Higher wattage for a resistor ever bad?

[isw]

In article <9b1acsFa8oU1@mid.individual.net>,
"Phil Allison" <phil_a@tpg.com.au> wrote:

"larry moe 'n curly"

When I come across a burnt resistor, I usually replace it with one
rated for twice the wattage as the original, but I was told it's
sometimes bad to do that. Why? I'm not referring to fuse resistors
but ordinary carbon composition resistors.


** Carbon comp resistors are rare and almost obsolete these days - did you
mean carbon film ?

Most resistor burn ups are the result of misuse or OTHER failures in the
equipment, so no upgrade is needed

If a new resistor of the same size gets unusually hot, then an upgrade is
justified.

BTW

2 and 3 watt carbon comp resistors that run hot ( 100C or more ) gradually
fall in value and get even hotter, ie a vicious cycle exists until complete
failure occurs.

Replace them with a wire wound type.

Which may or may not prevent oxidation of the solder joints and/or
damage to the circuit board where the resistor connects. I've seen many
instances where the power rating of the resistor was fine *for the
resistor* but not for the board it was mounted on.

Isaac

 

[Ron D.]

Got any penneys to replace a blown fuse?

 

[Wild_Bill]

Under-specked is one matter, but I'd be more worried about over-striped.. or
is that a hearse of a different color?

--
Cheers,
WB
..............


"Lord Valve" <detritus@ix.netcom.com> wrote in message
news:4E4B2915.63F51A0C@ix.netcom.com...

1) Under-specked. Runs too hot for the application.
Good idea in this case.

2) (Most common reason) Something else failed
and pulled excessive current through the resistor.
If you replace just the resistor, and use a higher
wattage part, you might cook other (more expensive)
stuff.

Lord Valve
American - so far

 

[JW]

On Wed, 17 Aug 2011 08:13:16 -0700 Don Lancaster <don@tinaja.com> wrote in
Message id: <9b241mFbl7U1@mid.individual.net>:

On 8/16/2011 7:21 PM, Jon Kirwan wrote:
On Tue, 16 Aug 2011 19:11:18 -0700 (PDT), "larry moe 'n
curly"<larrymoencurly@my-deja.com> wrote:

When I come across a burnt resistor, I usually replace it with one
rated for twice the wattage as the original, but I was told it's
sometimes bad to do that. Why? I'm not referring to fuse resistors
but ordinary carbon composition resistors.

Hmm. Not obvious why there would be a worry. The
differences amount to the following:

1) Longer body, and
2) Larger body diameter, and
3) More weight, and
3) Lower temperature at given power dissipation.

Other than the thought that it does have a fuse function,
which you dispute above, there can be:

A) The longer body or larger body diameter causes the wiring
to be too close to nearby parts, mechanically stresses
something, or blocks some hole that needs to be clear, or
B) The greater weight causes some problem (such as if it
were at the end of a propeller, for example), or
C) The lower temperature affects something else that depends
on the earlier higher temperature.

In short, I can't think of a problem that would not be pretty
obvious when you were replacing it. But then my imagination
ain't what it used to be, either.

Jon


If the original resistor burnt, something is wrong and needs fixed.

Not always true. Open up a Keithley 236 or 237 (if anyone has one) and
check the 2 watt drain resistors across the main input capacitors in the
power supply. You'll likely see that they've been getting extremely hot.
In time their resistance will lower until they burn out. Hopefully the
fuse goes first, but I've seen them catch fire. Replacing them with a 3
watt resistor fixes them.

Replacing the resistor with a bigger one is not in any manner a solution.

Not true in the case above.

 

[Michael A. Terrell]

"Ron D." wrote:

Got any penneys to replace a blown fuse?

Do you mean 'Pennies', or the department store?


--
Subject: Spelling Lesson

The last four letters in American.........I Can
The last four letters in Republican.......I Can
The last four letters in Democrats.........Rats

End of lesson. Test to follow in November, 2012

Remember, November is to be set aside as rodent extermination month.

 

[krw@att.bizzzzzzzzzzzz]

On Thu, 18 Aug 2011 05:28:49 -0400, JW <none@dev.null> wrote:

On Wed, 17 Aug 2011 08:13:16 -0700 Don Lancaster <don@tinaja.com> wrote in
Message id: <9b241mFbl7U1@mid.individual.net>:

On 8/16/2011 7:21 PM, Jon Kirwan wrote:
On Tue, 16 Aug 2011 19:11:18 -0700 (PDT), "larry moe 'n
curly"<larrymoencurly@my-deja.com> wrote:

When I come across a burnt resistor, I usually replace it with one
rated for twice the wattage as the original, but I was told it's
sometimes bad to do that. Why? I'm not referring to fuse resistors
but ordinary carbon composition resistors.

