sci.electronics.repair - 25 new messages in 9 topics - digest

sci.electronics.repair
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Today's topics:

==============================================================================
TOPIC: Electric fence operation problem
http://groups.google.com/group/sci.electronics.repair/t/eef28366a8aa3bbf?hl=en
==============================================================================

== 1 of 4 ==
Date: Thurs, Jul 8 2010 2:33 am
From: Franc Zabkar

On Thu, 8 Jul 2010 08:24:40 +0100, "N_Cook" <diverse@tcp.co.uk> put
finger to keyboard and composed:

>Franc Zabkar <fzabkar@iinternode.on.net> wrote in message
>news:e8u936t7msgm25002ne31halc1par3u74h@4ax.com...
>> On Wed, 7 Jul 2010 14:46:36 +0100, "N_Cook" <diverse@tcp.co.uk> put
>> finger to keyboard and composed:
>>
>> >What would people expect the intermediary DC to be? obviously higher than
>> >12V battery supply
>>
>> B20 Dry Battery Energiser:
>> http://www.forcefield-uk.co.uk/b20.htm
>>
>> If the above is your electric fence device, then the Stored Joules
>> rating of 0.2J should enable you to calculate the voltage across the
>> HV capacitor.
>>
>> E = 1/2 x C x V^2
>>
>> so V = sqrt (2 x 0.2 / C)

>The cap is 1uF , 280V ac rating. From the .5*C*V*V that comes to 630V, so
>something awry there.
>No more than 250V m 60% of likely DC rating, and I would have thought more
>like an equal split between 12V and 1800V so about 150V, transformers are
>much the same size if that is anything to go by

It may appear counterintuitive, but a rating of 280VAC/630VDC for a
metallised polypropylene or polyester capacitor is not uncommon.

http://www.aerovox.com/pdf/DC_Film_Axials.pdf
http://www.ibselectronics.com/pdf/pa/wima/wima_pulse_capacitors.pdf
http://www.descartes.com.tw/product/wima/wima_pdf/WIMA_MKP_4.pdf

See the Axial Metallized Polypropylene Capacitors on page 10 of the
first PDF.

In particular, there is a 1uF, 280VAC/630VDC cap, p/n ARPM10563KYUKZZ.

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

== 2 of 4 ==
Date: Thurs, Jul 8 2010 4:42 am
From: Meat Plow

On Thu, 8 Jul 2010 08:54:46 +0100, "N_Cook" <diverse@tcp.co.uk>wrote:

>If I ever get this thing working properly , how to check the average current
>drain?
>I am thinking 12V supply >- ammeter >- bank of 20V Cs summing to about 0.1F
>>- fencer unit
>

Find a cow, sheep or horse willing to test it.

== 3 of 4 ==
Date: Thurs, Jul 8 2010 4:52 am
From: "N_Cook"

Meat Plow <mhywatt@yahoo.com> wrote in message
news:3t134h.u5j.19.4@news.alt.net...
> On Thu, 8 Jul 2010 08:54:46 +0100, "N_Cook" <diverse@tcp.co.uk>wrote:
>
> >If I ever get this thing working properly , how to check the average
current
> >drain?
> >I am thinking 12V supply >- ammeter >- bank of 20V Cs summing to about
0.1F
> >>- fencer unit
> >
>
> Find a cow, sheep or horse willing to test it.

I don't think asking one "hoo moony mooliemoomps dooze this moozapper gizmoo
take" would get very far

== 4 of 4 ==
Date: Thurs, Jul 8 2010 4:32 pm
From: Franc Zabkar

On Thu, 8 Jul 2010 08:24:40 +0100, "N_Cook" <diverse@tcp.co.uk> put
finger to keyboard and composed:

If the device is designed to output its rated energy over a 9V-12V
supply range, then one would expect that the dump capacitor's voltage
would be regulated. Otherwise the variation in the stored energy would
be (12/9)^2 = 1.8X.

Is there any voltage feedback from the dump cap back to its charge
controller? I'd expect to see a resistive potential divider feeding
one input of an error amp (comparator?), and maybe a 5V or 2.5V
reference on the other input. You may be able to compute the voltage
from the resistance values.

