sci.electronics.repair - 26 new messages in 16 topics - digest

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

sci.electronics.repair@googlegroups.com

Today's topics:

==============================================================================
TOPIC: can i bring new life to this old VCR?
http://groups.google.com/group/sci.electronics.repair/t/b80bdaff85d3a3a6?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Oct 20 2010 12:24 am
From: "N_Cook"

Wild_Bill <wb_wildbill@XSPAMyahoo.com> wrote in message
news:pwovo.149918$zE6.8495@en-nntp-03.dc1.easynews.com...

Whats this with plastic bags for preservation. First you get brown oiliness
of the plasticiser? (from the plastic or the band?) in the bag after some
years and then they perish as "in the field".
I store salvaged bands in open cardboard boxes with a good sprinkling of
talcum
powder, or over suspended cardboard cones that then show automatically the
sizes, again dusted with talc. Every now and then a rogue one goes gooey but
it does not set the
remainder off like an infection.

==============================================================================
TOPIC: Huster / Muster ? smps maker
http://groups.google.com/group/sci.electronics.repair/t/ae5c7c0ba89c151f?hl=en
==============================================================================

== 1 of 2 ==
Date: Wed, Oct 20 2010 4:53 am
From: "N_Cook"

Handscrawled in white on laptop sort of smps inside a Fischer in ear amp.
Anyone recognise the name? Presumably bought in by Fischer
Selectable between 12V and 24V by external (but inside the amp casing)
selector slide switch , other marking is
ATPS 2324, about 2005

== 2 of 2 ==
Date: Wed, Oct 20 2010 5:07 am
From: "N_Cook"

probably Ansmann atps 2324 before branding up, bought in bulk by Fischer

==============================================================================
TOPIC: Phillips screw security bit?
http://groups.google.com/group/sci.electronics.repair/t/0dd92a1eef067d92?hl=en
==============================================================================

== 1 of 5 ==
Date: Wed, Oct 20 2010 4:59 am
From: "N_Cook"

David Nebenzahl <nobody@but.us.chickens> wrote in message
news:4cbe33a3$0$2451$822641b3@news.adtechcomputers.com...
> On 10/19/2010 4:07 PM Allodoxaphobia spake thus:
>
> > On Tue, 19 Oct 2010 09:28:28 -0700, PlainBill47@yawho.com wrote:
> >
> >> On Mon, 18 Oct 2010 12:09:59 -0700, "David Farber"
> >> <farberbear.unspam@aol.com> wrote:
> >>
> >>> I'm trying to disassemble a Kill-A-Watt P4460. A device that was
> >>> plugged into it had some electrical problem and caused the
> >>> circuit breaker in my house to trip. When I removed the
> >>> Kill-A-Watt from the ac outlet, the ground pin had a nice burn
> >>> mark on it and now the display is dead. There are three Phillips
> >>> screws on the back of the unit but one of them appears to have
> >>> one of those raised points in the center of it which prevent you
> >>> from putting in a regular bit. I cannot find any security tool in
> >>> my collection that fits this type of screw. I'm not even sure
> >>> what to search for online. The screw looks like a torx bit but it
> >>> only has four notches. Any idea what tool fits this?
> >>>
> >> The tool is called a Phillips Security Bit. They aren't uncommon.
> >> I've seen them at swap meets, ham fests, and are available on eBay.
> >
> > Harbor Freight sells a small rubber block holding 32 bits for all
> > manner of styles and sizes of such weird drivers. Use'em in a 1/4"
> > hex nut driver (or, 1/2" power drill....) All Made in Chia -- but
> > you can't avoid that easily now-a-days.
>
> I have that set, as I mentioned elsewhere in this thread, but it doesn't
> have the bit the O.P. needs (Phillips-with-a-hole-in-the-middle). It
> does, however, have some other interesting "security" bits, and as
> Michael Terrell pointed out, HF sells other security bit sets that may
> have it. The quality is very good, BTW.
>
> But any decent hardware store will probably have the needed bit. (*Not*
> the big orange store.)
>
>
> --
> The fashion in killing has an insouciant, flirty style this spring,
> with the flaunting of well-defined muscle, wrapped in flags.
>
> - Comment from an article on Antiwar.com (http://antiwar.com)

Has anyone mentioned cracking off the pip with a bit of ground down
toolsteel hammered punch-fashion in the head of the screws? Sometimes even
the shortened shaft of a pop-rivet (universal meaning?). I watched a "how do
they do it" on Peterbild ? USA truck maker and they called them Hucker bolts
?

