sci.electronics.repair@googlegroups.com

Today's topics:

* Blew another damn transformer on my Trane XB80 - 14 messages, 9 authors
http://groups.google.com/group/sci.electronics.repair/t/f883cd09a3a0b791?hl=en
* LG refrigerator model LBN2251#** problems - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/a8a81578d072145d?hl=en
* Yamaha StagePas300 - 3 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/737699f29c180409?hl=en
* WD 1TB Passport for sale? - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/43b047a7057f596c?hl=en
* (paypal payment)( http://www.24hours-online.com/) cheap wholesale ED hardy
Christan Audigier,LV,BOSS etc. brand caps hat belts and other products free
shipping - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/66520feb60dda7a2?hl=en
* Ampeg BA600 - 115 bass amp combo, 6 months old, ROHS - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/bc6178fc14fcf982?hl=en

==============================================================================
TOPIC: Blew another damn transformer on my Trane XB80
http://groups.google.com/group/sci.electronics.repair/t/f883cd09a3a0b791?hl=en
==============================================================================

== 1 of 14 ==
Date: Wed, Apr 13 2011 3:06 pm
From: clare@snyder.on.ca

On Wed, 13 Apr 2011 04:22:15 -0700 (PDT), "trader4@optonline.net"
<trader4@optonline.net> wrote:

>On Apr 12, 8:49 pm, d...@manx.misty.com (Don Klipstein) wrote:
>> In article <9fOdnZZQwKACfjnQnZ2dnUVZ_rmdn...@giganews.com>, Dave M wrote:
>> >Don Klipstein wrote:
>> >> In article <90j6ugFlu...@mid.individual.net>, Tony Miklos wrote:
>>
>> >>> Yes, the thread got too long.  If you saw the photo, and know the
>> >>> primary went open on 3 transformers, it sure looks like a problem on
>> >>> the primary side.  If the load was too much, those wires on the
>> >>> secondary side would most likely have been at the very least
>> >>> discolored from the heat.
>>
>> >>  This makes me think the most likely causes are:
>>
>> >> *   Improperly connecting the transformer (such as using only 1 of
>> >>  the 2 primaries of a 120/240V dual primary transformer)
>>
>> >> *   DC flowing through the secondary.  That can occur if the tranny's
>> >>  load has a fullwave rectifier with one diode open.  If the fullwave
>> >>  rectifier has discrete diodes or a dual diode, the problem may be a
>> >>  bad solder joint at one of the diodes.
>>
>> >That's not true.  an open rectifier does not allow DC current to flow
>> >through the secondary.  It's just 1/2 of the power line cycle.  During the
>> >opposite half of the cycle, no current flows in the secondary.  True, it's
>> >unidirectional current, but it's an intermittent current, not constant DC.
>> >If your statement were true, then half-wave rectifiers wouldn't be feasible.
>>
>>   A unidirectional pulsing waveform has a DC component.
>>
>>   That analyzes to a sum of DC, fundamental frequency AC, and AC at
>> harmonic frequencies.  The average as averaged over a whole cycle is the
>> DC component.
>>
>>   It is fairly well known that a transformer driving a halfwave rectified
>> load can run into core saturation problems from the DC component in the
>> unidirectionally pulsing current waveform.
>>
>> --
>>  - Don Klipstein (d...@misty.com)- Hide quoted text -
>>
>> - Show quoted text -
>
>Interesting theory. One helpful piece of info which it's quite
>amazing we
>still don't have is what the currents are on both sides of the
>transformer.
> For saturation to occur I would think the transformer would have to
>be close
>to fully loaded. Which it could be, given the trends to lower cost,
>cheaper
>components, etc.

As I posted in an earlier post (not sure what values I used, but I'll
run a scenario anyway), assuming a 2 ohm winding, a 2 volt DC
component will cause 1 AMP of current to flow in the winding. IF that
coil happens to be the primary of a 40va transformer, The full load
current on that transformer is about 350ma, so the probability that 1
amp of current in the primary, with no AC voltage applied, would have
more than saturated the core is pretty good.
Add the quiescent current of the primary, and you have a saturated
core. And that's just a 2 volt DC component on a 115 volt primary.