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

==============================================================================
TOPIC: Any Lighting experts on here ... ?
http://groups.google.com/group/sci.electronics.repair/t/75b7c3eccbec375b?hl=en
==============================================================================

== 1 of 1 ==
Date: Thurs, Jul 8 2010 6:16 am
From: zekfrivo@zekfrivolous.com (GregS)

In article <xhJXn.93452$x15.62255@hurricane>, "Arfa Daily" <arfa.daily@ntlworld.com> wrote:
>
>
>"Smitty Two" <prestwhich@earthlink.net> wrote in message
>news:prestwhich-8691C4.07324903072010@mx01.eternal-september.org...
>> In article <XCGXn.92913$x15.87937@hurricane>,
>> "Arfa Daily" <arfa.daily@ntlworld.com> wrote:
>>
>>> I'm looking for a couple of replacement ceramic lampholders to go in a
>>> disco
>>> lighting unit that's in for repair. This thing uses two 300 watt bi-pin
>>> halogen capsule bulbs, with a pin spacing of about 6.3mm as close as I
>>> can
>>> measure.
>>
>> The bulb base may be a G6.35, where the number refers to the pin spacing
>> in mm. Perhaps putting that into google will facilitate your search.
>> Here's one such link:
>>
>> http://www.donsbulbs.com/cgi-bin/r/b.pl/socket-db-tp61.html
>
>OK, found a suitable one in the UK and now ordered. Just a case of knowing
>what it is you're looking for.

I have had one on a pulled up on a webpage for days. Darn things are expensive.

I'll check out your link.

greg

==============================================================================
TOPIC: Surge Protectors
http://groups.google.com/group/sci.electronics.repair/t/9a42e9c9a84828d9?hl=en
==============================================================================

== 1 of 2 ==
Date: Thurs, Jul 8 2010 6:57 am
From: GS

On Jun 9, 3:20 pm, Jeffrey D Angus <jan...@suddenlink.net> wrote:
> GregS wrote:
> > I just checked, and its difficult to find surpressors that
> > are cheap. I found one for $30 and might get a discounted
> > price. This is a basic model..................
> > http://www.grainger.com/Grainger/items/1ECD1?Pid=search
>
> Well, you can't say inexpensive andGraingerin the same sentence.
> You'll find the exact same products elsewhere for 25-50% less.
>
> Jeff
>
> --
> Egotism is the anesthetic that dulls the pain of stupidity.
> Frank Leahy, Head coach, Notre Dame 1941-1954
>
> http://www.stay-connect.com

I finally hooked up a suppressor to the main box. I ordered the item
from Drillspot, and
received it from GRAINGER !

I also fooled around with my lightning arrestors on the deck outside.
I want to keep surge protector also in the separate garage. I also
need
to put something in my LED lighting string around the house. That
would be expensive to replace and difficult.

== 2 of 2 ==
Date: Thurs, Jul 8 2010 11:43 am
From: zekfrivo@zekfrivolous.com (GregS)

In article <71a4851a-f352-4760-a33e-33d43ff6ddfb@g19g2000yqc.googlegroups.com>, GS <zekor@comcast.net> wrote:
>On Jun 9, 3:20=A0pm, Jeffrey D Angus <jan...@suddenlink.net> wrote:
>> GregS wrote:
>> > I just checked, and its difficult to find surpressors that
>> > are cheap. I found one for $30 and might get a discounted
>> > price. This is a basic model..................
>> > =A0http://www.grainger.com/Grainger/items/1ECD1?Pid=3Dsearch
>>
>> Well, you can't say inexpensive andGraingerin the same sentence.
>> You'll find the exact same products elsewhere for 25-50% less.
>>
>> Jeff
>>
>> --
>> Egotism is the anesthetic that dulls the pain of stupidity.
>> Frank Leahy, Head coach, Notre Dame 1941-1954
>>
>> http://www.stay-connect.com
>
>I finally hooked up a suppressor to the main box. I ordered the item
>from Drillspot, and
>received it from GRAINGER !
>
>I also fooled around with my lightning arrestors on the deck outside.
>I want to keep surge protector also in the separate garage. I also
>need
>to put something in my LED lighting string around the house. That
>would be expensive to replace and difficult.

