On Apr 9, 10:24*pm, Congoleum Breckenridge wrote:
On 4/9/2011 1:37 AM, Smitty Two wrote:



In ,
* Steve *wrote:

snip

You might start at the beginning and make sure everything is hooked up
correctly. I mean, once you spring for yet another transformer. For
example, your latest fried transformer has six wires. The schematic
shows the secondary wire colors as blue and red. Given the location of
the blue and red wires on the pic of the transformer you have, that's
not quite intuitive.

And, it may not even be right. So I'd buy a new one, and check some
voltages on the bench. Put 120 into the black and white, and then
measure every other pair to make sure you understand which two wires are
really putting out 24 V.

Obviously, when you go to install it, clip and shrink tube the unused
wires, and make sure that leads are dressed so that they won't short
anywhere.

Then I'd be monitoring the damn thing, preferably with a voltmeter
perhaps on the primary and an ammeter on the secondary.

That 3rd transformer looks like a dual voltage (120/240) input.
If it is, it has two primary windings, and both need to be wire up to work.
Like this:http://www.eleinmec.com/figures/027_02.gif

To OP
this is a long shot but...
I noticed on the Trane wiring diagram that you posted that the
connections for the IGNITION circuit are shown to be near to the
connections for the primary of the transformer.

If there is some insulation problem on the ignition wires and the VERY
high voltage from the ignition circuit is sparking or jumping over to
the transformer primary circuit, this could cause the symptoms you are
seeing.

Make sure the wires that are part of the ignition circuit are not even
close to the anything else. and inspect them (with the power off) for
any sigh of cracks or other faults. These have very high voltage
like in a car spark plug and can jump several inches if there is an
insulation problem. And the problem would be intermittent. The
transformer primary voltage would look perfect except when the high
voltage spark jumps over to it and this could easily damage the
insulation on the transformer which is not designed for very high
voltages.

If you are an electrical novice, you may want to think about calling
in for some help at this point.

Mark

On 4/9/2011 9:41 PM, wrote:
On Sat, 09 Apr 2011 19:22:57 -0400, Jeff
wrote:



But first do as I suggested in another thread,look carefully for
anything burnt and check the polarity of the line. Make sure the neutral
is neutral. You can measure from the ground prong. See the note in the
schematic. I'm not so sure this didn't arc to the transformer shell,
from looking at the pic. You may wish to measure voltage (AC) from the
transformer shell to a guaranteed neutral.

It's AC so there is no polarity. It's single output, non grounded, so
it doesnt matter which direction either the primary or secondary are
connected. Good to have the white on neutral and the bloack on live,
but it will have NO EFFECT on the operation. - or the life of the
transformer.


Except that the schematic has a note at the top that says:

Important
Integrated Control is polarity sensitive.
Hot leg of 120V power supply must be connected to the black power lead...

Whats with that?

Otherwise I would fully agree with you.

It seems to me there is a flaw in the integrated control and whereas
I don't see how this could be a problem, it is easy enough to scratch
off the list. Troubleshooting is little more than eliminating possibilities.

Jeff

It is OK for the transformer to run a little warm, it shouldn't be hot.

There are two kinds of failures, one is a long term thermal failure
(which seemed likely when you said years had gone by), the other is a
transient short, or maybe not so transient. If that is the case then
something else will be bad. It may look burnt, or if it is a diode or
transistor it may just be shorted. You can Google how to test those.

Don't be afraid to put a quick finger on a transistor to see if it is
hot, or on the transformer.

As far as calculating what size fuse, you should know Ohms law. Current
* voltage is watts, or in this case V(olt)A(mps). 120V * 1/4A = 30 VA,
on the out side, 24V * 1.5 = 36 VA.

Note that there is a small surge when you turn on a device. So it may
peak higher at the instant of turning on. A fuse usually can absorb
that. The white ceramics are faster blowing and the slow blow ones
usually have a little coil inside the fuse to show it down and are
marked slow blow. When/if you fix this, leave in the fuses and we can
give you some guidance on more properly sizing them. But some fuse in
the ballpark is definitely better than nothing.

Jeff

"Phil Allison"

firstly an in-line fuse of say 1/4 amp ....


** Must be a "slo-blo" type fuse.



..... Phil

Actualy, no, you don't have to. I don't think you're
comptetent to answer this question. At work, I regularly
measure amperage without splicing into the circuit. You
should stick to things you know.

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


"David Nebenzahl" wrote in message
.com...

To measure current (which, properly speaking, is what you're
measuring,
not "amperage"), you have to break the circuit and put the
ammeter in
series with the circuit, so that all the current goes
through the meter.
(As opposed to measuring voltage, where you put the meter
*across*, or
in parallel with, the thing whose voltage you want to know.)

Glad you noticed. I hadn't looked at the pictures that
closely. I hope your trip charge isn't too much, in this
case?

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


"The Daring Dufas"
wrote in message ...

I just saw it in the picture and posted what the problem is.
I would have seen it immediately if I was hands on. Look at
the wire colors on the transformer especially the YELLOW, it
is taking the place of the RED wire for low voltage. Notice
the
yellow and blue are on one side of the transformer. I don't
know
why I didn't notice it before. ^_^

TDD

If you were a criminal, stealing 3AG glass Littlefuses,
would you be con-fused?

Still got an electrical problem to find.

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


"The Daring Dufas"
wrote in message ...