Hmm. Not obvious why there would be a worry. The
differences amount to the following:

1) Longer body, and
2) Larger body diameter, and
3) More weight, and
3) Lower temperature at given power dissipation.

Other than the thought that it does have a fuse function,
which you dispute above, there can be:

A) The longer body or larger body diameter causes the wiring
to be too close to nearby parts, mechanically stresses
something, or blocks some hole that needs to be clear, or
B) The greater weight causes some problem (such as if it
were at the end of a propeller, for example), or
C) The lower temperature affects something else that depends
on the earlier higher temperature.

In short, I can't think of a problem that would not be pretty
obvious when you were replacing it. But then my imagination
ain't what it used to be, either.

Jon


If the original resistor burnt, something is wrong and needs fixed.

Not always true. Open up a Keithley 236 or 237 (if anyone has one) and
check the 2 watt drain resistors across the main input capacitors in the
power supply. You'll likely see that they've been getting extremely hot.
In time their resistance will lower until they burn out. Hopefully the
fuse goes first, but I've seen them catch fire. Replacing them with a 3
watt resistor fixes them.

Well, it's obvious that using a 2W resistor is "something wrong". ;-)

Replacing the resistor with a bigger one is not in any manner a solution.

Not true in the case above.

Our rule was 50% underrating on all carbon comps, and tantalum caps. I try to
do the same with thick-film SMTs, now.

 

[Jon Kirwan]

On Thu, 18 Aug 2011 17:14:45 -0500, "krw@att.bizzzzzzzzzzzz"
<krw@att.bizzzzzzzzzzzz> wrote:

On Thu, 18 Aug 2011 05:28:49 -0400, JW <none@dev.null> wrote:

On Wed, 17 Aug 2011 08:13:16 -0700 Don Lancaster <don@tinaja.com> wrote in
Message id: <9b241mFbl7U1@mid.individual.net>:

On 8/16/2011 7:21 PM, Jon Kirwan wrote:
On Tue, 16 Aug 2011 19:11:18 -0700 (PDT), "larry moe 'n
curly"<larrymoencurly@my-deja.com> wrote:

When I come across a burnt resistor, I usually replace it with one
rated for twice the wattage as the original, but I was told it's
sometimes bad to do that. Why? I'm not referring to fuse resistors
but ordinary carbon composition resistors.

Hmm. Not obvious why there would be a worry. The
differences amount to the following:

1) Longer body, and
2) Larger body diameter, and
3) More weight, and
3) Lower temperature at given power dissipation.

Other than the thought that it does have a fuse function,
which you dispute above, there can be:

A) The longer body or larger body diameter causes the wiring
to be too close to nearby parts, mechanically stresses
something, or blocks some hole that needs to be clear, or
B) The greater weight causes some problem (such as if it
were at the end of a propeller, for example), or
C) The lower temperature affects something else that depends
on the earlier higher temperature.

In short, I can't think of a problem that would not be pretty
obvious when you were replacing it. But then my imagination
ain't what it used to be, either.

Jon


If the original resistor burnt, something is wrong and needs fixed.

Not always true. Open up a Keithley 236 or 237 (if anyone has one) and
check the 2 watt drain resistors across the main input capacitors in the
power supply. You'll likely see that they've been getting extremely hot.
In time their resistance will lower until they burn out. Hopefully the
fuse goes first, but I've seen them catch fire. Replacing them with a 3
watt resistor fixes them.

Well, it's obvious that using a 2W resistor is "something wrong". ;-)
snip

But I think his point in telling the story is that replacing
a resistor with a higher wattage isn't _always_ masking some
other problem. Sometimes, it is fixing the _actual_ problem
at hand. He was responding to Don's absolutist claim that,
"replacing the resistor with a bigger one is not in any
manner a solution."

Jon

 

[krw@att.bizzzzzzzzzzzz]

On Thu, 18 Aug 2011 21:05:04 -0700, Jon Kirwan <jonk@infinitefactors.org>
wrote:

On Thu, 18 Aug 2011 17:14:45 -0500, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:

On Thu, 18 Aug 2011 05:28:49 -0400, JW <none@dev.null> wrote:

On Wed, 17 Aug 2011 08:13:16 -0700 Don Lancaster <don@tinaja.com> wrote in
Message id: <9b241mFbl7U1@mid.individual.net>:

On 8/16/2011 7:21 PM, Jon Kirwan wrote:
On Tue, 16 Aug 2011 19:11:18 -0700 (PDT), "larry moe 'n
curly"<larrymoencurly@my-deja.com> wrote:

When I come across a burnt resistor, I usually replace it with one
rated for twice the wattage as the original, but I was told it's
sometimes bad to do that. Why? I'm not referring to fuse resistors
but ordinary carbon composition resistors.

Hmm. Not obvious why there would be a worry. The
differences amount to the following:

1) Longer body, and
2) Larger body diameter, and
3) More weight, and
3) Lower temperature at given power dissipation.

