Basic fuse question

[Arfa Daily]

"Phil Allison" <phil_a@tpg.com.au> wrote in message
news:bcdp0jFgrg3U1@mid.individual.net...

"dave"

A Dim Bulb current limiter will protect better than a Variac. fyi.

http://www.kendrick-amplifiers.com/mm5/merchant.mvc?Screen=PROD&Store_Code=KOS&Product_Code=KEN04-limiter&Category_Code=04


** A Variac alone provides no protection.

But the method I outlined is vastly superior to the old light bulb trick.

Variac + true rms current meter + fuse (which can be a fast blow type).

There are far too many anomalies when a series lamp is fitted to the AC
supply.


... Phil

Agreed. The dim bulb limiter is a bit of a catch-all largely designed for
production testing by people no necessarily skilled in electronics. A variac
used in the way you suggested, and the way that I too use mine, is just as
effective at avoiding burnups in a fuse-blower, whilst actually providing a
greater level of information about where to be looking for the problem. The
trick is that like an ESR meter, a degree of skill is required to use the
variac correctly (for this type of fault finding) and to interpret the
results obtained ...

Arfa

 

[Bob F]

Dan wrote:

Ok, let me quote the amazon page for you.

QUALITY USA brand fuses!! Set of 5 pieces, T3.15AH250V, T3.15A 250V,
T3.15 H250V, T3.15A 250V, T3.15H250V cartridge CERAMIC fuses 5X20mm
(3/16" X 3/4"), 3.15A 250V, SLOW-blow (Time Delay)

Yeah, I saw that. It also says "You will receive 5 fuses and they can
be either of these marking: T3.15AH250V, T3.15A 250V, T3.15 H250V,
T3.15A 250V, T3.15H250V." Not being a fuse expert, I don't know that
these are all in fact interchangeable, and I thought perhaps it might
be better to clarify the rating numbers with someone who's NOT trying
to 'sell me something'.


And again with focus on the rating:
3.15A 250V

And again with just the amperage
3.15A
The A is for Amps.
That helpful enough for you?


That's what I was looking for. That wasn't so hard, now was it? I
guess I'll leave it to you and your shrink to determine why you didn't
simply give that info to begin with, and instead felt the need to
make a total stranger feel stupid for asking a legitimate question in
an appropriate forum. My guess would be low self esteem, but check
Amazon, I bet they have a self-help book on it.

Is this the way YOU say thank you. Remind me no to respond to your posts.

 

[mike]

On 10/19/2013 11:53 AM, Bob F wrote:

Dan wrote:
Ok, let me quote the amazon page for you.

QUALITY USA brand fuses!! Set of 5 pieces, T3.15AH250V, T3.15A 250V,
T3.15 H250V, T3.15A 250V, T3.15H250V cartridge CERAMIC fuses 5X20mm
(3/16" X 3/4"), 3.15A 250V, SLOW-blow (Time Delay)

Yeah, I saw that. It also says "You will receive 5 fuses and they can
be either of these marking: T3.15AH250V, T3.15A 250V, T3.15 H250V,
T3.15A 250V, T3.15H250V." Not being a fuse expert, I don't know that
these are all in fact interchangeable, and I thought perhaps it might
be better to clarify the rating numbers with someone who's NOT trying
to 'sell me something'.


And again with focus on the rating:
3.15A 250V

And again with just the amperage
3.15A
The A is for Amps.
That helpful enough for you?


That's what I was looking for. That wasn't so hard, now was it? I
guess I'll leave it to you and your shrink to determine why you didn't
simply give that info to begin with, and instead felt the need to
make a total stranger feel stupid for asking a legitimate question in
an appropriate forum. My guess would be low self esteem, but check
Amazon, I bet they have a self-help book on it.

Is this the way YOU say thank you. Remind me no to respond to your posts.

Chill.
My bad, I forced the issue.
Blame me for my inciteful response.