== 2 of 5 ==
Date: Wed, Oct 20 2010 7:43 am
From: "Michael A. Terrell"

N_Cook wrote:
>
> Has anyone mentioned cracking off the pip with a bit of ground down
> toolsteel hammered punch-fashion in the head of the screws?

That can damage some equipment. The Kill-A-Watt P4460 is in a small
plastic case.

> Sometimes even
> the shortened shaft of a pop-rivet (universal meaning?). I watched a "how do
> they do it" on Peterbild ? USA truck maker and they called them Hucker bolts
> ?

Old truck driver's joke:

Old truckers never die. They just get a new PETERBILT

http://www.peterbilt.com/history.aspx

--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

== 3 of 5 ==
Date: Wed, Oct 20 2010 8:39 am
From: "N_Cook"

Michael A. Terrell <mike.terrell@earthlink.net> wrote in message
news:beudncu4sJGrnSLRnZ2dnUVZ_u-dnZ2d@earthlink.com...
>
> N_Cook wrote:
> >
> > Has anyone mentioned cracking off the pip with a bit of ground down
> > toolsteel hammered punch-fashion in the head of the screws?
>
>
> That can damage some equipment. The Kill-A-Watt P4460 is in a small
> plastic case.
>
>
> > Sometimes even
> > the shortened shaft of a pop-rivet (universal meaning?). I watched a
"how do
> > they do it" on Peterbild ? USA truck maker and they called them Hucker
bolts
> > ?
>
>
> Old truck driver's joke:
>
> Old truckers never die. They just get a new PETERBILT
>
>
> http://www.peterbilt.com/history.aspx
>
>
> --
> Politicians should only get paid if the budget is balanced, and there is
> enough left over to pay them.

so those blind rivets are Huck bolts

== 4 of 5 ==
Date: Wed, Oct 20 2010 8:59 am
From: "Michael A. Terrell"

N_Cook wrote:
>
> Michael A. Terrell <mike.terrell@earthlink.net> wrote in message
> news:beudncu4sJGrnSLRnZ2dnUVZ_u-dnZ2d@earthlink.com...
> >
> > N_Cook wrote:
> > >
> > > Has anyone mentioned cracking off the pip with a bit of ground down
> > > toolsteel hammered punch-fashion in the head of the screws?
> >
> >
> > That can damage some equipment. The Kill-A-Watt P4460 is in a small
> > plastic case.
> >
> >
> > > Sometimes even
> > > the shortened shaft of a pop-rivet (universal meaning?). I watched a
> "how do
> > > they do it" on Peterbild ? USA truck maker and they called them Hucker
> bolts
> > > ?
> >
> >
> > Old truck driver's joke:
> >
> > Old truckers never die. They just get a new PETERBILT
> >
> >
> > http://www.peterbilt.com/history.aspx
> >
> >
> > --
> > Politicians should only get paid if the budget is balanced, and there is
> > enough left over to pay them.
>
> so those blind rivets are Huck bolts

I've never heard that term before today.

--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

== 5 of 5 ==
Date: Wed, Oct 20 2010 10:10 am
From: David Nebenzahl

On 10/20/2010 8:39 AM N_Cook spake thus:

> Michael A. Terrell <mike.terrell@earthlink.net> wrote in message
> news:beudncu4sJGrnSLRnZ2dnUVZ_u-dnZ2d@earthlink.com...
>
>> Old truck driver's joke:
>>
>> Old truckers never die. They just get a new PETERBILT
>>
>> http://www.peterbilt.com/history.aspx
>
> so those blind rivets are Huck bolts

1. How can a rivet be a bolt?

2. That joke apparently flew right over your head.

--
The fashion in killing has an insouciant, flirty style this spring,
with the flaunting of well-defined muscle, wrapped in flags.

