Archived from groups: sci.electronics.repair,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips (More info?)

One of the ports of my NEC-based USB 2.0 card quit working because the
National Semiconductor LM3526 power controller chip failed. I'm
pretty sure that I didn't zap it with static (I always touch the
outher metal shell to the computer case before plugging it in) or try
to plug it in backwards. The data sheet for the LM3526 says that it's
protected against voltage, current, and even temperature, so what
happened?

National Semiconductor says that each USB port must have a 120uF or
larger tantalum capacitor between +5V and ground for protection
against transients that occur during hot-plugging, and NEC's example
schematic for their uPD720100A USB 2.0 chip shows the LM3526 using
150uF aluminum in parallel with 0.1uF ceramic. But my USB card has
only a 100uF aluminum capacitor and maybe a ceramic capacitor in
parallel for this. Could this be why the USB port got zapped? Would
it help to solder a tantalum in parallel as well? Will it hurt to add
it?

Archived from groups: sci.electronics.repair,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips (More info?)

"larrymoencurly" <larrymoencurly@my-deja.com> wrote in message
news:755e968a.0410031718.36d14f87@posting.google.com...
....
| National Semiconductor says that each USB port must have a 120uF or
| larger ....................................... But my USB card has
| only a 100uF aluminum capacitor and maybe a ceramic capacitor in
| parallel for this....

Close enough!

N

Archived from groups: sci.electronics.repair,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips (More info?)

On Mon, 04 Oct 2004 01:50:54 GMT, "NSM" <nowrite@to.me> wrote:

>
>"larrymoencurly" <larrymoencurly@my-deja.com> wrote in message
>news:755e968a.0410031718.36d14f87@posting.google.com...
>...
>| National Semiconductor says that each USB port must have a 120uF or
>| larger ....................................... But my USB card has
>| only a 100uF aluminum capacitor and maybe a ceramic capacitor in
>| parallel for this....
>
>Close enough!

Except the tantalum cap would have much lower esl & esr figures than an
aluminum cap, making it more effective.

otoh, tantalums can have a brilliant failure mode ;-)

Archived from groups: sci.electronics.repair,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips (More info?)

"larrymoencurly" <larrymoencurly@my-deja.com> wrote in message
news:755e968a.0410031718.36d14f87@posting.google.com...
> One of the ports of my NEC-based USB 2.0 card quit working because the
> National Semiconductor LM3526 power controller chip failed. I'm
> pretty sure that I didn't zap it with static (I always touch the
> outher metal shell to the computer case before plugging it in) or try
> to plug it in backwards. The data sheet for the LM3526 says that it's
> protected against voltage, current, and even temperature, so what
> happened?


Stuff just fails occasionally with no good explaination, could be it was
just a defective part that eventually quit.

Archived from groups: sci.electronics.repair,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips (More info?)

"James Sweet" <jamessweet@hotmail.com> wrote in message
news:lu58d.2427$r3.597@trnddc05...
|
| "larrymoencurly" <larrymoencurly@my-deja.com> wrote in message
| news:755e968a.0410031718.36d14f87@posting.google.com...
| > One of the ports of my NEC-based USB 2.0 card quit working because the
| > National Semiconductor LM3526 power controller chip failed. I'm
| > pretty sure that I didn't zap it with static (I always touch the
| > outher metal shell to the computer case before plugging it in) or try
| > to plug it in backwards. The data sheet for the LM3526 says that it's
| > protected against voltage, current, and even temperature, so what
| > happened?
|
|
| Stuff just fails occasionally with no good explaination, could be it was
| just a defective part that eventually quit.

Or as I say, "Everything works until it breaks". Then there are the three
brand new tubes I took off the shelf one at a time, each of which was bad.
Still can't get over that one.

N

Archived from groups: sci.electronics.repair,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips (More info?)

