A couple of months ago the heater quit coming on in my upstairs Trane XB80 HVAC
unit. It's been off warranty for about 2 years, and I am enough of a
do-it-yourselfer that I'm comfortable with simple repairs. I found that the
LED on the control board was not lighting up, and subsequently found that I was
not getting 24V output from the 115V-24V transformer. Sure enough, the 24V
circuit was open, so I found a local replacement transformer (not the exact
form factor, but same specs) and things worked fine after I replaced it. Now,
I have the very same problem (only this time it's the A/C that's trying to come
on; not that it matters), and once again 24V is missing on the output side of
the transformer. This time the 24V circuit has continuity, but the 115V
circuit is open. Of course, I can replace the transformer AGAIN, but I'd sure
like to know what could be causing this problem... Any ideas would be
appreciated. Thanks.

On 4/2/2011 2:10 PM, Steve Turner wrote:
A couple of months ago the heater quit coming on in my upstairs Trane
XB80 HVAC unit. It's been off warranty for about 2 years, and I am
enough of a do-it-yourselfer that I'm comfortable with simple repairs. I
found that the LED on the control board was not lighting up, and
subsequently found that I was not getting 24V output from the 115V-24V
transformer. Sure enough, the 24V circuit was open, so I found a local
replacement transformer (not the exact form factor, but same specs) and
things worked fine after I replaced it. Now, I have the very same
problem (only this time it's the A/C that's trying to come on; not that
it matters), and once again 24V is missing on the output side of the
transformer. This time the 24V circuit has continuity, but the 115V
circuit is open. Of course, I can replace the transformer AGAIN, but I'd
sure like to know what could be causing this problem... Any ideas would
be appreciated. Thanks.

Cheap transformers comes to mind???

Had other indications of transients? Any chance there's something on
the load side that's drawing excess current?

--

On 4/2/2011 3:23 PM, dpb wrote:
On 4/2/2011 2:10 PM, Steve Turner wrote:
A couple of months ago the heater quit coming on in my upstairs Trane
XB80 HVAC unit. It's been off warranty for about 2 years, and I am
enough of a do-it-yourselfer that I'm comfortable with simple repairs. I
found that the LED on the control board was not lighting up, and
subsequently found that I was not getting 24V output from the 115V-24V
transformer. Sure enough, the 24V circuit was open, so I found a local
replacement transformer (not the exact form factor, but same specs) and
things worked fine after I replaced it. Now, I have the very same
problem (only this time it's the A/C that's trying to come on; not that
it matters), and once again 24V is missing on the output side of the
transformer. This time the 24V circuit has continuity, but the 115V
circuit is open. Of course, I can replace the transformer AGAIN, but I'd
sure like to know what could be causing this problem... Any ideas would
be appreciated. Thanks.

Cheap transformers comes to mind???

That is what I think also. Google yields a slew of hits for 24 Trane
xformers.

Transformers can short inside (winding to winding) and they will wind up
smelling burnt. That may burn one of the leads leading in. The fact that
you have one with a primary failure, and another with a secondary leads
to thinking they are designed at the margin.

Someone that knows Trane might come along and offer an opinion. I
rarely saw opened transformers, and when I did it was on the input side.
Sometimes they put in fusible links in lieu of a fuse elsewhere, but
this would be audio gear...

Jeff

On 4/2/2011 3:37 PM, wrote:
On Sat, 02 Apr 2011 14:10:01 -0500, Steve Turner
wrote:

A couple of months ago the heater quit coming on in my upstairs Trane XB80 HVAC
unit. It's been off warranty for about 2 years, and I am enough of a
do-it-yourselfer that I'm comfortable with simple repairs. I found that the
LED on the control board was not lighting up, and subsequently found that I was
not getting 24V output from the 115V-24V transformer. Sure enough, the 24V
circuit was open, so I found a local replacement transformer (not the exact
form factor, but same specs) and things worked fine after I replaced it. Now,
I have the very same problem (only this time it's the A/C that's trying to come
on; not that it matters), and once again 24V is missing on the output side of
the transformer. This time the 24V circuit has continuity, but the 115V
circuit is open. Of course, I can replace the transformer AGAIN, but I'd sure
like to know what could be causing this problem... Any ideas would be
appreciated. Thanks.

You didn;t say how long the original one lasted. It could be that the
replacement was not strong enough. Ratings are not always everything,
they may mean PEAK output, which is only for short periods of time.
Besides that, they're likely something made in China or some other
foreign country and are cheaply made. If the original lasted for
years, try to get another one of them. Otherwise find a replacement
with a higher amperage. They're more durable.

Of course check your AC input (line) voltage. You may have a loose
connection on a neutral causing higher than normal voltages. And of
course lighting can cause surges to destroy things like this too.

The original lasted about 6 years. It was made in Mexico by Basler (model
BE25214009 class 2 XFMR; it also has C340041P04 printed on it). The primary
leg says "115V 60HZ 115V", and the secondary says "24V 35VA 24V". I can't seem
to find a replacement for it online anywhere.

The replacement was indeed made in China. It's an Edwards model 599:

http://www.edwards-signals.com/index...d=104&level=15

Perhaps (as you say) it's just cheaply made an not up to the task, and its
subsequent failure has nothing to do with the failure of the first.