Other than the thought that it does have a fuse function,
which you dispute above, there can be:

A) The longer body or larger body diameter causes the wiring
to be too close to nearby parts, mechanically stresses
something, or blocks some hole that needs to be clear, or
B) The greater weight causes some problem (such as if it
were at the end of a propeller, for example), or
C) The lower temperature affects something else that depends
on the earlier higher temperature.

In short, I can't think of a problem that would not be pretty
obvious when you were replacing it. But then my imagination
ain't what it used to be, either.

Jon


If the original resistor burnt, something is wrong and needs fixed.

Not always true. Open up a Keithley 236 or 237 (if anyone has one) and
check the 2 watt drain resistors across the main input capacitors in the
power supply. You'll likely see that they've been getting extremely hot.
In time their resistance will lower until they burn out. Hopefully the
fuse goes first, but I've seen them catch fire. Replacing them with a 3
watt resistor fixes them.

Well, it's obvious that using a 2W resistor is "something wrong". ;-)
snip

But I think his point in telling the story is that replacing
a resistor with a higher wattage isn't _always_ masking some
other problem. Sometimes, it is fixing the _actual_ problem
at hand. He was responding to Don's absolutist claim that,
"replacing the resistor with a bigger one is not in any
manner a solution."

I guess a smiley wasn't enough to tip you off that the point wasn't a serious
one. Not that it surprises me that you didn't get it.

 

[Jon Kirwan]

On Thu, 18 Aug 2011 23:19:27 -0500, "krw@att.bizzzzzzzzzzzz"
<krw@att.bizzzzzzzzzzzz> wrote:

On Thu, 18 Aug 2011 21:05:04 -0700, Jon Kirwan <jonk@infinitefactors.org
wrote:

On Thu, 18 Aug 2011 17:14:45 -0500, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:

On Thu, 18 Aug 2011 05:28:49 -0400, JW <none@dev.null> wrote:

On Wed, 17 Aug 2011 08:13:16 -0700 Don Lancaster <don@tinaja.com> wrote in
Message id: <9b241mFbl7U1@mid.individual.net>:

On 8/16/2011 7:21 PM, Jon Kirwan wrote:
On Tue, 16 Aug 2011 19:11:18 -0700 (PDT), "larry moe 'n
curly"<larrymoencurly@my-deja.com> wrote:

When I come across a burnt resistor, I usually replace it with one
rated for twice the wattage as the original, but I was told it's
sometimes bad to do that. Why? I'm not referring to fuse resistors
but ordinary carbon composition resistors.

Hmm. Not obvious why there would be a worry. The
differences amount to the following:

1) Longer body, and
2) Larger body diameter, and
3) More weight, and
3) Lower temperature at given power dissipation.

Other than the thought that it does have a fuse function,
which you dispute above, there can be:

A) The longer body or larger body diameter causes the wiring
to be too close to nearby parts, mechanically stresses
something, or blocks some hole that needs to be clear, or
B) The greater weight causes some problem (such as if it
were at the end of a propeller, for example), or
C) The lower temperature affects something else that depends
on the earlier higher temperature.

In short, I can't think of a problem that would not be pretty
obvious when you were replacing it. But then my imagination
ain't what it used to be, either.

Jon


If the original resistor burnt, something is wrong and needs fixed.

Not always true. Open up a Keithley 236 or 237 (if anyone has one) and
check the 2 watt drain resistors across the main input capacitors in the
power supply. You'll likely see that they've been getting extremely hot.
In time their resistance will lower until they burn out. Hopefully the
fuse goes first, but I've seen them catch fire. Replacing them with a 3
watt resistor fixes them.

Well, it's obvious that using a 2W resistor is "something wrong". ;-)
snip

But I think his point in telling the story is that replacing
a resistor with a higher wattage isn't _always_ masking some
other problem. Sometimes, it is fixing the _actual_ problem
at hand. He was responding to Don's absolutist claim that,
"replacing the resistor with a bigger one is not in any
manner a solution."

I guess a smiley wasn't enough to tip you off that the point wasn't a serious
one. Not that it surprises me that you didn't get it.

One can never be sure what a smiley means. And I'm kind of
proud of being literal-minded, anyway.

Jon

 

[larry moe 'n curly]

Don Lancaster wrote:

If the original resistor burnt, something is wrong and needs fixed.

Replacing the resistor with a bigger one is not in any manner a solution.

The burnt resistors were in series with zeners, one in a 30-year-old
TV's remote control receiver board, the others (burnt and bulging) in
a garage door opener containing 40xx series CMOS chips. I believe
all of these resistors were run at close to their power ratings
(garage door opener sat in 110-120F in summer). Also I had a CRT
multisync monitor that burned out the output transistor in a large
hybrid chip in its main power supply. It had a resistor connected to
it that was definitely run above its power rating, but just briefly at
turn-on, to help with a kick start circuit. It was only slightly
discolored, and I was told to not replace it with anything larger
because the low power rating may have been intended to provide
protection.

