Hi,

I have one PSU which the Live 1A Fuse blows repeatedly. I read that
changing the rectifier should solve thisproblem. However after
changing the rectifier, the fuse continues to be blown.
Any advise?

Thanks.
SeventhPrince七少爷

SeventhPrince七少爷 wrote:

Hi,

I have one PSU which the Live 1A Fuse blows repeatedly. I read that
changing the rectifier should solve thisproblem. However after
changing the rectifier, the fuse continues to be blown.
Any advise?

Thanks.
SeventhPrince七少爷

Find the short.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

Check the capacitor and regulating semiconductors.
Bob AZ

CJT wrote in :

SeventhPrince七少爷 wrote:

Hi,

I have one PSU which the Live 1A Fuse blows repeatedly. I read that
changing the rectifier should solve thisproblem. However after
changing the rectifier, the fuse continues to be blown.
Any advise?

Thanks.
SeventhPrince七少爷

Find the short.


Probably a shorted switcher transistor or secondary diode.
He should find a book on how switching power supplies work,or read the
application notes for the UC3842 IC.

--
Jim Yanik
jyanik
at
kua.net

"Jim Yanik" wrote in message
.. .
CJT wrote in :

SeventhPrinceä¸få°'ç^· wrote:

Hi,

I have one PSU which the Live 1A Fuse blows repeatedly. I read that
changing the rectifier should solve thisproblem. However after
changing the rectifier, the fuse continues to be blown.
Any advise?



Did you test the rectifier or just blindly replace it? If you're not able to
test semiconductors you'll dump a lot of money into this thing trying to get
it going and may well still fail.

"SeventhPrince???" wrote in message
ups.com...
Hi,

I have one PSU which the Live 1A Fuse blows repeatedly. I read that
changing the rectifier should solve thisproblem. However after
changing the rectifier, the fuse continues to be blown.
Any advise?

Thanks.
SeventhPrince???

Surely, the very first question to ask, before any of us can help, is what
type of supply is it - switch mode or linear ? Then the next one has got to
be, is the right fuse type being used ? If the supply has a damned great
transformer in it, and some big smoothers to stick an additional heavy load
on besides the core magnetization current at switch on, then if a ' T '
rated fuse is not being used as the replacement, it may well keep blowing at
switch on.

Arfa

Surely, the very first question to ask, before any of us can help, is what
type of supply is it - switch mode or linear ?

How do I differentiate between these 2?





Then the next one has got to
be, is the right fuse type being used ? If the supply has a damned great
transformer in it, and some big smoothers to stick an additional heavy load
on besides the core magnetization current at switch on, then if a ' T '
rated fuse is not being used as the replacement, it may well keep blowing at
switch on.

Yes, correct rating fuse is used. What are 'T' fuse and 'big smoothers' ?

Thanks.

Seventh Prince

Did you test the rectifier or just blindly replace it? If you're not able to
test semiconductors you'll dump a lot of money into this thing trying to get
it going and may well still fail.

How do I test the rectifies? Thanks

"???Seventh Prince" wrote in message
...
Surely, the very first question to ask, before any of us can help, is
what type of supply is it - switch mode or linear ?

How do I differentiate between these 2?





Then the next one has got to be, is the right fuse type being used ? If
the supply has a damned great transformer in it, and some big smoothers
to stick an additional heavy load on besides the core magnetization
current at switch on, then if a ' T ' rated fuse is not being used as the
replacement, it may well keep blowing at switch on.

Yes, correct rating fuse is used. What are 'T' fuse and 'big smoothers'
?

Thanks.

Seventh Prince

In all honesty, if you don't know how to tell apart switchers and linears,
don't know how to test a rectifier, don't know what a smoothing cap is, and
are able to determine that the fuse you are fitting is " correctly rated ",
without knowing what a ' T ' spec on a fuse is, then I don't think that you
are ever going to get to the bottom of the problem with or without the
group's help.

Power supplies, particularly switchers, are dangerous, and someone with your
apparent lack of knowledge should not be attempting to work on them, for his
own safety ....

Arfa

"???Seventh Prince" wrote in message
...


Did you test the rectifier or just blindly replace it? If you're not
able to
test semiconductors you'll dump a lot of money into this thing trying to
get
it going and may well still fail.

How do I test the rectifies? Thanks


It sounds like you've got a lot of homework to do before you try repairing
something, I assume you haven't read the sci.electronics.repair faq?

James Sweet wrote:
"???Seventh Prince" wrote in message
...


Did you test the rectifier or just blindly replace it? If you're not
able to
test semiconductors you'll dump a lot of money into this thing trying to
get
it going and may well still fail.

How do I test the rectifies? Thanks


It sounds like you've got a lot of homework to do before you try repairing
something, I assume you haven't read the sci.electronics.repair faq?