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Do Thermal Fuses Die of old Age?
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Jeff Wisnia
Mar 14, 2016, 12:56:59 PM3/14/16
to
Over the years I've had to replace maybe a half dozen thermal fuses
which appear to have failed without ever being heated beyond their rated
temperatures.
Most recently a small electric space heater used in our office under my
desk stopped working because its thermal fuse had opened. The fuse was a
MICROTEMP G4A0 121 degree C unit, and I'm pretty sure that nothing had
blocked air passage through the heater and caused its internal
temperature to rise enough to open the thermal fuss.
Jeff
--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.
which appear to have failed without ever being heated beyond their rated
temperatures.
Most recently a small electric space heater used in our office under my
desk stopped working because its thermal fuse had opened. The fuse was a
MICROTEMP G4A0 121 degree C unit, and I'm pretty sure that nothing had
blocked air passage through the heater and caused its internal
temperature to rise enough to open the thermal fuss.
Jeff
--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.
John Robertson
Mar 14, 2016, 1:20:27 PM3/14/16
to
On 03/14/2016 9:56 AM, Jeff Wisnia wrote:
> Over the years I've had to replace maybe a half dozen thermal fuses
> which appear to have failed without ever being heated beyond their rated
> temperatures.
>
> Most recently a small electric space heater used in our office under my
> desk stopped working because its thermal fuse had opened. The fuse was a
> MICROTEMP G4A0 121 degree C unit, and I'm pretty sure that nothing had
> blocked air passage through the heater and caused its internal
> temperature to rise enough to open the thermal fuss.
>
> Jeff
>
>
My expectation is yes, they do fail from age/power cycles. Most likely
> Over the years I've had to replace maybe a half dozen thermal fuses
> which appear to have failed without ever being heated beyond their rated
> temperatures.
>
> Most recently a small electric space heater used in our office under my
> desk stopped working because its thermal fuse had opened. The fuse was a
> MICROTEMP G4A0 121 degree C unit, and I'm pretty sure that nothing had
> blocked air passage through the heater and caused its internal
> temperature to rise enough to open the thermal fuss.
>
> Jeff
>
>
failure point is the wire to passive element junction...why not take it
apart and see?
John :-#)#
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
N_Cook
Mar 14, 2016, 2:21:14 PM3/14/16
to
On 14/03/2016 16:56, Jeff Wisnia wrote:
> Over the years I've had to replace maybe a half dozen thermal fuses
> which appear to have failed without ever being heated beyond their rated
> temperatures.
>
> Most recently a small electric space heater used in our office under my
> desk stopped working because its thermal fuse had opened. The fuse was a
> MICROTEMP G4A0 121 degree C unit, and I'm pretty sure that nothing had
> blocked air passage through the heater and caused its internal
> temperature to rise enough to open the thermal fuss.
>
> Jeff
>
>
They also have a current limit , but I do believe than can fail by
> Over the years I've had to replace maybe a half dozen thermal fuses
> which appear to have failed without ever being heated beyond their rated
> temperatures.
>
> Most recently a small electric space heater used in our office under my
> desk stopped working because its thermal fuse had opened. The fuse was a
> MICROTEMP G4A0 121 degree C unit, and I'm pretty sure that nothing had
> blocked air passage through the heater and caused its internal
> temperature to rise enough to open the thermal fuss.
>
> Jeff
>
>
deterioration or something
Cydrome Leader
Mar 14, 2016, 2:29:16 PM3/14/16
to
Jeff Wisnia <Jwis...@dumpthiscomcast.net> wrote:
> Over the years I've had to replace maybe a half dozen thermal fuses
> which appear to have failed without ever being heated beyond their rated
> temperatures.
>
> Most recently a small electric space heater used in our office under my
> desk stopped working because its thermal fuse had opened. The fuse was a
> MICROTEMP G4A0 121 degree C unit, and I'm pretty sure that nothing had
> blocked air passage through the heater and caused its internal
> temperature to rise enough to open the thermal fuss.
They seem to have poor aging characteristics. I've seen dead thermal fuses
> Over the years I've had to replace maybe a half dozen thermal fuses
> which appear to have failed without ever being heated beyond their rated
> temperatures.
>
> Most recently a small electric space heater used in our office under my
> desk stopped working because its thermal fuse had opened. The fuse was a
> MICROTEMP G4A0 121 degree C unit, and I'm pretty sure that nothing had
> blocked air passage through the heater and caused its internal
> temperature to rise enough to open the thermal fuss.
in completely unused spares heater assemblies sitting on shelves for
years. Everything was x-rayed so new ones could be custom made. Told them
to leave out the thermal fuses on the new ones.
pf...@aol.com
Mar 14, 2016, 2:43:26 PM3/14/16
to
On Monday, March 14, 2016 at 12:56:59 PM UTC-4, Jeff Wisnia wrote:
> Over the years I've had to replace maybe a half dozen thermal fuses
> which appear to have failed without ever being heated beyond their rated
> temperatures.