If the primary is 4 ohms instead of 2, you have half an amp with 2
volts, or 1 amp with 4 volts.

Doesn't take much to put 2 volts DC across a 115 volt line.

See http://sound.westhost.com/articles/xfmr-dc.htm for more
information from someone who may have a bit more credibility than you
guys may give me.

== 2 of 14 ==
Date: Wed, Apr 13 2011 4:22 pm
From: "Stormin Mormon"

So, it's cheaper to put a half wave rectifier in, instead of
a second coil of heater wire? I rather doubt that.

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

<clare@snyder.on.ca> wrote in message
news:h36cq692alhsro2jutb6ovlnnpqth2e767@4ax.com...

what happens if, say, the Mrs plugs her
cheap blow drier into the same circuit as the primary of the
transformer is plugged in to, and she puts the blow drier on
low (it
uses a half wave rectifier to drop the power to the
heater) - and you
end up with a DC component on the primary - which saturates
the
primary without any increase in secondary (load) current or
power.

== 3 of 14 ==
Date: Wed, Apr 13 2011 5:48 pm
From: "Phil Allison"

<clare@snyder.on.ca>

> As I posted in an earlier post (not sure what values I used, but I'll
> run a scenario anyway), assuming a 2 ohm winding, a 2 volt DC
> component will cause 1 AMP of current to flow in the winding. IF that
> coil happens to be the primary of a 40va transformer,

** A 40VA tranny designed for 120 volt 60 Hz operation has a primary
resistance of 16 ohms.

Getting a 2 volt DC offset on a 120 volt AC supply takes some doing.

> Doesn't take much to put 2 volts DC across a 115 volt line.

** Like hell.

For a 2 volt DC offset to exist, the peak voltage in one polarity must be
6.3 volts higher than the other.

With a typical impedance at the outlet of 0.25ohms, this equates to 25 amps
peak load in one polarity and none in the other.

> See http://sound.westhost.com/articles/xfmr-dc.htm for more
> information from someone who may have a bit more credibility than you
> guys may give me.

** I helped Rod write that article.

Toroidal trannys are very sensitive to DC offsets while regular E-core types
are hardly bothered by them - the difference is that while the former has
no air gaps in the core, the latter is full of them.

.... Phil

== 4 of 14 ==
Date: Wed, Apr 13 2011 7:39 pm
From: clare@snyder.on.ca

On Wed, 13 Apr 2011 19:22:37 -0400, "Stormin Mormon"
<cayoung61**spamblock##@hotmail.com> wrote:

>So, it's cheaper to put a half wave rectifier in, instead of
>a second coil of heater wire? I rather doubt that.

I don't remember the details, but I know quite a few DO work that way
- and they also used 12 volt DC blower motors, without a transformer,
by basically using the heater element as a rheostat..

== 5 of 14 ==
Date: Wed, Apr 13 2011 7:45 pm
From: "Phil Allison"

<clare@snyder.on.ca>
"Stormin Mormon"

>
>>So, it's cheaper to put a half wave rectifier in, instead of
>>a second coil of heater wire? I rather doubt that.
>
> I don't remember the details, but I know quite a few DO work that way
> - and they also used 12 volt DC blower motors, without a transformer,
> by basically using the heater element as a rheostat..

** My 1600 watt "Black & Decker" hot air gun is made exactly like that.

.... Phil

== 6 of 14 ==
Date: Wed, Apr 13 2011 8:51 pm
From: John Robertson

Steve Turner wrote:
> On 4/9/2011 7:29 PM, Jim Yanik wrote:
>> "robb"<some@where.on.net> wrote in
>> news:WfKdnQOvu_d2bz3QnZ2dnUVZ_uadnZ2d@earthlink.com:
>>
>>> "Steve Turner" wrote in message news:inoakf$qin$1@dont-email.me...
>>>
>>>> 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) here:
>>>>
>>>> http://www.flickr.com/photos/bbqboyee/sets/72157626457562742/
>>>>
>>>> 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/furnaces%20%28furn%29/product/22-1666-
>>> 07_04012009.pdf
>>>>
>>>> As you can probably see in the pictures, there is visible charring
>>>> of the 115V leads going into the transformer, and of course the 115V
>>>> circuit is open (again). 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.
>

Steve,

Not to be rude or anything, but a LOT of talk has gone on about your
problem and I have not seen any further posts from you on the matter. No
comments about any suggestions at all.