- Comment from an article on Antiwar.com (http://antiwar.com)

==============================================================================
TOPIC: Timer
http://groups.google.com/group/sci.electronics.repair/t/4a02c7bfebbc47ce?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Oct 20 2010 5:25 am
From: Art Todesco

On 10/19/2010 1:13 PM, David Nebenzahl wrote:
> On 10/19/2010 5:44 AM Art Todesco spake thus:
>
>> On 10/18/2010 8:08 PM, LSMFT wrote:
>>
>>> I'm trying to find a timer to do what I want. Descriptions on the
>>> internet are sadly inadaquate. I want a timer that if it has input,
>>> say from a thermostat, to come on for a set time (2 to 5 minutes)
>>> and cut off. And I want it to do this every 15 minutes to 2 hours.
>>> What kind of timer do I need. I don't mind wiring an octal socket
>>> it they come that way.
>>
>> If you're into building it yourself, here's a link to a schematic:
>> http://www.zen22142.zen.co.uk/Circuits/Timing/ivt.htm
>
> Wouldn't that be accomplished just as well and much more simply with a
> single 555 timer?
You might be able to do it with a single 555, but this one was already
designed and was easily adjustable for each part of the cycle.

==============================================================================
TOPIC: Repair or replacement of anti-glare coating on my Samsung UN40B6000?
http://groups.google.com/group/sci.electronics.repair/t/8aadefa12fcb5442?hl=en
==============================================================================

== 1 of 4 ==
Date: Wed, Oct 20 2010 5:26 am
From: Keith

All:
Does anyone have an idea about how to repair or replace my Samsung 40" LED TV's anti-glare coating? I
accidentally put a tear into the screen's anti-glare coating. Thank you.

Keith Lee

== 2 of 4 ==
Date: Wed, Oct 20 2010 5:48 am
From: "William Sommerwerck"

Assuming the coating is bonded to the glass or plastic in the same way
anti-reflection coatings are evaporated onto photographic lenses, there is
no simple way to fix it.

If the coating is a separate piece of material, it might be replaceable.

== 3 of 4 ==
Date: Wed, Oct 20 2010 6:51 am
From: Keith

William:
It seems to be a seperate piece of material.
If anyone knows of anyone near me in San Diego, CA north county area who could help in this, please email me
and I can contact them. Thank you.

Keith

== 4 of 4 ==
Date: Wed, Oct 20 2010 7:23 am
From: Jim Reid

On Wed, 20 Oct 2010 12:26:07 +0000 (UTC), Keith wrote:

> All:
> Does anyone have an idea about how to repair or replace my Samsung 40" LED TV's anti-glare coating? I
> accidentally put a tear into the screen's anti-glare coating. Thank you.
>
> Keith Lee

Keith, buddy, short career in the NBA, huh? Niggers, lazy asses.
--
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Tel: 239 433 4873 Email: ceo@emccdesign.com

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http://groups.google.com/group/sci.electronics.repair/t/6f592e91a234eb02?hl=en
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== 1 of 1 ==
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TOPIC: ADULT SEX GALLERY
http://groups.google.com/group/sci.electronics.repair/t/f95abdb30281aaef?hl=en
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==============================================================================
TOPIC: OT electronic / electrical translator book
http://groups.google.com/group/sci.electronics.repair/t/e627794deb65d2e8?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Oct 20 2010 12:56 pm
From: "Harrison Lighting and Neon"

I am trying to locate (the name of) a spanish to english translation book of
terms and part names for electrical (commercial wiring etc) and electronic
( tv, dvr, computer)
this is for a friend of mine who was educated in Mexico and is takeing
college courses here.
Can anyone reccomend such a book?

thanx in advance Herb Harrison

==============================================================================
TOPIC: laptop sound card
http://groups.google.com/group/sci.electronics.repair/t/3fb15a5d0cf15755?hl=en
==============================================================================

== 1 of 2 ==
Date: Wed, Oct 20 2010 2:14 pm
From: phaedrus

Hi all,

I blew my laptop sound card somehow. Not sure why it blew, but it was
working fine until I plugged a mic pre-amp into its mic socket to
record some voice. Strange thing is, I have done this before many many
times with the same settings, input mic, voltage supply, and its never
complained before. This time however, it's blown it, it seems. And
it's not a separate board, but built into the motherboard.