Not to worry; I read the directions. The red and orange
wires were
indeed taped up and not used; only the white and black
wires on the
input side were hooked up in the normal fashion. The blue
and yellow
wires on the 24V output side of the transformer were
hooked to the blue
and red wires (respectively) leading to the control board.
I measured
input and output voltages after installing the
transformer, and I
ensured that I was getting 24V on the output side before I
hooked those
leads to the control board. The control board then came up
with it the
flashing red LED to indicate normal ("no call for heat")
operation.

Well, that blew that theory! ^_^

TDD

Again, you demonstrate that you're not competent to comment.

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


"David Nebenzahl" wrote in message
s.com...
On 4/9/2011 2:55 PM Stormin Mormon spake thus:

You do make mistakes, now and again. This is one, such.

No.

I make mistakes. You're an ignoramus.

See the difference?


--
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*?)

As a heating and AC installer and repair tech, I assure you
that David's writings sound fancy, but he's not competent to
comment.

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


"Steve Turner" wrote in
message ...
On 4/9/2011 4:37 PM, David Nebenzahl wrote:

So install such a fuse, run the unit and see what happens.

If the fuse blows right away, it's probably too small, so
use the next bigger
fuse; let's say 1.5 A.

Now you want to stop at some point, let's say 2-3 amps,
because now you're
getting up to where you may be exposing whatever fault
there is with the unit
and risking blowing the transformer again. If this
happens, you're going to
have to bite the bullet and find out what's wrong with the
damn thing. But at
least your 3rd transformer will still be intact.

Great information David. Thanks!

Steve, read and follow the directions that came with the
meter. Not the David directions.

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


"David Nebenzahl" wrote in message
s.com...
On 4/9/2011 3:11 PM Steve Turner spake thus:


Interesting; thank you. My meter is an Extech MN26T:

http://www.extech.com/instruments/re...ls/MN26_UM.pdf

According to the operating instructions, my meter supports
"AC or DC Current
Measurement"

Yep. You've got a better meter than I, and it's up to this
task. Just
connect it as I described (be sure to use the correct
connectors on the
meter, the ones marked "10A" and "COM"), make sure it's on
the highest
current range (10A), and you're good to go.

You should contact the manufacturers of furnaces, and tell
them that they are doing it wrong. They will thank you.
Don't take no for an answer.

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



wrote in message
...


So install such a fuse, run the unit and see what happens.

If the fuse blows right away, it's probably too small, so
use the next
bigger fuse; let's say 1.5 A.

We don't need to guess here.
The transformer has a rating. NEVER fuse above the
transformer rating.
If the transformer is a 40va 24 volt transformer the MAXIMUM
fuse
rating is 40/24=1.66 amps - so a 1.5 amp fuse will protect
the
transformer - a 2 amp fuse will NOT.

On 4/9/2011 5:21 PM, Steve Turner wrote:
On 4/9/2011 3:43 PM, Smarty wrote:
On 4/8/2011 8:52 PM, Steve Turner wrote:
A continuation of the "Why does the 115V-24V transformer keep
blowing on my
Trane XB80?" discussion I started on 04/02/2011.

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

http://www.flickr.com/photos/bbqboye...7626457562742/

Trane's manual for the unit is here (for perhaps better viewing of
the wiring
diagrams that I also copied to my above flickr site as jpg images):


http://www.trane.com/webcache/un/fur...7_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). If you didn't see my first thread, this is the third
transformer the
unit has blown. In the previous discussion, it was discussed that
perhaps the
first one just blew because of old age (6 years), and the second
blew because
it wasn't a proper replacement (poor quality, made in China, etc.).
This
third unit is most certainly a proper replacement, and it's most
certainly
indicative of a real problem I have somewhere else in the unit. I
didn't see
any such charring on the previous two units, at least not like this.

I never got a real chance to test out the system after installing
this third
transformer. We had cool weather for several days, and I never tried
to force
the system to come on so I could monitor it; that was probably a
mistake.
Unfortunately, I was also absent from the premises during the
extended times
when the unit was most likely operational, so that didn't help either.
However, my family tells me that it WAS working and cooling the
house rather
nicely, for at least a day, perhaps two. I'm getting 115V in all the
right
places, so it doesn't look like an over-voltage condition to me.
Perhaps it's
an overheating condition? It looks to me like the only real load on
this
circuit is the blower motor; could the motor be causing this? The
blower
spins freely when I turn it by hand. Start capacitor on the motor
maybe?
Relay on the control board perhaps?

Steve,

If you are not comfortable with taking current measurements, or do
not have an
ammeter, or do not wish to sit there waiting for some unusual
condition which
is drawing too much current, you could temporarily install an in-line
fuse
holder and automotive cartridge fuse rated at or above the secondary
side
amperage which the transformer is rated. With this fuse installed on the
secondary side, in series with the load, you could then determine if
the load
is indeed drawing too much current from the secondary and burning out
the
transformer, versus primary side excess voltage being the problem.

A rough guess would be that the contactor coil should maybe be
drawing about a
quarter to a half an amp of current at 24V. The transformer secondary
should
not need to source a lot more than that amount of current to provide
adequate
power to the coil of the contactor.

Fuses are a lot cheaper than transformers......

There may be an intermittent short in the wiring to the coil, a short
in the
coil itself, a breakdown of the coil insulation allowing a short to
ground when
the coil heats up or cools or vibrates, etc.

