sci.electronics.repair@googlegroups.com

Today's topics:

* General relativity finally explained by Fitzpatrick's RPR - - (Relative
Phase Relationships). - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/3734d719a403efaa?hl=en
* general question: mainboard caps - 6 messages, 4 authors
http://groups.google.com/group/sci.electronics.repair/t/1bf5ee3341246b6a?hl=en
* followup: Carver PM-1.5a amp - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/07cfc4cb539da42f?hl=en
* My 1999 Toyota 4Runner digital clock is kaput (any ideas?) - 4 messages, 3
authors
http://groups.google.com/group/sci.electronics.repair/t/3ca13817756091e9?hl=en
* Dental Patients Before And After Images - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/ffba3b2da17229c7?hl=en
* OT: Video - I bet she will listen next time! - 4 messages, 4 authors
http://groups.google.com/group/sci.electronics.repair/t/0231af1c6c094716?hl=en
* Fender Showman from 1963 - 5 messages, 3 authors
http://groups.google.com/group/sci.electronics.repair/t/04710c995b7d7066?hl=en
* Music Man Sixty Five - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/b6026a75cd412799?hl=en
* Opened laptop battery to replace lithium ion cells (Lenovo X61 tablet PC) --
Where do I get replacement battery cells? - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/b825f0a2f4a3f913?hl=en

==============================================================================
TOPIC: General relativity finally explained by Fitzpatrick's RPR - - (Relative
Phase Relationships).
http://groups.google.com/group/sci.electronics.repair/t/3734d719a403efaa?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Sep 22 2010 12:46 am
From: fitz

General relativity finally explained by Fitzpatrick's RPR - -
(Relative Phase Relationships).

Our space is built up by the average amount elements are out of phase
with each other.

Repulsive forces are generated between elements that are out of phase
more than this average.

While elements more in phase, than this average (phase coherence),
produce attractive forces.

http://www.amperefitz.com/why.general.relativity.htm

Click link above to see why we have general relativity.

==============================================================================
TOPIC: general question: mainboard caps
http://groups.google.com/group/sci.electronics.repair/t/1bf5ee3341246b6a?hl=en
==============================================================================

== 1 of 6 ==
Date: Wed, Sep 22 2010 2:12 am
From: "larry moe 'n curly"

Michael wrote:

> Yes... I was having visions of getting the cap out then wondering,
> which way is negative... :-D

Usually there's a circle printed on the board under each electrolytic
capacitor, and the negative side is filled in, but Asus and Asrock
boards are marked the opposite way, so the filled area indicates the
positive lead instead.

There are YouTube videos about soldering and desoldering, and
BadCaps.net has a lot of information and also sells high-quality
caps. I think they also have a YouTube video.

In my novice opinion, a mainboard made with leaded solder needs a 40W
iron to solder it, a 50W iron to desolder it, and lead-free boards
need even more power. But a regular 50W iron can overheat its tip and
turn it blue or oxidize it, which really hurts heat conduction. There
are adjustable power irons for as little as $10, but I've found that
cheap irons don't last long or don't deliver as much heat to the tip
as good irons of the same power rating. BTW if you buy one off Ebay,
check the voltage because many are made only for 220VAC. If you're
going to spend much at all on an iron, consider getting a temperature-
controlled, 70W Goot PX-201, about $50, which should be able to handle
about anything, and Goot is a quality brand. Temperature-controlled
is better than adjustable power. With any iron, a chisel tip, about
2mm - 2.5mm wide, works better than a conical tip, and tips are best
cleaned with curly brass hair or a damp paper towel, not a sponge.

Manual desoldering vacuums work best if you can hold them on one side
of the board and the iron on the other side and see both sides at
once. Vacuum bulbs don't suck nearly as well as spring plungers do,
but the latter can strike and damage board at the moment the spring is
released. Addng a short length of rubber tubing can prevent the
damage.