 

[krw@att.bizzzzzzzzzzzz]

On Thu, 18 Aug 2011 22:26:16 -0700, Jon Kirwan <jonk@infinitefactors.org>
wrote:

On Thu, 18 Aug 2011 23:19:27 -0500, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:

On Thu, 18 Aug 2011 21:05:04 -0700, Jon Kirwan <jonk@infinitefactors.org
wrote:

On Thu, 18 Aug 2011 17:14:45 -0500, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:

On Thu, 18 Aug 2011 05:28:49 -0400, JW <none@dev.null> wrote:

On Wed, 17 Aug 2011 08:13:16 -0700 Don Lancaster <don@tinaja.com> wrote in
Message id: <9b241mFbl7U1@mid.individual.net>:

On 8/16/2011 7:21 PM, Jon Kirwan wrote:
On Tue, 16 Aug 2011 19:11:18 -0700 (PDT), "larry moe 'n
curly"<larrymoencurly@my-deja.com> wrote:

When I come across a burnt resistor, I usually replace it with one
rated for twice the wattage as the original, but I was told it's
sometimes bad to do that. Why? I'm not referring to fuse resistors
but ordinary carbon composition resistors.

Hmm. Not obvious why there would be a worry. The
differences amount to the following:

1) Longer body, and
2) Larger body diameter, and
3) More weight, and
3) Lower temperature at given power dissipation.

Other than the thought that it does have a fuse function,
which you dispute above, there can be:

A) The longer body or larger body diameter causes the wiring
to be too close to nearby parts, mechanically stresses
something, or blocks some hole that needs to be clear, or
B) The greater weight causes some problem (such as if it
were at the end of a propeller, for example), or
C) The lower temperature affects something else that depends
on the earlier higher temperature.

In short, I can't think of a problem that would not be pretty
obvious when you were replacing it. But then my imagination
ain't what it used to be, either.

Jon


If the original resistor burnt, something is wrong and needs fixed.

Not always true. Open up a Keithley 236 or 237 (if anyone has one) and
check the 2 watt drain resistors across the main input capacitors in the
power supply. You'll likely see that they've been getting extremely hot.
In time their resistance will lower until they burn out. Hopefully the
fuse goes first, but I've seen them catch fire. Replacing them with a 3
watt resistor fixes them.

Well, it's obvious that using a 2W resistor is "something wrong". ;-)
snip

But I think his point in telling the story is that replacing
a resistor with a higher wattage isn't _always_ masking some
other problem. Sometimes, it is fixing the _actual_ problem
at hand. He was responding to Don's absolutist claim that,
"replacing the resistor with a bigger one is not in any
manner a solution."

I guess a smiley wasn't enough to tip you off that the point wasn't a serious
one. Not that it surprises me that you didn't get it.

One can never be sure what a smiley means. And I'm kind of
proud of being literal-minded, anyway.

It certainly doesn't mean what's said is in all seriousness. Again, it
shouldn't be surprising to anyone that you don't "get it".

 

[Jon Kirwan]

On Fri, 19 Aug 2011 17:11:12 -0500, "krw@att.bizzzzzzzzzzzz"
<krw@att.bizzzzzzzzzzzz> wrote:

On Thu, 18 Aug 2011 22:26:16 -0700, Jon Kirwan <jonk@infinitefactors.org
wrote:

On Thu, 18 Aug 2011 23:19:27 -0500, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:

On Thu, 18 Aug 2011 21:05:04 -0700, Jon Kirwan <jonk@infinitefactors.org
wrote:

On Thu, 18 Aug 2011 17:14:45 -0500, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:

On Thu, 18 Aug 2011 05:28:49 -0400, JW <none@dev.null> wrote:

On Wed, 17 Aug 2011 08:13:16 -0700 Don Lancaster <don@tinaja.com> wrote in
Message id: <9b241mFbl7U1@mid.individual.net>:

On 8/16/2011 7:21 PM, Jon Kirwan wrote:
On Tue, 16 Aug 2011 19:11:18 -0700 (PDT), "larry moe 'n
curly"<larrymoencurly@my-deja.com> wrote:

When I come across a burnt resistor, I usually replace it with one
rated for twice the wattage as the original, but I was told it's
sometimes bad to do that. Why? I'm not referring to fuse resistors
but ordinary carbon composition resistors.

Hmm. Not obvious why there would be a worry. The
differences amount to the following:

1) Longer body, and
2) Larger body diameter, and
3) More weight, and
3) Lower temperature at given power dissipation.