 

[Phil Allison]

"Arfa Daily"

"Phil Allison"
"Arfa Daily"

So, bottom line, by all means try a replacement fuse first. You may be
lucky and get away with it. But be prepared for your new fuse to fail
immediately ... :-\

** Fuses cost money and I don't like to see them blow at switch on.

So my standard practice is to fit a new fuse and then connect the AC lead
to a Variac via a current meter ( true rms) and slowly wind up the
voltage. With a SMPS, the current reading should be small until it
suddenly strikes and runs at some voltage between 80V and 160V as shown
on the Variac's dial.

If a current near to the fuse's rating appears at a low setting on the
Variac, then its game over.


All agreed. I too always bring a fuse-blower up on the variac, looking for
the same tell-tales as you.

** OK, my test set up is used with ALL items for repair.

The AC current meter uses a Hall effect transducer ( totally isolates the
mains supply) feeding a true rms converter IC and then a 3.5 digit LED
display. There are two ranges, 2A and 20A with 1mA and 10mA resolution
respectively.

A standard 3 pin outlet is fitted to the front and all jobs get plugged in
there.

A BNC socket on the back of the unit provides a waveform for the scope that
is either 1V or 100mV per amp of AC current. Signal bandwidth is DC to 100
kHz and max output is +/- 10V, so current surges up to 100 amps peak can be
seen on the scope.

The current meter's electronics has its own AC lead so the Variac does not
affect it.

The set up easily caters for the smallest plug pak (wall wart) right up to
2.5kW/ch stage lighting dimmers and the largest power amps. Been in
continuous use now since 1996.



..... Phil

 

Phil Allison <phil_a@tpg.com.au> wrote:

Guitar amps regularly arrive with either no fuse or a glaringly wrong
size or type fuse - ie fast fuses in the AC.

I see Australian musicians have discovered the "universal replacement"
fuse, too - it's the fuse in a particular physical size with the biggest
number preceding the "A" printed on the box. It is guaranteed not to
blow - something else will usually pop before the fuse does.

I used to work on trucks where AGC 10 A fuses were routinely replaced
with 30 A fuses in an attempt to stop the fuse from blowing. Usually
the actual problem was that an added wire had been run through a hole
with no grommet, sleeving, etc and was grounding out.

For a while in the 70s, some US cars had "SFE" fuses that were all 0.25"
diameter but different lengths - lower ratings were physically shorter -
to help prevent overfusing. An SFE 4 was a little over 0.5", and an
SFE 20 was the same length (1.25") as an AGC fuse. I think it was a
good idea, but it went away with the changeover to the flat blade fuses.

> However, the ones I really hate arrive with NO fuse cap in the holder.

At a previous employer, one of our products was in a 6U 19" rackmount
chassis with two holders for 5 x 20 mm fuses on the back. We shipped
this in its own cardboard box, and it always showed up with everything
intact. Our customer then bolted that chassis into their cabinet, along
with other equipment, and shipped the whole shebang on a flatbed truck
to the site. When it got to site, there was a pretty good chance that
the fuse holder caps would be missing. We told them a) don't ship it
that way and b) put a piece of tape over the caps before shipping. They
ignored a), did b), and asked us for a case lot of replacement caps,
which we gave them.

In the previous generation of that product, the fuses were in the power
inlet module - one where you have to remove the main power connector to
open the little flap that lets you change the fuses. I don't know
whether that inlet module was eliminated from the design for cost or
customer reasons. (It wasn't quite an IEC inlet module, because the
incoming power was DC with a unique connector, but it was the same
idea.)

Matt Roberds

 

[Phil Allison]

<mroberds@att.net>

Phil Allison

Guitar amps regularly arrive with either no fuse or a glaringly wrong
size or type fuse - ie fast fuses in the AC.