Copper desoldering braid works if it's the right width (enough to soak
up all the solder from the hole in one try but not more, generally
2-3mm and the iron puts out plenty of heat. Cut off the used portion
immediately after use so it won't absorb heat from the next joint.
Don't pull out a lead unless all of the solder from the hole has been
removed, and test by wiggling the lead side to side. Generally if all
the solder doesn't come out in one try, it's best to fill the hole
with 60/40 or 63/37 solder and start all over.

Chip Quik may be the easiest and safest way to desolder because it
melts at under 150F, but it costs about $1 per inch.

Radio Shack sells an $11 desoldering iron with a vacuum bulb, and
other sources have a similar tool that has a spring-loaded plunger
vacuum instead. The Radio Shack iron doesn't seem to deliver quite
enough heat to the tip for multilayer boards, but people have modified
it with a better vacuum pump or by wrapping heat insulation above the
tip.

== 2 of 6 ==
Date: Wed, Sep 22 2010 9:23 am
From: Jeff Liebermann

On Wed, 22 Sep 2010 05:05:19 +0000 (UTC), Sergey Kubushyn
<ksi@koi8.net> wrote:

>Jeffrey Angus <jangus@suddenlink.net> wrote:
>> On 9/21/2010 11:29 PM, Sergey Kubushyn wrote:
>>> I recently restored and fully recapped two Kenwood KA-9100 amps. All the
>>> boards are phenolic and I used solder braid on them.
>>
>> And they are not multi layer boards with 0.010" traces.
>
>They are not. There is no such thing as _phenolic_ multi layer boards with
>0.010" traces.

Not yet. Some experiments in printed semiconductors and 3D circuits
use multilayer boards. However they don't use solder. They're
stapled together. They're also intended to be throw away assemblies,
so I wouldn't worry about repair.

>BTW, solder braid is very useful on _ANY_ board, including multilayer ones
>with 0.010" traces. It requires some skills of course but everything does. I
>do use it all the time.

I've been soldering for about 50 years, so I suspect I'm sufficiently
experienced to have made all the usual mistakes (several times). It's
not the lack of skill. I have no problem using braid on large objects
with small heat sinks. I have nothing but problems using braid on
small objects attached to large heat sinks. I this case, there's a
small leaded capacitor, connected to a rather large copper heat sink
of the power bus inside the PCB. You can see the effect when
unsoldering the capacitor leads. The ungrounded hot lead comes out
easily. The grounded lead is far more difficult. If the capacitors
are near the CPU and on a power bus, then both leads are difficult.
Braid is also quite suitable for unsolder connections where the solder
is easily accessible and exposed to the braid, such as large xformer
pins, terminal strips, wire terminals, some IC sockets, tube sockets,
etc.

Also remember that this is for what appears to be a beginner at
repair. It's easier to explain how to operate a solder sucker than
braid.

I forgot to mention the desoldering bulb, another device that barely
works:
<http://www.amazon.com/Weller-Desoldering-Bulb-Solder-Off/dp/B00011TUZY>
The only good part is that it's great finger exercise (I play piano).

I recently purchased one of the contrivances:
<http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220664298701>
It's a solder sucker hung on the back end of a hollow soldering iron.
It took a while to discover what was wrong with this idea. The amount
of vacuum generated is dependent on the unsuck to suck ratio of air
volumes. With an ordinary solder sucker, where the tip is close to
the piston, the ratio is rather large, thus offering a good vacuum.
Not so with this contrivance, as the volume of the hollow tube adds to
both volumes and results in much less vacuum. A larger diameter
piston or shorter soldering iron barrel would have made it work
better, but as it stands, the design sucks. 30 watts also seems
underpowered, the tip is too big, and it takes 10 minutes to warm up.
I haven't used it much, but I suspect that it will clog with dross
near the entrance to the solder sucker.

>It is not the rifle that shoots way off the target, it is the shooter.

True. However, I would rather use a guided missile (fancy desoldering
station) than to go off plinking at the target (solder braid).