I'm not going to spend any more time on this thread until we hear back
from the original poster with more information otherwise we are simply
blowing smoke (sorry - couldn't resist).

John :-#)#

--
(Please post followups or tech enquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

== 7 of 14 ==
Date: Wed, Apr 13 2011 9:32 pm
From: Steve Turner

On 4/13/2011 10:51 PM, John Robertson wrote:
> Steve Turner wrote:
>> On 4/9/2011 7:29 PM, Jim Yanik wrote:
>>> "robb"<some@where.on.net> wrote in
>>> news:WfKdnQOvu_d2bz3QnZ2dnUVZ_uadnZ2d@earthlink.com:
>>>
>>>> "Steve Turner" wrote in message news:inoakf$qin$1@dont-email.me...
>>>>
>>>>> 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) here:
>>>>>
>>>>> http://www.flickr.com/photos/bbqboyee/sets/72157626457562742/
>>>>>
>>>>> 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/furnaces%20%28furn%29/product/22-1666-
>>>> 07_04012009.pdf
>>>>>
>>>>> As you can probably see in the pictures, there is visible charring
>>>>> of the 115V leads going into the transformer, and of course the 115V
>>>>> circuit is open (again). 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.
>>
>
> Steve,
>
> Not to be rude or anything, but a LOT of talk has gone on about your problem
> and I have not seen any further posts from you on the matter. No comments about
> any suggestions at all.
>
> I'm not going to spend any more time on this thread until we hear back from the
> original poster with more information otherwise we are simply blowing smoke
> (sorry - couldn't resist).
>
> John :-#)#

Just mentioned elsewhere that I have a new transformer on order and I can't
really do anything until that arrives. Rest assured I appreciate all the input
and I'm taking it all into consideration. Thanks.

== 8 of 14 ==
Date: Wed, Apr 13 2011 9:41 pm
From: Vic Smith

On Wed, 13 Apr 2011 23:32:56 -0500, Steve Turner
<bbqboyee@swtacobell.net.invalid> wrote:

>
>Just mentioned elsewhere that I have a new transformer on order and I can't
>really do anything until that arrives. Rest assured I appreciate all the input
>and I'm taking it all into consideration. Thanks.

You bought the fuses, right?
I DON'T want to hear about another blown transformer.

--Vic

== 9 of 14 ==
Date: Wed, Apr 13 2011 9:43 pm
From: don@manx.misty.com (Don Klipstein)

In <4da54b91$0$26215$822641b3@news.adtechcomputers.com>, D Nebenzahl wrote:
>On 4/12/2011 9:23 PM Don Klipstein spake thus:
>
>> I have yet to look at these diagrams, but is the circuit board
>> powered by this tranny shown to "board level" as opposed to "component
>> level"? If so, then the board can have, probably does have, a rectifier
>> not shown in the diagram.
>
>With all the pontificating you've been doing here, Don, I would've
>thought you'd at least had glanced at the wiring diagrams the OP posted,
>way up there somewhere. Sheesh.
>
>The controller is shown as a block. It most certainly has at least one
>rectifier on it, as it contains electronics that no doubt requires DC
>power to operate. Thought you'd have figured it out. (Not just a relay
>board.)

With such indication even as described here giving low indication as
to rectification having a 1-component bridge rectifier, 4 discrete diodes,
a fed-with-center-tap 2-diode fullwave scheme, 2 separate diodes or a
single 3-lead dual-diode used for that...

If the controller is only shown as a block, how well does it show the
rectifier scheme, as in whether the rectifier's diodes are discrete
individual diodes or integrated into one rectifier package?