I see Australian musicians have discovered the "universal replacement"
fuse, too - it's the fuse in a particular physical size with the biggest
number preceding the "A" printed on the box. It is guaranteed not to
blow - something else will usually pop before the fuse does.

I used to work on trucks where AGC 10 A fuses were routinely replaced
with 30 A fuses in an attempt to stop the fuse from blowing.

** I have a box full of 20A, 25A 30A and 35A automotive 3AG fuses pulled
from guitar and power amps.

Not to mention all the blown ones wrapped in foil paper from a cigarette
pack.

However, the ones I really hate arrive with NO fuse cap in the holder.

At a previous employer, one of our products was in a 6U 19" rackmount
chassis with two holders for 5 x 20 mm fuses on the back. We shipped
this in its own cardboard box, and it always showed up with everything
intact. Our customer then bolted that chassis into their cabinet, along
with other equipment, and shipped the whole shebang on a flatbed truck
to the site. When it got to site, there was a pretty good chance that
the fuse holder caps would be missing. We told them a) don't ship it
that way and b) put a piece of tape over the caps before shipping. They
ignored a), did b), and asked us for a case lot of replacement caps,
which we gave them.

** In my example, the fuse caps were removed by the owners and thrown away
!!!

They all wrongly imagine techs can easily get spare ones to suit.

With many USA built guitar amps, it means drilling or punching a new hole in
the chassis to fit a new holder.

In the previous generation of that product, the fuses were in the power
inlet module - one where you have to remove the main power connector to
open the little flap that lets you change the fuses.

** That level sophistication of stops most of them in their tracks.



..... Phil

 

Em quinta-feira, 17 de outubro de 2013 20h55min39s UTC-3, Dan escreveu:

I need to replace a PSU fuse in an LCD monitor. The open fuse is

ceramic, 5 x 20 mm, and marked "T3.15AH250V", with no obvious spacing

between the various markings. I understand the speed rating (T) and the

voltage (250V), but I'm unclear on the amperage. Is it 3.15 amps, .15

amps, or 15 amps? Did some searching, but all I can find are pages

trying to sell fuses, not any giving how to read the ratings.



TIA



Dan

Hi,

The Ceramic Fuse can be found in a specialized electronic store. But this fuse is a specific component. I have the same problem. The Fuse 3,15a/H250v. You need to replace the same component because there is a reason about the form and type in this device. Be carefull. I try another fuse and got a explosion. Yeah.

 

On Thursday, October 17, 2013 at 8:29:15 PM UTC-5, Phil Allison wrote:

"mike"

Ok, let me quote the amazon page for you.

QUALITY USA brand fuses!! Set of 5 pieces, T3.15AH250V, T3.15A 250V, T3..15
H250V, T3.15A 250V, T3.15H250V cartridge CERAMIC fuses 5X20mm (3/16" X
3/4"), 3.15A 250V, SLOW-blow (Time Delay)


** Got any idea what the letter "T" stands for ?

Hint - it ain't "time".



... Phil

Hey, I know there is some joking around going on here (and some animosity, too apparently) but the "T" DOES actually stand for: "T = Time. Time Delay or Slow Blow.(Typically open between 100 and 300 ms @ ten times the rated current)"

Correct? Or am I missing something? BTW that comes from this google cached page:

http://webcache.googleusercontent.com/search?q=cache:E3algcJXUCMJ:highfields-arc.co.uk/constructors/info/fusecolours.htm+&cd=2&hl=en&ct=clnk&gl=us

I'm just trying to learn, I've got to replace that same damn fuse, and I'm frankly having a bitch of a time figuring out what's causing it to blow (it's the psu from a 32' flatscreen tv if that matters) Replaced a bunch of bad caps, and it powers up for about 3 seconds with a nice picture, and then bam blown fuse. Does rogaine help for hair regrowth that you pulled out yourself lol?

 

On Thursday, January 29, 2015 at 1:40:34 AM UTC-6, da...@daveryder.com wrote:

On Thursday, October 17, 2013 at 8:29:15 PM UTC-5, Phil Allison wrote:
"mike"

Ok, let me quote the amazon page for you.