--
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

== 3 of 6 ==
Date: Wed, Sep 22 2010 9:31 am
From: Meat Plow

On Wed, 22 Sep 2010 09:23:21 -0700, Jeff Liebermann wrote:

<snip>

> I've been soldering for about 50 years, so I suspect I'm sufficiently
> experienced to have made all the usual mistakes (several times). It's
> not the lack of skill.

<snip>

My first "job" in electronics was in the back room of my barber's shop
who had a little hobby business repairing electronics odds and ends. It
was where I learned how to solder. Especially after being told by one of
the barber's friends that I soldered like his grandmother :) That was in
1971. I was 16.

--
Live Fast, Die Young and Leave a Pretty Corpse

== 4 of 6 ==
Date: Wed, Sep 22 2010 11:11 am
From: Jeff Liebermann

On Wed, 22 Sep 2010 16:31:39 +0000 (UTC), Meat Plow
<mhywatt@yahoo.com> wrote:

>On Wed, 22 Sep 2010 09:23:21 -0700, Jeff Liebermann wrote:
>
><snip>
>
>> I've been soldering for about 50 years, so I suspect I'm sufficiently
>> experienced to have made all the usual mistakes (several times). It's
>> not the lack of skill.
>
><snip>
>
>My first "job" in electronics was in the back room of my barber's shop
>who had a little hobby business repairing electronics odds and ends. It
>was where I learned how to solder. Especially after being told by one of
>the barber's friends that I soldered like his grandmother :) That was in
>1971. I was 16.

That was a compliment.

I started with an Ungar wood burner at about 14 years old. The first
lesson I learned is that the power cord of the iron will melt and
short when I place the iron on it. It was downhill from there as my
father taught me to use a large copper gas fired furnace soldering
thing used to make industrial sewing machine attachments. By
comparison, the Ungar seemed easy. After several years of doing
everything wrong, the high skool electric shop teacher introduced me
to flux. Over the years, I learned the basics, like you can hold
solder in your mouth, but don't try it with copper wire. Far too many
Eico, Heathkit, and Knightkit constructions were great practice.

I recently tried to teach a friends 14 year old brat how to solder.
He's hopeless, but dedicated, and will eventually learn.

--
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 6 ==
Date: Wed, Sep 22 2010 11:42 am
From: Michael

On Sep 22, 9:23 am, Jeff Liebermann <je...@cruzio.com> wrote:
> On Wed, 22 Sep 2010 05:05:19 +0000 (UTC), Sergey Kubushyn
>
> <k...@koi8.net> wrote:
> >Jeffrey Angus <jan...@suddenlink.net> wrote:
> >> On 9/21/2010 11:29 PM, Sergey Kubushyn wrote:
> >>> I recently restored and fully recapped two Kenwood KA-9100 amps. All the
> >>> boards are phenolic and I used solder braid on them.
>
> >> And they are not multi layer boards with 0.010" traces.
>
> >They are not. There is no such thing as _phenolic_ multi layer boards with
> >0.010" traces.
>
> Not yet.  Some experiments in printed semiconductors and 3D circuits
> use multilayer boards.  However they don't use solder.  They're
> stapled together.  They're also intended to be throw away assemblies,
> so I wouldn't worry about repair.
>
> >BTW, solder braid is very useful on _ANY_ board, including multilayer ones
> >with 0.010" traces. It requires some skills of course but everything does. I
> >do use it all the time.
>
> I've been soldering for about 50 years, so I suspect I'm sufficiently
> experienced to have made all the usual mistakes (several times).  It's
> not the lack of skill.  I have no problem using braid on large objects
> with small heat sinks.  I have nothing but problems using braid on
> small objects attached to large heat sinks.  I this case, there's a
> small leaded capacitor, connected to a rather large copper heat sink
> of the power bus inside the PCB.  You can see the effect when
> unsoldering the capacitor leads.  The ungrounded hot lead comes out
> easily.  The grounded lead is far more difficult.  If the capacitors
> are near the CPU and on a power bus, then both leads are difficult.
> Braid is also quite suitable for unsolder connections where the solder
> is easily accessible and exposed to the braid, such as large xformer
> pins, terminal strips, wire terminals, some IC sockets, tube sockets,
> etc.  

