Toshiba TV29C90 problem; Image fades to black...

[Ron D.]

Put 3A automotive fuse on secondary. Use light bulb trick to find
shorts. Two 12 V light bulbs in series that draw no more than 40 VA.

 

[Jeff Thies]

On 4/10/2011 7:47 PM, Phil Allison wrote:

"Jeff Thies"
Phil Allison wrote:
"robb"


Yep, My A/C unit blew another transformer. Pictures (and wiring
diagram)
here:

http://www.flickr.com/photos/bbqboyee/sets/72157626457562742/

http://www.trane.com/webcache/un/furnaces%20%28furn%29/product/22-1666-07_04012009.pdf

As you can probably see in the pictures, there is visible charring of
the
115V leads going into the transformer, and of course the 115V circuit is
open (again).


** From the damage to the tranny visible in the photos - the primary has
developed an internal short ( due to insulation failure) and since there
is
no fuse link in series, the resulting current was high enough to make an
exposed wire leading to the terminals explode.

An internal short could develop due to heat alone because of an overload
on
the tranny - but this requires a fault to exist on the secondary side
which
seems not to be the case.

High voltage spikes on the primary could also cause insulation failure
leading to the damage seen in the pics - lightning does this sort of
thing.
So also could back emfs from the blower fan if the is a bad connection in
the AC supply feed.

I suggest you provide the next replacement for that vulnerable tranny
with
some "protection" - firstly an in-line fuse of say 1/4 amp AND a
capacitor wired across the primary of say 1uF rated for continuous use
across the AC supply.

If there is an overload on the tranny, the fuse will blow.

The 1uF capacitor should suppress spike voltages enough to save the
tranny
from harm.

1 uF sounds a little high.


** No it ain't.

I thought you had simply misspoke and that this was an honest error.

The reactance of a 1uF cap at 60Hz is: 2652 ohms (1/(2*pi*F*C)
Online calculator:
http://www.kusashi.com/reactance-c.php?f=60&c=1&stage=results

V^2/R = W

Assuming primary, as why would you put it on the secondary:

120^2 / 2652 = 5.43 W

Does that not seem wrong to you?

If not then go buy a 200V non polarized 1uF cap. It is no easy chore.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=131081

Jeff

 

[Tony Miklos]

On 4/10/2011 9:47 PM, Jeff Thies wrote:

On 4/10/2011 7:47 PM, Phil Allison wrote:
"Jeff Thies"
Phil Allison wrote:
"robb"


Yep, My A/C unit blew another transformer. Pictures (and wiring
diagram)
here:

http://www.flickr.com/photos/bbqboyee/sets/72157626457562742/

http://www.trane.com/webcache/un/furnaces%20%28furn%29/product/22-1666-07_04012009.pdf


As you can probably see in the pictures, there is visible charring of
the
115V leads going into the transformer, and of course the 115V
circuit is
open (again).


** From the damage to the tranny visible in the photos - the primary
has
developed an internal short ( due to insulation failure) and since
there
is
no fuse link in series, the resulting current was high enough to
make an
exposed wire leading to the terminals explode.

An internal short could develop due to heat alone because of an
overload
on
the tranny - but this requires a fault to exist on the secondary side
which
seems not to be the case.

High voltage spikes on the primary could also cause insulation failure
leading to the damage seen in the pics - lightning does this sort of
thing.
So also could back emfs from the blower fan if the is a bad
connection in
the AC supply feed.

I suggest you provide the next replacement for that vulnerable tranny
with
some "protection" - firstly an in-line fuse of say 1/4 amp AND a
capacitor wired across the primary of say 1uF rated for continuous use
across the AC supply.

If there is an overload on the tranny, the fuse will blow.

The 1uF capacitor should suppress spike voltages enough to save the
tranny
from harm.

1 uF sounds a little high.


** No it ain't.

I thought you had simply misspoke and that this was an honest error.

The reactance of a 1uF cap at 60Hz is: 2652 ohms (1/(2*pi*F*C)
Online calculator:
http://www.kusashi.com/reactance-c.php?f=60&c=1&stage=results

V^2/R = W

Assuming primary, as why would you put it on the secondary:

120^2 / 2652 = 5.43 W

Does that not seem wrong to you?

If not then go buy a 200V non polarized 1uF cap. It is no easy chore.

I have some big ass mylars, I think they are 4uF @ 200v.

 

[Phil Allison]

"Jeff Thies"
Phil Allison wrote:

I suggest you provide the next replacement for that vulnerable tranny
with
some "protection" - firstly an in-line fuse of say 1/4 amp AND a
capacitor wired across the primary of say 1uF rated for continuous use
across the AC supply.

