sci.electronics.repair@googlegroups.com

Today's topics:

* Power transistor question... - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/48e3a91c572ef00c?hl=en
* Fuse: fast blown vs slow blown - 10 messages, 3 authors
http://groups.google.com/group/sci.electronics.repair/t/075c97d6b6b6e1f0?hl=en
* zebra connector - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/22ac512ae9f1d16c?hl=en

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TOPIC: Power transistor question...
http://groups.google.com/group/sci.electronics.repair/t/48e3a91c572ef00c?hl=en
==============================================================================

== 1 of 2 ==
Date: Tues, May 31 2011 8:32 pm
From: "Dave"

"Jamie" <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in message
news:QVdFp.9148$rq2.7889@newsfe12.iad...
> Dave wrote:
>
>> "Phil Allison" <phil_a@tpg.com.au> wrote in message
>> news:94j1ebFms1U1@mid.individual.net...
>>
>>>"Meat Plow"
>>>
>>>
>>>>>http://www.youtube.com/watch?v=zEA5MfllPdg
>>>>
>>>>Not a bad little meter for the $$$$. Anyone who does work on consumer
>>>>electronics ought to have one or something similar. Removes a lot of
>>>>guess work.
>>>
>>>
>>>** I disagree.
>>>
>>>An LCR meter is more useful for design and production than in servicing.
>>>
>>>Many low cost DMMs include capacitance ranges that can measure from a few
>>>pF up to 200 or 2000uF.
>>>
>>>A dedicated ESR meter handles electros just fine while in circuit - and
>>>lets you test all kinds of cells too, which an LCR meter often cannot.
>>>
>>>Any DMM can read the resistance of an inductor or transformer winding.
>>>
>>>The only function left is to measure inductors for value.
>>>
>>>
>>>.... Phil
>>>
>>
>>
>> Wanted to thank *everyone* for the info and encouragement I have received
>> in this discussion. Bottom line for me, at least for now, is simply
>> don't test in-circuit (pop one lead and then test after discharging).
>> Have also found a ton of material on youtube and the net that convinces
>> me to get a dedicated ESR meter (or possibly build one.) Anyway, thanks
>> all for a very enlightening discussion.
>>
>> Take it easy...
>>
>> Dave
>>
>>
> I use a cheap B&K LCR, it does in circuit beautifully.
>
> Jamie
>
>

Hey Jamie, thanks for the note. So, how do you perform an in-circuit ESR
test on a suspect cap? Do you bother to discharge it, or do you just let
the circuitry around the cap do that? And how reliable are the numbers you
come up with? I tried to do an in-circuit test today on a cap and thought I
had gotten lucky with my first shot. A 10uF @ 100V cap gave me an ESR
reading of 42.15 in-circuit, but when I popped it out and tested it again it
dropped to 0.12. big difference! Still trying to figure out what I might
have been doing wrong...

Have since discovered a different cap that may actually be the problem. A
.22uF @ 50V cap with an ESR reading of 25+ ohms. Am thinking this component
may be where the vertical hold sync pulse gets lost, as it feeds an
oscillator/mixer transistor which feeds the output transistor of the
vertical hold circuitry. All of this two days after I discovered I had an
ESR meter and didn't know it. <shaking head>

Dave

== 2 of 2 ==
Date: Tues, May 31 2011 8:46 pm
From: "Phil Allison"

"Dave"
"Jamie
= Maynard A. Philbrook
= Lunatic, code scribbler & radio ham: KA1LPA

>
>> I use a cheap B&K LCR, it does in circuit beautifully.
>>

** Blatant lie.

> Hey Jamie, thanks for the note. So, how do you perform an in-circuit ESR
> test on a suspect cap?

** Jaime is a congenital bullshit artist.

Just IGNORE him.

> I tried to do an in-circuit test today on a cap and thought I had gotten
> lucky with my first shot. A 10uF @ 100V cap gave me an ESR reading of
> 42.15 in-circuit, but when I popped it out and tested it again it dropped
> to 0.12. big difference! Still trying to figure out what I might have
> been doing wrong...

** All that means is there is some resistance in parallel with the 10uF cap.

Any parallel resistance is computed to a misleading ESR number by an LCR
meter.

That's the problem.

With a dedicated ESR meter that measures the impedance of an electro at
100kHz, the effect of parallel resistors or diode junctions that may exist
is ignored.

.... Phil

==============================================================================
TOPIC: Fuse: fast blown vs slow blown
http://groups.google.com/group/sci.electronics.repair/t/075c97d6b6b6e1f0?hl=en
==============================================================================

== 1 of 10 ==
Date: Tues, May 31 2011 9:10 pm
From: Winston

Tim Wescott wrote:
> On 05/31/2011 10:16 AM, Winston wrote:

(...)

>> That's 'current' mode when you've got it connected to measure
>> voltage, yes?
>
> Uhhh...
>
>
>
> D'oh!