I find 90 volt gas discharge tubes. I could probably
use a lower voltage device. I don't know what else would be
self resetting.

greg

==============================================================================
TOPIC: Repairing an expensive speaker
http://groups.google.com/group/sci.electronics.repair/t/8fc3fa133c100ac4?hl=en
==============================================================================

== 1 of 10 ==
Date: Thurs, Jul 8 2010 7:40 am
From: John

I am repairing two 15" Tannoys of the Gold series. A $5k unit if we
could get them.

Un oscillation in a cassette deck I was using, produced a very lowed
sound that damaged the speakers.

One of them has 6 turns of the voice coil, lose and can be glued back.

On the old days I used to repair speakers using the same type of glue
that was used on the assembling of models. A type of glue that use
acetone as a solvent.
Today we have better types of glue like epoxy and I believe the harder
the glue the better the performance, the disadvantage is that using
epoxy will make a future repair very difficult.

Any suggestions ?

The coil on the second speaker is open and in very bad shape. I am
looking for a replacement.

Tannoy does not carry parts for this type of speaker but there is a
place in England that will sell me a cone assembly for about $300 usd.

== 2 of 10 ==
Date: Thurs, Jul 8 2010 7:57 am
From: "William Sommerwerck"

I would contact Annoy and ask exactly which adhesive it uses. Don't
substitute on the assumption that your choice would be superior to Annoy's.

== 3 of 10 ==
Date: Thurs, Jul 8 2010 8:40 am
From: zekfrivo@zekfrivolous.com (GregS)

In article <i14p13$usq$1@news.eternal-september.org>, "William Sommerwerck" <grizzledgeezer@comcast.net> wrote:
>I would contact Annoy and ask exactly which adhesive it uses. Don't
>substitute on the assumption that your choice would be superior to Annoy's.
>
>

To add to my other post, if he wants orginal, then stay orginal.
Also both units should be the identical.

greg

== 4 of 10 ==
Date: Thurs, Jul 8 2010 8:53 am
From: Meat Plow

On Thu, 08 Jul 2010 10:40:20 -0400, John <Ya@you.com>wrote:

>I am repairing two 15" Tannoys of the Gold series. A $5k unit if we
>could get them.
>
>Un oscillation in a cassette deck I was using, produced a very lowed
>sound that damaged the speakers.
>
>One of them has 6 turns of the voice coil, lose and can be glued back.
>
>On the old days I used to repair speakers using the same type of glue
>that was used on the assembling of models. A type of glue that use
>acetone as a solvent.
>Today we have better types of glue like epoxy and I believe the harder
>the glue the better the performance, the disadvantage is that using
>epoxy will make a future repair very difficult.
>
>Any suggestions ?
>
>The coil on the second speaker is open and in very bad shape. I am
>looking for a replacement.
>
>Tannoy does not carry parts for this type of speaker but there is a
>place in England that will sell me a cone assembly for about $300 usd.

Seek out a professional reconing shop. You need some specialized tools
of the trade and some talent to recone. My good friend did it for a
living until he passed away recently. He would advise the same even if
you didn't chose his service.

== 5 of 10 ==
Date: Thurs, Jul 8 2010 12:15 pm
From: root

Meat Plow <mhywatt@yahoo.com> wrote:
>
> Seek out a professional reconing shop. You need some specialized tools
> of the trade and some talent to recone. My good friend did it for a
> living until he passed away recently. He would advise the same even if
> you didn't chose his service.

You can buy kits for reconing speakers. It isn't a
hard job. You remove the flex outer rim from the
cone. Then you cut out the bulge covering the voice
coil and put shims (supplied with the kit) in to center
the cone. Then you glue new flex material around
the cone, and wait overnight. Then you remove the
shims and seal up the bulge with glue.

Apart from the overnight wait for glue to dry, it
only took me about half an hour the first time.
With practice I might be able to get it down to
10 minutes.

== 6 of 10 ==
Date: Thurs, Jul 8 2010 12:48 pm
From: Ron

On 08/07/2010 20:15, root wrote:
> Meat Plow<mhywatt@yahoo.com> wrote:
>>
>> Seek out a professional reconing shop. You need some specialized tools
>> of the trade and some talent to recone. My good friend did it for a
>> living until he passed away recently. He would advise the same even if
>> you didn't chose his service.
>
> You can buy kits for reconing speakers. It isn't a
> hard job. You remove the flex outer rim from the
> cone. Then you cut out the bulge covering the voice
> coil and put shims (supplied with the kit) in to center
> the cone. Then you glue new flex material around
> the cone, and wait overnight. Then you remove the
> shims and seal up the bulge with glue.
>
> Apart from the overnight wait for glue to dry, it
> only took me about half an hour the first time.
> With practice I might be able to get it down to
> 10 minutes.