Any suggestions on what to do about securing a replacement? When the first one
failed I made quite a few calls to local electrical supply houses with no luck
(and I live in Austin; it shouldn't be hard to find a suitable replacement)
before I found this Edwards transformer. We were having a hard freeze at the
time and I was just happy to find something I thought would work. This time
I'd rather be sure I get something that's up to the task.

Thanks for the help.

In article ,
Steve Turner wrote:

The replacement was indeed made in China. It's an Edwards model 599:

http://www.edwards-signals.com/index...d=104&level=15

I dunno what this means:

"Non-regenerative thermal overload protection"

but it *could* mean that the transformer has a thermal fuse. If so, it's
an easy and dirt cheap fix.

On Sat, 02 Apr 2011 14:10:01 -0500, Steve Turner
wrote:

A couple of months ago the heater quit coming on in my upstairs Trane XB80 HVAC
unit. It's been off warranty for about 2 years, and I am enough of a
do-it-yourselfer that I'm comfortable with simple repairs. I found that the
LED on the control board was not lighting up, and subsequently found that I was
not getting 24V output from the 115V-24V transformer. Sure enough, the 24V
circuit was open, so I found a local replacement transformer (not the exact
form factor, but same specs) and things worked fine after I replaced it. Now,
I have the very same problem (only this time it's the A/C that's trying to come
on; not that it matters), and once again 24V is missing on the output side of
the transformer. This time the 24V circuit has continuity, but the 115V
circuit is open. Of course, I can replace the transformer AGAIN, but I'd sure
like to know what could be causing this problem... Any ideas would be
appreciated. Thanks.
Chinese made transformers, in all likelihood. Crap quality, at any
rate. Try using one that is rated 50% to 100% higher than the original
and has a brand name on it

On Sat, 02 Apr 2011 15:03:52 -0500, Steve Turner
wrote:

On 4/2/2011 3:37 PM, wrote:
On Sat, 02 Apr 2011 14:10:01 -0500, Steve Turner
wrote:

A couple of months ago the heater quit coming on in my upstairs Trane XB80 HVAC
unit. It's been off warranty for about 2 years, and I am enough of a
do-it-yourselfer that I'm comfortable with simple repairs. I found that the
LED on the control board was not lighting up, and subsequently found that I was
not getting 24V output from the 115V-24V transformer. Sure enough, the 24V
circuit was open, so I found a local replacement transformer (not the exact
form factor, but same specs) and things worked fine after I replaced it. Now,
I have the very same problem (only this time it's the A/C that's trying to come
on; not that it matters), and once again 24V is missing on the output side of
the transformer. This time the 24V circuit has continuity, but the 115V
circuit is open. Of course, I can replace the transformer AGAIN, but I'd sure
like to know what could be causing this problem... Any ideas would be
appreciated. Thanks.

You didn;t say how long the original one lasted. It could be that the
replacement was not strong enough. Ratings are not always everything,
they may mean PEAK output, which is only for short periods of time.
Besides that, they're likely something made in China or some other
foreign country and are cheaply made. If the original lasted for
years, try to get another one of them. Otherwise find a replacement
with a higher amperage. They're more durable.

Of course check your AC input (line) voltage. You may have a loose
connection on a neutral causing higher than normal voltages. And of
course lighting can cause surges to destroy things like this too.

The original lasted about 6 years. It was made in Mexico by Basler (model
BE25214009 class 2 XFMR; it also has C340041P04 printed on it). The primary
leg says "115V 60HZ 115V", and the secondary says "24V 35VA 24V". I can't seem
to find a replacement for it online anywhere.

The replacement was indeed made in China. It's an Edwards model 599:

http://www.edwards-signals.com/index...d=104&level=15

Perhaps (as you say) it's just cheaply made an not up to the task, and its
subsequent failure has nothing to do with the failure of the first.

Any suggestions on what to do about securing a replacement? When the first one
failed I made quite a few calls to local electrical supply houses with no luck
(and I live in Austin; it shouldn't be hard to find a suitable replacement)
before I found this Edwards transformer. We were having a hard freeze at the
time and I was just happy to find something I thought would work. This time
I'd rather be sure I get something that's up to the task.

Thanks for the help.


Get yourself an industrial grade control transformer, like a triad
f107z or f108u available from Newark for about $19 or $34
respectively. The 107 is 48va, the 108 is 96. Personally I'd go for
the 108 because of it's form factor and it has leads, not solder
terminals.

A Hammond166l24 fir about $25 or a 166N24 for about $36 might be even
better (simpler connections) from the same source

What you do NOT want is another "home depot" bell or thermostat
transformer.

On Apr 2, 12:10*pm, Steve Turner
wrote:
A couple of months ago the heater quit coming on in my upstairs Trane XB80 HVAC
unit. *It's been off warranty for about 2 years, and I am enough of a
do-it-yourselfer that I'm comfortable with simple repairs. *I found that the
LED on the control board was not lighting up, and subsequently found that I was
not getting 24V output from the 115V-24V transformer. *Sure enough, the 24V
circuit was open, so I found a local replacement transformer (not the exact
form factor, but same specs) and things worked fine after I replaced it. *Now,
I have the very same problem (only this time it's the A/C that's trying to come
on; not that it matters), and once again 24V is missing on the output side of
the transformer. *This time the 24V circuit has continuity, but the 115V
circuit is open. *Of course, I can replace the transformer AGAIN, but I'd sure
like to know what could be causing this problem... *Any ideas would be
appreciated. *Thanks.