Smarty

Yes Smarty, I would very much like to try this approach because I
don't want to zap any more transformers. Lots of people have
suggested it, but there appear to be more types of fuses than there
are insects, and I have no idea what *exact* type to look for. That's
why I asked earlier in this thread if this particular transformer:

http://www.pexsupply.com/White-Rodge...unt-14937000-p


with a built-in manual reset would be a much cleaner solution that
serves the same purpose, but I got no responses.

The specs on the original transformer we Class 2, 115V primary
(60hz), 24V (35VA) secondary. Any chance you could point me to some
_exact_ fuse solutions for this application? There's a virtual
six-pack of beer in it for you. :-)
Here is the fuse holder, available at Radio Shack for a couple bucks:
http://www.radioshack.com/product/in...ductId=2102784

Ask the Radio Shack clerk to sell you some compatible fuses which are
fast acting approx 1 or 1.5 amp size. If your transformer is 35VA rated,
it should be able to pump out an amp continuously without damage. A 1
amp fuse will allow it to provide 24 VA (24 volts X 1 amp) which is well
below the rating.

Your contactor should not draw anywhere near 24VA, and if it does, the
problem needs to be in either the contactor or the wiring to the contactor.

Good luck.

On 4/9/2011 10:22 PM, Phil Allison wrote:
"robb"


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

http://www.flickr.com/photos/bbqboye...7626457562742/

http://www.trane.com/webcache/un/fur...7_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.

I would think .01 uF at 400V would be a better bet. Or an MOV (metal
oxide varistor) or three (across the line and then from each side to
ground).

I don't think this is a voltage spike problem though. Voltage spikes
take out other components first.

Jeff



..... Phil

On Apr 10, 12:18*am, Jeff Thies wrote:
On 4/9/2011 9:41 PM, wrote:





On Sat, 09 Apr 2011 19:22:57 -0400, Jeff
wrote:

* *But first do as I suggested in another thread,look carefully for
anything burnt and check the polarity of the line. Make sure the neutral
is neutral. You can measure from the ground prong. See the note in the
schematic. I'm not so sure this didn't arc to the transformer shell,
from looking at the pic. You may wish to measure voltage (AC) from the
transformer shell to a guaranteed neutral.

It's AC so there is no polarity. It's single output, non grounded, so
it doesnt matter which direction either the primary or secondary are
connected. Good to have the white on neutral and the bloack on live,
but it will have NO EFFECT on the operation. - or the life of the
transformer.

Except that the schematic has a note at the top that says:

Important
Integrated Control is polarity sensitive.
Hot leg of 120V power supply must be connected to the black power lead...

* *Whats with that?

I recently installed a Rheem and the installation manual clearly
stated
that the furnace would not start and would come up with a fault
condition if the hot and neutral were reversed. Don;t know exactly
how that one is wired or designed vs the Trane, but at least for
Rheem it does make a difference. But I suspect the main effect
is that the controller board detects it and just causes a fault. I
don't see how a reversed hot/neutral would be causing this guys
problem,
but it is one thing I would have checked long ago, or if I didn't
understand the basic steps, I would have called in a pro.






* *Otherwise I would fully agree with you.

* *It seems to me there is a flaw in the integrated control and whereas
I don't see how this could be a problem, it is easy enough to scratch
off the list. Troubleshooting is little more than eliminating possibilities.

* *Jeff









* *It is OK for the transformer to run a little warm, it shouldn't be hot.

* *There are two kinds of failures, one is a long term thermal failure
(which seemed likely when you said years had gone by), the other is a
transient short, or maybe not so transient. If that is the case then
something else will be bad. It may look burnt, or if it is a diode or
transistor it may just be shorted. You can Google how to test those.

* *Don't be afraid to put a quick finger on a transistor to see if it is
hot, or on the transformer.

As far as calculating what size fuse, you should know Ohms law. Current
* voltage is watts, or in this case V(olt)A(mps). 120V * 1/4A = 30 VA,
on the out side, 24V * 1.5 = 36 VA.

* *Note that there is a small surge when you turn on a device. So it may
peak higher at the instant of turning on. A fuse usually can absorb
that. The white ceramics are faster blowing and the slow blow ones
usually have a little coil inside the fuse to show it down and are
marked slow blow. When/if you fix this, leave in the fuses and we can
give you some guidance on more properly sizing them. But some fuse in
the ballpark is definitely better than nothing.

* *Jeff- Hide quoted text -

- Show quoted text -- Hide quoted text -

- Show quoted text -

On Apr 9, 8:29*pm, Jim Yanik wrote:
"robb" wrote innews:WfKdnQOvu_d2bz3QnZ2dnUVZ_uadnZ2d@earthlink. com:





"Steve Turner" *wrote in ...

A continuation of the "Why does the 115V-24V transformer keep
blowing on my Trane XB80?" discussion I started on 04/02/2011.

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

* *http://www.flickr.com/photos/bbqboye...7626457562742/

Trane's manual for the unit is here (for perhaps better viewing of
the wiring diagrams that I also copied to my above flickr site as
jpg images):

http://www.trane.com/webcache/un/fur...oduct/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). *If you didn't see my first thread, this is
the third transformer the unit has blown. *In the previous
discussion, it was discussed that perhaps the first one just blew
because of old age (6 years), and the second blew because it wasn't
a proper replacement (poor quality, made in China, etc.). *This
third unit is most certainly a proper replacement, and it's most
certainly indicative of a real problem I have somewhere else in the
unit. *I didn't see any such charring on the previous two units, at
least not like this.