Obviously a re-boot hasn't solved the problem. Neither did trying to
play audio via Linux instead of Windows. So it has to be a hardware
failure. But the symptoms are not normal. If it had been a case that I
had whacked too much power into the input, I would expect the initial
amplifier stage to fail resulting in mostly just very low output audio
levels. But what I get is more like I blew the speakers on a home
stereo by turning up the volume far too loud. It sounds really raspy
like the speaker coils have partly decatched from their cones! Tried
using known-good earphones from the earphone socket, but the result is
the same.

I am gonna have to trash this lappie if someone here can't think of
something I might have overlooked. Any suggestions?

Thanks,

VLC.

== 2 of 2 ==
Date: Wed, Oct 20 2010 2:42 pm
From: bok118@zonnet.nl (Gerard Bok)

On Wed, 20 Oct 2010 14:14:34 -0700 (PDT), phaedrus
<orion.osiris@virgin.net> wrote:

>I blew my laptop sound card somehow.
>it's not a separate board, but built into the motherboard.

>I am gonna have to trash this lappie if someone here can't think of
>something I might have overlooked. Any suggestions?

Just connect a USB sound device ?

--
Kind regards,
Gerard Bok

==============================================================================
TOPIC: ASICS Onitsuka Tiger offers the various choices for the customers
http://groups.google.com/group/sci.electronics.repair/t/cf820239ea2c04ab?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Oct 20 2010 5:44 pm
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==============================================================================
TOPIC: Sometimes, a sledge - hammer is the right tool ... :-)
http://groups.google.com/group/sci.electronics.repair/t/2bc7695b4fb03244?hl=en
==============================================================================

== 1 of 2 ==
Date: Wed, Oct 20 2010 6:05 pm
From: "Arfa Daily"

Well, figuratively speaking, anyway !

Today, a Carlsbro mixer desk landed on my bench. At power up, a few leds
flickered and flashed pathetically, before it settling with a couple of the
output bar leds alight. Other than this, it did not a lot. Oddly, at the
bottom of the two bar columns, are two more leds marked "DC" and "+15" and
"-15". The "+15" was alight, but not the "-15".

The power supply is a separate linear unit, screwed to the bottom of the
desk, and connected to the main board by a ribbon cable. I was able to
measure +15v and +5v at this connector, but no -15v, which seemed to go
along with with what the diagnostic leds on the front panel were saying.
However, with the power supply unplugged, -15v returned, at which point, my
heart sank. You could measure a virtual dead short to ground on the -15v pin
at the board end.

It's a single board, so the next 20 minutes were spent removing knobs,
screws and jack nuts to get the board out. It was double sided with
thousands of tiny vias, and a mixture of surface mount and through hole
technology, including many through hole SIL opamps. Shorts like this are
very difficult to track down. It could be any decoupling capacitor anywhere
on the board, or any IC. I tried all the usual stuff like using a low ohms
meter to see if I could get close to the location, but the results were
inconclusive. Nothing was running hot, as the linear regulator was in full
overload foldback, so not supplying enough current into the short.

So I decided it was make or break time, and got out my sledge - hammer in
the form of a bench power supply. I disconnected the unit's own power
supply, and set my bench one to -12v and a current limit of 1 amp, hooked it
to the shorted rail, and settled back to wait for the smoke. There wasn't
any, so I went round with a MK 1 finger to see if I could find a hot IC. I
finally burnt my finger on a little surface mount 4880. Quicker than you
could say "soldering iron" I had it whipped off the board. Then I burnt my
finger again on the spot where it had been ... :-(

It finally turned out to be a tiny gnat's-cock sized surface mount cap right
next to the IC, that was short circuit. It was pumping so much heat into the
board, that it was hotting up the IC as well. In the absence of a schematic,
I'm guessing that it's just an 0.1uF ceramic decoupler. That's what it looks
like anyway, so that's what it's got in it now as a replacement. In view of
the relatively small value of this mixer, I think that the sledge - hammer
'tune for maximum smoke' approach was about the only one that was
commercially viable, and in this case, it worked out nicely. Now all I need
is a few more faults like that. Don't know about anyone else, but I have
found the last three weeks to be the worst I have ever suffered in 20 years
of working for myself, both in terms of quantity, and quality of work. I
think we still have a very long way to go in recovering from the recent
recession. Anyone care to comment on how you're finding it on the
westpondian side ? Jeff, Mark , Meat ?

