I am working on a philips LCD tv with a broken psu. It was completely
dead and on opening it I found the usual story of bulging caps, signs
of overheating on the pcb thanks to the cramped vent-free design, etc
etc.
ZD 2 measures s/c, it is a P6KE16A, 16 volt 'transient voltage
suppresor' according to the datasheet he
http://www.datasheetcatalog.org/data...cs/mXuquwt.pdf

I'd like to know more about these components compared to a common-or-
garden zener. Apart from perhaps the faster protection action I'm not
clear on how they differ...
-B

"b" wrote in message
...
I am working on a philips LCD tv with a broken psu. It was completely
dead and on opening it I found the usual story of bulging caps, signs
of overheating on the pcb thanks to the cramped vent-free design, etc
etc.
ZD 2 measures s/c, it is a P6KE16A, 16 volt 'transient voltage
suppresor' according to the datasheet he
http://www.datasheetcatalog.org/data...cs/mXuquwt.pdf

I'd like to know more about these components compared to a common-or-
garden zener. Apart from perhaps the faster protection action I'm not
clear on how they differ...
-B


Do a search on Wikipedia for TVS diode, that should give you some
information.

Shaun

On Sat, 9 Jan 2010 17:51:48 -0600, "Shaun" put
finger to keyboard and composed:

"b" wrote in message
...
I am working on a philips LCD tv with a broken psu. It was completely
dead and on opening it I found the usual story of bulging caps, signs
of overheating on the pcb thanks to the cramped vent-free design, etc
etc.
ZD 2 measures s/c, it is a P6KE16A, 16 volt 'transient voltage
suppresor' according to the datasheet he
http://www.datasheetcatalog.org/data...cs/mXuquwt.pdf

I'd like to know more about these components compared to a common-or-
garden zener. Apart from perhaps the faster protection action I'm not
clear on how they differ...
-B


Do a search on Wikipedia for TVS diode, that should give you some
information.

Shaun

What is a Silicon Transient Voltage Suppressor and how does it work?
http://www.vishay.com/docs/88436/appnote.pdf

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Franc Zabkar wrote in message
...
On Sat, 9 Jan 2010 17:51:48 -0600, "Shaun" put
finger to keyboard and composed:

"b" wrote in message
...
I am working on a philips LCD tv with a broken psu. It was completely
dead and on opening it I found the usual story of bulging caps, signs
of overheating on the pcb thanks to the cramped vent-free design, etc
etc.
ZD 2 measures s/c, it is a P6KE16A, 16 volt 'transient voltage
suppresor' according to the datasheet he

http://www.datasheetcatalog.org/data...ronics/mXuquwt
..pdf

I'd like to know more about these components compared to a common-or-
garden zener. Apart from perhaps the faster protection action I'm not
clear on how they differ...
-B


Do a search on Wikipedia for TVS diode, that should give you some
information.

Shaun

What is a Silicon Transient Voltage Suppressor and how does it work?
http://www.vishay.com/docs/88436/appnote.pdf

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

But,unlike zeners , are they guaranteed to go short circuit if they end up
in what becomes a sustained overvoltage rather than just a transient
situation ? or 2 different clases of VTS ?

On Mon, 11 Jan 2010 08:25:42 -0000, "N_Cook" put
finger to keyboard and composed:

But,unlike zeners , are they guaranteed to go short circuit if they end up
in what becomes a sustained overvoltage rather than just a transient
situation ? or 2 different clases of TVS ?

I watch various hard drive forums. HDs nowadays use TVS diodes on
their +5V and +12V rails. A sustained overvoltage from, say, a 19V
laptop adapter always (?) shorts the 12V diode, unless it is protected
by a fusible zero-ohm resistor.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Franc Zabkar wrote in message
...
On Mon, 11 Jan 2010 08:25:42 -0000, "N_Cook" put
finger to keyboard and composed:

But,unlike zeners , are they guaranteed to go short circuit if they end
up
in what becomes a sustained overvoltage rather than just a transient
situation ? or 2 different clases of TVS ?