I noticed that one of the capacitor leads is connected to what looks
like a fat copper trace (ground?) The other lead seems soldered to
just a tiny little circle... if I hadn't looked closely, I might have
soldered it to ground by mistake too...

>
> Also remember that this is for what appears to be a beginner at
> repair.  It's easier to explain how to operate a solder sucker than
> braid.

Yes I'm a beginner at this, and thanks!

> I forgot to mention the desoldering bulb, another device that barely
> works:
> <http://www.amazon.com/Weller-Desoldering-Bulb-Solder-Off/dp/B00011TUZY>
> The only good part is that it's great finger exercise (I play piano).

I heard that the bulb doesn't work very well. My dad has one. And
hey, I play the piano too! Trying to learn how to play George
Winston's piano solos... The Cradle is pretty straightforward, but, oh
man, his variations on the Carol of the Bells is extremely tough!

Michael

== 6 of 6 ==
Date: Wed, Sep 22 2010 11:55 am
From: Meat Plow

On Wed, 22 Sep 2010 11:11:56 -0700, Jeff Liebermann wrote:

> On Wed, 22 Sep 2010 16:31:39 +0000 (UTC), Meat Plow <mhywatt@yahoo.com>
> wrote:
>
>>On Wed, 22 Sep 2010 09:23:21 -0700, Jeff Liebermann wrote:
>>
>><snip>
>>
>>> I've been soldering for about 50 years, so I suspect I'm sufficiently
>>> experienced to have made all the usual mistakes (several times). It's
>>> not the lack of skill.
>>
>><snip>
>>
>>My first "job" in electronics was in the back room of my barber's shop
>>who had a little hobby business repairing electronics odds and ends. It
>>was where I learned how to solder. Especially after being told by one of
>>the barber's friends that I soldered like his grandmother :) That was in
>>1971. I was 16.
>
> That was a compliment.
>
> I started with an Ungar wood burner at about 14 years old. The first
> lesson I learned is that the power cord of the iron will melt and short
> when I place the iron on it. It was downhill from there as my father
> taught me to use a large copper gas fired furnace soldering thing used
> to make industrial sewing machine attachments. By comparison, the Ungar
> seemed easy. After several years of doing everything wrong, the high
> skool electric shop teacher introduced me to flux. Over the years, I
> learned the basics, like you can hold solder in your mouth, but don't
> try it with copper wire. Far too many Eico, Heathkit, and Knightkit
> constructions were great practice.
>
> I recently tried to teach a friends 14 year old brat how to solder. He's
> hopeless, but dedicated, and will eventually learn.

LOL! We had wood burners but I think I was only 10. I can't imagine the
politics of selling those thing to children of that age as a child's toy
these days.

--
Live Fast, Die Young and Leave a Pretty Corpse

==============================================================================
TOPIC: followup: Carver PM-1.5a amp
http://groups.google.com/group/sci.electronics.repair/t/07cfc4cb539da42f?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Sep 22 2010 3:24 am
From: "N_Cook"

What is the prognosis for PAT/insulation testing of these "magnetic field"
amps, knocking out diac/triac etc ? with 3.9M, R8, between ground and one
side of the mains transformer. Triac protection ccts are isolated from
ground, IIRC, where used in amps.

==============================================================================
TOPIC: My 1999 Toyota 4Runner digital clock is kaput (any ideas?)
http://groups.google.com/group/sci.electronics.repair/t/3ca13817756091e9?hl=en
==============================================================================

== 1 of 4 ==
Date: Wed, Sep 22 2010 4:38 am
From: Kruse

On Sep 21, 9:52 pm, Hachiroku ハチロク <anonym...@not-for-mail.invalid>
wrote:
> On Tue, 21 Sep 2010 19:40:57 -0500, Steve Barker wrote:
> > On 9/21/2010 1:14 AM, Y Knot wrote:
> >> Any ideas how to fix the $250 Toyota 4Runner digital clock?
>
> > ya, run it off in a river and buy an American car.
>
> Why would he want a downgrade?
>

Maybe he's tired of taking a Toyota in every other week for the
recalls.........