Arfa

== 2 of 2 ==
Date: Wed, Oct 20 2010 8:41 pm
From: stratus46@yahoo.com

On Oct 20, 6:05 pm, "Arfa Daily" <arfa.da...@ntlworld.com> wrote:
> Well, figuratively speaking, anyway !
>
> Today, a Carlsbro mixer desk landed on my bench. At power up, a few leds
> flickered and flashed pathetically, before it settling with a couple of the
> output bar leds alight. Other than this, it did not a lot. Oddly, at the
> bottom of the two bar columns, are two more leds marked "DC" and "+15" and
> "-15". The "+15" was alight, but not the "-15".
>
> The power supply is a separate linear unit, screwed to the bottom of the
> desk, and connected to the main board by a ribbon cable. I was able to
> measure +15v and +5v at this connector, but no -15v, which seemed to go
> along with with what the diagnostic leds on the front panel were saying.
> However, with the power supply unplugged, -15v returned, at which point, my
> heart sank. You could measure a virtual dead short to ground on the -15v pin
> at the board end.
>
> It's a single board, so the next 20 minutes were spent removing knobs,
> screws and jack nuts to get the board out. It was double sided with
> thousands of tiny vias, and a mixture of surface mount and through hole
> technology, including many through hole SIL opamps. Shorts like this are
> very difficult to track down. It could be any decoupling capacitor anywhere
> on the board, or any IC. I tried all the usual stuff like using a low ohms
> meter to see if I could get close to the location, but the results were
> inconclusive. Nothing was running hot, as the linear regulator was in full
> overload foldback, so not supplying enough current into the short.
>
> So I decided it was make or break time, and got out my sledge - hammer in
> the form of a bench power supply. I disconnected the unit's own power
> supply, and set my bench one to -12v and a current limit of 1 amp, hooked it
> to the shorted rail, and settled back to wait for the smoke. There wasn't
> any, so I went round with a MK 1 finger to see if I could find a hot IC. I
> finally burnt my finger on a little surface mount 4880. Quicker than you
> could say "soldering iron" I had it whipped off the board. Then I burnt my
> finger again on the spot where it had been ... :-(
>
> It finally turned out to be a tiny gnat's-cock sized surface mount cap right
> next to the IC, that was short circuit. It was pumping so much heat into the
> board, that it was hotting up the IC as well. In the absence of a schematic,
> I'm guessing that it's just an 0.1uF ceramic decoupler. That's what it looks
> like anyway, so that's what it's got in it now as a replacement. In view of
> the relatively small value of this mixer, I think that the sledge - hammer
> 'tune for maximum smoke' approach was about the only one that was
> commercially viable, and in this case, it worked out nicely. Now all I need
> is a few more faults like that. Don't know about anyone else, but I have
> found the last three weeks to be the worst I have ever suffered in 20 years
> of working for myself, both in terms of quantity, and quality of work. I
> think we still have a very long way to go in recovering from the recent
> recession. Anyone care to comment on how you're finding it on the
> westpondian side ? Jeff, Mark , Meat ?
>
> Arfa

If the power is distributed with actual planes in the PCB it would be
difficult to do it any other way. If power is distributed in a 'tree'
you could have restricted the current to get a few hundred mV into the
board and then look for the Voltage differentials with a meter. OR if
its a 'tree', you can start measuring the ohms at each capacitor. With
my trusty old Fluke 8060 I correctly identified which hole was shorted
to the ground plane of a new PCB. The 2 holes were separated by 0.1
inch ( 2.54 mm. I know YOU know) connected with a 0.01 inch trace on 1
oz copper. Good meters are essential.