I watch various hard drive forums. HDs nowadays use TVS diodes on
their +5V and +12V rails. A sustained overvoltage from, say, a 19V
laptop adapter always (?) shorts the 12V diode, unless it is protected
by a fusible zero-ohm resistor.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

A zener would normally burn up/ go open circuit in overvoltage but do VTS
normally (but not guaranteed) go short thus providing crowbar protection if
fuse/fusible R/ current limiting/ps shut down, upstream. 80 percent/90
percent/ 99 percent of the time go s/c rather than o/c , any
guesses/knowlege?

And for completeness, in general terms.
I know it must vary with manufacturer/type of overload (eg from repeated
short term overloads/various amount of one-off overload, surges rather than
transients etc)
I think I've only ever come across 3 failed VTS, all s/c, so 80 percent
failing s/c , generally say
Over the years I would , gut-feeling , say zeners fail o/c 80 percent of the
time.
Anyone else's experiences to add here for a concensus view from experience?

Some interesting failure mode comparisons on this ap note
http://www.littelfuse.com/data/en/Ap...tes/an9768.pdf

On Mon, 11 Jan 2010 08:55:58 -0000, "N_Cook" put
finger to keyboard and composed:

Franc Zabkar wrote in message
.. .
On Mon, 11 Jan 2010 08:25:42 -0000, "N_Cook" put
finger to keyboard and composed:

But,unlike zeners , are they guaranteed to go short circuit if they end
up
in what becomes a sustained overvoltage rather than just a transient
situation ? or 2 different clases of TVS ?

I watch various hard drive forums. HDs nowadays use TVS diodes on
their +5V and +12V rails. A sustained overvoltage from, say, a 19V
laptop adapter always (?) shorts the 12V diode, unless it is protected
by a fusible zero-ohm resistor.

- Franc Zabkar

A zener would normally burn up/ go open circuit in overvoltage but do VTS
normally (but not guaranteed) go short thus providing crowbar protection if
fuse/fusible R/ current limiting/ps shut down, upstream. 80 percent/90
percent/ 99 percent of the time go s/c rather than o/c , any
guesses/knowlege?

I would think that they would go s/c, but will eventually go o/c if
the fault current is sustained.

The TVS failures I've seen have all been s/c because the PSU has shut
down.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

On 11 ene, 20:48, Franc Zabkar wrote:
On Mon, 11 Jan 2010 08:55:58 -0000, "N_Cook" put
finger to keyboard and composed:



Franc Zabkar wrote in message
.. .
On Mon, 11 Jan 2010 08:25:42 -0000, "N_Cook" put
finger to keyboard and composed:

But,unlike zeners , are they guaranteed to go short circuit if they end
up
in what becomes a sustained overvoltage rather than just a transient
situation ? or 2 different clases of TVS ?

I watch various hard drive forums. HDs nowadays use TVS diodes on
their +5V and +12V rails. A sustained overvoltage from, say, a 19V
laptop adapter always (?) shorts the 12V diode, unless it is protected
by a fusible zero-ohm resistor.

- Franc Zabkar
A zener would normally burn up/ go open circuit in overvoltage but do VTS
normally (but not guaranteed) go short thus providing crowbar protection if
fuse/fusible R/ current limiting/ps shut down, upstream. 80 percent/90
percent/ 99 percent of the time go s/c rather than o/c , any
guesses/knowlege?

I would think that they would go s/c, but will eventually go o/c if
the fault current is sustained.

