sci.electronics.repair@googlegroups.com

Today's topics:

* BWS688 is dead - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/b88c19d1c4c5cfb2?hl=en
* opposite of an RF Modulator? - 4 messages, 4 authors
http://groups.google.com/group/sci.electronics.repair/t/8b592fa97d607ae0?hl=en
* ? on NTE56041 for touch-on lamp - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/d2558d31335920e5?hl=en
* AC current sensor with interface - 3 messages, 3 authors
http://groups.google.com/group/sci.electronics.repair/t/7447c1bcf49c904f?hl=en
* Today's Lead Free Crap Solder Stories ... - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/161210aa2275c858?hl=en

==============================================================================
TOPIC: BWS688 is dead
http://groups.google.com/group/sci.electronics.repair/t/b88c19d1c4c5cfb2?hl=en
==============================================================================

== 1 of 2 ==
Date: Thurs, May 20 2010 11:04 am
From: Merciadri Luca

On May 19, 11:36 pm, "Vale" <V...@fastwebnet.it> wrote:
> "Merciadri Luca" <merciadril...@gmail.com> ha scritto nel messaggionews:82a3b96d-e49f-4306-97ed-747f46d7ad7f@m4g2000vbl.googlegroups.com...
> On May 19, 8:44 pm, Meat Plow <mhyw...@yahoo.com> wrote:
>
>
>
> > On Wed, 19 May 2010 20:13:16 +0200, Vale wrote:
> > > "Merciadri Luca" <merciadril...@gmail.com> ha scritto nel messaggio
> > > news:bf873332-81d6-4c08-8219-
>
> > b82e32fd3...@e21g2000vbl.googlegroups.com...
>
> > > On May 18, 9:40 pm, Meat Plow <mhyw...@yahoo.com> wrote:
> > >> On Tue, 18 May 2010 12:23:14 -0700, Merciadri Luca wrote:
> > >> > On May 18, 8:28 pm, Meat Plow <mhyw...@yahoo.com> wrote:
> > >> >> On Tue, 18 May 2010 10:56:56 -0700, Merciadri Luca wrote:
> > >> >> > On May 18, 7:53 pm, Meat Plow <mhyw...@yahoo.com> wrote:
> > >> >> >> On Tue, 18 May 2010 10:49:02 -0700, Merciadri Luca wrote:
> > >> >> >> > On May 18, 7:44 pm, Meat Plow <mhyw...@yahoo.com> wrote:
> > >> >> >> >> Sorry to hear one BWS688 isn't working.
>
> No problem. The fact is that I'm not an electronic guru, sure. Note
> that I'm not Italian, and that I consequently can't write topics in
> Italian.
>
> Sorry Luca, your name & surname looks like just as mine, Italian.
> Go ahead, get passionated in electronics and for shure you'll became as
> expert as Meat Plow....
> Can't help you with your gizmo, but it looks like it just doesn't transmit.
> You will need some skill to investigate the power out RF stage as well as
> the typical other basic circuits involved in p.s.
> Good luck!

Thanks both. Actually, I _can_ verify if measures are correct at the
transmitter, but how can I know e.g. which voltages I should get
between a point A and a point B, both points being well defined? There
is absolutely no manual or tech. specs. for the transmitter.

@Vale: You couldn't guess that I'm not really Italian. That is, my
name & surnames are Italian, but I'm not. But there is absolutely no
problem to it. :)

== 2 of 2 ==
Date: Thurs, May 20 2010 12:48 pm
From: "Vale"

"Merciadri Luca" <merciadriluca@gmail.com> ha scritto nel messaggio
news:c171e01f-10dd-4892-afe0-736a1572dcc3@s41g2000vba.googlegroups.com...
On May 19, 11:36 pm, "Vale" <V...@fastwebnet.it> wrote:
> "Merciadri Luca" <merciadril...@gmail.com> ha scritto nel
> messaggionews:82a3b96d-e49f-4306-97ed-747f46d7ad7f@m4g2000vbl.googlegroups.com...
> On May 19, 8:44 pm, Meat Plow <mhyw...@yahoo.com> wrote:
>
>
> Sorry Luca, your name & surname looks like just as mine, Italian.
> Go ahead, get passionated in electronics and for shure you'll became as
> expert as Meat Plow....
> Can't help you with your gizmo, but it looks like it just doesn't
> transmit.
> You will need some skill to investigate the power out RF stage as well as
> the typical other basic circuits involved in p.s.
> Good luck!

>Thanks both. Actually, I _can_ verify if measures are correct at the
>transmitter, but how can I know e.g. which voltages I should get
>between a point A and a point B, both points being well defined? There
>is absolutely no manual or tech. specs. for the transmitter.

Luca, I'll have a look around to see if I can find a diagram/repair manual
for you.
I've got a pair of hooks were to look at.
I'll let you know.