If anyone here sees that noted to such extent that it's not a waste of
my time to take a look there, please pipe up!
--
- Don Klipstein (don@misty.com)

== 10 of 14 ==
Date: Wed, Apr 13 2011 10:12 pm
From: "Phil Allison"

"Vic Smith"
Steve Turner
>>
>>Just mentioned elsewhere that I have a new transformer on order and I
>>can't
>>really do anything until that arrives. Rest assured I appreciate all the
>>input
>>and I'm taking it all into consideration. Thanks.
>
> You bought the fuses, right?
> I DON'T want to hear about another blown transformer.
>

** Be real smart for the OP to purchase some OTHER 120/24 volt tranny and
use it.

The things are a dime a dozen.

And fit a "slo-blo" 1/4 amp fuse to the primary.

.... Phil

== 11 of 14 ==
Date: Wed, Apr 13 2011 10:19 pm
From: Tony Hwang

Phil Allison wrote:
> "Vic Smith"
> Steve Turner
>>>
>>> Just mentioned elsewhere that I have a new transformer on order and I
>>> can't
>>> really do anything until that arrives. Rest assured I appreciate all the
>>> input
>>> and I'm taking it all into consideration. Thanks.
>>
>> You bought the fuses, right?
>> I DON'T want to hear about another blown transformer.
>>
>
> ** Be real smart for the OP to purchase some OTHER 120/24 volt tranny and
> use it.
>
> The things are a dime a dozen.
>
> And fit a "slo-blo" 1/4 amp fuse to the primary.
>
>
>
> .... Phil
>
> Hmmm,
What is fuse gonna do? Instead of blowing x-former,, blow fuses?
Then still it is not right. Let;s go back from begining. How old
is the system? When this blowing tranny started? From day 1 or some
time(month, years after the system is installed? If tranny is hot to
touch when in use, that is rad flag.

== 12 of 14 ==
Date: Wed, Apr 13 2011 10:41 pm
From: Smitty Two

In article <io5tea$b6u$1@dont-email.me>,
Steve Turner <bbqboyee@swtacobell.net.invalid> wrote:

> Just mentioned elsewhere that I have a new transformer on order and I can't
> really do anything until that arrives.

Sure you could. You could open up those other two transformers and check
for an open thermal fuse. As I recall, you said neither of them failed
in the same manner as the third. I still say you could have 3 distinct,
unrelated failures.

== 13 of 14 ==
Date: Wed, Apr 13 2011 11:09 pm
From: "Phil Allison"

"Tony Hwang"

>> ** Be real smart for the OP to purchase some OTHER 120/24 volt tranny
>> and
>> use it.
>>
>> The things are a dime a dozen.
>>
>> And fit a "slo-blo" 1/4 amp fuse to the primary.
>>
>> What is fuse gonna do?

** Blow immediately if the tranny is overloaded.

> Instead of blowing x-former,, blow fuses?

** This is the usual purpose of fuses.

> Then still it is not right.

** Then you can find the cause of the overload - cos the tranny still
functions.

Fuckwit.

.... Phil

== 14 of 14 ==
Date: Wed, Apr 13 2011 11:10 pm
From: John Robertson

Steve Turner wrote:
> On 4/13/2011 10:51 PM, John Robertson wrote:
>> Steve Turner wrote:
>>> On 4/9/2011 7:29 PM, Jim Yanik wrote:
>>>> "robb"<some@where.on.net> wrote in
>>>> news:WfKdnQOvu_d2bz3QnZ2dnUVZ_uadnZ2d@earthlink.com:
>>>>
>>>>> "Steve Turner" wrote in message news:inoakf$qin$1@dont-email.me...
>>>>>
>>>>>> 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) here:
>>>>>>
>>>>>> http://www.flickr.com/photos/bbqboyee/sets/72157626457562742/
>>>>>>
>>>>>> 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/furnaces%20%28furn%29/product/22-1666-
>>>>>
>>>>> 07_04012009.pdf
>>>>>>
>>>>>> As you can probably see in the pictures, there is visible charring
>>>>>> of the 115V leads going into the transformer, and of course the 115V
>>>>>> circuit is open (again). 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.
>>>
>>
>> Steve,
>>
>> Not to be rude or anything, but a LOT of talk has gone on about your
>> problem
>> and I have not seen any further posts from you on the matter. No
>> comments about
>> any suggestions at all.
>>
>> I'm not going to spend any more time on this thread until we hear back
>> from the
>> original poster with more information otherwise we are simply blowing
>> smoke
>> (sorry - couldn't resist).
>>
>> John :-#)#
>
> Just mentioned elsewhere that I have a new transformer on order and I
> can't really do anything until that arrives. Rest assured I appreciate
> all the input and I'm taking it all into consideration. Thanks.
>