Other than the thought that it does have a fuse function,
which you dispute above, there can be:

A) The longer body or larger body diameter causes the wiring
to be too close to nearby parts, mechanically stresses
something, or blocks some hole that needs to be clear, or
B) The greater weight causes some problem (such as if it
were at the end of a propeller, for example), or
C) The lower temperature affects something else that depends
on the earlier higher temperature.

In short, I can't think of a problem that would not be pretty
obvious when you were replacing it. But then my imagination
ain't what it used to be, either.

Jon


If the original resistor burnt, something is wrong and needs fixed.

Not always true. Open up a Keithley 236 or 237 (if anyone has one) and
check the 2 watt drain resistors across the main input capacitors in the
power supply. You'll likely see that they've been getting extremely hot.
In time their resistance will lower until they burn out. Hopefully the
fuse goes first, but I've seen them catch fire. Replacing them with a 3
watt resistor fixes them.

Well, it's obvious that using a 2W resistor is "something wrong". ;-)
snip

But I think his point in telling the story is that replacing
a resistor with a higher wattage isn't _always_ masking some
other problem. Sometimes, it is fixing the _actual_ problem
at hand. He was responding to Don's absolutist claim that,
"replacing the resistor with a bigger one is not in any
manner a solution."

I guess a smiley wasn't enough to tip you off that the point wasn't a serious
one. Not that it surprises me that you didn't get it.

One can never be sure what a smiley means. And I'm kind of
proud of being literal-minded, anyway.

It certainly doesn't mean what's said is in all seriousness. Again, it
shouldn't be surprising to anyone that you don't "get it".

You just insist on being insulting, no matter what. Which
shouldn't surprise anyone, either.

Jon

 

[cjt]

On 08/16/2011 09:11 PM, larry moe 'n curly wrote:

When I come across a burnt resistor, I usually replace it with one
rated for twice the wattage as the original, but I was told it's
sometimes bad to do that. Why? I'm not referring to fuse resistors
but ordinary carbon composition resistors.

A different sized resistor will have different characteristics at high
frequency, so if those characteristics matter, there could be a problem.

 

[krw@att.bizzzzzzzzzzzz]

On Fri, 19 Aug 2011 16:47:55 -0700, Jon Kirwan <jonk@infinitefactors.org>
wrote:

On Fri, 19 Aug 2011 17:11:12 -0500, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:

On Thu, 18 Aug 2011 22:26:16 -0700, Jon Kirwan <jonk@infinitefactors.org
wrote:

On Thu, 18 Aug 2011 23:19:27 -0500, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:

On Thu, 18 Aug 2011 21:05:04 -0700, Jon Kirwan <jonk@infinitefactors.org
wrote:

On Thu, 18 Aug 2011 17:14:45 -0500, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:

On Thu, 18 Aug 2011 05:28:49 -0400, JW <none@dev.null> wrote:

On Wed, 17 Aug 2011 08:13:16 -0700 Don Lancaster <don@tinaja.com> wrote in
Message id: <9b241mFbl7U1@mid.individual.net>:

On 8/16/2011 7:21 PM, Jon Kirwan wrote:
On Tue, 16 Aug 2011 19:11:18 -0700 (PDT), "larry moe 'n
curly"<larrymoencurly@my-deja.com> wrote:

When I come across a burnt resistor, I usually replace it with one
rated for twice the wattage as the original, but I was told it's
sometimes bad to do that. Why? I'm not referring to fuse resistors
but ordinary carbon composition resistors.

Hmm. Not obvious why there would be a worry. The
differences amount to the following:

1) Longer body, and
2) Larger body diameter, and
3) More weight, and
3) Lower temperature at given power dissipation.

Other than the thought that it does have a fuse function,
which you dispute above, there can be:

A) The longer body or larger body diameter causes the wiring
to be too close to nearby parts, mechanically stresses
something, or blocks some hole that needs to be clear, or
B) The greater weight causes some problem (such as if it
were at the end of a propeller, for example), or
C) The lower temperature affects something else that depends
on the earlier higher temperature.

In short, I can't think of a problem that would not be pretty
obvious when you were replacing it. But then my imagination
ain't what it used to be, either.

Jon


If the original resistor burnt, something is wrong and needs fixed.

Not always true. Open up a Keithley 236 or 237 (if anyone has one) and
check the 2 watt drain resistors across the main input capacitors in the
power supply. You'll likely see that they've been getting extremely hot.
In time their resistance will lower until they burn out. Hopefully the
fuse goes first, but I've seen them catch fire. Replacing them with a 3
watt resistor fixes them.

Well, it's obvious that using a 2W resistor is "something wrong". ;-)
snip

But I think his point in telling the story is that replacing
a resistor with a higher wattage isn't _always_ masking some
other problem. Sometimes, it is fixing the _actual_ problem
at hand. He was responding to Don's absolutist claim that,
"replacing the resistor with a bigger one is not in any
manner a solution."