>@Vale: You couldn't guess that I'm not really Italian. That is, my
>name & surnames are Italian, but I'm not. But there is absolutely no
>problem to it. :)

You're from Liege,is it?
I have been working several years around you and I met many Italians, born
in Belgium but reluctant to define themselves Italians.
Is it true, they are not and I don't blame at all.
I'll let you know for the gizmo, I have a couple of friends working in that
area, maybe they can give me access to the company database.
Ciao

==============================================================================
TOPIC: opposite of an RF Modulator?
http://groups.google.com/group/sci.electronics.repair/t/8b592fa97d607ae0?hl=en
==============================================================================

== 1 of 4 ==
Date: Thurs, May 20 2010 11:36 am
From: Jim Yanik

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in
news:ht3f3e$jpu$1@news.eternal-september.org:

> I think this is a troll, but...
>
> To make a long story short... Almost all TVs have inputs for analog audio
> and video. By that I mean "baseband" (not RF) signals, such as composite
> NTSC or component 1080p. With high-quality cabling, you should be able to
> run these signals to multiple sets.
>
>
>

I don't know if those outputs are made to drive -multiple- sets.
I believe they are only 1:1.

They still require impedance matching,too.

--
Jim Yanik
jyanik
at
localnet
dot com

== 2 of 4 ==
Date: Thurs, May 20 2010 11:48 am
From: UCLAN

mm wrote:

> Does there exist the opposite of an RF Modulator? Something that will
> take RF and turn it into digital for a digital tv?

Well, a RF *demodulator* takes analog RF and converts it to analog A/V. A
A->D converter will convert that to digital.

> Can I convert the analog back to digital for the digital tvs?

A A->D converter will do the trick. $$ for video.

Question: For the digital TVs, why not just use the original digital
signal?

== 3 of 4 ==
Date: Thurs, May 20 2010 12:05 pm
From: David Nebenzahl

On 5/20/2010 11:36 AM Jim Yanik spake thus:

> "William Sommerwerck" <grizzledgeezer@comcast.net> wrote in
> news:ht3f3e$jpu$1@news.eternal-september.org:
>
>> I think this is a troll, but...
>>
>> To make a long story short... Almost all TVs have inputs for analog audio
>> and video. By that I mean "baseband" (not RF) signals, such as composite
>> NTSC or component 1080p. With high-quality cabling, you should be able to
>> run these signals to multiple sets.
>
> I don't know if those outputs are made to drive -multiple- sets.
> I believe they are only 1:1.
>
> They still require impedance matching,too.

Just curious: what *is* the impedance of such cables? I'm guessing it's
not the 50 or 75 ohms of RF cabling.

--
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)

== 4 of 4 ==
Date: Thurs, May 20 2010 3:31 pm
From: "Michael A. Terrell"

David Nebenzahl wrote:
>
> On 5/20/2010 11:36 AM Jim Yanik spake thus:
>
> > "William Sommerwerck" <grizzledgeezer@comcast.net> wrote in
> > news:ht3f3e$jpu$1@news.eternal-september.org:
> >
> >> I think this is a troll, but...
> >>
> >> To make a long story short... Almost all TVs have inputs for analog audio
> >> and video. By that I mean "baseband" (not RF) signals, such as composite
> >> NTSC or component 1080p. With high-quality cabling, you should be able to
> >> run these signals to multiple sets.
> >
> > I don't know if those outputs are made to drive -multiple- sets.
> > I believe they are only 1:1.
> >
> > They still require impedance matching,too.
>
> Just curious: what *is* the impedance of such cables? I'm guessing it's
> not the 50 or 75 ohms of RF cabling.

They have to be made to drive a 75 ohm load to work with a standard
video input. If you can turn off the 75 ohm termination in all but the
last monitor, you can drive multiple monitors. I used the tuner & power
supply from a damaged VCR 20+ years ago as a secondary demodulator at
the TV station I worked at. I looped it back into a spare input on the
3M video router so the director could see what our views saw, instead of
our in hose video. That cost be $2, instead of over $3,000 for a
commercial demodulator like the one we used at our transmitter site.