Per other post...

And of
course lighting can cause surges to destroy things like this too.

the problem may be on the supply side rather than the load side.

I would suggest a surge protector of some sort on the supply side.

and as others have suggested, a better / continuos duty higher rating
transformer from Newark.

cheers
Bob

"Steve Turner" wrote in message
...
On 4/2/2011 3:37 PM, wrote:
On Sat, 02 Apr 2011 14:10:01 -0500, Steve Turner
wrote:
The original lasted about 6 years. It was made in Mexico by Basler (model
BE25214009 class 2 XFMR; it also has C340041P04 printed on it). The
primary leg says "115V 60HZ 115V", and the secondary says "24V 35VA 24V".
I can't seem to find a replacement for it online anywhere.

The replacement was indeed made in China. It's an Edwards model 599:

http://www.edwards-signals.com/index...d=104&level=15

Perhaps (as you say) it's just cheaply made an not up to the task, and its
subsequent failure has nothing to do with the failure of the first.

Any suggestions on what to do about securing a replacement? When the
first one failed I made quite a few calls to local electrical supply
houses with no luck (and I live in Austin; it shouldn't be hard to find a
suitable replacement) before I found this Edwards transformer. We were
having a hard freeze at the time and I was just happy to find something I
thought would work. This time I'd rather be sure I get something that's
up to the task.


What you got seems to be for door bells. That is for a short on time. The
control board needs one rated for continious duty. You should be able to
just ask for a transformer that is rated for 115 or 120 volts input and 24
volts output. The volt/amp (VA ) rating should be 35. A higher V/A rating
will be ok also. It will just cost more and may be larger in physical size.

There is one on ebay that will work if you don't mind wires insteadof screw
terminals.
Trane Transformer 35806009 TRN-101

It has a 40 VA secondary which should be just slightly higher than needed
and it will run slightly cooler and may last longer than the origional. It
is less than $ 25 including shipping.

I would think there would be a Trane dealer in town that would have
something that would work for you in a large town.

"Smitty Two" wrote in message
news
In article ,
Steve Turner wrote:

The replacement was indeed made in China. It's an Edwards model 599:

http://www.edwards-signals.com/index...d=104&level=15

I dunno what this means:

"Non-regenerative thermal overload protection"

but it *could* mean that the transformer has a thermal fuse. If so, it's
an easy and dirt cheap fix.

Smitty... All the transformers like that type that I have opened have the
thermo fuse underneath the taping over the windings. I carefully get to it
and add a 1 amp fuse in place of it. WW

"WW" wrote in message
. ..

but it *could* mean that the transformer has a thermal fuse. If so, it's
an easy and dirt cheap fix.

Smitty... All the transformers like that type that I have opened have the
thermo fuse underneath the taping over the windings. I carefully get to it
and add a 1 amp fuse in place of it. WW

Why a 1 amp fuse ? If on the 120 volt size, it would be over twice the
needed value and if on the secondary side, it would be too small. Also it
would not be a thermal overload,but a current overload fuse.

On 4/2/2011 3:46 PM, Smitty Two wrote:
In ,
Steve wrote:

The replacement was indeed made in China. It's an Edwards model 599:

http://www.edwards-signals.com/index...d=104&level=15

I dunno what this means:

"Non-regenerative thermal overload protection"

but it *could* mean that the transformer has a thermal fuse. If so, it's
an easy and dirt cheap fix.

Some small transformers have a self resetting thermal circuit breaker.
I assume the Edwards transformer has a one-shot thermal fuse (cheaper).

TDD

In article ,
The Daring Dufas wrote:




I assume the Edwards transformer has a one-shot thermal fuse (cheaper).

TDD

That's what I'm guessing "non-regenerative" means, but I'm not sure.

In article ,
"Ralph Mowery" wrote:

"WW" wrote in message
. ..

but it *could* mean that the transformer has a thermal fuse. If so, it's
an easy and dirt cheap fix.

Smitty... All the transformers like that type that I have opened have the
thermo fuse underneath the taping over the windings. I carefully get to it
and add a 1 amp fuse in place of it. WW

Why a 1 amp fuse ? If on the 120 volt size, it would be over twice the
needed value and if on the secondary side, it would be too small. Also it
would not be a thermal overload,but a current overload fuse.

Yeah, I'd say either bypass it or replace it with a new thermal fuse.
Putting a current fuse in there seems odd.

On 4/2/2011 4:29 PM, wrote:
If you need it fast, call some heating supply companies. Austin being
a large city should have several heating supply stores.

I would have, but having discovered this on a Saturday afternoon everything was
closed.

If you can wait to mailorder it, go to Graingers.
http://www.grainger.com
They have all of that electrical stuff, motors, etc.

Yep, that solution has crossed my mind. There's a Grainger's about 15 miles
away from my house.