I never got a real chance to test out the system after installing
this third transformer. *We had cool weather for several days, and I
never tried to force the system to come on so I could monitor it;
that was probably a mistake. Unfortunately, I was also absent from
the premises during the extended times when the unit was most likely
operational, so that didn't help either. However, my family tells me
that it WAS working and cooling the house rather nicely, for at
least a day, perhaps two. *I'm getting 115V in all the right places,
so it doesn't look like an over-voltage condition to me. *Perhaps
it's an overheating condition? *It looks to me like the only real
load on this circuit is the blower motor; could the motor be causing
this? *The blower spins freely when I turn it by hand. *Start
capacitor on the motor maybe? *Relay on the control board perhaps?

a bad start cap would not affect the 24v control transformer,that just
powers the controller board and relays.
either something is loading the transformer or a problem with input
voltage.



It also could be powering a thermostat. Some of them will take power
from the transformer circuit. For example, I have a Honeywell
VisionPro
that has an optional 24V connection to power the thermostat, with
batteries then being the backup. Doing it that way allows the display
to be backlit 24/7 too.

Also, it's not unusual to have humdifiers tied into the 24V circuit
too.

Again, he needs to start doing some basic current measurements,
starting at the transformer and find out how much current the whole
thing is drawing and then if it's high, work to isolate it. If the
current
is normal, then I'd put in a 1.5 amp fuse in the secondary
temporarily.
Contrary to the suggestions to use a fast blow, I'd probably just use
a regular one, as whatever is capable of destroying a transformer
should be most capable of opening any fuse.













Just a thought,

When you put the new transformer in does the *"Diagnostic Light" LED
turn on ?
Does the LED blink or flash in one of the patterns indicated in the
"diagnostic codes" section that you posted a link to ?

The "diagnostic codes" *imply that the control board can detect
several of the problems mentioned by others.
Maybe a good starting point as there is not enough time to test with
test equipment.

That's a good idea too.





robb

a line voltage monitor may be needed to see if there's some short-term
overvoltage applied to the transformer,and a oscilloscope may determine if
the input waveform is sinusoidal or otherwise,because 60hz iron core
tranformers don't like extreme distortion on their input,it gets converted
to heat,not output voltage.

I don't see how he could have a waveform that is so out of shape that
it
burns up this one specific transformer, yet there are no apparent
complaints of any other problems in the house. Or how you'd get
such a badly distorted waveform in the house in the first place.




a DMM will not show line distortion or short
term overvoltages.
are the wires burned close to the transformer,or over their entire length?

--
Jim Yanik
jyanik
at
localnet
dot com- Hide quoted text -

- Show quoted text -- Hide quoted text -

- Show quoted text -

To OP
this is a long shot but...
I noticed on the Trane wiring diagram that you posted that the
connections for the IGNITION circuit are shown to be near to the
connections for the primary of the transformer.

If there is some insulation problem on the ignition wires and the VERY
high voltage from the ignition circuit is sparking or jumping over to
the transformer primary circuit, this could cause the symptoms you are
seeing.

Make sure the wires that are part of the ignition circuit are not even
close to the anything else. and inspect them (with the power off) for
any sigh of cracks or other faults. These have very high voltage
like in a car spark plug and can jump several inches if there is an
insulation problem. And the problem would be intermittent. The
transformer primary voltage would look perfect except when the high
voltage spark jumps over to it and this could easily damage the
insulation on the transformer which is not designed for very high
voltages.

If you are an electrical novice, you may want to think about calling
in for some help at this point.

Mark

"Mark" wrote in message
...
To OP
this is a long shot but...
I noticed on the Trane wiring diagram that you posted that the
connections for the IGNITION circuit are shown to be near to the
connections for the primary of the transformer.
snip
Mark

Everything I see on the diagrams says this is a HSI (Hot Surface
Igniter) type of furnace. There is no high voltage in that type
of igniter.
David

On Apr 10, 11:55*am, "David" wrote:
"Mark" *wrote in message
...
To OP
this is a long shot but...
I noticed on the Trane wiring diagram that you posted that the
connections for the IGNITION circuit are shown to be near to the
connections for the primary of the transformer.
snip
Mark

Everything I see on the diagrams says this is a HSI (Hot Surface
Igniter) type of furnace. There is no high voltage in that type
of igniter.
David

David,
I think you are right...

well it sounded good anyway....

regards
Mark

On 4/10/2011 6:37 AM Stormin Mormon spake thus:

Steve, read and follow the directions that came with the
meter. Not the David directions.

What, you're saying mine are wrong? Exactly how, pray tell?

You really are an idiot.


--
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*?)

On 4/9/2011 6:11 PM, David Nebenzahl wrote:
On 4/9/2011 2:55 PM Stormin Mormon spake thus:

You do make mistakes, now and again. This is one, such.

No.

I make mistakes. You're an ignoramus.

See the difference?



Oh this is so cute. Now it's time for a group hug.


alt.home.repair

Since you are being insulting, I won't bother to try to help
you.

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


"David Nebenzahl" wrote in message
s.com...
On 4/10/2011 6:37 AM Stormin Mormon spake thus:

Steve, read and follow the directions that came with the
meter. Not the David directions.