If there is an overload on the tranny, the fuse will blow.

The 1uF capacitor should suppress spike voltages enough to save the
tranny from harm.

1 uF sounds a little high.


** No it ain't.

I thought you had simply misspoke and that this was an honest error.

The reactance of a 1uF cap at 60Hz is: 2652 ohms (1/(2*pi*F*C)
Online calculator:
http://www.kusashi.com/reactance-c.php?f=60&c=1&stage=results

V^2/R = W

Assuming primary, as why would you put it on the secondary:

120^2 / 2652 = 5.43 W

Does that not seem wrong to you?

** Completely.

Such a cap dissipates no energy at all.

What planet do you come from ??

If not then go buy a 200V non polarized 1uF cap. It is no easy chore.

** 1uF caps for use across the AC supply are cheap and plentiful.

Typical examples are metallised polypropylene " class X2 " types and sell
for $1 or $2 each.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=399-5466-ND


What planet do you come from ??



..... Phil

 

[Phil Allison]

"Tony Miklos"

I have some big ass mylars, I think they are 4uF @ 200v.

** They won't last long if connected across the AC supply.



..... Phil

 

[Tony Miklos]

On 4/10/2011 10:48 PM, Phil Allison wrote:

"Tony Miklos"

I have some big ass mylars, I think they are 4uF @ 200v.


** They won't last long if connected across the AC supply.



.... Phil

I know, I was just about to reply to my post saying that the voltage
rating is VDC.

 

[Phil Allison]

"Tony Miklos"
Phil Allison wrote:

I have some big ass mylars, I think they are 4uF @ 200v.


** They won't last long if connected across the AC supply.


I know, I was just about to reply to my post saying that the voltage
rating is VDC.

** Film caps rated at 600VDC will generally last a fair while wired across a
120 volt AC supply ( but not with a 240VAC supply ) - but is it far better
to use a purpose designed and agency approved "class X1" or "classX2"
capacitor.




.... Phil

 

On Sun, 10 Apr 2011 12:22:13 +1000, "Phil Allison" <phil_a@tpg.com.au>
wrote:

"robb"


Yep, My A/C unit blew another transformer. Pictures (and wiring diagram)
here:

http://www.flickr.com/photos/bbqboyee/sets/72157626457562742/

http://www.trane.com/webcache/un/furnaces%20%28furn%29/product/22-1666-07_04012009.pdf

As you can probably see in the pictures, there is visible charring of the
115V leads going into the transformer, and of course the 115V circuit is
open (again).


** From the damage to the tranny visible in the photos - the primary has
developed an internal short ( due to insulation failure) and since there is
no fuse link in series, the resulting current was high enough to make an
exposed wire leading to the terminals explode

An internal short could develop due to heat alone because of an overload on
the tranny - but this requires a fault to exist on the secondary side which
seems not to be the case.

High voltage spikes on the primary could also cause insulation failure
leading to the damage seen in the pics - lightning does this sort of thing.
So also could back emfs from the blower fan if the is a bad connection in
the AC supply feed.

I suggest you provide the next replacement for that vulnerable tranny with
some "protection" - firstly an in-line fuse of say 1/4 amp AND a
capacitor wired across the primary of say 1uF rated for continuous use
across the AC supply.

If there is an overload on the tranny, the fuse will blow.

The 1uF capacitor should suppress spike voltages enough to save the tranny
from harm.

A capacitor across an AC supply??????????????? As a surge
protector????
Have not heard of that before.

A capacitor across the AC line would appear as a load - and could
form a resonant l/ci tank circuit, which would also appear as a low
resistance -causing high current to flow

There are 2 other POSSIBLE issues here though - - -.

Both are perhaps long shots - but mabee worth investigating.

The transformer primary APPEARS to be saturating.
Primary current on an unloaded transformer CAN, in some cases, excede
full load current. Possibly the transformer requires MORE load on the
secondary than it is getting.

An example is a microwave oven transformer. With no load on either the
high voltage or low voltage secondary, the primary will generally
saturate and overheat. If you remove the high voltage secondary and
add your own windings to make a "custom" transformer, it is not
uncommon for the primary to saturate at no/low loads - overheating the
transformer.

Like I said - a long shot, but possibly worth investigating. adding a
small 24 volt pilot light across the secondary MAY solve that kind of
a problem.

The other POSSIBILITY is a DC bias on the primary, which WILL cause
saturation on 1/2 cycle of the AC. Need a scope to check that
effectively - or something like a 10uf nonpolarized capacitor and a
100K ohm 1/2 watt resistor in series across the primary, with a DC
voltmeter connected across the cap. Make all connections BEFORE
turning on the mains power. You should expect to see readings of +/-
approx 25-35mv across the cap in a normal residential situation.

