This would be the perfect recipe for a loud, loud pop. It really depends on how the capacitor are made, but I would advise against it anyway. The insulation will heat and the capacitor will either explode or short making a loud pop either way; blowing itself or blowing the fuse/breaker. In clear, do not try!
Sébastien
Sébastien
First: Do you really have 70 volts?djdamix said:
Secondly: If you are prepared to measure the max voltage you may use those 63 volts caps. I have used 40 V Seimens since 1977! at 46-47 volts. the amp works still.
If you measure where the leakage current starts to rise, there you have the max voltage.
I measured a pair of old RIFA caps with 70 VDC rating and they started to leak at 84 volts.
My advise to you is still that you should have enough headroom so 80 or 100 V is my recommendation.
The result is almost random. Some capacitors will withstand the overvotage for years, others will fail after some minutes due to overheating...
When the capacitor overheats, pressure builds up inside. Big capacitors have a built-in valve to release the pressure before the capacitor has a chance to explode. In small ones the metal can is designed to break and release the pressure in a specific direction, usually in the vertical axis
Exploding is not likely to happen with small overvoltages, but it may happen
Anyway, appliying overvoltage to capacitors is a dangerous practice. If you decide to try it, remember that you do it at your own risk and that you will be the only one responsible of the consequences
When the capacitor overheats, pressure builds up inside. Big capacitors have a built-in valve to release the pressure before the capacitor has a chance to explode. In small ones the metal can is designed to break and release the pressure in a specific direction, usually in the vertical axis
Exploding is not likely to happen with small overvoltages, but it may happen
Anyway, appliying overvoltage to capacitors is a dangerous practice. If you decide to try it, remember that you do it at your own risk and that you will be the only one responsible of the consequences
I have not witnessed the explosion of a large PSU cap, however, I have seen the results. It is serious let me tell you. A small metal cap in a tube oscilloscope once blew up and I was to repair the unit.
The mess generated by the cap was unbelievable. It had evenly spread its entire contents across the inside of the whole unit and there was nothing left of the metal can.
The mess generated by the cap was unbelievable. It had evenly spread its entire contents across the inside of the whole unit and there was nothing left of the metal can.
Overvoltage of caps.
I would highly suggest not to go over the rated voltage. I have seen large caps blow and it is a BIG MESS! It will fill a room with stinky smoke that lingers for days.
There was a high end manufacturer (with an Italian name) who used 63 volt 100 ufd caps on his amp boards. The power supply was +/- 70 volts. I ended up repairing a lot of these amps because these caps would explode and spray stuff all over the inside of the amp.
I have also seen problems caused by high line voltage when there was not sufficient safety margin.
Spend the extra money and play it safe. Best regards, Steve
I would highly suggest not to go over the rated voltage. I have seen large caps blow and it is a BIG MESS! It will fill a room with stinky smoke that lingers for days.
There was a high end manufacturer (with an Italian name) who used 63 volt 100 ufd caps on his amp boards. The power supply was +/- 70 volts. I ended up repairing a lot of these amps because these caps would explode and spray stuff all over the inside of the amp.
I have also seen problems caused by high line voltage when there was not sufficient safety margin.
Spend the extra money and play it safe. Best regards, Stevei think the answer is clear so far, you're taking a risk not worth taking for the extra cost .
ill personly avoid use voltages that match the expected rail voltage as id feel uneasy about it, should leave a margin incase of high line voltage,
using a 63v cap on a 70v rail tho, id never even consider.
ill personly avoid use voltages that match the expected rail voltage as id feel uneasy about it, should leave a margin incase of high line voltage,
using a 63v cap on a 70v rail tho, id never even consider.
Depending on the application of electrolytic capacitors you MUST de-rate the nominal voltage (and ripple current) applied to the capacitor.
A good guideline is never to apply more than 80% of the nominal voltage of the capacitor. This means that
A 50V capacitor should never have more than 40V applied to it.
A 63V capacitor should never have more than 50V applied to it.
A 80V capacitor should never have more than 63V applied to it.
A 100V capacitor should never have more than 80V applied to it.
These are general rules I learned during my teen years as an apprentice. Of course they are up for discussion, but my advice is to follow them as de-rating always is a good idea.
I know that some companies de-rate their caps even more, so take this seriously!
\Jens
A good guideline is never to apply more than 80% of the nominal voltage of the capacitor. This means that
A 50V capacitor should never have more than 40V applied to it.
A 63V capacitor should never have more than 50V applied to it.
A 80V capacitor should never have more than 63V applied to it.
A 100V capacitor should never have more than 80V applied to it.
These are general rules I learned during my teen years as an apprentice. Of course they are up for discussion, but my advice is to follow them as de-rating always is a good idea.
I know that some companies de-rate their caps even more, so take this seriously!
\Jens
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