What, you're saying mine are wrong? Exactly how, pray tell?

You really are an idiot.


--
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*?)

On 4/10/2011 2:17 PM, Tony Miklos wrote:
On 4/9/2011 6:11 PM, David Nebenzahl wrote:
On 4/9/2011 2:55 PM Stormin Mormon spake thus:

You do make mistakes, now and again. This is one, such.

No.

I make mistakes. You're an ignoramus.

See the difference?



Oh this is so cute. Now it's time for a group hug.


alt.home.repair

DON"T TOUCH ME MAN! ^_^

TDD

Excuse me while I slip into my cast iron underwear. I feel a
bit in jeopardy. Sounds like that dude be going after the
wrong meat.

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


"The Daring Dufas" wrote in
message ...
On 4/10/2011 2:17 PM, Tony Miklos wrote:
On 4/9/2011 6:11 PM, David Nebenzahl wrote:


Oh this is so cute. Now it's time for a group hug.


alt.home.repair

DON"T TOUCH ME MAN! ^_^

TDD

On 4/9/2011 5:19 PM, The Daring Dufas wrote:
On 4/9/2011 12:43 PM, Tony Miklos wrote:
On 4/9/2011 11:55 AM, Steve Turner wrote:
On 4/9/2011 10:29 AM, The Daring Dufas wrote:
On 4/9/2011 8:30 AM, Tony Miklos wrote:
On 4/9/2011 12:38 AM, David Nebenzahl wrote:
On 4/8/2011 8:22 PM Steve Turner spake thus:

On 4/8/2011 7:58 PM, David Nebenzahl wrote:

On 4/8/2011 5:52 PM Steve Turner spake thus:

A continuation of the "Why does the 115V-24V transformer keep
blowing on my Trane XB80?" discussion I started on 04/02/2011.

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

http://www.flickr.com/photos/bbqboye...7626457562742/

Trane's manual for the unit is here (for perhaps better viewing
of the wiring diagrams that I also copied to my above flickr site
as jpg images):

http://www.trane.com/webcache/un/fur...7_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). If you didn't see my
first thread, this is the third transformer the unit has blown.
In the previous discussion, it was discussed that perhaps the
first
one just blew because of old age (6 years), and the second
blew because it wasn't a proper replacement (poor quality, made
in China, etc.). This third unit is most certainly a proper
replacement, and it's most certainly indicative of a real problem
I have somewhere else in the unit. I didn't see any such charring
on the previous two units, at least not like this.

How 'bout installing an in-line fuse next time you replace the
xfmr? I'd put it on the secondary side. That way, if there is an
overload, the fuse will blow instead.

Thinking maybe I should spring for a transformer with a manual
reset,
like this one:

http://www.pexsupply.com/White-Rodge...unt-14937000-p







Would that protect me from having to replace the damn transformer
every time? It looks like the circuit breaker is on the 24V output
side; I'm a little fuzzy on how that would protect the input side of
the transformer...?

Why in the world would you think you need to protect the primary
side?

Look at the picture. The primary side has been overheated, the
secondary
side looks fine. Looks like an over voltage problem to me.

I wonder if our intrepid OP has done the basics involved in
troubleshooting
instead of flitting around from place to place?
In the case of a power problem, you always start at the source by
measuring voltage and current. It could be a very simple problem
like a bit of insulation skinned off a thermostat wire that only
shorts out when everything is buttoned up and vibration from the
running unit causes the short circuit. If you ever watched the TV
program MASH, you would see the surgeons run the intestines looking
for a nick in the wall of the organ. Wiring is the same way sometimes.
I'll inspect the wiring and often find a small cut or tiny area where
insulation is missing and sometimes the wire is bent over a sharp edge
of the cabinet where it's fine until you close things up. I wonder if
the supply voltage to the transformer is what it's supposed to be? Most
domestic household air handler/furnaces are powered by 120vac but some
may require 240vac if there are electric heat strips. I would check the
voltage feeding the transformer first.

TDD

Yes, I've done all those things. The supply voltage is fine. I've
inspected the wiring at great length and can find no evidence of
problems; it all looks pristine. It's a gas furnace, and there are no
220 circuits running anywhere near that area of the house.

Thanks.

It doesn't take any 220 (240) circuits to cause that.

I think someone already mentioned the possibility of a bad neutral
connection allowing the supply voltage to shoot up.

TDD

You are correct, I mentioned that back a day or three ago.

On 4/9/2011 5:21 PM, Steve Turner wrote:
On 4/9/2011 3:43 PM, Smarty wrote:
On 4/8/2011 8:52 PM, Steve Turner wrote:
A continuation of the "Why does the 115V-24V transformer keep
blowing on my
Trane XB80?" discussion I started on 04/02/2011.

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

http://www.flickr.com/photos/bbqboye...7626457562742/

Trane's manual for the unit is here (for perhaps better viewing of
the wiring
diagrams that I also copied to my above flickr site as jpg images):


http://www.trane.com/webcache/un/fur...7_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). If you didn't see my first thread, this is the third
transformer the
unit has blown. In the previous discussion, it was discussed that
perhaps the
first one just blew because of old age (6 years), and the second blew
because
it wasn't a proper replacement (poor quality, made in China, etc.). This
third unit is most certainly a proper replacement, and it's most
certainly
indicative of a real problem I have somewhere else in the unit. I
didn't see
any such charring on the previous two units, at least not like this.