Lets say you read 275mv DC on the line, and the transformer primary
resistance is 2 ohms.. That will put a DC current of 137.5ma through
the primary - which when added to the normal AC current on the one
half cycle will greatly excede the saturation current of the primary.

A half wave rectified load on the same circuit could put a DC
component across the line.

An AC (nonpolarized) capacitor IN SERIES with the primary would
remove the DC component from the primary winding, but finding a
capacitor that would ballast the primary properly (allow full rated
primary current) while not causing a series resonance (which would
appear as a short circuit across the mains) is not something I would
try to calculate.

..... Phil

 

[Phil Allison]

<clare@snyder.on.ca>
"Phil Allison"

High voltage spikes on the primary could also cause insulation failure
leading to the damage seen in the pics - lightning does this sort of
thing.
So also could back emfs from the blower fan if the is a bad connection in
the AC supply feed.

I suggest you provide the next replacement for that vulnerable tranny with
some "protection" - firstly an in-line fuse of say 1/4 amp AND a
capacitor wired across the primary of say 1uF rated for continuous use
across the AC supply.

If there is an overload on the tranny, the fuse will blow.

The 1uF capacitor should suppress spike voltages enough to save the tranny
from harm.



A capacitor across an AC supply??????????????? As a surge
protector????
Have not heard of that before.

** Then your ignorance is showing.

The stated reason for the capacitor was in relation to the "blower fan"
inside the same unit as the small tranny.

The event the cap has to deal with is a back emf surge generated by that
fan when the AC supply is suddenly disconnected - for whatever reason.

A capacitor across the AC line would appear as a load

** Draws 45mA continuously.

Yawnnnnnnn....

- and could form a resonant l/ci tank circuit,

** Yawnnnnnn....

(snip absurd drivel)

There are 2 other POSSIBLE issues here though - - -.

Both are perhaps long shots - but mabee worth investigating.

The transformer primary APPEARS to be saturating.

** The primary appears to be EXPLODING !!

You ridiculous wanker.


..... Phil

 

[Jeff Thies]

On 4/10/2011 10:46 PM, Phil Allison wrote:

"Jeff Thies"
Phil Allison wrote:

I suggest you provide the next replacement for that vulnerable tranny
with
some "protection" - firstly an in-line fuse of say 1/4 amp AND a
capacitor wired across the primary of say 1uF rated for continuous use
across the AC supply.

If there is an overload on the tranny, the fuse will blow.

The 1uF capacitor should suppress spike voltages enough to save the
tranny from harm.

1 uF sounds a little high.


** No it ain't.

I thought you had simply misspoke and that this was an honest error.

The reactance of a 1uF cap at 60Hz is: 2652 ohms (1/(2*pi*F*C)
Online calculator:
http://www.kusashi.com/reactance-c.php?f=60&c=1&stage=results

V^2/R = W

Assuming primary, as why would you put it on the secondary:

120^2 / 2652 = 5.43 W

Does that not seem wrong to you?

** Completely.

Such a cap dissipates no energy at all.

What planet do you come from ??

What a jerk you are. You do realize that is 45mA running through that.

Jeff

 

[Phil Allison]

"Jeff Thies"

Phil Allison wrote:
"Jeff Thies"
Phil Allison wrote:

I suggest you provide the next replacement for that vulnerable tranny
with
some "protection" - firstly an in-line fuse of say 1/4 amp AND a
capacitor wired across the primary of say 1uF rated for continuous
use
across the AC supply.

If there is an overload on the tranny, the fuse will blow.

The 1uF capacitor should suppress spike voltages enough to save the
tranny from harm.

1 uF sounds a little high.


** No it ain't.

I thought you had simply misspoke and that this was an honest error.

The reactance of a 1uF cap at 60Hz is: 2652 ohms (1/(2*pi*F*C)
Online calculator:
http://www.kusashi.com/reactance-c.php?f=60&c=1&stage=results

V^2/R = W

Assuming primary, as why would you put it on the secondary:

120^2 / 2652 = 5.43 W

Does that not seem wrong to you?

** Completely.

Such a cap dissipates no energy at all.

What planet do you come from ??

What a jerk you are. You do realize that is 45mA running through that.

** What sort of know nothing JERK thinks that capacitors dissipate energy
??

Then proceeds to calculate the reactive impedance and treat it the same as
resistance ??

Big bad.

Zero out of ten.