Hi Steve,

Have you tried asking Trane themselves if they have a suggestion as to
the cause of the problem?

http://www.trane.com/Residential/Customer-Care/Feed-Back

Of course they may just send you to your local dealer, but it is worth a
try...

John :-#)#

--
(Please post followups or tech enquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

==============================================================================
TOPIC: LG refrigerator model LBN2251#** problems
http://groups.google.com/group/sci.electronics.repair/t/a8a81578d072145d?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Apr 13 2011 3:17 pm
From: Franc Zabkar

On Sun, 10 Apr 2011 16:42:38 -0700 (PDT), klem kedidelhopper
<captainvideo462009@gmail.com> put finger to keyboard and composed:

FWIW, here are service manuals for LG fridges sold on the Australian
market:
http://www.jordansmanuals.com/Default.aspx?Brand=LG&Product=Fridge&Model=New%20Folder

Exploded diagrams and parts lists for your model series:
http://www.searspartsdirect.com/partsdirect/part-model/LBN2251

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

==============================================================================
TOPIC: Yamaha StagePas300
http://groups.google.com/group/sci.electronics.repair/t/737699f29c180409?hl=en
==============================================================================

== 1 of 3 ==
Date: Wed, Apr 13 2011 3:21 pm
From: Ron

On 13/04/2011 21:20, Gareth Magennis wrote:
>
>
> "Ron" <ron@lunevalleyaudio.com> wrote in message
> news:BKednfpR2PqgbDjQnZ2dnUVZ7sadnZ2d@bt.com...
>> On 13/04/2011 19:16, Gareth Magennis wrote:
>>>
>>>
>>> "Ron" <ron@lunevalleyaudio.com> wrote in message
>>> news:eJGdnZL4h_LfGzjQnZ2dnUVZ8h6dnZ2d@bt.com...
>>>> Yamaha StagePas
>>>>
>>>> Did I read somewhere that it's inadvisable to use metal bodied jacks
>>>> on the amplifier module outputs as the left and right grounds are at
>>>> differing potentials?
>>>>
>>>> Or did I imagine that?
>>>>
>>>> Ron(UK)
>>>
>>>
>>>
>>> Yes, I said that.
>>>
>>>
>>> But particularly metal right angle jacks that are almost bound to end in
>>> disaster.
>>>
>>>
>>> Gareth.
>>
>> Ah thanks Gareth, I checked the circuit diag and yes the two amps are
>> 'out of phase' I`ve been asked a couple of times to make short link
>> cables with right angled jacks for the 'docked' amp to its own
>> speaker. I`ll have to warn customers in future.
>>
>> Ron
>
>
> I don't quite understand how such designs ever make it to production.
>
>
> Gareth.

Probably because they aren't designed by the people who use and abuse
them.

Ron

== 2 of 3 ==
Date: Thurs, Apr 14 2011 12:37 am
From: "N_Cook"

Gareth Magennis <sound.service@btconnect.com> wrote in message
news:PLlpp.3819$Ir.2740@newsfe13.ams2...
>
>
> "Ron" <ron@lunevalleyaudio.com> wrote in message
> news:eJGdnZL4h_LfGzjQnZ2dnUVZ8h6dnZ2d@bt.com...
> > Yamaha StagePas
> >
> > Did I read somewhere that it's inadvisable to use metal bodied jacks on
> > the amplifier module outputs as the left and right grounds are at
> > differing potentials?
> >
> > Or did I imagine that?
> >
> > Ron(UK)
>
>
>
> Yes, I said that.
>
>
> But particularly metal right angle jacks that are almost bound to end in
> disaster.
>
>
> Gareth.
>