I never got a real chance to test out the system after installing
this third
transformer. We had cool weather for several days, and I never tried
to force
the system to come on so I could monitor it; that was probably a
mistake.
Unfortunately, I was also absent from the premises during the
extended times
when the unit was most likely operational, so that didn't help either.
However, my family tells me that it WAS working and cooling the house
rather
nicely, for at least a day, perhaps two. I'm getting 115V in all the
right
places, so it doesn't look like an over-voltage condition to me.
Perhaps it's
an overheating condition? It looks to me like the only real load on this
circuit is the blower motor; could the motor be causing this? The blower
spins freely when I turn it by hand. Start capacitor on the motor maybe?
Relay on the control board perhaps?

Steve,

If you are not comfortable with taking current measurements, or do not
have an
ammeter, or do not wish to sit there waiting for some unusual
condition which
is drawing too much current, you could temporarily install an in-line
fuse
holder and automotive cartridge fuse rated at or above the secondary side
amperage which the transformer is rated. With this fuse installed on the
secondary side, in series with the load, you could then determine if
the load
is indeed drawing too much current from the secondary and burning out the
transformer, versus primary side excess voltage being the problem.

A rough guess would be that the contactor coil should maybe be drawing
about a
quarter to a half an amp of current at 24V. The transformer secondary
should
not need to source a lot more than that amount of current to provide
adequate
power to the coil of the contactor.

Fuses are a lot cheaper than transformers......

There may be an intermittent short in the wiring to the coil, a short
in the
coil itself, a breakdown of the coil insulation allowing a short to
ground when
the coil heats up or cools or vibrates, etc.

Smarty

Yes Smarty, I would very much like to try this approach because I don't
want to zap any more transformers. Lots of people have suggested it, but
there appear to be more types of fuses than there are insects, and I
have no idea what *exact* type to look for. That's why I asked earlier
in this thread if this particular transformer:

http://www.pexsupply.com/White-Rodge...unt-14937000-p


with a built-in manual reset would be a much cleaner solution that
serves the same purpose, but I got no responses.

The specs on the original transformer we Class 2, 115V primary
(60hz), 24V (35VA) secondary. Any chance you could point me to some
_exact_ fuse solutions for this application? There's a virtual six-pack
of beer in it for you. :-)

It appears the breaker/reset is on the secondary side, so yes please buy
that transformer and install it. That will at least settle the debate
(well mostly me) of those who says the problem is on the primary side.
If it burns up that transformer then I'm correct. If it only trips the
breaker, well... it's probably on the secondary side.

"Jeff Thies"
Phil Allison wrote:
"robb"


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

http://www.flickr.com/photos/bbqboye...7626457562742/

http://www.trane.com/webcache/un/fur...7_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 would think .01 uF at 400V would be a better bet.

** Think again.

Or an MOV (metal oxide varistor) or three (across the line and then from
each side to ground).

** Bad idea.

I don't think this is a voltage spike problem though. Voltage spikes take
out other components first.

** Not on the AC supply they don't.


...... Phil

On 4/9/2011 9:08 PM, wrote:
On Sat, 09 Apr 2011 14:37:10 -0700, David Nebenzahl
wrote:

On 4/9/2011 2:21 PM Steve Turner spake thus:

On 4/9/2011 3:43 PM, Smarty wrote:

On 4/8/2011 8:52 PM, Steve Turner wrote:

A continuation of the "Why does the 115V-24V transformer keep
blowing on my Trane XB80?" discussion I started on 04/02/2011.

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

http://www.flickr.com/photos/bbqboye...7626457562742/

Trane's manual for the unit is here (for perhaps better viewing
of the wiring diagrams that I also copied to my above flickr site
as jpg images):

http://www.trane.com/webcache/un/fur...7_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). If you didn't see my first thread, this is the third transformer the
unit has blown. In the previous discussion, it was discussed that perhaps the
first one just blew because of old age (6 years), and the second blew because
it wasn't a proper replacement (poor quality, made in China, etc.). This
third unit is most certainly a proper replacement, and it's most certainly
indicative of a real problem I have somewhere else in the unit. I didn't see
any such charring on the previous two units, at least not like this.

I never got a real chance to test out the system after installing this third
transformer. We had cool weather for several days, and I never tried to force
the system to come on so I could monitor it; that was probably a mistake.
Unfortunately, I was also absent from the premises during the extended times
when the unit was most likely operational, so that didn't help either.
However, my family tells me that it WAS working and cooling the house rather
nicely, for at least a day, perhaps two. I'm getting 115V in all the right
places, so it doesn't look like an over-voltage condition to me. Perhaps it's
an overheating condition? It looks to me like the only real load on this
circuit is the blower motor; could the motor be causing this? The blower
spins freely when I turn it by hand. Start capacitor on the motor maybe?
Relay on the control board perhaps?

If you are not comfortable with taking current measurements, or do not have an
ammeter, or do not wish to sit there waiting for some unusual condition which
is drawing too much current, you could temporarily install an in-line fuse
holder and automotive cartridge fuse rated at or above the secondary side
amperage which the transformer is rated. With this fuse installed on the
secondary side, in series with the load, you could then determine if the load
is indeed drawing too much current from the secondary and burning out the
transformer, versus primary side excess voltage being the problem.

