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Today's topics:
* Technics SA-310 Intermittent Weak Left Channel - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/24c0d76fe3922429?hl=en
* Grain-of-wheat bulbs - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/80801ab1fbd67e8f?hl=en
* Cause of blown fuse. - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/e4e620ad717ceda2?hl=en
* Beyond AWG - 5 messages, 4 authors
http://groups.google.com/group/sci.electronics.repair/t/6108ec0943f8d321?hl=en
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TOPIC: Technics SA-310 Intermittent Weak Left Channel
http://groups.google.com/group/sci.electronics.repair/t/24c0d76fe3922429?hl=en
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== 1 of 1 ==
Date: Sun, Aug 15 2010 6:29 pm
From: "William R. Walsh"
Hi!
> Measure the B+ at the output stage on the suspect channel as you apply a
> 1khz sine wave from min to max output and report back.
I don't have any way of doing that. Any other ideas for a test that would
produce a similar result?
William
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TOPIC: Grain-of-wheat bulbs
http://groups.google.com/group/sci.electronics.repair/t/80801ab1fbd67e8f?hl=en
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== 1 of 1 ==
Date: Sun, Aug 15 2010 8:21 pm
From: "Paul Hovnanian P.E."
David Nebenzahl wrote:
>
> On 7/29/2010 11:07 AM Paul Hovnanian P.E. spake thus:
>
> > I'm looking for a couple of these to repair some (antique) equipment. They
> > should be 1.5V, about 30mA and produce a relatively 'white' light at this
> > current. Some Radio Shack 6V, 100mA bulbs draw approximately the correct
> > current at 1.5V, but they are too reddish and dim to be of any use.
> >
> > These are used in an old photographic light meter as a null indicator. LEDs
> > won't work at this voltage level (too dim and no where near linear
> > brightness vs voltage).
>
> Is that meter by any chance a Gossen? the type with two bulbs that light
> up equally bright when the dial is adjusted correctly? I had one of
> those when I was a kid. Luna Pro?
Yes.
One lamp is burned out. I measured the voltage and lamp current of the
good one. I'll be replacing both of them (just to keep the differential
circuit properly balanced).
--
Paul Hovnanian mailto:Paul@Hovnanian.com
------------------------------------------------------------------
c (velocity of light in a vacuum) = 1.8x10^12 furlongs per fortnight
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TOPIC: Cause of blown fuse.
http://groups.google.com/group/sci.electronics.repair/t/e4e620ad717ceda2?hl=en
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== 1 of 1 ==
Date: Sun, Aug 15 2010 8:32 pm
From: "Paul Hovnanian P.E."
William Sommerwerck wrote:
>
> > The fuses sat right in the centre of the power amplifier
> > print. [???] I would guess protection of the output stage.
> > The mains fuse was OK. The set is still playing.
>
> Driving a low-impedance speaker at high volumes can cause this. (I had it
> happen once.)
>
> LET ME REPEAT, because no one seems to be paying attention. A fuse (or
> fuses) can pop for no /obvious/ reason. It doesn't mean the amplifier is
> defective, or that the fuses are likely to blow again. This sort of thing
> happens every day, and is nothing to worry about. *
My brother-in-law had a problem with his stereo when he moved into a
'new' house. The place has 8 built-in speakers and he has a state of the
art surround sound power amp. But when he cranks the volume up, the amp
shuts down (solid state protection, no fuses were harmed).
So I did a bit of poking around. First thing, the speaker jack plate on
the wall had only two pairs of terminals. Left and right, we assumed.
Bad news, as it was probably wired with 4 speakers in parallel to each
side. Then I popped the wall plate off. All 8 speakers were wired to one
terminal pair. The right power amp was driving 8 paralleled speakers.
The left power amp drove nothing.
Fortunately, all of the speaker wiring came down behind the terminal
plate. And his amp has (more than) eight outputs. So now they all get
their own speaker.
--
Paul Hovnanian mailto:Paul@Hovnanian.com
------------------------------------------------------------------
f u cn rd ths u r usng unx
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TOPIC: Beyond AWG
http://groups.google.com/group/sci.electronics.repair/t/6108ec0943f8d321?hl=en
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== 1 of 5 ==
Date: Sun, Aug 15 2010 8:42 pm
From: "Paul Hovnanian P.E."
I have a d'Arsonval meter movement to repair. The voltage coil has a
number of breaks and will have to be rewound. After removing the old
coil, I measured the wire diameter. It appears to be copper, about 1.8
mil in diameter over the enamel insulation.