I guess a smiley wasn't enough to tip you off that the point wasn't a serious
one. Not that it surprises me that you didn't get it.

One can never be sure what a smiley means. And I'm kind of
proud of being literal-minded, anyway.

It certainly doesn't mean what's said is in all seriousness. Again, it
shouldn't be surprising to anyone that you don't "get it".

You just insist on being insulting, no matter what. Which
shouldn't surprise anyone, either.

Sorry if the truth hurts but it is the truth.

 

[Jon Kirwan]

On Fri, 19 Aug 2011 22:05:36 -0500, "krw@att.bizzzzzzzzzzzz"
<krw@att.bizzzzzzzzzzzz> wrote:

On Fri, 19 Aug 2011 16:47:55 -0700, Jon Kirwan <jonk@infinitefactors.org
wrote:

On Fri, 19 Aug 2011 17:11:12 -0500, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:

On Thu, 18 Aug 2011 22:26:16 -0700, Jon Kirwan <jonk@infinitefactors.org
wrote:

On Thu, 18 Aug 2011 23:19:27 -0500, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:

On Thu, 18 Aug 2011 21:05:04 -0700, Jon Kirwan <jonk@infinitefactors.org
wrote:

On Thu, 18 Aug 2011 17:14:45 -0500, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:

On Thu, 18 Aug 2011 05:28:49 -0400, JW <none@dev.null> wrote:

On Wed, 17 Aug 2011 08:13:16 -0700 Don Lancaster <don@tinaja.com> wrote in
Message id: <9b241mFbl7U1@mid.individual.net>:

On 8/16/2011 7:21 PM, Jon Kirwan wrote:
On Tue, 16 Aug 2011 19:11:18 -0700 (PDT), "larry moe 'n
curly"<larrymoencurly@my-deja.com> wrote:

When I come across a burnt resistor, I usually replace it with one
rated for twice the wattage as the original, but I was told it's
sometimes bad to do that. Why? I'm not referring to fuse resistors
but ordinary carbon composition resistors.

Hmm. Not obvious why there would be a worry. The
differences amount to the following:

1) Longer body, and
2) Larger body diameter, and
3) More weight, and
3) Lower temperature at given power dissipation.

Other than the thought that it does have a fuse function,
which you dispute above, there can be:

A) The longer body or larger body diameter causes the wiring
to be too close to nearby parts, mechanically stresses
something, or blocks some hole that needs to be clear, or
B) The greater weight causes some problem (such as if it
were at the end of a propeller, for example), or
C) The lower temperature affects something else that depends
on the earlier higher temperature.

In short, I can't think of a problem that would not be pretty
obvious when you were replacing it. But then my imagination
ain't what it used to be, either.

Jon


If the original resistor burnt, something is wrong and needs fixed.

Not always true. Open up a Keithley 236 or 237 (if anyone has one) and
check the 2 watt drain resistors across the main input capacitors in the
power supply. You'll likely see that they've been getting extremely hot.
In time their resistance will lower until they burn out. Hopefully the
fuse goes first, but I've seen them catch fire. Replacing them with a 3
watt resistor fixes them.

Well, it's obvious that using a 2W resistor is "something wrong". ;-)
snip

But I think his point in telling the story is that replacing
a resistor with a higher wattage isn't _always_ masking some
other problem. Sometimes, it is fixing the _actual_ problem
at hand. He was responding to Don's absolutist claim that,
"replacing the resistor with a bigger one is not in any
manner a solution."

I guess a smiley wasn't enough to tip you off that the point wasn't a serious
one. Not that it surprises me that you didn't get it.

One can never be sure what a smiley means. And I'm kind of
proud of being literal-minded, anyway.

It certainly doesn't mean what's said is in all seriousness. Again, it
shouldn't be surprising to anyone that you don't "get it".

You just insist on being insulting, no matter what. Which
shouldn't surprise anyone, either.

Sorry if the truth hurts but it is the truth.

You insulted above without provocation. And then continue to
repeat your error, again and again, without even being aware
of just how that makes you look.

I suppose that must be the painful truth you are talking
about. You have my pity.

Jon

 

[NT]

On Aug 17, 3:41 am, "Martin Riddle" <martin_...@verizon.net> wrote:

"larry moe 'n curly" <larrymoencu...@my-deja.com> wrote in messagenews:4765c808-4b10-438c-b419-872be457422e@cf8g2000vbb.googlegroups.com...

When I come across a burnt resistor, I usually replace it with one
rated for twice the wattage as the original, but I was told it's
sometimes bad to do that.  Why?  I'm not referring to fuse resistors
but ordinary carbon composition resistors.

No, it shouldn't be a problem. Different wattage is usually associated
with size.
If the resistor was 'cooked' then it was running at or beyond it's
rating. Which means there was something else in the circuit that is
defective.