A rough guess would be that the contactor coil should maybe be drawing about a
quarter to a half an amp of current at 24V. The transformer secondary should
not need to source a lot more than that amount of current to provide adequate
power to the coil of the contactor.

Fuses are a lot cheaper than transformers......

There may be an intermittent short in the wiring to the coil, a short in the
coil itself, a breakdown of the coil insulation allowing a short to ground when
the coil heats up or cools or vibrates, etc.

Yes Smarty, I would very much like to try this approach because I don't want to
zap any more transformers. Lots of people have suggested it, but there appear
to be more types of fuses than there are insects, and I have no idea what
*exact* type to look for.

Well, it's not exactly rocket science. And you can't hurt anything,
unless you get a fuse that's too big (i.e., rated at too many amps).

First thing you gotta figure out is how much current your transformer is
rated at. Since your wiring diagrams don't say, we have to take an
educated guess.

The only thing connected to the transformer is a thingamajig called the
"integrated furnace control" (IFC). Even without seeing this thing, I
can guess with confidence that it's an electronic circuit board which
controls the operation of the furnace. Since it undoubtedly does so
through relays (either mechanical or electronic), it's safe to assume
that it doesn't draw much current.

Let's say 1 amp to start. We could be wrong, but that's a good starting
point. So what we need is a fuse rated at *at least* 24 volts (could be
much more, up to 120 or 240 volts), and *exactly* 1 amp. To be on the
safe side, let's get a "fast blow" fuse. Hey, fuses are cheaper than
transformers, right?

So install such a fuse, run the unit and see what happens.

If the fuse blows right away, it's probably too small, so use the next
bigger fuse; let's say 1.5 A.

We don't need to guess here.
The transformer has a rating. NEVER fuse above the transformer rating.
If the transformer is a 40va 24 volt transformer the MAXIMUM fuse
rating is 40/24=1.66 amps - so a 1.5 amp fuse will protect the
transformer - a 2 amp fuse will NOT.

And on the primary we have a max of .332 amps, I'd say a 1/4amp slow
blow would work.

On 4/9/2011 10:06 PM, John Robertson wrote:
Steve Turner wrote:
On 4/9/2011 7:29 PM, Jim Yanik wrote:
wrote in
m:

"Steve Turner" wrote in message ...

A continuation of the "Why does the 115V-24V transformer keep
blowing on my Trane XB80?" discussion I started on 04/02/2011.

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

http://www.flickr.com/photos/bbqboye...7626457562742/

Trane's manual for the unit is here (for perhaps better viewing of
the wiring diagrams that I also copied to my above flickr site as
jpg images):



http://www.trane.com/webcache/un/fur...oduct/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). If you didn't see my first thread, this is
the third transformer the unit has blown. In the previous
discussion, it was discussed that perhaps the first one just blew
because of old age (6 years), and the second blew because it wasn't
a proper replacement (poor quality, made in China, etc.). This
third unit is most certainly a proper replacement, and it's most
certainly indicative of a real problem I have somewhere else in the
unit. I didn't see any such charring on the previous two units, at
least not like this.

I never got a real chance to test out the system after installing
this third transformer. We had cool weather for several days, and I
never tried to force the system to come on so I could monitor it;
that was probably a mistake. Unfortunately, I was also absent from
the premises during the extended times when the unit was most likely
operational, so that didn't help either. However, my family tells me
that it WAS working and cooling the house rather nicely, for at
least a day, perhaps two. I'm getting 115V in all the right places,
so it doesn't look like an over-voltage condition to me. Perhaps
it's an overheating condition? It looks to me like the only real
load on this circuit is the blower motor; could the motor be causing
this? The blower spins freely when I turn it by hand. Start
capacitor on the motor maybe? Relay on the control board perhaps?

a bad start cap would not affect the 24v control transformer,that just
powers the controller board and relays.
either something is loading the transformer or a problem with input
voltage.


Just a thought,

When you put the new transformer in does the "Diagnostic Light" LED
turn on ?
Does the LED blink or flash in one of the patterns indicated in the
"diagnostic codes" section that you posted a link to ?

The "diagnostic codes" imply that the control board can detect
several of the problems mentioned by others.
Maybe a good starting point as there is not enough time to test with
test equipment.

robb



a line voltage monitor may be needed to see if there's some short-term
overvoltage applied to the transformer,and a oscilloscope may
determine if
the input waveform is sinusoidal or otherwise,because 60hz iron core
tranformers don't like extreme distortion on their input,it gets
converted
to heat,not output voltage. a DMM will not show line distortion or short
term overvoltages.
are the wires burned close to the transformer,or over their entire
length?

I peeled the insulation back from the hot and neutral wires and the
burning only occurred right at the terminals, no more than 1/4" into
the wiring.


So the problem is the joint of the transformer wiring to the lugs. They
may have cold solder joints, or the lug may be slightly loose - enough
to crack the solder connection over time. Your transformer may still be
good!

When you are examining the transformer wire make sure it is stripped
enough to get good solder coverage. Burn off the insulation (enamel) -
do not sand, scrape, or try to erode it because if you scratch the wire
it will break at the scratch.

Re-solder the transformer connectors after first making sure the wire
has at least two complete wraps around the solder lug and the solder
makes a good meniscus joint to the wire and lug. Also use a good grade
of solder, not regular 60/40, find some 63/37 solder (Kester is best) -
this solder resists cold solder joints due to movement when cooling by
solidifying very fast.