If I'm not mistaken, both doorbell and thermostat transformers operate
at 24v. Go to a large hardware store like Ace, and see if they have
anything. If physical mounting is not a big issue, any transformer
with 115vac input and 24vac output should work as long as the current
is the same or higher. You need 35va, I'd find one with the highest
(VA) rating as possible. Just make sure the in/out are the same
voltage.
By the way, 35va is pretty flimsy, and made in China means it's as
minimal as possible on the specs.

One other thing, have you contacted the Trane Company?
http://www.trane.com
Maybe they can use next day shipping (of course that is pricey).

You're having a HARD FREEZE in Texas right now? Geezzzz, I'd think it
would be 80 deg or higher now.....

No, the hard freeze was a few months back when the first transformer failed.
This time it's the air conditioner I want to run but cannot...

Thanks for the advice.

On Sat, 02 Apr 2011 13:46:05 -0700, Smitty Two
wrote:

In article ,
Steve Turner wrote:

The replacement was indeed made in China. It's an Edwards model 599:

http://www.edwards-signals.com/index...d=104&level=15

I dunno what this means:

"Non-regenerative thermal overload protection"

but it *could* mean that the transformer has a thermal fuse. If so, it's
an easy and dirt cheap fix.
but it also means the dang thing overheated.

On 4/2/2011 9:07 PM, Smitty Two wrote:
In articleTt6dnVBo95UBNwrQnZ2dnUVZ_qWdnZ2d@earthlink .com,
"Ralph wrote:

wrote in message
. ..

but it *could* mean that the transformer has a thermal fuse. If so, it's
an easy and dirt cheap fix.

Smitty... All the transformers like that type that I have opened have the
thermo fuse underneath the taping over the windings. I carefully get to it
and add a 1 amp fuse in place of it. WW

Why a 1 amp fuse ? If on the 120 volt size, it would be over twice the
needed value and if on the secondary side, it would be too small. Also it
would not be a thermal overload,but a current overload fuse.

Yeah, I'd say either bypass it or replace it with a new thermal fuse.
Putting a current fuse in there seems odd.

I just popped the covers on both transformers. There is no evidence of a fuse
in either one.

I made a mistake in my original description. I just metered the old
transformer and it's the input side that's bad, not the 24V output side as I
originally claimed. So the 115V input side is open on both the original and
replacement transformers, and the 24V sides are fine. I think that rules out
any load issues on the output side.

I must say, you guys have been very helpful! I've been a Usenet guy since the
mid nineties, but this is the first time I've had the occasion to drop in on
a.h.r and seek advice, and I'm glad I did. Thanks for all the advice.

In article ,
Steve Turner wrote:



I just popped the covers on both transformers. There is no evidence of a
fuse
in either one.

I just metered the old
transformer and it's the input side that's bad

The thermal fuse is *under* the tape or paper wrapping. Rip it off and
look. I'd say it's quite likely that you can fix both those transformers
for a few dollars.

In article ,
wrote:

On Sat, 02 Apr 2011 13:46:05 -0700, Smitty Two
wrote:

In article ,
Steve Turner wrote:

The replacement was indeed made in China. It's an Edwards model 599:

http://www.edwards-signals.com/index...d=104&level=15

I dunno what this means:

"Non-regenerative thermal overload protection"

but it *could* mean that the transformer has a thermal fuse. If so, it's
an easy and dirt cheap fix.
but it also means the dang thing overheated.

Nah, it just means the fuse blew from age, thermal cycling, and
vibration.

On 4/2/2011 9:49 PM, Steve Turner wrote:
On 4/2/2011 9:07 PM, Smitty Two wrote:
In articleTt6dnVBo95UBNwrQnZ2dnUVZ_qWdnZ2d@earthlink .com,
"Ralph wrote:

wrote in message
. ..

but it *could* mean that the transformer has a thermal fuse. If so,
it's
an easy and dirt cheap fix.

Smitty... All the transformers like that type that I have opened
have the
thermo fuse underneath the taping over the windings. I carefully get
to it
and add a 1 amp fuse in place of it. WW

Why a 1 amp fuse ? If on the 120 volt size, it would be over twice the
needed value and if on the secondary side, it would be too small.
Also it
would not be a thermal overload,but a current overload fuse.

Yeah, I'd say either bypass it or replace it with a new thermal fuse.
Putting a current fuse in there seems odd.

I just popped the covers on both transformers. There is no evidence of a
fuse in either one.

I made a mistake in my original description. I just metered the old
transformer and it's the input side that's bad, not the 24V output side
as I originally claimed. So the 115V input side is open on both the
original and replacement transformers, and the 24V sides are fine. I
think that rules out any load issues on the output side.

I must say, you guys have been very helpful! I've been a Usenet guy
since the mid nineties, but this is the first time I've had the occasion
to drop in on a.h.r and seek advice, and I'm glad I did. Thanks for all
the advice.

The fuses and/or breakers are always installed on the primaries of the
small transformers. The HVAC supply houses sell an external circuit
breaker used for testing systems so you don't have to keep replacing
transformers when servicing a system. :-)

TDD

On 4/2/2011 2:10 PM, Steve Turner wrote:
A couple of months ago the heater quit coming on in my upstairs Trane
XB80 HVAC unit. It's been off warranty for about 2 years, and I am
enough of a do-it-yourselfer that I'm comfortable with simple repairs. I
found that the LED on the control board was not lighting up, and
subsequently found that I was not getting 24V output from the 115V-24V
transformer. Sure enough, the 24V circuit was open, so I found a local
replacement transformer (not the exact form factor, but same specs) and
things worked fine after I replaced it. Now, I have the very same
problem (only this time it's the A/C that's trying to come on; not that
it matters), and once again 24V is missing on the output side of the
transformer. This time the 24V circuit has continuity, but the 115V
circuit is open. Of course, I can replace the transformer AGAIN, but I'd
sure like to know what could be causing this problem... Any ideas would
be appreciated. Thanks.