Most resistors are metal film nowadays, carbon comps are hard to come
by.
(But Carbon comps do handle peak currents much better than metal films.)

Cheers

fwiw most TH parts are carbon film
Carbon comp, at least from the suppliers I use, are horribly
expensive. Just due to the small market for them I guess, they
certainly used to be the cheapest.


NT

 

[krw@att.bizzzzzzzzzzzz]

On Fri, 19 Aug 2011 22:12:59 -0700, Jon Kirwan <jonk@infinitefactors.org>
wrote:

On Fri, 19 Aug 2011 22:05:36 -0500, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:

On Fri, 19 Aug 2011 16:47:55 -0700, Jon Kirwan <jonk@infinitefactors.org
wrote:

On Fri, 19 Aug 2011 17:11:12 -0500, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:

On Thu, 18 Aug 2011 22:26:16 -0700, Jon Kirwan <jonk@infinitefactors.org
wrote:

On Thu, 18 Aug 2011 23:19:27 -0500, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:

On Thu, 18 Aug 2011 21:05:04 -0700, Jon Kirwan <jonk@infinitefactors.org
wrote:

On Thu, 18 Aug 2011 17:14:45 -0500, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:

On Thu, 18 Aug 2011 05:28:49 -0400, JW <none@dev.null> wrote:

On Wed, 17 Aug 2011 08:13:16 -0700 Don Lancaster <don@tinaja.com> wrote in
Message id: <9b241mFbl7U1@mid.individual.net>:

On 8/16/2011 7:21 PM, Jon Kirwan wrote:
On Tue, 16 Aug 2011 19:11:18 -0700 (PDT), "larry moe 'n
curly"<larrymoencurly@my-deja.com> wrote:

When I come across a burnt resistor, I usually replace it with one
rated for twice the wattage as the original, but I was told it's
sometimes bad to do that. Why? I'm not referring to fuse resistors
but ordinary carbon composition resistors.

Hmm. Not obvious why there would be a worry. The
differences amount to the following:

1) Longer body, and
2) Larger body diameter, and
3) More weight, and
3) Lower temperature at given power dissipation.

Other than the thought that it does have a fuse function,
which you dispute above, there can be:

A) The longer body or larger body diameter causes the wiring
to be too close to nearby parts, mechanically stresses
something, or blocks some hole that needs to be clear, or
B) The greater weight causes some problem (such as if it
were at the end of a propeller, for example), or
C) The lower temperature affects something else that depends
on the earlier higher temperature.

In short, I can't think of a problem that would not be pretty
obvious when you were replacing it. But then my imagination
ain't what it used to be, either.

Jon


If the original resistor burnt, something is wrong and needs fixed.

Not always true. Open up a Keithley 236 or 237 (if anyone has one) and
check the 2 watt drain resistors across the main input capacitors in the
power supply. You'll likely see that they've been getting extremely hot.
In time their resistance will lower until they burn out. Hopefully the
fuse goes first, but I've seen them catch fire. Replacing them with a 3
watt resistor fixes them.

Well, it's obvious that using a 2W resistor is "something wrong". ;-)
snip

But I think his point in telling the story is that replacing
a resistor with a higher wattage isn't _always_ masking some
other problem. Sometimes, it is fixing the _actual_ problem
at hand. He was responding to Don's absolutist claim that,
"replacing the resistor with a bigger one is not in any
manner a solution."

I guess a smiley wasn't enough to tip you off that the point wasn't a serious
one. Not that it surprises me that you didn't get it.

One can never be sure what a smiley means. And I'm kind of
proud of being literal-minded, anyway.

It certainly doesn't mean what's said is in all seriousness. Again, it
shouldn't be surprising to anyone that you don't "get it".

You just insist on being insulting, no matter what. Which
shouldn't surprise anyone, either.

Sorry if the truth hurts but it is the truth.

You insulted above without provocation. And then continue to
repeat your error, again and again, without even being aware
of just how that makes you look.

The truth is not an insult. You rarely "get it". Lefties are like that.

I suppose that must be the painful truth you are talking
about.

Is it painful? If so, seek help. It's certainly not painful to point out the
truth.

You have my pity.

You really need to look in the mirror.