>
> Most recently a small electric space heater used in our office under my
> desk stopped working because its thermal fuse had opened. The fuse was a
> MICROTEMP G4A0 121 degree C unit, and I'm pretty sure that nothing had
> blocked air passage through the heater and caused its internal
> temperature to rise enough to open the thermal fuss.
>
> Jeff
They most certainly do die of old age. As do regular current-limited fuses. If ever one wants some very dry amusement, bring a glass fuse close to its current limit and watch the filament dance inside the glass.
> Over the years I've had to replace maybe a half dozen thermal fuses
> which appear to have failed without ever being heated beyond their rated
> temperatures.
>
> Most recently a small electric space heater used in our office under my
> desk stopped working because its thermal fuse had opened. The fuse was a
> MICROTEMP G4A0 121 degree C unit, and I'm pretty sure that nothing had
> blocked air passage through the heater and caused its internal
> temperature to rise enough to open the thermal fuss.
>
> Jeff
Peter Wieck
Melrose Park, PA
Jeff Wisnia
Mar 14, 2016, 2:44:40 PM3/14/16
to
The only PIA for me is now that I'm retired and no longer working for a
company which does business with component suppliers I have to find out
where to buy things like those thermal fuses myself. (When Mozart was my
age he'd been dead for 45 years.)
Radio Shack used to carry thermal fuses and I could have one sent to a
local store two blocks away from our home for pickup by me at no extra
charge, but they're kaput now so I had to go online and buy one for 75
cents and pay a minimum $5.50 for S&H.
Oh well, I would have used up that many dollars in driving costs running
around trying to find one locally, and it's still cheaper than buying a
new heater.
Yes I could have just shorted it out and been extra careful using the
heater, but my luck is so bad that if someone gave me a cemetery people
would stop dying. I might burn down the whole building with that heater
and have some smart investigator tie it to my replacing the thermal fuse
with a piece of wire.
Jeff Wisnia
Mar 14, 2016, 3:06:19 PM3/14/16
to
installed in the four metal bodied table lamps I'd added "touch dimmers" to.
When the 150 watt bulbs I use in those lamps burned out the "thermal
arc" would often send the touch dimmers to the graveyard, so I added
fuse holders and fuses to the lamps. Those fuses protect the touch
dimmers, even though I have to replace a 15 cent fuse almost every time
a bulb burns out.
It's still worth having touch dimmers in the lamps because SWMBO and I
don't have to stick our arms up under the lamp shade and fumble around
for the rotary switch on the socket.
Look165
Mar 14, 2016, 4:38:05 PM3/14/16
to
My opinion is electrical peak ( = overvoltage ) !
Jeff Wisnia a écrit :
Jeff Wisnia a écrit :
Cydrome Leader
Mar 14, 2016, 5:22:20 PM3/14/16
to
Jeff Wisnia <Jwis...@dumpthiscomcast.net> wrote:
>
>
> Cydrome Leader wrote:
>> Jeff Wisnia <Jwis...@dumpthiscomcast.net> wrote:
>>> Over the years I've had to replace maybe a half dozen thermal fuses
>>> which appear to have failed without ever being heated beyond their rated
>>> temperatures.
>>>
>>> Most recently a small electric space heater used in our office under my
>>> desk stopped working because its thermal fuse had opened. The fuse was a
>>> MICROTEMP G4A0 121 degree C unit, and I'm pretty sure that nothing had
>>> blocked air passage through the heater and caused its internal
>>> temperature to rise enough to open the thermal fuss.
>>
>> They seem to have poor aging characteristics. I've seen dead thermal fuses
>> in completely unused spares heater assemblies sitting on shelves for
>> years. Everything was x-rayed so new ones could be custom made. Told them
>> to leave out the thermal fuses on the new ones.
>>
>>
>>
> Thanks folks, I think my guess about aging effects was probably correct.
>
> The only PIA for me is now that I'm retired and no longer working for a
> company which does business with component suppliers I have to find out
> where to buy things like those thermal fuses myself. (When Mozart was my
> age he'd been dead for 45 years.)
>
> Radio Shack used to carry thermal fuses and I could have one sent to a
> local store two blocks away from our home for pickup by me at no extra
> charge, but they're kaput now so I had to go online and buy one for 75
> cents and pay a minimum $5.50 for S&H.
Ha! RS was my thermal fuse and sketchy crimp terminal supplier of choice
>
>
> Cydrome Leader wrote:
>> Jeff Wisnia <Jwis...@dumpthiscomcast.net> wrote:
>>> Over the years I've had to replace maybe a half dozen thermal fuses
>>> which appear to have failed without ever being heated beyond their rated
>>> temperatures.