A few years ago mine went and I happened to have a little radio shack
transformer hanging around. I wanted heat right away so I installed it
(not using the center tap). Still works. Not rated for watt I'm using
it for but I've never seen a fused or non-fused transformer start a fire
so I sleep well. I did fuse it though I forget the value.

On Apr 2, 3:45*pm, "A. Baum" wrote:
On Sat, 02 Apr 2011 14:10:01 -0500, Steve Turner wrote:
A couple of months ago the heater quit coming on in my upstairs Trane
XB80 HVAC unit. *It's been off warranty for about 2 years, and I am
enough of a do-it-yourselfer that I'm comfortable with simple repairs.
I found that the LED on the control board was not lighting up, and
subsequently found that I was not getting 24V output from the 115V-24V
transformer. *Sure enough, the 24V circuit was open, so I found a local
replacement transformer (not the exact form factor, but same specs) and
things worked fine after I replaced it. *Now, I have the very same
problem (only this time it's the A/C that's trying to come on; not that
it matters), and once again 24V is missing on the output side of the
transformer. *This time the 24V circuit has continuity, but the 115V
circuit is open. *Of course, I can replace the transformer AGAIN, but
I'd sure like to know what could be causing this problem... *Any ideas
would be appreciated. *Thanks.

Probably should measure the power consumption and see if it is in or out
of spec with the transformer if you can find the specs. If it's in watts
the formula is volts x amps. 24 volts x 500 miliamps = 12 watts and so
forth. If the draw is higher than the specs of the transformer then
something on the 24 volt circuit is drawing too much current. You might
be able to spec the transformer by calling Trane.

We have a winner folks. My vote for the best answer. Instead of
speculating
on transformers, I'd put an amp meter on the transformer and find out
what
the load really is. It's not going to do any good changing
transformers if there
is a failing component somewhere else that is drawing a large
current.. Or
if the load side has been overloaded by wiring something else into it
that
should not be.

On Apr 2, 5:39*pm, DD_BobK wrote:
On Apr 2, 12:10*pm, Steve Turner
wrote:

A couple of months ago the heater quit coming on in my upstairs Trane XB80 HVAC
unit. *It's been off warranty for about 2 years, and I am enough of a
do-it-yourselfer that I'm comfortable with simple repairs. *I found that the
LED on the control board was not lighting up, and subsequently found that I was
not getting 24V output from the 115V-24V transformer. *Sure enough, the 24V
circuit was open, so I found a local replacement transformer (not the exact
form factor, but same specs) and things worked fine after I replaced it.. *Now,
I have the very same problem (only this time it's the A/C that's trying to come
on; not that it matters), and once again 24V is missing on the output side of
the transformer. *This time the 24V circuit has continuity, but the 115V
circuit is open. *Of course, I can replace the transformer AGAIN, but I'd sure
like to know what could be causing this problem... *Any ideas would be
appreciated. *Thanks.

Per other post...

And of

course lighting can cause surges to destroy things like this too. *

the problem may be on the supply side rather than the load side.

I would suggest a surge protector of some sort on the supply side.

and as others have suggested, *a better / continuos duty higher rating
transformer from Newark.

cheers
Bob

It would be pretty unusual for lightning to keep destroying the same
single
transformer in an HVAC unit without also detroying other things like
the
electronics board in the same furnace, or other appliances, eqpt, etc
in
the house. I've seen heard of lots of stuff inside a house getting
hit
by a surge, but never just a transformer, which should be among the
most surge immune devices, for a variety of physics based reasons.

On 4/2/2011 11:49 PM, Smitty Two wrote:
In ,
Steve wrote:



I just popped the covers on both transformers. There is no evidence of a
fuse
in either one.

I just metered the old
transformer and it's the input side that's bad

The thermal fuse is *under* the tape or paper wrapping. Rip it off and
look. I'd say it's quite likely that you can fix both those transformers
for a few dollars.

Yes. Or it may just be a bit of thinner wire, that is what I used to
see. But you have to do some cutting to get to it.

I can't speak to recent generation transformers, I haven't fixed one
in 10 years, but I used to "fix" quite a few and never had subsequent
problems. When you fix audio gear the customer often is bent on trying
to destroy it again!

Jeff

The Daring Dufas wrote:
On 4/2/2011 3:46 PM, Smitty Two wrote:
In ,
Steve wrote:

The replacement was indeed made in China. It's an Edwards model
599: http://www.edwards-signals.com/index...d=104&level=15

I dunno what this means:

"Non-regenerative thermal overload protection"

but it *could* mean that the transformer has a thermal fuse. If so,
it's an easy and dirt cheap fix.

Some small transformers have a self resetting thermal circuit breaker.
I assume the Edwards transformer has a one-shot thermal fuse
(cheaper).

