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300 watt dc to dc converter

LectricCircuit

Apr 7, 2017
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On the top of the board you can see the 330uf tantalum capacitor. The one on my board blew and I was wondering if I could replace it with an electrolytic capacitors and if so would the value need to be different or do I keep it the same?
 

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davenn

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I was wondering if I could replace it with an electrolytic capacitors and if so would the value need to be different or do I keep it the same?

why not just use another tant type ?
an electrolytic would have the same uF and voltage rating but is going to be lots bigger
 

LectricCircuit

Apr 7, 2017
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why not just use another tant type ?
an electrolytic would have the same uF and voltage rating but is going to be lots bigger

When I researched why the tant cap blew I found a lot of ppl saying that tant caps are very unstable and have a lot of issues and that for the most part newer circuits don't even use them unless there is a specific benefit for its use. Just don't want the same problem to keep happening
 

Harald Kapp

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This looks like a 330 µF, 6.3 V capacitor.
You'll be hard pressed to find an equivalent electrolytic capacitor. Right you are in noticing that tantalum capacitors are well known for being unreliable. However, you can improve reliability by using a 10 V type instead of the 6.3 V type - provided you get hold of one of the same size.

Electrolytic capacitors are not without problems of their own. They can (and they do) loose electrolyte over time. The warmer, the faster. As the capacitor in question is quenched between two coils which probabaly get warm, this is not the best place to mount ana electrolytic capacitor.

My suggestion:
  1. Get a 330 µF, 10 V polymer tantalum capacitor (the polymer electrode makes it less sensitive to mechanical stress).
  2. Solder carefully and quickly - heat will put additional stress on the capacitor.
  3. Get the converter up and running with no load or only a light load for starters. This will minimize ripple current in the capacitor, thus minimizing self-heating.
    Give the capacitor at least 10 minutes to settle (this will improve the stability of the dielectric) before using the converter under full load.
 

davenn

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When I researched why the tant cap blew I found a lot of ppl saying that tant caps are very unstable and have a lot of issues

as Harald said, they have some issues, but so do electros. ... both will fail when mistreated ... and the most common mistreatment is el-cheapo manufacturers will put under rated ones into circuits to save a few cents. If used correctly a tant will out live an electro by decades


and that for the most part newer circuits don't even use them unless there is a specific benefit for its use

This is incorrect .... I work with high tech and freaking expensive electronics and they are still full of tant's
If there was any major issue with them, these manufacturers wouldn't be using them

The biggest advantages of tant's is their much smaller size for a given uF and voltage rating and long life


Dave
 

LectricCircuit

Apr 7, 2017
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This looks like a 330 µF, 6.3 V capacitor.
You'll be hard pressed to find an equivalent electrolytic capacitor. Right you are in noticing that tantalum capacitors are well known for being unreliable. However, you can improve reliability by using a 10 V type instead of the 6.3 V type - provided you get hold of one of the same size.

Electrolytic capacitors are not without problems of their own. They can (and they do) loose electrolyte over time. The warmer, the faster. As the capacitor in question is quenched between two coils which probabaly get warm, this is not the best place to mount ana electrolytic capacitor.

My suggestion:
  1. Get a 330 µF, 10 V polymer tantalum capacitor (the polymer electrode makes it less sensitive to mechanical stress).
  2. Solder carefully and quickly - heat will put additional stress on the capacitor.
  3. Get the converter up and running with no load or only a light load for starters. This will minimize ripple current in the capacitor, thus minimizing self-heating.
    Give the capacitor at least 10 minutes to settle (this will improve the stability of the dielectric) before using the converter under full load.
Thank u. I will do the upgrade to 10v. This is by far the best site I've been on. All my questions get answered fast and with good responses. Thanks again.
 
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