Assuming everyone has the eservice schema to hand. Where exactly is the
inverter in one ch of the 300 ? , I can see it in the 500 circuits

== 3 of 3 ==
Date: Thurs, Apr 14 2011 12:49 am
From: "N_Cook"

I've just noticed it written vertically at the amps . I thought the plug in
amps themselves were identical. Taking a closer look one is marked LF
6479e-01
and the other b instead of e, will have to look at the SM as otherwise
physically look the same. Just as well I marked where each came from as I
thiought they were interchangeable. But then as long as an "unmatched" pair
then would it matter which way round, assuming the ERR line worked correctly

==============================================================================
TOPIC: WD 1TB Passport for sale?
http://groups.google.com/group/sci.electronics.repair/t/43b047a7057f596c?hl=en
==============================================================================

== 1 of 2 ==
Date: Wed, Apr 13 2011 4:35 pm
From: Keith

All:
If so, then, please post your email address here so we can talk.

Keith Lee

== 2 of 2 ==
Date: Wed, Apr 13 2011 4:58 pm
From: Franc Zabkar

On Wed, 13 Apr 2011 23:35:50 +0000 (UTC), Keith
<keithdlee2000@gmail.com> put finger to keyboard and composed:

>All:
> If so, then, please post your email address here so we can talk.
>
>Keith Lee

Are you looking to buy one for spare parts? If so, then be aware that
these products have hardware encryption in the Initio INIC-1607E
USB-SATA bridge IC. Furthermore, if this IC is integrated into the
hard drive's PCB, then there will be a further complication, namely
that the 8-pin serial flash memory at location U12 stores unique,
drive specific, "adaptive" information which needs to be transferred
to the donor PCB.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

==============================================================================
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http://groups.google.com/group/sci.electronics.repair/t/66520feb60dda7a2?hl=en
==============================================================================

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==============================================================================
TOPIC: Ampeg BA600 - 115 bass amp combo, 6 months old, ROHS
http://groups.google.com/group/sci.electronics.repair/t/bc6178fc14fcf982?hl=en
==============================================================================

== 1 of 1 ==
Date: Thurs, Apr 14 2011 12:31 am
From: "N_Cook"

Yet another owner forgoing replacement/repair within warranty. I imagine the
importer has no replacements in stock as the whole batch has the same
faults. Perhaps bass guitarists should use pneumatics and proper compressors
to shift air.
Mechanical rattle noise due to brass cylinder spacers used over the control
pot bushes , loose bush nuts, so rattle.
But more importantly
At moderate levels an electronic crackle is the main problem. Remove the
screws in the cab to release the amp and one caged nut falls into the amp
space due to cracked cage. And a nut ( now known) falls out of its cage in
the screened off ps+pa section. The PA although supposedly 600W uses only
TO220 ,(4 x TOP66 in the smps).
Amp and its casing 6Kg but 22x21x16 inch cab and 15 inch sp only 18Kg so
maybe part of the problem.
TO220 in the PA is 3 on pcb , 3 on one section of heatsink and 4 on another,
no fans. As slab SMR nearby are 22R I assume for the moment the o/p devices
are powerFET. Each bank of TO220 held down by cross bar and 2 screws.
This is my scale of screwdriver torque
1 light finger pressure around handle
2 strong finger pressure
3 fist
4 2 hands
5 wrench
6 impact driver
Testing the cross bar screws (they do have captive spring and plain washers)
torque measures about 2 , 1 and
then 1.5 and 0
The absent one either dropping out unseen as I knew a captive nut was loose
inside or still trapped under ps or pa.
So I assume silipads had compressed but these are 1.8mm thick porcelain,
even less compressible than mica. They were still in place surprisingle but
you could slide them with fingers and the TO220 nearest absent screw.
As distortion was crackle rather than push-pull failure distortion hopefully
solder failure , think I can see ring cracks with x30 microscope at awkward
angle, pushing around the loose TO220 legs not obviously moving at solder
points) rather than some thermal runaway devices.
So how to do an airframe type castellated nut plus lock-wire fix? for these
screws. 1mm wide pair of cross slots ground in the screw heads and st/st
wire looped and twisted in a slot and around the cross-bar?

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