And that takes care of the knackered voice coil does it?

Ron(UK)

--
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We are a community of 7 million users fighting spam.
SPAMfighter has removed 1397 of my spam emails to date.
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== 7 of 10 ==
Date: Thurs, Jul 8 2010 3:56 pm
From: Meat Plow

On Thu, 8 Jul 2010 19:15:18 +0000 (UTC), root <NoEMail@home.org>wrote:

>
>Meat Plow <mhywatt@yahoo.com> wrote:
>>
>> Seek out a professional reconing shop. You need some specialized tools
>> of the trade and some talent to recone. My good friend did it for a
>> living until he passed away recently. He would advise the same even if
>> you didn't chose his service.
>
>You can buy kits for reconing speakers. It isn't a
>hard job.

Trust me, it isn't an easy fix. Just what fucking experience do you
think I might not have had with reconing. Don't make assumptions.

== 8 of 10 ==
Date: Thurs, Jul 8 2010 4:01 pm
From: Meat Plow

On Thu, 08 Jul 2010 20:48:38 +0100, Ron
<ron@lunevalleyaudio.com>wrote:

>On 08/07/2010 20:15, root wrote:
>> Meat Plow<mhywatt@yahoo.com> wrote:
>>>
>>> Seek out a professional reconing shop. You need some specialized tools
>>> of the trade and some talent to recone. My good friend did it for a
>>> living until he passed away recently. He would advise the same even if
>>> you didn't chose his service.
>>
>> You can buy kits for reconing speakers. It isn't a
>> hard job. You remove the flex outer rim from the
>> cone. Then you cut out the bulge covering the voice
>> coil and put shims (supplied with the kit) in to center
>> the cone. Then you glue new flex material around
>> the cone, and wait overnight. Then you remove the
>> shims and seal up the bulge with glue.
>>
>> Apart from the overnight wait for glue to dry, it
>> only took me about half an hour the first time.
>> With practice I might be able to get it down to
>> 10 minutes.
>
>And that takes care of the knackered voice coil does it?
>
>Ron(UK)

The 10 minute recone part really bothers me. Sure with production line
jigs, shims, guides and people who do maybe a 100 per day that is a
tangible goal. But for an average Joe buying reconing parts and being
successful is not the average outcome. Sure there are exceptions so if
you want to try it on your own good luck.

== 9 of 10 ==
Date: Thurs, Jul 8 2010 5:45 pm
From: "Arfa Daily"

"Meat Plow" <mhywatt@yahoo.com> wrote in message
news:3t2ats.t4n.19.4@news.alt.net...
> On Thu, 08 Jul 2010 20:48:38 +0100, Ron
> <ron@lunevalleyaudio.com>wrote:
>
>>On 08/07/2010 20:15, root wrote:
>>> Meat Plow<mhywatt@yahoo.com> wrote:
>>>>
>>>> Seek out a professional reconing shop. You need some specialized tools
>>>> of the trade and some talent to recone. My good friend did it for a
>>>> living until he passed away recently. He would advise the same even if
>>>> you didn't chose his service.
>>>
>>> You can buy kits for reconing speakers. It isn't a
>>> hard job. You remove the flex outer rim from the
>>> cone. Then you cut out the bulge covering the voice
>>> coil and put shims (supplied with the kit) in to center
>>> the cone. Then you glue new flex material around
>>> the cone, and wait overnight. Then you remove the
>>> shims and seal up the bulge with glue.
>>>
>>> Apart from the overnight wait for glue to dry, it
>>> only took me about half an hour the first time.
>>> With practice I might be able to get it down to
>>> 10 minutes.
>>
>>And that takes care of the knackered voice coil does it?
>>
>>Ron(UK)
>
> The 10 minute recone part really bothers me. Sure with production line
> jigs, shims, guides and people who do maybe a 100 per day that is a
> tangible goal. But for an average Joe buying reconing parts and being
> successful is not the average outcome. Sure there are exceptions so if
> you want to try it on your own good luck.