John :-#)#

Hi John, fancy meeting you here! Wait, I didn't realize this is cross
posted to sci.electronics.repair Now I know why you are here. Glad you
liked the package.

Tony

On 4/9/2011 10:22 PM, Phil Allison wrote:
"robb"


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

http://www.flickr.com/photos/bbqboye...7626457562742/

http://www.trane.com/webcache/un/fur...7_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.

Oh my gawd, someone agrees with me. Looking at the picture says a lot.
Burnt on the primary side, looks like new on the secondary. And this
is the third transformer with an open primary!


I don't know about a the 1uF cap, seems way too high so I'll delete what
was below and pretend I didn't see it.

On 4/10/2011 5:07 PM, Stormin Mormon wrote:
Excuse me while I slip into my cast iron underwear. I feel a
bit in jeopardy. Sounds like that dude be going after the
wrong meat.


No, I don't swing that direction.

"Tony Miklos don't know much"


** 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.

Oh my gawd, someone agrees with me. Looking at the picture says a lot.
Burnt on the primary side, looks like new on the secondary. And this is
the third transformer with an open primary!


I don't know about a the 1uF cap, seems way too high

** Why ?????

It ( likely ) needs to absorb a transient back emf generated by a powerful
blower fan.

Non puny size cap will ever do that and using 1uF cases no harm whatsoever.


so I'll delete what was below and pretend I didn't see it.

** Nothing like doing the old Ostrich trick when the brain gets overloaded.

Wot a jerk off.


..... Phil

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.

On 4/9/2011 5:19 PM, The Daring Dufas wrote:
On 4/9/2011 12:43 PM, Tony Miklos wrote:
On 4/9/2011 11:55 AM, Steve Turner wrote:
On 4/9/2011 10:29 AM, The Daring Dufas wrote:
On 4/9/2011 8:30 AM, Tony Miklos wrote:
On 4/9/2011 12:38 AM, David Nebenzahl wrote:
On 4/8/2011 8:22 PM Steve Turner spake thus:

On 4/8/2011 7:58 PM, David Nebenzahl wrote:

I I
[christmas presents]

You want to cancell the group hug, then?

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


"Tony Miklos" wrote in message
...
On 4/10/2011 5:07 PM, Stormin Mormon wrote:
Excuse me while I slip into my cast iron underwear. I feel
a
bit in jeopardy. Sounds like that dude be going after the
wrong meat.


No, I don't swing that direction.

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)
he

http://www.flickr.com/photos/bbqboye...7626457562742/

http://www.trane.com/webcache/un/fur...7_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.p...&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/Dk...dll?Cat=131081

Jeff

On 4/10/2011 9:19 PM, Stormin Mormon wrote:
You want to cancell the group hug, then?


Oh, I get it now! You didn't notice I was being sarcastic!

On Sat, 09 Apr 2011 18:33:34 -0700, David Nebenzahl
wrote:

On 4/9/2011 6:28 PM spake thus:

On Sat, 09 Apr 2011 16:57:57 -0500, The Daring Dufas
wrote:

On 4/9/2011 1:13 PM, Stormin Mormon wrote:

Agree, sounds like electrical problem, and the OP isn't quite
skilled enough to find it.

I just saw it in the picture and posted what the problem is. I
would have seen it immediately if I was hands on. Look at the wire
colors on the transformer especially the YELLOW, it is taking the
place of the RED wire for low voltage. Notice the yellow and blue
are on one side of the transformer. I don't know why I didn't
notice it before. ^_^

You are sure that's the problem??
There are NO STANDARDS when it comes to transformer wiring colours
(outside of the radio/communications industry, and even there, the
beauty of standards is there are so many to choose from)

Ain't that the truth!

He needs to go by the wiring diagram that came with the transformer,
and VERIFY IT WITH A VOLTMETER.

Which he has already done, if you'd bothered to read all his postings.
I read them. I understood them. I was just replying to the notion
that he had connected the transformer wrong, based on wire colours.

NEVER ASSume anything - check the instructions, follow the
instructions, and verify the results. Particularly with today's supply
chain issues you NEVER ASSume something is what it says it is. Quality
control is not anything close to what it was in, say, the seventies,
and evenTHEN, it was not unheard of to have wrong documentation, or
improperly assembled product (but not nearly as common)

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)
he

http://www.flickr.com/photos/bbqboye...7626457562742/

http://www.trane.com/webcache/un/fur...7_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.p...&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.

On 4/10/2011 7:30 PM spake thus:

On Sat, 09 Apr 2011 18:33:34 -0700, David Nebenzahl
wrote:

On 4/9/2011 6:28 PM spake thus:

He needs to go by the wiring diagram that came with the
transformer, and VERIFY IT WITH A VOLTMETER.

Which he has already done, if you'd bothered to read all his
postings.

I read them. I understood them. I was just replying to the notion
that he had connected the transformer wrong, based on wire colours.

NEVER ASSume anything - check the instructions, follow the
instructions, and verify the results. Particularly with today's supply
chain issues you NEVER ASSume something is what it says it is.

True that.

One thing nobody's yet explained about this whole puzzle is why there's
an extra set of leads from the transformer (as shown in the O.P.'s
pictures) that aren't being used. What's that all about?


--
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*?)

"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.p...&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/Dk...me=399-5466-ND


What planet do you come from ??



..... Phil

"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