>>>
>>> Most recently a small electric space heater used in our office under my
>>> desk stopped working because its thermal fuse had opened. The fuse was a
>>> MICROTEMP G4A0 121 degree C unit, and I'm pretty sure that nothing had
>>> blocked air passage through the heater and caused its internal
>>> temperature to rise enough to open the thermal fuss.
>>
>> They seem to have poor aging characteristics. I've seen dead thermal fuses
>> in completely unused spares heater assemblies sitting on shelves for
>> years. Everything was x-rayed so new ones could be custom made. Told them
>> to leave out the thermal fuses on the new ones.
>>
>>
>>
> Thanks folks, I think my guess about aging effects was probably correct.
>
> The only PIA for me is now that I'm retired and no longer working for a
> company which does business with component suppliers I have to find out
> where to buy things like those thermal fuses myself. (When Mozart was my
> age he'd been dead for 45 years.)
>
> Radio Shack used to carry thermal fuses and I could have one sent to a
> local store two blocks away from our home for pickup by me at no extra
> charge, but they're kaput now so I had to go online and buy one for 75
> cents and pay a minimum $5.50 for S&H.
too.
Jon Elson
Mar 14, 2016, 6:24:14 PM3/14/16
to
Jeff Wisnia wrote:
> Over the years I've had to replace maybe a half dozen thermal fuses
> which appear to have failed without ever being heated beyond their rated
> temperatures.
>
> Most recently a small electric space heater used in our office under my
> desk stopped working because its thermal fuse had opened. The fuse was a
> MICROTEMP G4A0 121 degree C unit, and I'm pretty sure that nothing had
> blocked air passage through the heater and caused its internal
> temperature to rise enough to open the thermal fuss.
>
> Jeff
>
>
After having the thermal fuse in our dishwasher fail several times, and then
> Over the years I've had to replace maybe a half dozen thermal fuses
> which appear to have failed without ever being heated beyond their rated
> temperatures.
>
> Most recently a small electric space heater used in our office under my
> desk stopped working because its thermal fuse had opened. The fuse was a
> MICROTEMP G4A0 121 degree C unit, and I'm pretty sure that nothing had
> blocked air passage through the heater and caused its internal
> temperature to rise enough to open the thermal fuss.
>
> Jeff
>
>
an aftermarket part fail on the first time it was used, I bought some from
Digi-Key. Hmmmph, should have known better, DON'T solder it in without a
heat sink! The (2nd) new part seems to be working fine. Instead of $15
each for a nice piece in a plastic housing with 1/4" quick-connect
terminals, I can get a bare sensor/fuse for $1.50 from Digi-Key.
Jon
Jeff Wisnia
Mar 15, 2016, 12:29:33 PM3/15/16
to
arrives and I solder it in place.
John-Del
Mar 15, 2016, 2:13:34 PM3/15/16
to
Ian Field
Mar 15, 2016, 4:16:26 PM3/15/16
to
"N_Cook" <div...@tcp.co.uk> wrote in message
news:nc6v8q$ru2$1...@dont-email.me...
Once or twice I've even seen corrosion kill a fuse, but most thermal types
are in sealed encapsulation. That would be an unlikely failure mode.
Ian Field
Mar 15, 2016, 4:21:36 PM3/15/16
to
<pf...@aol.com> wrote in message
news:f122697d-8ae2-41b4...@googlegroups.com...
failure rates during soldering.
Occasionally, a bad crimp makes a resistive join that heats up and pushes it
past the trip point.
Jeff Wisnia
Mar 15, 2016, 4:56:33 PM3/15/16
to
lugs on the heater's thermostat and its heating element.
Jon Elson
Mar 15, 2016, 5:58:55 PM3/15/16
to
John-Del wrote:
>
> Make sure any plug in types have a clean and tight contact, or there'll be
> heat generator at the plug.
Yes, the kit that came with the aftermarket replacement had all this, and I
>
> Make sure any plug in types have a clean and tight contact, or there'll be
> heat generator at the plug.
replaced it, but it still blew the thermal fuse the first time we used it.
The Digi-Key replacement has held for several months, now.
Jon
Bob F
Mar 19, 2016, 4:14:21 PM3/19/16
to
amdx
Mar 21, 2016, 6:17:14 PM3/21/16
to
where I put them.
I have a circuit that I built a few years ago, 12V 500ma wallwart,
driving a 7809 regulator. Recently the circuit quit working, I measured
the voltage to the 9v regulator. I was 0.328 volts, I didn't figure it
was a shorted load, because the wallwart was not warm. It turns out the
primary of the wallwart is open, most likely the thermal fuse.
It was a little odd to get the 0.328V while connected to the load, but I
guess the 7809 draws very little current at low voltage. I installed
another wallwart and all is fine.
Mikek
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