NSM wrote:

> "James Sweet" <jamessweet@hotmail.com> wrote in message
> news:lu58d.2427$r3.597@trnddc05...
> |
> | "larrymoencurly" <larrymoencurly@my-deja.com> wrote in message
> | news:755e968a.0410031718.36d14f87@posting.google.com...
> | > One of the ports of my NEC-based USB 2.0 card quit working because the
> | > National Semiconductor LM3526 power controller chip failed. I'm
> | > pretty sure that I didn't zap it with static (I always touch the
> | > outher metal shell to the computer case before plugging it in) or try
> | > to plug it in backwards. The data sheet for the LM3526 says that it's
> | > protected against voltage, current, and even temperature, so what
> | > happened?
> |
> |
> | Stuff just fails occasionally with no good explaination, could be it was
> | just a defective part that eventually quit.
>
> Or as I say, "Everything works until it breaks".

HEY!! That's MY line.

> Then there are the three
> brand new tubes I took off the shelf one at a time, each of which was bad.
> Still can't get over that one.

Find the guy who put the defective ones back on the shelf <g>.

>
> N
>
>

Archived from groups: sci.electronics.repair,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips (More info?)

"James Sweet" <jamessweet@hotmail.com> wrote in message news:<lu58d.2427$r3.597@trnddc05>...

> Stuff just fails occasionally with no good explaination, could be
> it was just a defective part that eventually quit.

I am eternally grateful for your answer, which not only completely
solved my problem with the USB port but will also magically turn the
rest of my life into bliss. So please give me your address so that I
can send you a $500 check, no, make that a blank check -- your advice
was that good.

Archived from groups: sci.electronics.repair,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips (More info?)

On 4 Oct 2004 13:57:43 -0700, larrymoencurly@my-deja.com
(larrymoencurly) wrote:

>"James Sweet" <jamessweet@hotmail.com> wrote in message news:<lu58d.2427$r3.597@trnddc05>...
>
>> Stuff just fails occasionally with no good explaination, could be
>> it was just a defective part that eventually quit.
>
>I am eternally grateful for your answer, which not only completely
>solved my problem with the USB port but will also magically turn the
>rest of my life into bliss. So please give me your address so that I
>can send you a $500 check, no, make that a blank check -- your advice
>was that good.

Believe it or not, it was a good and reasonable response, given the
information he had to work with.

Tom

Archived from groups: sci.electronics.repair,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips (More info?)

On Mon, 04 Oct 2004 03:21:58 +0000, daytripper wrote:

> On Mon, 04 Oct 2004 01:50:54 GMT, "NSM" <nowrite@to.me> wrote:
>
>>
>>"larrymoencurly" <larrymoencurly@my-deja.com> wrote in message
>>news:755e968a.0410031718.36d14f87@posting.google.com...
>>...
>>| National Semiconductor says that each USB port must have a 120uF or
>>| larger ....................................... But my USB card has
>>| only a 100uF aluminum capacitor and maybe a ceramic capacitor in
>>| parallel for this....
>>
>>Close enough!
>
> Except the tantalum cap would have much lower esl & esr figures than an
> aluminum cap, making it more effective.
>
> otoh, tantalums can have a brilliant failure mode ;-)

So do engineers when they're bringing up a system where all
of the tantallums were inserted backwards. You want to see fireworks!
(well,it was 25 years ago - I've mostly recovered and the tinninus
isn't so bad. <twitch> )

--
Keith

Archived from groups: sci.electronics.repair,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips (More info?)

keith wrote:

> On Mon, 04 Oct 2004 03:21:58 +0000, daytripper wrote:
>
>
>>On Mon, 04 Oct 2004 01:50:54 GMT, "NSM" <nowrite@to.me> wrote:
>>
>>
>>>"larrymoencurly" <larrymoencurly@my-deja.com> wrote in message
>>>news:755e968a.0410031718.36d14f87@posting.google.com...
>>>...
>>>| National Semiconductor says that each USB port must have a 120uF or
>>>| larger ....................................... But my USB card has
>>>| only a 100uF aluminum capacitor and maybe a ceramic capacitor in
>>>| parallel for this....
>>>
>>>Close enough!
>>
>>Except the tantalum cap would have much lower esl & esr figures than an
>>aluminum cap, making it more effective.
>>
>>otoh, tantalums can have a brilliant failure mode ;-)
>
>
> So do engineers when they're bringing up a system where all
> of the tantallums were inserted backwards. You want to see fireworks!
> (well,it was 25 years ago - I've mostly recovered and the tinninus
> isn't so bad. <twitch> )
>

LOL. Yeah, I'll bet.