The TVS failures I've seen have all been s/c because the PSU has shut down.


thanks for all the replies. so, seems like this is purely for
protection while zeners can be sued for regulation.
the one here is s/c and the psu was utterly dead. there are a few
bulged caps and its a cramped crappy design so no real mystery. it
must have gone s/c as the rails crept up and it could no longer handle
the suppression of transients. Owner reported strange noises before it
died.
-B

"b" wrote in message
...
On 11 ene, 20:48, Franc Zabkar wrote:
On Mon, 11 Jan 2010 08:55:58 -0000, "N_Cook" put
finger to keyboard and composed:



Franc Zabkar wrote in message
.. .
On Mon, 11 Jan 2010 08:25:42 -0000, "N_Cook" put
finger to keyboard and composed:

But,unlike zeners , are they guaranteed to go short circuit if they
end
up
in what becomes a sustained overvoltage rather than just a transient
situation ? or 2 different clases of TVS ?

I watch various hard drive forums. HDs nowadays use TVS diodes on
their +5V and +12V rails. A sustained overvoltage from, say, a 19V
laptop adapter always (?) shorts the 12V diode, unless it is protected
by a fusible zero-ohm resistor.

- Franc Zabkar
A zener would normally burn up/ go open circuit in overvoltage but do
VTS
normally (but not guaranteed) go short thus providing crowbar protection
if
fuse/fusible R/ current limiting/ps shut down, upstream. 80 percent/90
percent/ 99 percent of the time go s/c rather than o/c , any
guesses/knowlege?

I would think that they would go s/c, but will eventually go o/c if
the fault current is sustained.

The TVS failures I've seen have all been s/c because the PSU has shut
down.


thanks for all the replies. so, seems like this is purely for
protection while zeners can be sued for regulation.
the one here is s/c and the psu was utterly dead. there are a few
bulged caps and its a cramped crappy design so no real mystery. it
must have gone s/c as the rails crept up and it could no longer handle
the suppression of transients. Owner reported strange noises before it
died.
-B

Hello B,

Here's a description for TVS diodes that talk about the difference between
them and zeners.

http://www.semtech.com/images/datash...tvs_diodes.pdf

Shaun

Another question: what do the suffixes 'A' or 'CA' refer to? I ask
because I have been unable to find the exact replacement but have a
P6KE20CA. Not ideal, since the voltage rathing is 4v higher but I
assume it's better than nothing. Or would this be a bad idea due to
the different suffix?
cheers.
-B

b wrote:
what do the suffixes 'A' or 'CA' refer to?

http://google.com/search?q=transorb+...CA-denotes-*-*

JeffM wrote in message
...
b wrote:
what do the suffixes 'A' or 'CA' refer to?


http://google.com/search?q=transorb+...2+%22+suffix-C
A-denotes-*-*


But what is the function of
*-*
in the search string ?

b wrote:
what do the suffixes 'A' or 'CA' refer to?

JeffM wrote:
http://google.com/search?q=transorb+...CA-denotes-*-*

N_Cook wrote:
But what is the function of *-* in the search string ?

Wildcards. Google (alone, AFAIK) allows those.
When the results page appears, the words that appear in the phrase
where the asterisks are[1] will be highlighted
(along with the requested text).

....and, of course, the day after I post the link,
Google stops indexing the page. 8-(

Note also that when properly rendered on a schematic,
a CA device will have a nose-to-nose symbol reprentation.
..
..
[1] A hyphen is a valid word separator (as is a period).

so far I've been unable to find the part in question. As I need to
return this unit soon, I'm loath to leave it without some form of o/p
protection, is there anything strightforward I could add to this psu
to protect the appliance 'downstream'? possibly some form of crowbar
at least.
-B

Plenty of them in stock :

http://www.mouser.com/Search/Refine....eyword=P6KE16A

No minimum order , but I dont know if they do international orders.





"b" wrote in message
...
so far I've been unable to find the part in question. As I need to
return this unit soon, I'm loath to leave it without some form of o/p
protection, is there anything strightforward I could add to this psu
to protect the appliance 'downstream'? possibly some form of crowbar
at least.
-B

b wrote:
I've been unable to find the part in question.

This describes Igor's Spam-Free Custom Search:
http://groups.google.com/group/sci.e....custom.search
You should bookmark the Google page.

Not only did it find the item,
4 entities thought it was worthwhile to pay for an ad for that term.