--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

==============================================================================
TOPIC: ? on NTE56041 for touch-on lamp
http://groups.google.com/group/sci.electronics.repair/t/d2558d31335920e5?hl=en
==============================================================================

== 1 of 1 ==
Date: Thurs, May 20 2010 12:15 pm
From: "Dave"

I am attempting to fix my Mother-in-law's touch-on/touch-off lamp, which
appears to have a faulty BT136-600E triac in it. The sub for this is the
NTE56041, but that part doesn't turn on the lights when I install it and
touch the metal body of the lamp. The original part at least tried to turn
the lights on when the metal body of the lamp was touched, but failed to do
so completely (they flickered while the lamp was being held in the hands).
Examining the PC board into which the triac is mounted, the leftmost
terminal is ground, the middle is hot, and the rightmost would appear to be
the gate, but has no voltage on it when the lamp is plugged in and held for
examination. Actually, it has .004 VAC on it, but 0.00 VDC, with the triac
removed from the circuit. And when the triac is inserted into the circuit,
and the lamp held for examination this same voltage (.004 VAC) is present in
the light sockets. It seems as if the triac is trying to turn the lights
on, but not quite making it. I am therefore wondering if I should
(effectively) reverse the connections going to MT1 and MT2, making them no
longer GND and HOT (respectively) but making MT1 HOT and MT2 GND. Could it
be that this light (and circuit board with it's triac) which was made in
Taiwan, has these leads backwards from what the NTE56041 is expecting? I
hesitate to make this change without a great deal of thought, as I suspect,
if I am wrong, it might make the body of the lamp HOT to the touch.
Thoughts and considerations are sought, and more than welcome. I am not
sure what to do.

Thanks,

Dave

==============================================================================
TOPIC: AC current sensor with interface
http://groups.google.com/group/sci.electronics.repair/t/7447c1bcf49c904f?hl=en
==============================================================================

== 1 of 3 ==
Date: Thurs, May 20 2010 1:49 pm
From: whit3rd

On May 20, 2:33 am, Geir Holmavatn <gei...@gmail.com> wrote:
> Hi,
>
> I'm looking for non-contact current sensors for 0-60/70A AC connected to
> some digital interface (1-wire, GPIB, RS422, ethernet etc).  

> I need to monitor and register AC current with a computer from different
> appliances...

There's three obvious branches: you can go the full industrial-
automation
route (with DIN racks, enclosures, modules) - about $100-300 per
module,
and they'll talk RS-485 or Ethernet, or.... www.bb-elec.com has a
catalog
of this kind of thing, but I haven't used them.

You can go the flexible-but-crufty route, and use any old ammeters,
with a video camera aimed at them. The computer just captures
some images, at the end of the day you can review it all.

The slickest solution, though, is to park a data logger (small
battery-powered
recording meter) at the appliance, and occasionally download its
contents by walking over and plugging it into your laptop.

== 2 of 3 ==
Date: Thurs, May 20 2010 2:09 pm
From: Geir Holmavatn

Den 20.05.2010 19:38, skrev David Nebenzahl:

> How 'bout an inexpensive current xformer, which seems to be what the OP
> wants?

I need a *digital* interface which can be read / monitored by a computer.

The Coleparmer module does the trick, but it just goes to max 25A and I
hoped such modules would be less expensive than those...

Other comments?

rgds

Geir

== 3 of 3 ==
Date: Thurs, May 20 2010 2:44 pm
From: mike

Geir Holmavatn wrote:
> Hi,
>
> I'm looking for non-contact current sensors for 0-60/70A AC connected to
> some digital interface (1-wire, GPIB, RS422, ethernet etc). The
> measured cable should run through a hole in the sensor and not be
> galvanically connected.
>
> I need to monitor and register AC current with a computer from different
> appliances...
>
> Thanks for comments and tips on where I can find such sensors..
>
> regards Geir

You don't say exactly what you're trying to accomplish,
so this may be tangent to your requirements....but I'll try
not to let that stop me.

I set out to instrument my home for the purpose of
energy conservation. I intended to use a current probe
and PIC processor to acquire the current data and
send it via RS232 either directly or via RS232-Bluetooth
adapter.

I started with Mike's metrology rule #1:
Never ask a question unless the answer will modify
your future behavior.

And a corollary: Real-time data without real-time
control is overkill. All it gives you is worry.

I went around the house with a RMS power meter measuring
everything that would unplug.
The bad news is that a bunch of things like a wireless
telephone at 5W each really add up.
The worse news is that I'm unwilling to give them up.
I did unplug infrequently used vampire devices.

Since most things are either on or off. If you know
the consumption, you don't have to measure it in real-time.

A Kill-A-Watt device for under $20 will measure and log
data for you. But you have to interrupt the circuit.

Moving on to the harder devices, I started with the
biggest energy consumers.

First stop was the furnace. It's gas. Hmmm.
I determined from watching the gas meter go around
that the 60KBTU/HR rating was pretty accurate. So, it
was sufficient to measure the on-time. For that,
I used a hunk of cardboard on a microswitch that
opens when the furnace fan comes on placed over a vent.
I used an old Palm III to plot the on-time. Calculate
the gas cost plus the fan cost determined using a
hand-held current clamp meter completes the calculation.

For most things, they're either on or off. If you use
'em less, you save. Knowing exaclty how much you're saving
TODAY isn't useful. If your furnace thermostat is already
as low as you can tolerate, you've done all you can.
And you didn't need a single measurement to reach that
conclusion.