..... Phil

 

On Mon, 11 Apr 2011 13:25:02 +1000, "Phil Allison" <phil_a@tpg.com.au>
wrote:

clare@snyder.on.ca
"Phil Allison"


High voltage spikes on the primary could also cause insulation failure
leading to the damage seen in the pics - lightning does this sort of
thing.
So also could back emfs from the blower fan if the is a bad connection in
the AC supply feed.

I suggest you provide the next replacement for that vulnerable tranny with
some "protection" - firstly an in-line fuse of say 1/4 amp AND a
capacitor wired across the primary of say 1uF rated for continuous use
across the AC supply.

If there is an overload on the tranny, the fuse will blow.

The 1uF capacitor should suppress spike voltages enough to save the tranny
from harm.



A capacitor across an AC supply??????????????? As a surge
protector????
Have not heard of that before.


** Then your ignorance is showing.

The stated reason for the capacitor was in relation to the "blower fan"
inside the same unit as the small tranny.

The event the cap has to deal with is a back emf surge generated by that
fan when the AC supply is suddenly disconnected - for whatever reason.


A capacitor across the AC line would appear as a load

** Draws 45mA continuously.

Yawnnnnnnn....

- and could form a resonant l/ci tank circuit,

** Yawnnnnnn....

(snip absurd drivel)


There are 2 other POSSIBLE issues here though - - -.

Both are perhaps long shots - but mabee worth investigating.

The transformer primary APPEARS to be saturating.


** The primary appears to be EXPLODING !!

You ridiculous wanker.


.... Phil

Phil - your mamma should wash your mouth out with soap.

I SAID the other two scenarios were long shots - but so is everything
else that has been suggested. The windings of the trasnformer do not
APPEAR to be overheated - looks like just blackened at the connections
between the winding and the connecting wires.

It is definitely a strange failure - and I don't think it has been
properly analyzed to determine exactly what/where the problem is.
As Arthur Conan Doyle said, "after you have eliminated all the
possibilities, whatever remains, however improbable, must be the
truth"

 

[Phil Allison]

<clare@snyder.on.ca>

** The primary appears to be EXPLODING !!

You ridiculous wanker.

Phil - your mamma should wash your mouth out with soap.

** You need to get your hands off of it.

I SAID the other two scenarios were long shots ..

** And I said they were ridiculous drivel.

- but so is everything else that has been suggested.

** Your opinion is based on your ignorance only.

The windings of the trasnformer do not
APPEAR to be overheated - looks like just blackened at the connections
between the winding and the connecting wires.

** See the vaporised metal coating deposited on the plastic cover next to
the tranny?

That is a damn EXPLOSION !!

It happened very suddenly and made a loud bang too.

I said:

" High voltage spikes on the primary could also cause insulation failure
leading to the damage seen in the pics - lightning does this sort of thing.
So also could back emfs from the blower fan if the is a bad connection in
the AC supply feed."

If the insulation on the enamel wire of the primary is punctured by a HIGH
VOLTAGE SPIKE, effectively shorting out most of the primary - then the
120 AC supply ( no fuse exists remember ) will easily turn the two exposed
wire ends into metal vapour !!!

Cos they just became the fuses.

It just so happens that many small transformers made in China, India & Sri
Lanka etc are very prone to this sort of failure - due to bad manufacturing
practices.



..... Phil

 

[Stormin Mormon]

What is this "old light bulb trick"?

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Ron D." <ron.dozier@gmail.com> wrote in message
news:874969f6-f77c-41f5-8ed1-4c19d492f4fe@k9g2000yqi.googlegroups.com...
Put 3A automotive fuse on secondary. Use light bulb trick
to find
shorts. Two 12 V light bulbs in series that draw no more
than 40 VA.

 

[Phil Allison]

"Stormin Mormon"

What is this "old light bulb trick"?

** You need to ask Agent 86 that one....




.... Phil

 

[Jeff Thies]

On 4/10/2011 11:29 PM, Phil Allison wrote:

"Jeff Thies"
Phil Allison wrote:
"Jeff Thies"
Phil Allison wrote:

I suggest you provide the next replacement for that vulnerable tranny
with
some "protection" - firstly an in-line fuse of say 1/4 amp AND a
capacitor wired across the primary of say 1uF rated for continuous
use
across the AC supply.

If there is an overload on the tranny, the fuse will blow.

The 1uF capacitor should suppress spike voltages enough to save the
tranny from harm.

1 uF sounds a little high.


** No it ain't.

I thought you had simply misspoke and that this was an honest error.