== 2 of 4 ==
Date: Wed, Sep 22 2010 4:38 am
From: Kruse

On Sep 21, 5:30 pm, PlainBil...@yawho.com wrote:
> On Tue, 21 Sep 2010 06:14:24 +0000 (UTC), Y Knot <yk...@unut.com>
> wrote:
>
> >Any ideas how to fix the $250 Toyota 4Runner digital clock?
>
> Why bother.  It's accurate twice a day; more than you could say when
> it was 'working'.
>

An old joke that probably doesn't apply to a digital clock.

== 3 of 4 ==
Date: Wed, Sep 22 2010 5:05 am
From: "Michael A. Terrell"

Kruse wrote:
>
> On Sep 21, 5:30 pm, PlainBil...@yawho.com wrote:
> > On Tue, 21 Sep 2010 06:14:24 +0000 (UTC), Y Knot <yk...@unut.com>
> > wrote:
> >
> > >Any ideas how to fix the $250 Toyota 4Runner digital clock?
> >
> > Why bother. It's accurate twice a day; more than you could say when
> > it was 'working'.
> >
>
> An old joke that probably doesn't apply to a digital clock.

It's never right, and it's never wrong. ;-)

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

== 4 of 4 ==
Date: Wed, Sep 22 2010 7:44 am
From: notbob

On 2010-09-21, Y Knot <yknot@unut.com> wrote:
> Any ideas how to fix the $250 Toyota 4Runner digital clock?

You'd be better off asking in a toyota centric newsgroup. There's at
least three high traffic toyota groups in the alt.autos domain,
including trucks.

nb

==============================================================================
TOPIC: Dental Patients Before And After Images
http://groups.google.com/group/sci.electronics.repair/t/ffba3b2da17229c7?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Sep 22 2010 5:52 am
From: jennifer <123cosmeticdentist@gmail.com>

http://www.valleycosmeticdentist.com/gallery-veneers.php -- Welcome
to About Cosmetic Dentistry section of Before and After photos for
cosmetic dentistry procedure

==============================================================================
TOPIC: OT: Video - I bet she will listen next time!
http://groups.google.com/group/sci.electronics.repair/t/0231af1c6c094716?hl=en
==============================================================================

== 1 of 4 ==
Date: Wed, Sep 22 2010 7:03 am
From: RoadRunner

Don't question it, just watch. How one man deals with a misbehaving
wife...

http://www.craigboyce.com/Videos/WebFinds/TakingBackThePants.shtml

== 2 of 4 ==
Date: Wed, Sep 22 2010 7:20 am
From: Jeffrey Angus

On 9/22/2010 9:03 AM, RoadRunner wrote:
> Don't question it, just watch. How one man deals with a misbehaving
> wife...
>
> http://www.craigboyce.com/Videos/WebFinds/TakingBackThePants.shtml

The follow up video, of course, is where she calmly walks up and
empties the magazine into his chest, smiles and says, "The next
time, they won't be blanks."

Jeff

== 3 of 4 ==
Date: Wed, Sep 22 2010 10:02 am
From: Frank

On 9/22/2010 10:03 AM, RoadRunner wrote:
> Don't question it, just watch. How one man deals with a misbehaving
> wife...
>
> http://www.craigboyce.com/Videos/WebFinds/TakingBackThePants.shtml

Sending to a couple of gun toting females but I'll be damned if I'll
show my wife ;)

== 4 of 4 ==
Date: Wed, Sep 22 2010 11:57 am
From: PlainBill47@yawho.com

On Wed, 22 Sep 2010 10:03:18 -0400, RoadRunner <asdf@aol.com> wrote:

>Don't question it, just watch. How one man deals with a misbehaving
>wife...
>
>http://www.craigboyce.com/Videos/WebFinds/TakingBackThePants.shtml
Some things a man should always remember:
1. If she ever saw 'Something to Talk About' she knows how to make
you very sick.
2. She knows where you sleep.
3. She knows the pillow over your face trick.
4. She knows that duct tape can make it a permanent solution.

