sci.electronics.repair@googlegroups.com

Today's topics:

* Blew another damn transformer on my Trane XB80 - 4 messages, 4 authors
http://groups.google.com/group/sci.electronics.repair/t/f883cd09a3a0b791?hl=en
* Servis M6712W (washing machine) - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/96927913b917139e?hl=en

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TOPIC: Blew another damn transformer on my Trane XB80
http://groups.google.com/group/sci.electronics.repair/t/f883cd09a3a0b791?hl=en
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== 1 of 4 ==
Date: Tues, Apr 12 2011 7:32 pm
From: Mark

To the OP...
another long shot..

it looks like the primary of the transformer is wired in series with
the door safety switch. Is it possible that the door safety switch
is loose and arcing. This could cause a high voltage to appear at the
transformer and cause the insulation to fail...

Mark

== 2 of 4 ==
Date: Tues, Apr 12 2011 8:03 pm
From: Tony Hwang

Phil Allison wrote:
> "Dave M"
>>
>>
>> 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.
>
> ** So the average value is non zero and that means there is a DC component
> to the current.
>
>> True, it's unidirectional current, but it's an intermittent current, not
>> constant DC.
>
> ** It will show a nice, steady reading on a DC current meter.
>
> The interesting thing is how there is no corresponding DC component in the
> primary current.
>
>
> .... Phil
>
> Hi,
Lots of ripple. If it were on audio circuit, lots of hum!!!!
>
>
>
>
>
>
>
>
>
>
>

== 3 of 4 ==
Date: Tues, Apr 12 2011 9:23 pm
From: don@manx.misty.com (Don Klipstein)

In <rj1aq6lpg08u5m3l8tqn1q3j8vjtiun6be@4ax.com>, clare@snyder.on.ca wrote:
>On 13 Apr 2011 09:57:33 +1000, "Phil Allison" <phil_a@tpg.com.au> wrote:

>>"Dave M"
>>>
>>> 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.
>>
>>** So the average value is non zero and that means there is a DC component
>>to the current.
>>
>>> True, it's unidirectional current, but it's an intermittent current, not
>>> constant DC.
>>
>>** It will show a nice, steady reading on a DC current meter.
>>
>>The interesting thing is how there is no corresponding DC component in the
>>primary current.
>>
>>.... Phil
>
>Unless the half wave rectifier is on the PRIMARY side.

There won't be a rectifier feeding the primary of a transformer with DC.
A transformer does not pass DC from one winding to another the way it does
with AC.

Changing AC that transformers work with to DC that electronics work with
has to occur downstream of the transformer.

>I don't see any evidence of that on any of the diagrams I saw, but is
>there something else on this furnace circuit? By code there cannot be
>- but we don't know know this to be the case - or what is on the
>circuit if there is.

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.
--
- Don Klipstein (don@misty.com)

== 4 of 4 ==
Date: Wed, Apr 13 2011 12:07 am
From: David Nebenzahl

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.)

--
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*?)

==============================================================================
TOPIC: Servis M6712W (washing machine)
http://groups.google.com/group/sci.electronics.repair/t/96927913b917139e?hl=en
==============================================================================

== 1 of 1 ==
Date: Tues, Apr 12 2011 9:02 pm
From: Smitty Two

In article <io2j3a$hni$1@dont-email.me>,
"William Sommerwerck" <grizzledgeezer@comcast.net> wrote:

> > I have this machine which works fine until at the end
> > of the cycle it makes a ticking noise which is very
> > annoying. Does anyone have a solution?
>
> It's common for electromechanical timers to make clicking noises, especially
> between cycles. If the machine completes the full wash cycle, there's
> nothing to worry about.

OP didn't say he was worried, he said he was annoyed. He could unplug
the machine, that would stop the damn ticking.

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