Replacing Rectifier

[jkeny]

Simple question but I can't find the answer - I'm replacing a 4 pin rectifier of 10A rating with 4 individual diodes of 6A rating - is my new rectifier 6A or 24A rating or neither?

[AndrewT]

using four 6A diodes in bridge format gives a 6A bridge rectifier.

[jkeny]

Thank you Andrew, so I would need to use 4 * 10A diodes in full wave bridge mode to replace this rectifier & retain the same power handling?

Edit: Has anybody got a recommendation for a good, fast, soft recovery 30A diode to be used as rectifier in a digital amp, rectifying PS before input to switching trafo?

[jkeny]

The amp is a 7*100W Panasonic Digital receiver SA-XR57 with max voltage of 40V - do I need a 20A rectifier i.e. 40V*20A = 800Watts?

[AndrewT]

no,
the smoothing capacitors supply the transient current.
The rectifiers top up the smoothing caps.
I have power amps that use 1n5402 (3A) as discrete bridge rectifiers and they have never blown.

If you are using your amp properly then each channel could be ticking over with an average output of 1W/channel. Add on the quiescent dissipation of around 20W and total loading is under 30W.
That amounts to 375mA average rms charging current.
But rectifiers do not charge at RMS rate they switch on and off at mains frequency rate and peak currents are of the order of 10 times the average rate.
the peak current of many diodes is around 50 to 200 times their continuous rating.

[richie00boy]

Why are you replacing the rectifier, has it blown? If so just replace it with something of the same current and voltage rating, or more.

[jkeny]

Thanks for the replies, guys - I have replaced it with ultrafast, soft recovery diodes as the rectifier & notice a slightly smoother, more silky sound - I just wondered if there was enough juice in the bridge now but it seems OK