G²

==============================================================================
TOPIC: connecting TTL o/p together
http://groups.google.com/group/sci.electronics.repair/t/ee9dba9a9d28a99c?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Oct 20 2010 6:07 pm
From: "Arfa Daily"

"JW" <none@dev.null> wrote in message
news:u36ob6973lh5777esr61p3re7g3lmj34i4@4ax.com...
> On Fri, 15 Oct 2010 16:21:34 -0700 (PDT) "fynnashba@yahoo.com"
> <fynnashba@yahoo.com> wrote in Message id:
> <4abefe43-8a42-4a8b-b92a-e4e5340f9fce@g8g2000yqa.googlegroups.com>:
>
>>
>> Hi l'm building a circuit and l need an 8 input OR gate(does anyone
>>know of one ?) this is not available so l'm using 74LS32 - Dual input
>>Quad or gate. the problem is can l connect all the outputs together as
>>one just like that? thanks
>
> How about an STM 74HC4078? Mouser has stock. Part #511-M74HC4078.

I already suggested that a coupla days back ... :-)

Arfa

==============================================================================
TOPIC: varicap diode testing?
http://groups.google.com/group/sci.electronics.repair/t/91a7f7edae59afb9?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Oct 20 2010 7:18 pm
From: mynick

On Oct 18, 9:37 am, Jeff Liebermann <je...@cruzio.com> wrote:
> On Mon, 18 Oct 2010 06:41:25 -0700 (PDT), mynick <anglom...@yahoo.com>
> wrote:
>
> >if you test an OK varicapdiode with analog reistance meter what are
> >you supposed to get?
>
> Avaricapis just an ordinary diode. When reverse biased, it acts as
> a capacitor which varies with the applied reverse bias. It never
> conducts current in the forward direction. Never... Ever...
>
> >Does it get hot/warm in battery powered
> >transmitter
>
> No.
>
> >(if not than the element suspected to be a varactor and
> >mounted to stick a little bit out of the transmitter box, could be
> >an ic diode although it could not transmit trough walls, could it?)
>
> I have no idea. Perhaps it would be helpful if you would disclose:
> 1. What are you trying to accomplish?
> 2. What are you working on? (Make and model)?
> 3. What have you done so far and what happen?
>
> --
> Jeff Liebermann je...@cruzio.com
> 150 Felker St #D http://www.LearnByDestroying.com
> Santa Cruz CA 95060http://802.11junk.com
> Skype: JeffLiebermann AE6KS 831-336-2558

Thanks for reply
this is a photo of the outdoor part of the wireless thermometer that
stopped working
http://img517.imageshack.us/img517/7053/img00331n.jpg
checked discrete elements ok but no bias voltage at (varicap?)diode-
that, kind of
a transparent element, seen up front close to battery contacts having
resistance in both directions od 6Kohms,
any ideas?

==============================================================================
TOPIC: Whirlpool electric stove, model RF0100, trips the breaker.
http://groups.google.com/group/sci.electronics.repair/t/2d6ac70cbeb19c93?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Oct 20 2010 3:20 pm
From: "David Farber"

This Whirlpool electric stove, model number RF0100, appears to be an older
model. If you're wondering what blasted the ground lead of my Kill-A-Watt
meter which I posted about a two days ago in the thread about the Phillips
security screw, this is the culprit. The schematic is here:
http://members.dslextreme.com/users/farberbear/Repair/Electric-stove.jpg as
I photographed it from the back of the stove.

I used to have it hooked up to a 240 volt circuit as indicated in the
schematic and it worked ok. But, now I don't have a 240V line. Or at least
not yet. I was trying to at least get it to work on 120V because only the
oven will be used and at very low heat, probably around 200 degrees to cook
some ceramics. The stovetop and broiler wires have been disconnected because
they are not needed. This particular model does not have a light or a clock
as shown in the schematic. I wired it so that L1 went to hot (black), L2
went to N (white), and N to ground (green). The load across the electric
plug, hot to neutral, with the oven switch on is 17 ohms. That makes sense
to me. However the impedance reading from neutral to ground makes no sense
to me. I've tried two different dvm's and they both give bizarre results.
When starting at the 2M ohm range, the meter starts at about 700k and counts
down to about 300k and holds there. When I move the switch over to the 20M
ohm range, the meter starts at about 2.3M ohm and counts up. The other meter
which is a portable meter counts backward too and then the minus sign
appears on the meter as if current is coming into the meter. From what I can
see, there aren't any capacitors or semiconductors interfering. The oven
thermostat has a thermocouple wired to it which for some reason is not shown
in the schematic. I opened the thermostat and found an interesting
mechanical coupling that moves a slider bar that depresses either the oven
element switch, the broil element switch, or both. Then there is the
thermocouple wire which is wrapped(?) internally around the rotating control
that selects the oven temperature. I don't usually open oven thermostats so
I'm not sure what exactly is going on inside. Once you open the thermostat,
there is a spring inside the device which displaces everything outside the
container. In any case, at room temperature, there is a connection from L1
to the bake and broil terminals so I know it's sending power through to
those elements.