 

[Jon Kirwan]

On Sat, 20 Aug 2011 12:28:22 -0500, "krw@att.bizzzzzzzzzzzz"
<krw@att.bizzzzzzzzzzzz> wrote:

On Fri, 19 Aug 2011 22:12:59 -0700, Jon Kirwan <jonk@infinitefactors.org
wrote:

On Fri, 19 Aug 2011 22:05:36 -0500, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:

On Fri, 19 Aug 2011 16:47:55 -0700, Jon Kirwan <jonk@infinitefactors.org
wrote:

On Fri, 19 Aug 2011 17:11:12 -0500, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:

On Thu, 18 Aug 2011 22:26:16 -0700, Jon Kirwan <jonk@infinitefactors.org
wrote:

On Thu, 18 Aug 2011 23:19:27 -0500, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:

On Thu, 18 Aug 2011 21:05:04 -0700, Jon Kirwan <jonk@infinitefactors.org
wrote:

On Thu, 18 Aug 2011 17:14:45 -0500, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:

On Thu, 18 Aug 2011 05:28:49 -0400, JW <none@dev.null> wrote:

On Wed, 17 Aug 2011 08:13:16 -0700 Don Lancaster <don@tinaja.com> wrote in
Message id: <9b241mFbl7U1@mid.individual.net>:

On 8/16/2011 7:21 PM, Jon Kirwan wrote:
On Tue, 16 Aug 2011 19:11:18 -0700 (PDT), "larry moe 'n
curly"<larrymoencurly@my-deja.com> wrote:

When I come across a burnt resistor, I usually replace it with one
rated for twice the wattage as the original, but I was told it's
sometimes bad to do that. Why? I'm not referring to fuse resistors
but ordinary carbon composition resistors.

Hmm. Not obvious why there would be a worry. The
differences amount to the following:

1) Longer body, and
2) Larger body diameter, and
3) More weight, and
3) Lower temperature at given power dissipation.

Other than the thought that it does have a fuse function,
which you dispute above, there can be:

A) The longer body or larger body diameter causes the wiring
to be too close to nearby parts, mechanically stresses
something, or blocks some hole that needs to be clear, or
B) The greater weight causes some problem (such as if it
were at the end of a propeller, for example), or
C) The lower temperature affects something else that depends
on the earlier higher temperature.

In short, I can't think of a problem that would not be pretty
obvious when you were replacing it. But then my imagination
ain't what it used to be, either.

Jon


If the original resistor burnt, something is wrong and needs fixed.

Not always true. Open up a Keithley 236 or 237 (if anyone has one) and
check the 2 watt drain resistors across the main input capacitors in the
power supply. You'll likely see that they've been getting extremely hot.
In time their resistance will lower until they burn out. Hopefully the
fuse goes first, but I've seen them catch fire. Replacing them with a 3
watt resistor fixes them.

Well, it's obvious that using a 2W resistor is "something wrong". ;-)
snip

But I think his point in telling the story is that replacing
a resistor with a higher wattage isn't _always_ masking some
other problem. Sometimes, it is fixing the _actual_ problem
at hand. He was responding to Don's absolutist claim that,
"replacing the resistor with a bigger one is not in any
manner a solution."

I guess a smiley wasn't enough to tip you off that the point wasn't a serious
one. Not that it surprises me that you didn't get it.

One can never be sure what a smiley means. And I'm kind of
proud of being literal-minded, anyway.

It certainly doesn't mean what's said is in all seriousness. Again, it
shouldn't be surprising to anyone that you don't "get it".

You just insist on being insulting, no matter what. Which
shouldn't surprise anyone, either.

Sorry if the truth hurts but it is the truth.

You insulted above without provocation. And then continue to
repeat your error, again and again, without even being aware
of just how that makes you look.

The truth is not an insult. You rarely "get it". Lefties
are like that.

Still can't stop being insulting and not just to me. And you
imagine this is _my_ problem. I have to love it.

I suppose that must be the painful truth you are talking
about.

Is it painful? If so, seek help. It's certainly not
painful to point out the truth.

You gotta keep perseverating without end. I'm bored.

You have my pity.

You really need to look in the mirror.

I'll leave you to suffer on at your war against whole groups
you hate. I've see nothing new here to discuss so the thread
is now yours. I'm bored.

Jon

 

[John Fields]

On Sat, 20 Aug 2011 02:51:54 -0700 (PDT), NT <meow2222@care2.com>
wrote:

On Aug 17, 3:41 am, "Martin Riddle" <martin_...@verizon.net> wrote:
"larry moe 'n curly" <larrymoencu...@my-deja.com> wrote in messagenews:4765c808-4b10-438c-b419-872be457422e@cf8g2000vbb.googlegroups.com...

When I come across a burnt resistor, I usually replace it with one
rated for twice the wattage as the original, but I was told it's
sometimes bad to do that.  Why?  I'm not referring to fuse resistors
but ordinary carbon composition resistors.

No, it shouldn't be a problem. Different wattage is usually associated
with size.
If the resistor was 'cooked' then it was running at or beyond it's
rating. Which means there was something else in the circuit that is
defective.

Most resistors are metal film nowadays, carbon comps are hard to come
by.
(But Carbon comps do handle peak currents much better than metal films.)

Cheers

fwiw most TH parts are carbon film

---
What do you mean by "TH"?

--
JF

 

[Phil Allison]

"John Fields"

fwiw most TH parts are carbon film

---
What do you mean by "TH"?

** Through Hole.

Dear, oh dear .....



..... Phil