Next, I tackled the electric water heater. The wires
are accessible, so I used a clamp-on probe from an old
Triplett analog meter. It's much better than more modern
sensors because it puts out 500mV/Amp.
Plugged that into a Radio-shack
DVM with RS232 output and used a laptop to log the result.
Now, I know how much it costs to take a hot shower or
wash a load of clothes. The thermostat is already as low
as I can tolerate. Not much use for additional
measurements. The plan to use a PIC to measure the sensor
output and transmit it via RS232 or bluetooth has been aborted.

Kitchen appliances weren't worth measuring. I'm not
gonna stop reheating my coffee just because I have
real-time data on the microwave. See Rule #1 above.
I did buy an energy-efficient fridge.

The air conditioner wiring wasn't accessible, so I
took an alternative approach.
Our neighborhood just got those newfangled digital
power meters from the power company. Mine puts out
an infrared pulse for every watt-hour consumed.

WalMart sells individual cake slices in a plastic
box that is a nice friction-fit over the power
meter cylinder. It's just the right size to put
in a PDA. The handspring visor variant of the
Palm III works better because the IR sensor is
on the side.

A little bit of code and a lot of hair-pulling
later, I have a program that graphs and logs
power consumption. And since it measures
exactly what the power company charges for, I
don't have to worry about power factor, etc.

If you control what else comes on at the same
time, you can determine the "signature" of various
major power consumers. That done, you can
usually tell what's going on/off from the log.

The PDA cake-boxed onto the power meter can do anything
I need to monitor electricity consumption.

Now that I have the data and have modified
my behavior, the measurements stuff in in a
drawer. Refinement plans have been aborted.
I'm really glad I didn't invest a lot of $$$
in permanent measurement and control facilities.

Rule #1 rules...

YMMV.

==============================================================================
TOPIC: Today's Lead Free Crap Solder Stories ...
http://groups.google.com/group/sci.electronics.repair/t/161210aa2275c858?hl=en
==============================================================================

== 1 of 1 ==
Date: Thurs, May 20 2010 6:20 pm
From: "Arfa Daily"

The first is the Warrior amp that I posted on here about, looking for
schematics. None were found, and as expected, the importer ignored my pleas,
so I decided I would spend a half hour on it 'blind'.

It turned out to not be too difficult to get the main PCB out, complete with
heatsinks and back panel. The wiring was long enough to allow the board to
be turned over, without having to disconnect everything. The fault was that
one of the two identical output stages was behaving as a pretty good half
wave rectifier, but only with a load connected. With no load, an applied
sine wave was perfectly symmetrical at the output terminals, and of similar
size to the good channel. With a load connected, the negative excursions
disappeared almost totally. Nothing was burning, and the the output protect
didn't even fire until the wick was turned well up, which led me to believe
that the problem may well be back in the driver stages or earlier. As there
are two identical amps, I figured that I would start with a few comparitive
resistance checks between channels. Quickly, I found that at the base pin of
one of the driver transistors, I had a reading of 3k or so on the good
channel, but open circuit at the same point on the bad channel. I followed
the print back and took another reading and Lo! - 3k ...

So I went back to the transistor leg - open, but at the joint, 3k. I tell
you, I examined that joint with the strongest light and magnifier that I
have, but you could not see a problem with it. However, as soon as it was
resoldered, 3k on the leg as well, and the amp then worked normally. This is
the problem with lead free. You can no longer spot bad joints by eye, and
they don't behave like conventional bad joints any more.

The second one was a Vox combo. This one was reported as "goes off after a
while - tap top to get it back". It actually ran for about 2 hours, during
which time I thrashed the output stage so hard you couldn't touch the
heatsink, and periodically knocked seven bells out of it with the butt end
of a large philips screwdy. At no time did it show any signs of
intermittency. I was actually on the phone to the store that it came to me
from, to check if they knew the owner, and whether he was savvy, or a
numpty, when it went off. Just like that. No provocation. You could then
lightly tap the top of the chassis just about anywhere, and it would come
and go at will. So easy was it to make it do it, you would have thought that
the joint causing it would have been really easily spotted. I twisted and
wiggled everything I could, but nothing made it do it, but still the
lightest tap, and there it went.

Eventually, after a frustrating session of blanket resoldering that did no
good at all, I came to a power resistor standing up off the board. It was a
component that I had previously twisted. This time I pulled it, and one leg
just came right out of the board. The joint looked perfectly normal - for
lead-free that is - but it had not whetted the resistor leg at all. How the
hell could that take two hours to go bad, not be responsive at all before
that time, and then when it has gone bad, not respond to twisting, but be so
tap sensitive that you could make it come and go with a feather? I HATE
lead-free with a passion.

If it ever finds its way into avionics, be afraid, be VERY afraid ...

Arfa

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