Fast recovery diodes help / advice please ?

AndrewGM · 14th April 2009, 07:08 PM

I need some advice on selecting the right schottkys for my power amp and cd player.

My power amp at the moment uses IN 5402 - 3 A / 200 volt
alongside 4 old Aerovox 10,000 uf 63 volt caps.
I wish to replace the existing PS caps with something bigger like 15,000 uf @ 63 volt or maybe 100.
From comments read my understanding is that I will also need to up the value of the diodes if I am to safely increase the value of the main PS Caps.
Can anyone confirm and suggest which value schottky's to buy.
Is 6 amps and 1000 volts just too far ?
The Tranny has a 420 VA rating on a protection relay that opens after 10 seconds.

Finally then, which values of schottkys do I need for the PS stage of the Alpha 5 plus CD player please ?

Thanks in advance

Andrew

Bigun · 14th April 2009, 08:09 PM

I'm using BYW29E's from NXP which Digikey sell for 70c a piece when you buy more than a few. They are fast but they are also soft-recovery. Some people believe this reduces HF contamination of the sound.

AndrewGM · 14th April 2009, 08:17 PM

Gareth thanks for the reply

I'll look em up right now.

Thank you

Andrew

AndrewGM · 14th April 2009, 08:24 PM

Had a look, excellent spec but sadly TO 220's won't work
or fit, the current ones are axial type and lay flat.

Solder pads are a long way apart too.

I'll keep hunting unless you have another suggestion ?

Appreciate your input

Andrew

Andy Bartha · 14th April 2009, 08:52 PM

There are many types of high speed low noise diodes available at the current and voltage ratings you need. ON diodes, which were motorola, still produce the MUR high speed, low noise soft recovery types are still available. Vishay also makes very nice shattky type diodes. There are many others. You are looking for a D 41 type axial diodes. At least that is what I remember.

AndrewGM · 14th April 2009, 09:34 PM

Thanks very much.

I'll take a look at those too.

I just want to make sure I'm doing the right thing.
If I increase the capacitance of the PS smoothing caps
I don't want to upset anything else in the process.

Thank you

Regards

Andrew

Andy Bartha · 14th April 2009, 09:44 PM

repacing the power supply caps with higher quality and larger value caps can be very good as long as the caps fit and you do not go overboard with the larger value. 15K uf is very reasonable.

AndrewGM · 14th April 2009, 09:52 PM

That's what I needed !
Someone who just knows.

So, going from 10,000 uf to 15,000 uf is OK and safe
and I can maybe leave the existing IN 5402 rect diodes in place
( 3 amp 200 V )
That would be great and less work !

Presumably the voltage rating is less important providing it's not lower than the exisitng caps ?

Thanks again !

Andrew

johnnyx · 14th April 2009, 09:58 PM

You could use UF5402, the ultrafast soft recovery version of your original diodes. RS have them.

Mr Evil · 14th April 2009, 09:59 PM

Are you sure you need to replace them? Larger reservoir capacitors means higher peak charging current, but the surge current for 1N5402 is specified as a substantial 200A.

14th April 2009, 07:08 PM	#1
AndrewGM diyAudio Member Join Date: Jun 2008	Fast recovery diodes help / advice please ? I need some advice on selecting the right schottkys for my power amp and cd player. My power amp at the moment uses IN 5402 - 3 A / 200 volt alongside 4 old Aerovox 10,000 uf 63 volt caps. I wish to replace the existing PS caps with something bigger like 15,000 uf @ 63 volt or maybe 100. From comments read my understanding is that I will also need to up the value of the diodes if I am to safely increase the value of the main PS Caps. Can anyone confirm and suggest which value schottky's to buy. Is 6 amps and 1000 volts just too far ? The Tranny has a 420 VA rating on a protection relay that opens after 10 seconds. Finally then, which values of schottkys do I need for the PS stage of the Alpha 5 plus CD player please ? Thanks in advance Andrew

14th April 2009, 08:09 PM	#2
Bigun diyAudio Member Join Date: Jan 2009 Location: K-W Ontario Blog Entries: 2	I'm using BYW29E's from NXP which Digikey sell for 70c a piece when you buy more than a few. They are fast but they are also soft-recovery. Some people believe this reduces HF contamination of the sound. __________________ "The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.

14th April 2009, 09:59 PM	#10
Mr Evil diyAudio Member Join Date: Aug 2004 Location: Behind you	Are you sure you need to replace them? Larger reservoir capacitors means higher peak charging current, but the surge current for 1N5402 is specified as a substantial 200A. __________________ https://mrevil.asvachin.eu/

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14th April 2009, 08:17 PM	#3
AndrewGM diyAudio Member Join Date: Jun 2008	Gareth thanks for the reply I'll look em up right now. Thank you Andrew

14th April 2009, 08:24 PM	#4
AndrewGM diyAudio Member Join Date: Jun 2008	Had a look, excellent spec but sadly TO 220's won't work or fit, the current ones are axial type and lay flat. Solder pads are a long way apart too. I'll keep hunting unless you have another suggestion ? Appreciate your input Andrew

14th April 2009, 08:52 PM	#5
Andy Bartha diyAudio Member Join Date: Sep 2004 Location: Oregon	There are many types of high speed low noise diodes available at the current and voltage ratings you need. ON diodes, which were motorola, still produce the MUR high speed, low noise soft recovery types are still available. Vishay also makes very nice shattky type diodes. There are many others. You are looking for a D 41 type axial diodes. At least that is what I remember.

14th April 2009, 09:34 PM	#6
AndrewGM diyAudio Member Join Date: Jun 2008	Thanks very much. I'll take a look at those too. I just want to make sure I'm doing the right thing. If I increase the capacitance of the PS smoothing caps I don't want to upset anything else in the process. Thank you Regards Andrew

14th April 2009, 09:44 PM	#7
Andy Bartha diyAudio Member Join Date: Sep 2004 Location: Oregon	repacing the power supply caps with higher quality and larger value caps can be very good as long as the caps fit and you do not go overboard with the larger value. 15K uf is very reasonable.

14th April 2009, 09:52 PM	#8
AndrewGM diyAudio Member Join Date: Jun 2008	That's what I needed ! Someone who just knows. So, going from 10,000 uf to 15,000 uf is OK and safe and I can maybe leave the existing IN 5402 rect diodes in place ( 3 amp 200 V ) That would be great and less work ! Presumably the voltage rating is less important providing it's not lower than the exisitng caps ? Thanks again ! Andrew

14th April 2009, 09:58 PM	#9
johnnyx diyAudio Member Join Date: Jan 2004 Location: manchester	You could use UF5402, the ultrafast soft recovery version of your original diodes. RS have them.

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