The fuse for my Fluke 79 multimeter retails for $10.00.
(Ten U.S. Dollars)

http://www.flukeonlinestore.com/3478682.html

Guess what prompted that discovery.

Go ahead. Guess. :)

--Winston <-- It's better, now.

== 2 of 10 ==
Date: Tues, May 31 2011 9:25 pm
From: "Phil Allison"

"Winston"

> The fuse for my Fluke 79 multimeter retails for $10.00.
> (Ten U.S. Dollars)
>
> http://www.flukeonlinestore.com/3478682.html
>
> Guess what prompted that discovery.
>
> Go ahead. Guess. :)

** That fuse is designed to protect the multi-meter, its leads ( and you )
from a worst case scenario.

That scenario is when you probe a 415 volt, 3 phase power outlet with the
meter accidentally set to the 10 amp range.

A standard glass fuse would simply arc from end to end, the probes and leads
would explode and cover you in hot metal and the meter would become a write
off.

The specified ( fast acting, high rupture current, high voltage fuse ) would
merely produce a loud pop.

.... Phil

== 3 of 10 ==
Date: Tues, May 31 2011 9:30 pm
From: Winston

Phil Allison wrote:
> "Winston"
>
>> The fuse for my Fluke 79 multimeter retails for $10.00.
>> (Ten U.S. Dollars)
>>
>> http://www.flukeonlinestore.com/3478682.html
>>
>> Guess what prompted that discovery.
>>
>> Go ahead. Guess. :)
>
>
> ** That fuse is designed to protect the multi-meter, its leads ( and you )
> from a worst case scenario.
>
> That scenario is when you probe a 415 volt, 3 phase power outlet with the
> meter accidentally set to the 10 amp range.
>
> A standard glass fuse would simply arc from end to end, the probes and leads
> would explode and cover you in hot metal and the meter would become a write
> off.
>
> The specified ( fast acting, high rupture current, high voltage fuse ) would
> merely produce a loud pop.

I didn't know that.

How about this one?
http://www.flukeonlinestore.com/3478747.html

--Winston :)

== 4 of 10 ==
Date: Tues, May 31 2011 9:45 pm
From: "Phil Allison"

"Winston"
> Phil Allison wrote:
>> "Winston"
>>
>>> The fuse for my Fluke 79 multimeter retails for $10.00.
>>> (Ten U.S. Dollars)
>>>
>>> http://www.flukeonlinestore.com/3478682.html
>
>> ** That fuse is designed to protect the multi-meter, its leads ( and
>> you )
>> from a worst case scenario.
>>
>> That scenario is when you probe a 415 volt, 3 phase power outlet with the
>> meter accidentally set to the 10 amp range.
>>
>> A standard glass fuse would simply arc from end to end, the probes and
>> leads
>> would explode and cover you in hot metal and the meter would become a
>> write
>> off.
>>
>> The specified ( fast acting, high rupture current, high voltage fuse )
>> would
>> merely produce a loud pop.
>
> I didn't know that.

** Cos you know fuck all about anything.

> How about this one?
> http://www.flukeonlinestore.com/3478747.html
>

** Standard glass (fast) fuse by the look of it.

.... Phil

== 5 of 10 ==
Date: Tues, May 31 2011 9:57 pm
From: Winston

Phil Allison wrote:
> "Winston"

(...)

>> I didn't know that.
>
> ** Cos you know fuck all about anything.

It's a continuing problem.
Watta ya gonna do. :)

>> How about this one?
>> http://www.flukeonlinestore.com/3478747.html
>>
>
> ** Standard glass (fast) fuse by the look of it.

It must be ~36 times safer than a commodity GMA
fuse in a multimeter application, yes?
http://www.amazon.com/125mA-250v-Fuses-0-125A-5x20mm/dp/B004HLZYVI

Fluke wouldn't overcharge for that part either,
surely.

--Winston

== 6 of 10 ==
Date: Tues, May 31 2011 10:09 pm
From: "Phil Allison"

"Winston"
> Phil Allison wrote:
>
>>> I didn't know that.
>>
>> ** Cos you know fuck all about anything.
>
> It's a continuing problem.
> Watta ya gonna do. :)
>
>>> How about this one?
>>> http://www.flukeonlinestore.com/3478747.html
>>>
>>
>> ** Standard glass (fast) fuse by the look of it.
>
> It must be ~36 times safer than a commodity GMA
> fuse in a multimeter application, yes?
> http://www.amazon.com/125mA-250v-Fuses-0-125A-5x20mm/dp/B004HLZYVI
>
> Fluke wouldn't overcharge for that part either,
> surely.

** The price is very steep.

But I expect the fuse IS safe when used in the Fluke DMMs it is specified
for.

The scenario with a 0.125A fuse is nothing like the one with the 10A range
fuse.

Typical 0.125A rated fast fuses have resistances of 8 to 10 ohms - which
limits the fault current to a value the fuse can easily break.