The reactance of a 1uF cap at 60Hz is: 2652 ohms (1/(2*pi*F*C)
Online calculator:
http://www.kusashi.com/reactance-c.php?f=60&c=1&stage=results

V^2/R = W

Assuming primary, as why would you put it on the secondary:

120^2 / 2652 = 5.43 W

Does that not seem wrong to you?

** Completely.

Such a cap dissipates no energy at all.

What planet do you come from ??

What a jerk you are. You do realize that is 45mA running through that.


** What sort of know nothing JERK thinks that capacitors dissipate energy
??

It doesn't have to dissipate energy to explode. That is a lot of joules.

Then proceeds to calculate the reactive impedance and treat it the same as
resistance ??

Big bad.

So I left out the PF, so what?

Zero out of ten.

My first encounter with you, but no doubt others have had the same
reaction. Telling an inexperienced OP to put in a 1mF cap without any
specifics, and that for the dubious goal of "suppressing" the back EMF
of a motor running off the line has a disconnect from reality.
Transformers are generally much hardier devices than the solid state
components they feed.

Say what you want. You've already made your mark and I really don't
care what you add. I've taken away what I need to know about yourself,
and the OP is off somewhere else.

Happy now?

Jeff

.... Phil

 

[Smitty Two]

In article <inv5oj$nkt$1@news.albasani.net>,
Jeff Thies <jeff_thies@att.net> wrote:

My first encounter with you

Jeff, since you don't hang out on s.e.r., I'll clue you in about Phil.
Regardless of what he knows or doesn't know, he calls everyone a
fuckwit, and worse, all the time. Virtually every sentence of every post
is chock full of derision. If you choose to dialogue with him, you'll
get great heaping portions of his demented abuse. So don't take it
personally.

 

[Jeff Thies]

On 4/11/2011 11:25 AM, Smitty Two wrote:

In article<inv5oj$nkt$1@news.albasani.net>,
Jeff Thies<jeff_thies@att.net> wrote:

My first encounter with you

Jeff, since you don't hang out on s.e.r., I'll clue you in about Phil.
Regardless of what he knows or doesn't know, he calls everyone a
fuckwit, and worse, all the time. Virtually every sentence of every post
is chock full of derision. If you choose to dialogue with him, you'll
get great heaping portions of his demented abuse. So don't take it
personally.

Thanks. That's about what I surmised. A North American version of Rod
Speed.

Some people I'll read consistently, I'll put him in the other group.

Jeff

 

[David Nebenzahl]

On 4/11/2011 8:25 AM Smitty Two spake thus:

In article <inv5oj$nkt$1@news.albasani.net>,
Jeff Thies <jeff_thies@att.net> wrote:

My first encounter with you

Jeff, since you don't hang out on s.e.r., I'll clue you in about Phil.
Regardless of what he knows or doesn't know, he calls everyone a
fuckwit, and worse, all the time. Virtually every sentence of every post
is chock full of derision. If you choose to dialogue with him, you'll
get great heaping portions of his demented abuse. So don't take it
personally.

That's true, and it's also true that he often acts--seriously, no
joke--like he's off his meds.

But it's also true that he knows more about electronics than probably
all the "experts" here (a.h.r.) put together. And it is possible to
engage him in serious dialog on electronic topics, as shown by recent
threads in s.e.r. So while he can be abusive, you ought to listen to his
technical advice, which is golden.


--
The current state of literacy in our advanced civilization:

yo
wassup
nuttin
wan2 hang
k
where
here
k
l8tr
by

- from Usenet (what's *that*?)

 

[The Daring Dufas]

On 4/11/2011 1:46 PM, Meat Plow wrote:

On Mon, 11 Apr 2011 11:30:33 -0700, David Nebenzahl wrote:

On 4/11/2011 8:25 AM Smitty Two spake thus:

In article<inv5oj$nkt$1@news.albasani.net>,
Jeff Thies<jeff_thies@att.net> wrote:

My first encounter with you

Jeff, since you don't hang out on s.e.r., I'll clue you in about Phil.
Regardless of what he knows or doesn't know, he calls everyone a
fuckwit, and worse, all the time. Virtually every sentence of every
post is chock full of derision. If you choose to dialogue with him,
you'll get great heaping portions of his demented abuse. So don't take
it personally.

That's true, and it's also true that he often acts--seriously, no
joke--like he's off his meds.

But it's also true that he knows more about electronics than probably
all the "experts" here (a.h.r.) put together.

That's debatable. Phil is a troll with decent knowledge in electronics.
He sets traps like a spider spins a web then comes back to pounce on
those in the trap. I think Phil gets a lot of his knowledge on Google.

Google? Is that some new kind of mind altering drug? ^_^

TDD