have your specifications.

Conclusion: Finding a replacement capacitor can be a little tricky, however once you identify the specifications of your existing cap you can easily click through the filters provided on the Digi-Key website and a replacement can be found. We also have a blog that helps talk about identifying your specifications.

Do you have questions on finding a replacement capacitor? Let us know by commenting below or create a post in the Part Identification Category and our team of Engineers and Engineering Technicians can help identify and cross the capacitor that you have.


Trying to id this capacitor on a GeForce4 TI 4200 video card. Trying to decide if it is a 6.3 volt 330 uF or a 33uF. It is 6mm in diameter and 8 mm tall.

Hello Tekall4!

Welcome to the forum! Do you happen to know the manufacturer of this part? The marking call outs are different for each manufacturer. Also, if you have access to a schematic of the board we may be able to ID the part that way as well.

I believe it is a UWT0J331MCL1GS‎, Nichicon CAP ALUM 330UF 20% 6.3V SMD. The datasheet illustration and dimensions appear to match.

We do have those in stock, please see link below. Glenda

Can y’all tell me whether the Nichicon UPS and UPJ caps are okay in this application? It’s the beginning of a regulated linear power supply in an oscilloscope and there is a dc-dc switcher for HV on the board, but most all the electrolytics are in the linear ps chain after the bridge rectifiers.

Hello KB5VXX. Yes, both series of caps that you mentioned are specifically designed for power supplies. The datasheets for both the UPS and the UPJ series state their purpose is for power supplies at the top of the datasheet. Click those links to take a look at the datasheets.

I often see a recommendation to use capacitors with “low ESR” but this field is always blank on digikey. I read another post on this forum that says Q, dissipation factor (DF), or Tan δ are how manufacturers indicate ESR, but I only see these on data sheets. How can I filter the capacitor list on digikey to only display low ESR capacitors? And what value is “low”?

For these capacitor types the Digi-Key pages include ESR as a value you can search and sort on.

  • Aluminum Electrolytic
  • Aluminum - Polymer
  • Film
  • Tantalum
  • Tantalum - Polymer

Compared to those types, ceramic capacitors generally have very low ESR and no consistent rating system from manufacturers because this is usually not an issue for this type.

Carefully check the data sheet for the IC or circuit module that is requiring a low ESR capacitor.

You will usually find that they are saying you can use a low-ESR tantalum/electrolytic or you can use any ceramic.

In specific case, e.g. some switching power supply controller IC’s, the data sheet will specify a specific ESR for a ceramic capacitor, but every time I have encountered that they also give a list of suitable parts they have checked.
See these posts for more information:

As with all things it is relative to other alternatives and varies from one application to another. So only the company that required a low value can actually answer that question.

If I filter for through-hole aluminum electrolytic, in stock, there are 17,121 results. If I filter to show only those with an ESR value, there are only 2,767. If I filter to show only specific brands like Nichicon or Panasonic there are 45 capacitors left. Rubycon, zero.

When I buy capacitors it’s for replacing old ones in power supplies and other circuits, so I don’t know what ESR is needed. I keep seeing recommendations to use “low” ESR so I thought I should consider that when buying. It makes sense that “low” is relative and depends on the circuit. I have also seen discussion about having too low of ESR can be bad in some situations.

Low ESR electrolytic are rare, expensive and only needed under rare circumstances.

In that case you simply want to cross reference the existing part to a replacement part, no need to worry about individual specifications. The original design engineer did all the math to select the original part.

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