I've gotten replacements at radio shack on one occasion, although their chioces
are limited.

On 4/3/2011 8:18 AM, wrote:
On Apr 2, 3:45 pm, "A. wrote:
On Sat, 02 Apr 2011 14:10:01 -0500, Steve Turner wrote:
A couple of months ago the heater quit coming on in my upstairs Trane
XB80 HVAC unit. It's been off warranty for about 2 years, and I am
enough of a do-it-yourselfer that I'm comfortable with simple repairs.
I found that the LED on the control board was not lighting up, and
subsequently found that I was not getting 24V output from the 115V-24V
transformer. Sure enough, the 24V circuit was open, so I found a local
replacement transformer (not the exact form factor, but same specs) and
things worked fine after I replaced it. Now, I have the very same
problem (only this time it's the A/C that's trying to come on; not that
it matters), and once again 24V is missing on the output side of the
transformer. This time the 24V circuit has continuity, but the 115V
circuit is open. Of course, I can replace the transformer AGAIN, but
I'd sure like to know what could be causing this problem... Any ideas
would be appreciated. Thanks.

Probably should measure the power consumption and see if it is in or out
of spec with the transformer if you can find the specs. If it's in watts
the formula is volts x amps. 24 volts x 500 miliamps = 12 watts and so
forth. If the draw is higher than the specs of the transformer then
something on the 24 volt circuit is drawing too much current. You might
be able to spec the transformer by calling Trane.

We have a winner folks. My vote for the best answer. Instead of
speculating
on transformers, I'd put an amp meter on the transformer and find out
what
the load really is. It's not going to do any good changing
transformers if there
is a failing component somewhere else that is drawing a large
current.. Or
if the load side has been overloaded by wiring something else into it
that
should not be.

You do know that the common lead (often blue colored) for the 24volts is
usually grounded to the metal cabinet of the air handler. A bit of
insulation skinned off a thermostat wire could cause a short circuit
when the bare copper comes in contact with the air handler cabinet.

TDD

On 4/3/2011 11:29 AM, Bob F wrote:
The Daring Dufas wrote:
On 4/2/2011 3:46 PM, Smitty Two wrote:
In ,
Steve wrote:

The replacement was indeed made in China. It's an Edwards model
599: http://www.edwards-signals.com/index...d=104&level=15

I dunno what this means:

"Non-regenerative thermal overload protection"

but it *could* mean that the transformer has a thermal fuse. If so,
it's an easy and dirt cheap fix.

Some small transformers have a self resetting thermal circuit breaker.
I assume the Edwards transformer has a one-shot thermal fuse
(cheaper).

I've gotten replacements at radio shack on one occasion, although their chioces
are limited.



I used to purchase the little glass capsule automatic circuit breakers
from the electronic supply house under the ECG brand name. I loved those
big old ECG and SK parts books. ^_^

TDD

On Sat, 02 Apr 2011 20:50:41 -0700, Smitty Two
wrote:

In article ,
wrote:

On Sat, 02 Apr 2011 13:46:05 -0700, Smitty Two
wrote:

In article ,
Steve Turner wrote:

The replacement was indeed made in China. It's an Edwards model 599:

http://www.edwards-signals.com/index...d=104&level=15

I dunno what this means:

"Non-regenerative thermal overload protection"

but it *could* mean that the transformer has a thermal fuse. If so, it's
an easy and dirt cheap fix.
but it also means the dang thing overheated.

Nah, it just means the fuse blew from age, thermal cycling, and
vibration.
In 18 months? If so it was crap to start with.

In article ,
wrote:

On Sat, 02 Apr 2011 20:50:41 -0700, Smitty Two
wrote:

In article ,
wrote:

On Sat, 02 Apr 2011 13:46:05 -0700, Smitty Two
wrote:

In article ,
Steve Turner wrote:

The replacement was indeed made in China. It's an Edwards model 599:

http://www.edwards-signals.com/index...d=104&level=15

I dunno what this means:

"Non-regenerative thermal overload protection"

but it *could* mean that the transformer has a thermal fuse. If so, it's
an easy and dirt cheap fix.
but it also means the dang thing overheated.

Nah, it just means the fuse blew from age, thermal cycling, and
vibration.
In 18 months? If so it was crap to start with.

I'll give you that. But OP has now stated that the OEM part was primary
open as well, and that one lasted 6 years.

On 4/3/2011 3:19 PM, Smitty Two wrote:
In ,
wrote:

On Sat, 02 Apr 2011 20:50:41 -0700, Smitty Two
wrote:

In ,
wrote:

On Sat, 02 Apr 2011 13:46:05 -0700, Smitty Two
wrote:

In ,
Steve wrote:

The replacement was indeed made in China. It's an Edwards model 599:

http://www.edwards-signals.com/index...d=104&level=15

I dunno what this means:

"Non-regenerative thermal overload protection"

but it *could* mean that the transformer has a thermal fuse. If so, it's
an easy and dirt cheap fix.
but it also means the dang thing overheated.

Nah, it just means the fuse blew from age, thermal cycling, and
vibration.
In 18 months? If so it was crap to start with.

I'll give you that. But OP has now stated that the OEM part was primary
open as well, and that one lasted 6 years.

Correct. The replacement (which had a power rating of 40VA, whereas the
original was only 35VA) only lasted two months.