QUALITY USA brand fuses!! Set of 5 pieces, T3.15AH250V, T3.15A 250V, T3.15
H250V, T3.15A 250V, T3.15H250V cartridge CERAMIC fuses 5X20mm (3/16" X
3/4"), 3.15A 250V, SLOW-blow (Time Delay)


** Got any idea what the letter "T" stands for ?

Hint - it ain't "time".



... Phil

Hey, I know there is some joking around going on here (and some animosity, too apparently) but the "T" DOES actually stand for: "T = Time. Time Delay or Slow Blow.(Typically open between 100 and 300 ms @ ten times the rated current)"

Correct? Or am I missing something? BTW that comes from this google cached page:

http://webcache.googleusercontent.com/search?q=cache:E3algcJXUCMJ:highfields-arc.co.uk/constructors/info/fusecolours.htm+&cd=2&hl=en&ct=clnk&gl=us

I'm just trying to learn, I've got to replace that same damn fuse, and I'm frankly having a bitch of a time figuring out what's causing it to blow (it's the psu from a 32' flatscreen tv if that matters) Replaced a bunch of bad caps, and it powers up for about 3 seconds with a nice picture, and then bam blown fuse. Does rogaine help for hair regrowth that you pulled out yourself lol?

Oh and another thing that has me curious is the fuse was wrapped in rubber shrinkwrap, even though it wasn't anywhere near anything metallic that could short it out, any ideas why?

 

[Phil Allison]

da...@daveryder.com wrote:

** Got any idea what the letter "T" stands for ?

Hint - it ain't "time".


Hey, I know there is some joking around going on here (and some animosity, too apparently) but the "T" DOES actually stand for: "T = Time. Time Delay or Slow Blow.(Typically open between 100 and 300 ms @ ten times the rated current)"

Correct? Or am I missing something?

** Yes - the word with that T as the initial letter.

It's the German word "Trage" meaning "dragged out" or leaden.

All the letter codes on common fuses are for German words.

F = " Flink " for quickly or rapid.

http://www.thefusewarehouse.com/pages/learn_fuse_markings.php


Amaze your friends...


.... Phil

 

[Mike]

On Wed, 28 Jan 2015 23:46:26 -0800, dave wrote:

Oh and another thing that has me curious is the fuse was wrapped in
rubber shrinkwrap, even though it wasn't anywhere near anything metallic
that could short it out, any ideas why?

That's easier to guess: to protect anyone who happens to be looking at the
fuse when it blows and the glass casing shatters?

Mike.

 

[mike]

On 1/28/2015 11:40 PM, dave@daveryder.com wrote:

On Thursday, October 17, 2013 at 8:29:15 PM UTC-5, Phil Allison wrote:
"mike"

Ok, let me quote the amazon page for you.

QUALITY USA brand fuses!! Set of 5 pieces, T3.15AH250V, T3.15A 250V, T3.15
H250V, T3.15A 250V, T3.15H250V cartridge CERAMIC fuses 5X20mm (3/16" X
3/4"), 3.15A 250V, SLOW-blow (Time Delay)


** Got any idea what the letter "T" stands for ?

Hint - it ain't "time".



... Phil

Hey, I know there is some joking around going on here (and some animosity, too apparently) but the "T" DOES actually stand for: "T = Time. Time Delay or Slow Blow.(Typically open between 100 and 300 ms @ ten times the rated current)"

Correct? Or am I missing something? BTW that comes from this google cached page:

http://webcache.googleusercontent.com/search?q=cache:E3algcJXUCMJ:highfields-arc.co.uk/constructors/info/fusecolours.htm+&cd=2&hl=en&ct=clnk&gl=us

I'm just trying to learn, I've got to replace that same damn fuse, and I'm frankly having a bitch of a time figuring out what's causing it to blow (it's the psu from a 32' flatscreen tv if that matters) Replaced a bunch of bad caps, and it powers up for about 3 seconds with a nice picture, and then bam blown fuse. Does rogaine help for hair regrowth that you pulled out yourself lol?