Interestingly, I was discussing exactly this issue with the owner of the
music shop that I do a lot of work for, just this week. He rents a lot of
biiiiigggg PA equipment out - kilowatt amps and 4 x 15 bass cabs and such.
These get damaged by inept users all the time, apparently. I suggested that
it must cost him a fortune in replacement speakers, but he said "Oh no - I
just re-cone them". I asked him how long he had been doing this and he said
years, but I had never seen this going on in his shop. Anyway, I asked him
how long it took, and how hard a job it was, and did he have lots of
specialist shims and feeler gauges and jigs and what have you. Nope, he
said. He reckons it takes him but a few minutes (literally) to do the job.
He says that the most time consuming part is making sure that all the crud
from the burnt up voice coil, is removed from the airgap. He uses a
combination of compressed air, and sticky tape to do this. As to centering
the new cone's voice coil, he says that most replacement kits come with a
set of four plastic spacer shims, but that many modern designs are
fundamentally self - centering anyway. He reckoned that it was basically a
piece of piss job that just needed a little care, and that much bollocks was
talked on the subject. I might ask him to let me know next time he's got one
to do, as I would like to watch him at work ...

Arfa

== 10 of 10 ==
Date: Thurs, Jul 8 2010 6:19 pm
From: Grant

On Thu, 08 Jul 2010 19:01:39 -0400, Meat Plow <mhywatt@yahoo.com> wrote:

>On Thu, 08 Jul 2010 20:48:38 +0100, Ron
><ron@lunevalleyaudio.com>wrote:
>
>>On 08/07/2010 20:15, root wrote:
>>> Meat Plow<mhywatt@yahoo.com> wrote:
>>>>
>>>> Seek out a professional reconing shop. You need some specialized tools
>>>> of the trade and some talent to recone. My good friend did it for a
>>>> living until he passed away recently. He would advise the same even if
>>>> you didn't chose his service.
>>>
>>> You can buy kits for reconing speakers. It isn't a
>>> hard job. You remove the flex outer rim from the
>>> cone. Then you cut out the bulge covering the voice
>>> coil and put shims (supplied with the kit) in to center
>>> the cone. Then you glue new flex material around
>>> the cone, and wait overnight. Then you remove the
>>> shims and seal up the bulge with glue.
>>>
>>> Apart from the overnight wait for glue to dry, it
>>> only took me about half an hour the first time.
>>> With practice I might be able to get it down to
>>> 10 minutes.
>>
>>And that takes care of the knackered voice coil does it?
>>
>>Ron(UK)
>
>The 10 minute recone part really bothers me. Sure with production line
>jigs, shims, guides and people who do maybe a 100 per day that is a
>tangible goal. But for an average Joe buying reconing parts and being
>successful is not the average outcome. Sure there are exceptions so if
>you want to try it on your own good luck.

A little OT...

Took me some hours to resolder bad joint between cone wire and the flex
wire, by the time I found and arranged some foam rubber to lift the cone
outwards enough to gain access, clean off some of the black insulator
stuff very carefully to find the wires underneath and the bad solder
joint. The speakers date back about 30 years.

Then many attempts to get a good solder joint, the low-mid 7" speaker
has very fine wire to the cone. But the repair done with much patience,
and has lasted a few years now :)

It's worth the effort to try repair expensive speaker drivers, at worst,
you're still stuck with a bad speaker needing replacement. Nothing but
time to lose?

Grant.

==============================================================================
TOPIC: paypal payment brand cap,shawl,belt,wallet,under wear,and so on.http://
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http://groups.google.com/group/sci.electronics.repair/t/12b86e72dd08c340?hl=en
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== 1 of 1 ==
Date: Thurs, Jul 8 2010 10:19 am
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==============================================================================
TOPIC: How to dissolve clear plastic coat from circuit boards?
http://groups.google.com/group/sci.electronics.repair/t/3589eaf245b53d57?hl=en
==============================================================================

== 1 of 4 ==
Date: Thurs, Jul 8 2010 3:26 pm
From: "Robbie Hatley"

Greetings, group. I've got a sticky issue here. I'm repairing a number of circuit
boards from a manufacturer who coats their boards after assembly with some
sort of plastic clear coat. (Polyurethane, maybe? Indoors it's clear and
colorless, but outdoors under skylight, it glows a pale blue.) It makes probing
and soldering/unsoldering quite difficult. What's the best way to remove it?