I've seen as high as 75 VA, might last longer.

Of course, the trasnformer might be a symptom of some other
problem.

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


"Steve Turner"
wrote in message ...


I'll give you that. But OP has now stated that the OEM
part was primary
open as well, and that one lasted 6 years.

Correct. The replacement (which had a power rating of 40VA,
whereas the
original was only 35VA) only lasted two months.

It blows because something is drawing too much current.

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


"Steve Turner" wrote in
message ...
A couple of months ago the heater quit coming on in my
upstairs Trane XB80 HVAC
unit. It's been off warranty for about 2 years, and I am
enough of a
do-it-yourselfer that I'm comfortable with simple repairs.
I found that the
LED on the control board was not lighting up, and
subsequently found that I was
not getting 24V output from the 115V-24V transformer. Sure
enough, the 24V
circuit was open, so I found a local replacement transformer
(not the exact
form factor, but same specs) and things worked fine after I
replaced it. Now,
I have the very same problem (only this time it's the A/C
that's trying to come
on; not that it matters), and once again 24V is missing on
the output side of
the transformer. This time the 24V circuit has continuity,
but the 115V
circuit is open. Of course, I can replace the transformer
AGAIN, but I'd sure
like to know what could be causing this problem... Any
ideas would be
appreciated. Thanks.

On 4/3/2011 10:48 AM, Jeff Thies wrote:
On 4/2/2011 11:49 PM, Smitty Two wrote:
In ,
Steve wrote:



I just popped the covers on both transformers. There is no evidence of a
fuse
in either one.

I just metered the old
transformer and it's the input side that's bad

The thermal fuse is *under* the tape or paper wrapping. Rip it off and
look. I'd say it's quite likely that you can fix both those transformers
for a few dollars.

Yes. Or it may just be a bit of thinner wire, that is what I used to
see. But you have to do some cutting to get to it.

I can't speak to recent generation transformers, I haven't fixed one in
10 years, but I used to "fix" quite a few and never had subsequent
problems. When you fix audio gear the customer often is bent on trying
to destroy it again!

Since the replacement part is readily available, and in an upgrade for
not much, just replace it. In my case, the transformers were hard to
come by.

The parts that may draw power are not likely to be a little damage,
they will either be blown or not. This will either work or not.
Switching supplies lead to such nebulous territory, and it is doubtful
this has any. Telltale signs for those are puffy tops of capacitors. You
can check transistors and diodes for shorts easily.

It's also doubtful this is surge related.

BTW, transformers are really rated in VA (volt amps), not watts.

Jeff


Jeff

On 4/4/2011 9:19 AM, Stormin Mormon wrote:
It blows because something is drawing too much current.

Probably not. More likely it just gave up as it was designed too near
the margins.

Jeff

On 4/2/2011 3:28 PM, wrote:
On Sat, 02 Apr 2011 15:03:52 -0500, Steve Turner
wrote:

On 4/2/2011 3:37 PM, wrote:
On Sat, 02 Apr 2011 14:10:01 -0500, Steve Turner
wrote:

A couple of months ago the heater quit coming on in my upstairs Trane XB80 HVAC
unit. It's been off warranty for about 2 years, and I am enough of a
do-it-yourselfer that I'm comfortable with simple repairs. I found that the
LED on the control board was not lighting up, and subsequently found that I was
not getting 24V output from the 115V-24V transformer. Sure enough, the 24V
circuit was open, so I found a local replacement transformer (not the exact
form factor, but same specs) and things worked fine after I replaced it. Now,
I have the very same problem (only this time it's the A/C that's trying to come
on; not that it matters), and once again 24V is missing on the output side of
the transformer. This time the 24V circuit has continuity, but the 115V
circuit is open. Of course, I can replace the transformer AGAIN, but I'd sure
like to know what could be causing this problem... Any ideas would be
appreciated. Thanks.

You didn;t say how long the original one lasted. It could be that the
replacement was not strong enough. Ratings are not always everything,
they may mean PEAK output, which is only for short periods of time.
Besides that, they're likely something made in China or some other
foreign country and are cheaply made. If the original lasted for
years, try to get another one of them. Otherwise find a replacement
with a higher amperage. They're more durable.

Of course check your AC input (line) voltage. You may have a loose
connection on a neutral causing higher than normal voltages. And of
course lighting can cause surges to destroy things like this too.

The original lasted about 6 years. It was made in Mexico by Basler (model
BE25214009 class 2 XFMR; it also has C340041P04 printed on it). The primary
leg says "115V 60HZ 115V", and the secondary says "24V 35VA 24V". I can't seem
to find a replacement for it online anywhere.

The replacement was indeed made in China. It's an Edwards model 599:

http://www.edwards-signals.com/index...d=104&level=15

Perhaps (as you say) it's just cheaply made an not up to the task, and its
subsequent failure has nothing to do with the failure of the first.

Any suggestions on what to do about securing a replacement? When the first one
failed I made quite a few calls to local electrical supply houses with no luck
(and I live in Austin; it shouldn't be hard to find a suitable replacement)
before I found this Edwards transformer. We were having a hard freeze at the
time and I was just happy to find something I thought would work. This time
I'd rather be sure I get something that's up to the task.

