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Old 10-20-2013, 07:14 AM   #1
senz_90
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Default 1n5819 rectifier replace with 1n4007 rectifier??

just a simple dumb question. 5 hours ago i just getting a psu that really "new" from my friend. i think those are used just for about 2-3 months before failed. It hasn't even a hair of dust insidely !! so i just open the case and looking for the culprits, smelling and looking round and i notices one diode has burned on the board. so i checks it in circuit. it has low reading resistance both forward and reverse. desoldering it and see the diode is 1n5819. i have a 1n4007 on my box same amperege as those diode, trying to replace it and get a good result. but the question, it is dangerous for my cpu if i using those 1n4007 instead 1n5819 in the psu to powering my psu? also it could long last? yes i have download the datasheet already, but i didn't know exactly, i think the expert one on repairing usually know about universal replacement parts. any short answer appreciated. thank you
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Old 10-20-2013, 07:27 AM   #2
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Default Re: 1n5819 rectifier replace with 1n4007 rectifier??

1N5819 is a fast, low loss, schottky rectifier.
1N4007 Is a slow, high loss, silicon rectifier.

No, you cannot. The 1N4007 will likely last a few minutes before failure, probably less.
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Old 10-20-2013, 08:37 AM   #3
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Default Re: 1n5819 rectifier replace with 1n4007 rectifier??

Quote:
Originally Posted by tom66 View Post
1N5819 is a fast, low loss, schottky rectifier.
1N4007 Is a slow, high loss, silicon rectifier.

No, you cannot. The 1N4007 will likely last a few minutes before failure, probably less.
i just powering her about 2-3 minutes because fear of damage anythings. her is almost looks like a new PSU.

thank you for your kind answer
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Old 10-20-2013, 09:25 AM   #4
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Default Re: 1n5819 rectifier replace with 1n4007 rectifier??

A 1N5819 is a 1A, 40V Schottky rectifier; its V(f) at 1A is .6V, and it is very fast. A 1N4007 is a 1A, 1000V standard recovery rectifier; its V(f) at 1A is 1V, and its reverse recovery time is ~920nS. If the circuit in the P/S requires either the lower forward drop or the very fast reverse recovery time, a 1N4007 will fail pretty quickly, though it may take more than a few minutes. I strongly recommend that you replace that 1N4007 with a 1A-3A, 40V-60V Schottky rectifier, as I don't think the circuit designer would specify a Schottky rectifier without a reason.
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Old 10-20-2013, 10:27 AM   #5
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Default Re: 1n5819 rectifier replace with 1n4007 rectifier??

Quote:
Originally Posted by PeteS in CA View Post
A 1N5819 is a 1A, 40V Schottky rectifier; its V(f) at 1A is .6V, and it is very fast. A 1N4007 is a 1A, 1000V standard recovery rectifier; its V(f) at 1A is 1V, and its reverse recovery time is ~920nS. If the circuit in the P/S requires either the lower forward drop or the very fast reverse recovery time, a 1N4007 will fail pretty quickly, though it may take more than a few minutes. I strongly recommend that you replace that 1N4007 with a 1A-3A, 40V-60V Schottky rectifier, as I don't think the circuit designer would specify a Schottky rectifier without a reason.
I will changes it and make sure didn't turn it on until get a right component. i have think same as you before that designer inserting schottky rectifier without a reason, but my knowledge isn't good enough about this ,because im not an electrical student.
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Old 10-20-2013, 11:53 AM   #6
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Default Re: 1n5819 rectifier replace with 1n4007 rectifier??

I have seen some switching PSUs use a 1N4007 in the secondary to feed the SMPS chip. Bad, but surprised it worked. I guess the low current requirements may let it work (milliamperes) but I was surprised that the reverse recovery time was fast enough.

If you had an UF4007 instead, these probably are better for replacing a 1N5819, but even these are a terrible replacement due to the Vf drop being higher.
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Old 10-20-2013, 01:09 PM   #7
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Default Re: 1n5819 rectifier replace with 1n4007 rectifier??

I'm guessing a UF4007 is a 1A, 1000V ultra-fast - 25-50nS reverse recovery time. Fast, but probably a 1.2V-1.5V V(f) at 1A.
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Old 10-21-2013, 09:21 AM   #8
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Default Re: 1n5819 rectifier replace with 1n4007 rectifier??

Quote:
Originally Posted by eccerr0r View Post
I have seen some switching PSUs use a 1N4007 in the secondary to feed the SMPS chip. Bad, but surprised it worked. I guess the low current requirements may let it work (milliamperes) but I was surprised that the reverse recovery time was fast enough.

If you had an UF4007 instead, these probably are better for replacing a 1N5819, but even these are a terrible replacement due to the Vf drop being higher.
Quote:
Originally Posted by PeteS in CA View Post
I'm guessing a UF4007 is a 1A, 1000V ultra-fast - 25-50nS reverse recovery time. Fast, but probably a 1.2V-1.5V V(f) at 1A.
i have FR107 on my store box, but didn't know it match or not, im just too busy on my college, maybe tomorrow i'll buy it. thank you for suggest
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Old 10-22-2013, 12:35 AM   #9
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Default Re: 1n5819 rectifier replace with 1n4007 rectifier??

Use FR107 . I have used many but still no complains back !!
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Old 10-22-2013, 12:44 AM   #10
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Default Re: 1n5819 rectifier replace with 1n4007 rectifier??

FR107 is probably more similar to UF4007 (might be a clone actually) than the 1N5819.
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Old 10-22-2013, 02:56 AM   #11
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Default Re: 1n5819 rectifier replace with 1n4007 rectifier??

Yes it's less efficient and if the 1N5819 failed in a short time then the UF4007 will faster but at least it will work for a quick test.
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Old 10-22-2013, 06:18 AM   #12
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Default Re: 1n5819 rectifier replace with 1n4007 rectifier??

A standard recovery rectifier (e.g. 1N4007) has a 50%-70% higher v(f) than a schottky (i.e. higher loss when conducting); it also switches off slower, so it also has higher losses when switching. The latter losses become increasingly significant as the frequency being switched increases (i.e. not significant at 50Hz or 60Hz, but critical at SMPS frequencies).

An ultrafast has a V(f) ~20% higher than a standard recovery rectifier, and 80%-100% higher than a schottky. So I think an ultrafast would probably last longer than a standard recovery rectifier, but overheating is certainly possible, and other things might suffer (e.g. efficiency, cross-regulation, low-line regulation).
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Old 10-22-2013, 01:09 PM   #13
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Default Re: 1n5819 rectifier replace with 1n4007 rectifier??

wow. i dont even hope could get any answer for this dumb question. smps frequency using a high frequency maybe around kHz-MHz as i know if not wrong, so it must to be consider when using the rectifier (different with linear psu that almost same as mains frequency) and guess what? i dont have good enough knowledge about the rights replacement.haha. btw i have fixed her and her running well now, thank you for all of kind (especially the friend those kindly give me)
i had learn much from this forum.

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Old 05-31-2016, 05:36 PM   #14
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Smile Re: 1n5819 rectifier replace with 1n4007 rectifier??

hi , you can use BYS21 OR BYV10---40 OR SB140
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