Here's the dark side of replacing caps.
Switching power supplies often work by stuffing pulses of current thru
inductors into caps from a higher voltage.
Primary failure mode of caps is increased series resistance, ESR.

When that resistance increases, there's a step in voltage across the cap
when the current is being stuffed in. The regulator is looking at
average voltage, so it reduces the output voltage slightly to make the
average voltage, including that step, to be the desired output.

Over time, that step gets bigger and bigger. You don't see any symptoms
until the step gets big enough to disrupt the circuit.

By the time the system shuts down, damage may have been done.

Had one monitor where the system processor had been fried by the peak
voltage. Had 19V spikes on a 5V supply.

In another, there were totem-pole fets driving the transformer for the
backlight. One of them had been damaged and had high leakage. The
backlight came up and ran for a few seconds until the other fet overheated
and blew the fuse.

That's why it's often a good idea to change all the caps at once.
If you're lucky, and most are, you caught it before permanent damage was
done.

So, back to your problem...
Most any fuse of the correct current rating should work for more than
three seconds. Yes, the right fuse is best, but fix the circuit first.

 

On Thursday, January 29, 2015 at 9:44:57 AM UTC-6, John Robertson wrote:

On 01/29/2015 1:16 AM, Phil Allison wrote:
da...@daveryder.com wrote:



** Got any idea what the letter "T" stands for ?

Hint - it ain't "time".


Hey, I know there is some joking around going on here (and some animosity, too apparently) but the "T" DOES actually stand for: "T = Time. Time Delay or Slow Blow.(Typically open between 100 and 300 ms @ ten times the rated current)"

Correct? Or am I missing something?


** Yes - the word with that T as the initial letter.

It's the German word "Trage" meaning "dragged out" or leaden.

All the letter codes on common fuses are for German words.

F = " Flink " for quickly or rapid.

http://www.thefusewarehouse.com/pages/learn_fuse_markings.php


Amaze your friends...


.... Phil


Isn't that chart just for the European fuses? It is interesting none the
less...

John :-#)#

--
(Please post followups or tech inquiries to the 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."

Thanks everyone for being so helpful, it's always cool to pick the brains of some guys who know what they're doing ps about the shrink wrap, it's not a glass fuse, it's a ceramic fuse so the wrapping is still sort of a mystery I guess. Anyway thanks again I'll keep plugging away at it til I figure it out

Dave

 

[Allodoxaphobia]

On Wed, 28 Jan 2015 23:40:28 -0800 (PST), dave@daveryder.com wrote:

> ... (it's the psu from a 32' flatscreen tv if that matters)

Wow! Are you operating a small drive-in multi-media center?

 

[John Robertson]

On 01/29/2015 1:16 AM, Phil Allison wrote:

da...@daveryder.com wrote:



** Got any idea what the letter "T" stands for ?

Hint - it ain't "time".


Hey, I know there is some joking around going on here (and some animosity, too apparently) but the "T" DOES actually stand for: "T = Time. Time Delay or Slow Blow.(Typically open between 100 and 300 ms @ ten times the rated current)"

Correct? Or am I missing something?


** Yes - the word with that T as the initial letter.

It's the German word "Trage" meaning "dragged out" or leaden.

All the letter codes on common fuses are for German words.

F = " Flink " for quickly or rapid.

http://www.thefusewarehouse.com/pages/learn_fuse_markings.php


Amaze your friends...


.... Phil

Isn't that chart just for the European fuses? It is interesting none the
less...

John :-#)#

--
(Please post followups or tech inquiries to the 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."