Thats down below the AWG chart I've got. 40 AWG is 3.14 mils. Anyone
have a link to a chart that goes down to 45 AWG? And does anyone have a
link to a supplier (with specs) of this size wire? Since I'm measuring
the diameter over enamel, it would be better to compare what I've got to
finished magnet wire specs.
--
Paul Hovnanian mailto:Paul@Hovnanian.com
------------------------------------------------------------------
I bet the human brain is a kludge. -- Marvin Minsky
== 2 of 5 ==
Date: Sun, Aug 15 2010 9:02 pm
From: Grant
On Sun, 15 Aug 2010 20:42:22 -0700, "Paul Hovnanian P.E." <Paul@Hovnanian.com> wrote:
>I have a d'Arsonval meter movement to repair. The voltage coil has a
>number of breaks and will have to be rewound. After removing the old
>coil, I measured the wire diameter. It appears to be copper, about 1.8
>mil in diameter over the enamel insulation.
>
>Thats down below the AWG chart I've got. 40 AWG is 3.14 mils. Anyone
>have a link to a chart that goes down to 45 AWG? And does anyone have a
>link to a supplier (with specs) of this size wire? Since I'm measuring
>the diameter over enamel, it would be better to compare what I've got to
>finished magnet wire specs.
Do you need to stay original? Is less turns of heavier wire
plus an amplifier an option?
Fine work, not something I'd want try unless the thing had
great value.
Grant.
== 3 of 5 ==
Date: Sun, Aug 15 2010 9:19 pm
From: "tm"
"Paul Hovnanian P.E." <Paul@Hovnanian.com> wrote in message
news:4C68B39E.1BDB6434@Hovnanian.com...
>I have a d'Arsonval meter movement to repair. The voltage coil has a
> number of breaks and will have to be rewound. After removing the old
> coil, I measured the wire diameter. It appears to be copper, about 1.8
> mil in diameter over the enamel insulation.
>
> Thats down below the AWG chart I've got. 40 AWG is 3.14 mils. Anyone
> have a link to a chart that goes down to 45 AWG? And does anyone have a
> link to a supplier (with specs) of this size wire? Since I'm measuring
> the diameter over enamel, it would be better to compare what I've got to
> finished magnet wire specs.
>
> --
> Paul Hovnanian mailto:Paul@Hovnanian.com
> ------------------------------------------------------------------
> I bet the human brain is a kludge. -- Marvin Minsky
This may be of use.
http://upload.wikimedia.org/wikipedia/en/2/28/Gauge_Chart.pdf
tm
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== 4 of 5 ==
Date: Sun, Aug 15 2010 9:23 pm
From: Jeff Liebermann
On Sun, 15 Aug 2010 20:42:22 -0700, "Paul Hovnanian P.E."
<Paul@Hovnanian.com> wrote:
>I have a d'Arsonval meter movement to repair. The voltage coil has a
>number of breaks and will have to be rewound. After removing the old
>coil, I measured the wire diameter. It appears to be copper, about 1.8
>mil in diameter over the enamel insulation.
>
>Thats down below the AWG chart I've got. 40 AWG is 3.14 mils. Anyone
>have a link to a chart that goes down to 45 AWG? And does anyone have a
>link to a supplier (with specs) of this size wire? Since I'm measuring
>the diameter over enamel, it would be better to compare what I've got to
>finished magnet wire specs.
<http://www.mwswire.com>
<http://www.mwswire.com/pdf_files/mws_tech_book/copper_magnet_wire_data.pdf>
They have insulated wire down to #55 AWG.
Hint: Use a microscope with a wire gauge reticle.
I'm impressed that you're still able to do such fine work. My
eyesight and manual dexterity are slowly disappearing as I get older.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
== 5 of 5 ==
Date: Sun, Aug 15 2010 9:32 pm
From: "tm"
"Paul Hovnanian P.E." <Paul@Hovnanian.com> wrote in message
news:4C68B39E.1BDB6434@Hovnanian.com...
>I have a d'Arsonval meter movement to repair. The voltage coil has a
> number of breaks and will have to be rewound. After removing the old
> coil, I measured the wire diameter. It appears to be copper, about 1.8
> mil in diameter over the enamel insulation.
>
> Thats down below the AWG chart I've got. 40 AWG is 3.14 mils. Anyone
> have a link to a chart that goes down to 45 AWG? And does anyone have a
> link to a supplier (with specs) of this size wire? Since I'm measuring
> the diameter over enamel, it would be better to compare what I've got to
> finished magnet wire specs.
>
> --
> Paul Hovnanian mailto:Paul@Hovnanian.com
> ------------------------------------------------------------------
> I bet the human brain is a kludge. -- Marvin Minsky
And this might be a source.
tm
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