You get a similar result plugging non keyed circuit boards into a vertical
card rack 180 degrees reversed.

Archived from groups: sci.electronics.repair,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips (More info?)

"keith" <krw@att.bizzzz> wrote in message
newsan.2004.10.05.01.56.40.575135@att.bizzzz...

| So do engineers when they're bringing up a system where all
| of the tantallums were inserted backwards. You want to see fireworks!
| (well,it was 25 years ago - I've mostly recovered and the tinninus
| isn't so bad. <twitch> )

I recall being told of a large TTL circuit board which was powered up with
reverse polarity. This was noticed due to the considerable amount of heat
being given off.

Everyone was mystified when the correctly rewired board worked OK. I guess
TTL is a little more tolerant than is generally believed.

N

Archived from groups: sci.electronics.repair,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips (More info?)

forgive me for not immediately recommending you open the controller chip and
place it under your scanning electron microscope to search for signs of
electromigration...


"larrymoencurly" <larrymoencurly@my-deja.com> wrote in message
news:755e968a.0410041257.1581ba4c@posting.google.com...
> "James Sweet" <jamessweet@hotmail.com> wrote in message
news:<lu58d.2427$r3.597@trnddc05>...
>
> > Stuff just fails occasionally with no good explaination, could be
> > it was just a defective part that eventually quit.
>
> I am eternally grateful for your answer, which not only completely
> solved my problem with the USB port but will also magically turn the
> rest of my life into bliss. So please give me your address so that I
> can send you a $500 check, no, make that a blank check -- your advice
> was that good.

Archived from groups: sci.electronics.repair,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips (More info?)

"larrymoencurly" <larrymoencurly@my-deja.com> wrote in message
news:755e968a.0410041257.1581ba4c@posting.google.com...
> "James Sweet" <jamessweet@hotmail.com> wrote in message
news:<lu58d.2427$r3.597@trnddc05>...
>
> > Stuff just fails occasionally with no good explaination, could be
> > it was just a defective part that eventually quit.
>
> I am eternally grateful for your answer, which not only completely
> solved my problem with the USB port but will also magically turn the
> rest of my life into bliss. So please give me your address so that I
> can send you a $500 check, no, make that a blank check -- your advice
> was that good.


Just what sort of answer did you expect? I seem to have misplaced my crystal
ball and I can't find my spell book either. How is anyone supposed to tell
you why a chip failed? It just happens.

Archived from groups: sci.electronics.repair,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips (More info?)

"larrymoencurly" <larrymoencurly@my-deja.com> wrote in message
news:755e968a.0410041257.1581ba4c@posting.google.com...
| "James Sweet" <jamessweet@hotmail.com> wrote in message
news:<lu58d.2427$r3.597@trnddc05>...
|
| > Stuff just fails occasionally with no good explaination, could be
| > it was just a defective part that eventually quit.
|
| I am eternally grateful for your answer, which not only completely
| solved my problem with the USB port but will also magically turn the
| rest of my life into bliss. So please give me your address so that I
| can send you a $500 check, no, make that a blank check -- your advice
| was that good.

Assuming you are being sarcastic (it's not clear), I refer to this as a
CatRan question, i.e., "I was typing away on my computer and I was holding
the keyboard above my head and I was watching the screen through my toes
when all of a sudden the cat ran over my stomach and I noticed the screen
blinked twice. What causes that"?

N