Thanks for the help.


Get yourself an industrial grade control transformer, like a triad
f107z or f108u available from Newark for about $19 or $34
respectively. The 107 is 48va, the 108 is 96. Personally I'd go for
the 108 because of it's form factor and it has leads, not solder
terminals.

A Hammond166l24 fir about $25 or a 166N24 for about $36 might be even
better (simpler connections) from the same source

What you do NOT want is another "home depot" bell or thermostat
transformer.

Whatever you use must be "Class 2". That means there is not enough power
available on the secondary to cause a fire. Using a class 2 transformer
allows using light weight thermostat wire instead of power wiring.

Class 2 heating system transformers can be easily installed to be safe,
with primary wiring not exposed - may or may not be true of the
transformers above.

Modifying a class 2 transformer by replacing internal fuses with
external fuses makes the source not class 2. If you knew what you were
doing you could probably protect the secondary with a fuse. I wouldn't.

I agree with looking at the secondary current.

--
bud--

On 4/4/2011 2:57 PM, wrote:
On Mon, 04 Apr 2011 09:50:54 -0400, Jeff
wrote:

On 4/4/2011 9:19 AM, Stormin Mormon wrote:
It blows because something is drawing too much current.

Probably not. More likely it just gave up as it was designed too near
the margins.

Jeff
I think it imay be safe to say something drew too much power for THAT
transformer - however - a primary could fail open even if it NEVER had
a load on the secondary (in which case, for THAT transformer, even NO
load was too much.

Lots of REAL crappy electrical "goods" on the market today.

Just picked up a new White Rodgers model 90-T40F3 (input 120/208/240V, output
24V 40VA) from a local supplier that has a form factor very similar to the
original. White Rodgers also makes the control board into which the 24V feeds,
so hopefully bodes well for it being a proper replacement.

On 4/4/2011 4:22 PM, Steve Turner wrote:
On 4/4/2011 2:57 PM, wrote:
On Mon, 04 Apr 2011 09:50:54 -0400, Jeff
wrote:

On 4/4/2011 9:19 AM, Stormin Mormon wrote:
It blows because something is drawing too much current.

Probably not. More likely it just gave up as it was designed too near
the margins.

Jeff
I think it imay be safe to say something drew too much power for THAT
transformer - however - a primary could fail open even if it NEVER had
a load on the secondary (in which case, for THAT transformer, even NO
load was too much.

Lots of REAL crappy electrical "goods" on the market today.

Just picked up a new White Rodgers model 90-T40F3 (input 120/208/240V,
output 24V 40VA) from a local supplier that has a form factor very
similar to the original. White Rodgers also makes the control board into
which the 24V feeds, so hopefully bodes well for it being a proper
replacement.

Good.

Give a feel after it has run for a while to see how warm it gets, you
may wish to do that with other components also, and an IR thermometer
once over if you have one.

Jeff

Steve Turner wrote:
A couple of months ago the heater quit coming on in my upstairs Trane
XB80 HVAC unit. It's been off warranty for about 2 years, and I am
enough of a do-it-yourselfer that I'm comfortable with simple
repairs. I found that the LED on the control board was not lighting
up, and subsequently found that I was not getting 24V output from the
115V-24V transformer. Sure enough, the 24V circuit was open, so I
found a local replacement transformer (not the exact form factor, but
same specs) and things worked fine after I replaced it. Now, I have
the very same problem (only this time it's the A/C that's trying to
come on; not that it matters), and once again 24V is missing on the
output side of the transformer. This time the 24V circuit has
continuity, but the 115V circuit is open. Of course, I can replace
the transformer AGAIN, but I'd sure like to know what could be
causing this problem... Any ideas would be appreciated. Thanks.

TWO is (probably) a coincidence; THREE would be a trend.

On 4/4/2011 7:33 PM, HeyBub wrote:
Steve Turner wrote:
A couple of months ago the heater quit coming on in my upstairs Trane
XB80 HVAC unit. It's been off warranty for about 2 years, and I am
enough of a do-it-yourselfer that I'm comfortable with simple
repairs. I found that the LED on the control board was not lighting
up, and subsequently found that I was not getting 24V output from the
115V-24V transformer. Sure enough, the 24V circuit was open, so I
found a local replacement transformer (not the exact form factor, but
same specs) and things worked fine after I replaced it. Now, I have
the very same problem (only this time it's the A/C that's trying to
come on; not that it matters), and once again 24V is missing on the
output side of the transformer. This time the 24V circuit has
continuity, but the 115V circuit is open. Of course, I can replace
the transformer AGAIN, but I'd sure like to know what could be
causing this problem... Any ideas would be appreciated. Thanks.

TWO is (probably) a coincidence; THREE would be a trend.


I've heard that in music, if you make a single mistake, it's just a
mistake. Make the same mistake twice, and it's jazz.

Jeff

As the badguy in the Ian Fleming book said to Bond, James
Bond:

"Once is happenstance. Twice is coincidence. Three times is
enemy action."

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


"HeyBub" wrote in message
m...

continuity, but the 115V circuit is open. Of course, I
can replace
the transformer AGAIN, but I'd sure like to know what
could be
causing this problem... Any ideas would be appreciated.
Thanks.

TWO is (probably) a coincidence; THREE would be a trend.