Not trusting anything about these electrical readings, I first plugged the
oven into my Sencore PR57 isolation transformer. The transformer can only
supply about 300 watts but I was more interested in measuring leakage
current. No surprise when the low side leakage to the metal frame measured
full deflection even with the power off to the oven. Not exactly the best
situation. The high side leakage was zero. I turned up the voltage slowly
and the current seemed to rise proportionately to the 17 ohm load until I
stopped at about 300 watts. I should mention that the heating element did
not seem to get warm. Also, the heating element impedance matched the load
across the power plug so that seemed like a good sign.

Then I plugged it directly into the wall outlet via the Kill-A-Watt meter. I
turned on the oven switch and an instant trip of the circuit breaker at the
sub panel occurred. So where is all this extra current coming from to cook
the ground plug on my Kill-A-Watt and trip the breaker? I must be missing
something very obvious.

Thanks for your reply.
--
David Farber
Los Osos, CA

==============================================================================
TOPIC: Good LED TV repair men in San Diego County area?
http://groups.google.com/group/sci.electronics.repair/t/4ed1121fdbf133bb?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Oct 20 2010 3:12 pm
From: Keith

All:
Does anyone know of a safe, reliable, and honest LED TV repairman in the San Diego County area? If so,
please email or post me here.

Keith

==============================================================================
TOPIC: Whirlpool RF0100 electric stove trips breaker.
http://groups.google.com/group/sci.electronics.repair/t/88c59b94b9023959?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Oct 20 2010 8:37 pm
From: "David Farber"

This Whirlpool electric stove, model number RF0100, appears to be an older
model. If you were wondering what blasted the ground lead of my Kill-A-Watt
meter which I posted about two days ago in the thread about the Phillips
security screw, this is the culprit. The schematic is here:
http://members.dslextreme.com/users/farberbear/Repair/Electric-stove.jpg as
I photographed it from the back of the stove.

I used to have the stove hooked up to a 240 volt circuit as indicated in the
schematic and it worked ok. But, now I don't have a 240V line. Or at least
not yet. I was trying to at least get it to work on 120V because only the
oven will be used and at very low heat, probably around 200 degrees to cook
some ceramics. The stovetop and broiler wires have been disconnected because
they are not needed. This particular model does not have a light or a clock
as shown in the schematic. I wired it so that L1 went to hot (black), L2
went to N (white), and N to ground (green). The load across the electric
plug, hot to neutral, with the oven switch on, is 17 ohms. That makes sense
to me. However the impedance reading from neutral to ground makes no sense
to me. I've tried two different dvm's and they both give bizarre results.
When starting at the 2M ohm range, the meter starts at about 700k and counts
down to about 300k and holds there. When I move the switch over to the 20M
ohm range, the meter starts at about 2.3M ohm and counts up. The other meter
which is a portable meter counts backward too and then the minus sign
appears on the meter as if current is coming into the meter. From what I can
see, there aren't any capacitors or semiconductors interfering. The oven
thermostat has a thermocouple wired to it which for some reason is not shown
in the schematic. I opened the thermostat and found an interesting
mechanical coupling that moves a slider bar that depresses either the oven
element switch, the broil element switch, or both. Then there is the
thermocouple wire which is wrapped(?) internally around the rotating control
that selects the oven temperature. I don't usually open oven thermostats so
I'm not sure what exactly is going on inside because once you open the
thermostat,
there is a spring inside the device which displaces everything. In any case,
at room
temperature, there is a connection from L1 to the bake and broil terminals
so I know
it's sending power through to those elements.

Thanks for your reply.
--
David Farber
Los Osos, CA

==============================================================================

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