A 10 amp fuse may well have a resistance of only a few milliohms, so the
fault current is only limited by the resistance of the DMM's leads.

A current of 40 amps is easy enough for a small fuse to break, while one of
over 4000 amps is not.

Capice?

.... Phil

== 7 of 10 ==
Date: Tues, May 31 2011 10:34 pm
From: Winston

Phil Allison wrote:
> "Winston"

(...)

>> Fluke wouldn't overcharge for that part either,
>> surely.
>
> ** The price is very steep.

We agree.

> But I expect the fuse IS safe when used in the Fluke DMMs it is specified
> for.

Both the 'Fluke' brand and the commodity brand are safe, I suspect.

It wouldn't shock me to learn both kinds are sourced from the same
place.

> The scenario with a 0.125A fuse is nothing like the one with the 10A range
> fuse.
>
> Typical 0.125A rated fast fuses have resistances of 8 to 10 ohms - which
> limits the fault current to a value the fuse can easily break.
>
> A 10 amp fuse may well have a resistance of only a few milliohms, so the
> fault current is only limited by the resistance of the DMM's leads.
>
> A current of 40 amps is easy enough for a small fuse to break, while one of
> over 4000 amps is not.

We agree on that, too.

--Winston

== 8 of 10 ==
Date: Tues, May 31 2011 11:46 pm
From: "Phil Allison"

"Winston"
> Phil Allison wrote:
>> "Winston"
>
>> ** The price is very steep.
>
> We agree.

** Yawnnnnnnnnnnnn....

>
>> But I expect the fuse IS safe when used in the Fluke DMMs it is specified
>> for.
>
> Both the 'Fluke' brand and the commodity brand are safe, I suspect.
>
> It wouldn't shock me to learn both kinds are sourced from the same
> place.
>

** Nothing shocks a fuckwit like you.

>> The scenario with a 0.125A fuse is nothing like the one with the 10A
>> range
>> fuse.
>>
>> Typical 0.125A rated fast fuses have resistances of 8 to 10 ohms -
>> which
>> limits the fault current to a value the fuse can easily break.
>>
>> A 10 amp fuse may well have a resistance of only a few milliohms, so the
>> fault current is only limited by the resistance of the DMM's leads.
>>
>> A current of 40 amps is easy enough for a small fuse to break, while one
>> of
>> over 4000 amps is not.
>
> We agree on that, too.

** GIANT Yawwnnnnnnnnnnnnnnnnnnn

Piss off wanker.

... Phil

== 9 of 10 ==
Date: Tues, May 31 2011 11:46 pm
From: Man-wai Chang

> ** Funny, I have any number of fuses in my bins with "BS 1362" printed on
> them.

Coz you are in USA, not Hong Kong (ex-UK colony)! :)

--
@~@ Might, Courage, Vision, SINCERITY.
/ v \ Simplicity is Beauty! May the Force and farces be with you!
/( _ )\ (x86_64 Ubuntu 9.10) Linux 2.6.39
^ ^ 14:44:01 up 6 days 23:46 0 users load average: 1.00 1.01 1.05
不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA):
http://www.swd.gov.hk/tc/index/site_pubsvc/page_socsecu/sub_addressesa

== 10 of 10 ==
Date: Tues, May 31 2011 11:49 pm
From: "Phil Allison"

"Man-wai Chang"
>>
>> ** Funny, I have any number of fuses in my bins with "BS 1362" printed on
>> them.
>
> Coz you are in USA, not Hong Kong (ex-UK colony)! :)

** Hey - rice muncher.

I am in Sydney, Australia.

BS1362 fuses are used in professional dimmers imported from the UK.

.... Phil

==============================================================================
TOPIC: zebra connector
http://groups.google.com/group/sci.electronics.repair/t/22ac512ae9f1d16c?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Jun 1 2011 12:34 am
From: "Vale"

"Shaun" <spam@nomail.com> ha scritto nel messaggio
news:oagFp.19079$pi2.11588@newsfe11.iad...
>
>
> "Vale" wrote in message
> news:jK8Fp.29619$GZ3.6759@tornado.fastwebnet.it...
>
>
> "Jeff Liebermann" <jeffl@cruzio.com> ha scritto nel messaggio
> news:ev1au6l4fk6hevq9fvne7qhm8q5cp0qqrg@4ax.com...
>> On Mon, 30 May 2011 17:43:17 +0200, "Vale" <vale@fastwebnet.it> wrote:
>>
>>>My expensive multimeter has got broken plastic pins that hold the lcd
>>>disply
>>>on the pcb.
>>
>
> Thanks all.I solved, hope for long time.
>
> What brand is your meter? You can probably order parts for it if it is
> not too old. When you do order parts, order new zebra strips aswell.
>
It's a Chauvin Arnoux. It is a good idea investigate on spares/kits.I'll do
it, thanks.

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