So far, I've tried:

91% isopropyl alcohol:
Loosens bond between coat and board, but doesn't dissolve coat.

Unknown solvent in unmarked 55-gallon drum (possibly toluene-based):
Dissolves coat, but very slowly, requiring a lot of scrubbing with a brush.
Noxious fumes.

CRC Letra-Motive Electric Parts Cleaner:
Dissolves coat, but slowly, requiring a lot of scrubbing with a brush.
Turns coat into a thick goo that mucks-up brush and is hard to rinse out.
Noxious fumes.

Are there better options?

--
Varnished,
Robbie Hatley
lonewolf [[at]] well [[dot]] com

== 2 of 4 ==
Date: Thurs, Jul 8 2010 3:56 pm
From: PeterD

On Thu, 8 Jul 2010 15:26:10 -0700, "Robbie Hatley"
<see.my.sig@for.my.contact.info> wrote:

>
>Greetings, group. I've got a sticky issue here. I'm repairing a number of circuit
>boards from a manufacturer who coats their boards after assembly with some
>sort of plastic clear coat. (Polyurethane, maybe? Indoors it's clear and
>colorless, but outdoors under skylight, it glows a pale blue.) It makes probing
>and soldering/unsoldering quite difficult. What's the best way to remove it?
>
>So far, I've tried:
>
>91% isopropyl alcohol:
> Loosens bond between coat and board, but doesn't dissolve coat.
>
>Unknown solvent in unmarked 55-gallon drum (possibly toluene-based):
> Dissolves coat, but very slowly, requiring a lot of scrubbing with a brush.
> Noxious fumes.
>
>CRC Letra-Motive Electric Parts Cleaner:
> Dissolves coat, but slowly, requiring a lot of scrubbing with a brush.
> Turns coat into a thick goo that mucks-up brush and is hard to rinse out.
> Noxious fumes.
>
>Are there better options?

Try Acetone.

== 3 of 4 ==
Date: Thurs, Jul 8 2010 6:27 pm
From: "William Sommerwerck"

> Try acetone.

But with great caution. Acetone attacks a lot of plastics.

== 4 of 4 ==
Date: Thurs, Jul 8 2010 7:24 pm
From: dplatt@radagast.org (Dave Platt)

In article <PtKdnWFfL-8fzavRRVn_vwA@giganews.com>,
Robbie Hatley <see.my.sig@for.my.contact.info> wrote:

>Greetings, group. I've got a sticky issue here. I'm repairing a number
>of circuit
>boards from a manufacturer who coats their boards after assembly with some
>sort of plastic clear coat. (Polyurethane, maybe? Indoors it's clear and
>colorless, but outdoors under skylight, it glows a pale blue.) It makes probing
>and soldering/unsoldering quite difficult. What's the best way to remove it?

Google "conformal coating stripper".

MG chemicals makes one, which the MSDS says contains

1-methyl-2-pyrrolidinone
Dibasic Ester (Mixture)
Dimethyl Glutarate 55-65%
Dimethyl Adipate 10-25%
Dimethyl Succinate 15-25%
D'Limonene

Another source might be Miller-Stephenson (their D0319B or
MS-115 strippers)... the former handles both urethane and epoxy
coatings, the latter is optimized for epoxy.

Conformal coatings may be urethane, epoxy, acrylic, or silicone. I
believe that the urethane types are the most common but I could well
be wrong about taht. The pale-blue glow you observed is probably a
UV-fluorescent tracer dye, added to the liquid coating so that boards
can be checked during manufacture to ensure that they're properly
coated.

--
Dave Platt <dplatt@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

==============================================================================
TOPIC: National VP-7750A Wow and Flutter Meter
http://groups.google.com/group/sci.electronics.repair/t/adf741e894c11d88?hl=en
==============================================================================

== 1 of 1 ==
Date: Thurs, Jul 8 2010 5:44 pm
From: Sergey Kubushyn

I'm looking for a service/operation manual for National VP-7750A Wow and
Flutter meter. No such manual at usual places, Google returns just questions
"Where to find one."

Any information would be highly appreciated.

---
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* KSI@home KOI8 Net < > The impossible we do immediately. *
* Las Vegas NV, USA < > Miracles require 24-hour notice. *
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