 

[Phil Allison]

Arfa Daily wrote:

Nah. They've got that wrong Phil.
"FF" is Fuckin' Fast "F" is just Fast
"M" is Meedjum" "T" is Time and "TT" is Tea Time which I believe means
you've got enough time to make a cup of tea while it decides whether to blow
...

** Works for me....



..... Phil

 

[Phil Allison]

John Robertson wrote:

** Yes - the word with that T as the initial letter.

It's the German word "Trage" meaning "dragged out" or leaden.

All the letter codes on common fuses are for German words.

F = " Flink " for quickly or rapid.

http://www.thefusewarehouse.com/pages/learn_fuse_markings.php



Isn't that chart just for the European fuses?

** Whooah - hold on a mo there.

Q. Who uses European standard fuses ?

A. Everyone does.

Common appliance fuses come in just two sizes: 20x5mm and 6.3x30mm or 3AG.

European and Asian makers produce both sizes and dominate the market because of lower cost. In 40 years of buying and using such fuses, I cannot remember seeing a pack labelled "Made in USA"



..... Phil

 

[Arfa Daily]

"Phil Allison" <pallison49@gmail.com> wrote in message
news:3a6805ae-ec07-4e16-82dc-8dfdad6a4c84@googlegroups.com...

da...@daveryder.com wrote:



** Got any idea what the letter "T" stands for ?

Hint - it ain't "time".


Hey, I know there is some joking around going on here (and some
animosity, too apparently) but the "T" DOES actually stand for: "T =
Time. Time Delay or Slow Blow.(Typically open between 100 and 300 ms @
ten times the rated current)"

Correct? Or am I missing something?


** Yes - the word with that T as the initial letter.

It's the German word "Trage" meaning "dragged out" or leaden.

All the letter codes on common fuses are for German words.

F = " Flink " for quickly or rapid.

http://www.thefusewarehouse.com/pages/learn_fuse_markings.php

Nah. They've got that wrong Phil. "FF" is Fuckin' Fast "F" is just Fast
"M" is Meedjum" "T" is Time and "TT" is Tea Time which I believe means
you've got enough time to make a cup of tea while it decides whether to blow
....

Arfa

Amaze your friends...


... Phil

 

[John Robertson]

On 01/30/2015 5:41 AM, Phil Allison wrote:

John Robertson wrote:



** Yes - the word with that T as the initial letter.

It's the German word "Trage" meaning "dragged out" or leaden.

All the letter codes on common fuses are for German words.

F = " Flink " for quickly or rapid.

http://www.thefusewarehouse.com/pages/learn_fuse_markings.php



Isn't that chart just for the European fuses?


** Whooah - hold on a mo there.

Q. Who uses European standard fuses ?

A. Everyone does.

Common appliance fuses come in just two sizes: 20x5mm and 6.3x30mm or 3AG.

European and Asian makers produce both sizes and dominate the market because of lower cost. In 40 years of buying and using such fuses, I cannot remember seeing a pack labelled "Made in USA"



..... Phil

On this side of the pond we have Cooper/BUSS fuses which say "Made in
the USA" in my stock, just got some from Digi-Key.

I think you are in the UK, right Phil?

John :-#)#

--
(Please post followups or tech inquiries to the 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."

 

[Phil Allison]

John Robertson wrote:

Isn't that chart just for the European fuses?


** Whooah - hold on a mo there.

Q. Who uses European standard fuses ?

A. Everyone does.

Common appliance fuses come in just two sizes: 20x5mm and 6.3x30mm or 3AG.

European and Asian makers produce both sizes and dominate the market because of lower cost. In 40 years of buying and using such fuses, I cannot remember seeing a pack labelled "Made in USA"



On this side of the pond we have Cooper/BUSS fuses which say "Made in
the USA" in my stock, just got some from Digi-Key.

I think you are in the UK, right Phil?

** No, Sydney Australia.

Fuses come from either Asia or Europe via Farnell.



.... Phil