PlainBill

==============================================================================
TOPIC: Fender Showman from 1963
http://groups.google.com/group/sci.electronics.repair/t/04710c995b7d7066?hl=en
==============================================================================

== 1 of 5 ==
Date: Wed, Sep 22 2010 7:23 am
From: "N_Cook"

Known history with this , from its purchase in Germany onwards, including
its original set of valves (not in there and used now, but will test out of
curiosity). What are the main potential safety/reliability issues with an
amp of this age? All the cotton covered wiring looks good but is there some
test/procedure more convincing as to insualting value? Bakelite brittleness
in the valve bases? metallurgical failure of springiness of valve
contacts?
Someone modified to 3 core mains cable and made an earth point, for 240V
land, at some point in its history. Numerous caps replaced in 1991 and 1997
and some carbon R replaced with MO at some point. I've not checked the main
caps yet.

== 2 of 5 ==
Date: Wed, Sep 22 2010 8:17 am
From: Meat Plow

On Wed, 22 Sep 2010 15:23:05 +0100, N_Cook wrote:

> Known history with this , from its purchase in Germany onwards,
> including its original set of valves (not in there and used now, but
> will test out of curiosity). What are the main potential
> safety/reliability issues with an amp of this age? All the cotton
> covered wiring looks good but is there some test/procedure more
> convincing as to insualting value? Bakelite brittleness in the valve
> bases? metallurgical failure of springiness of valve contacts?
> Someone modified to 3 core mains cable and made an earth point, for 240V
> land, at some point in its history. Numerous caps replaced in 1991 and
> 1997 and some carbon R replaced with MO at some point. I've not checked
> the main caps yet.

No known safety issues other than mains wiring. These were pretty
reliable amps. I own a 1970 Showman USA model. Someone tried to turn it
into a 100 watt model by replacing the iron and adding two octals to the
already blanked out chassis. I ripped all that stuff out and put new
output iron in it. It's not worth much but it does sound sweet.

--
Live Fast, Die Young and Leave a Pretty Corpse

== 3 of 5 ==
Date: Wed, Sep 22 2010 9:39 am
From: "N_Cook"

Meat Plow <mhywatt@yahoo.com> wrote in message
news:pan.2010.09.22.15.17.33@hahahahahahahah.nutz.I.am...
> On Wed, 22 Sep 2010 15:23:05 +0100, N_Cook wrote:
>
> > Known history with this , from its purchase in Germany onwards,
> > including its original set of valves (not in there and used now, but
> > will test out of curiosity). What are the main potential
> > safety/reliability issues with an amp of this age? All the cotton
> > covered wiring looks good but is there some test/procedure more
> > convincing as to insualting value? Bakelite brittleness in the valve
> > bases? metallurgical failure of springiness of valve contacts?
> > Someone modified to 3 core mains cable and made an earth point, for 240V
> > land, at some point in its history. Numerous caps replaced in 1991 and
> > 1997 and some carbon R replaced with MO at some point. I've not checked
> > the main caps yet.
>
> No known safety issues other than mains wiring. These were pretty
> reliable amps. I own a 1970 Showman USA model. Someone tried to turn it
> into a 100 watt model by replacing the iron and adding two octals to the
> already blanked out chassis. I ripped all that stuff out and put new
> output iron in it. It's not worth much but it does sound sweet.
>
>
>
> --
> Live Fast, Die Young and Leave a Pretty Corpse

Closer look and the cotton covering to the wiring between the output heaters
is "perished", crumbling to dust, and needs replacing. Strange having a load
of Mullard, Brimar and Z&I Aero valves to test

== 4 of 5 ==
Date: Wed, Sep 22 2010 9:47 am
From: Meat Plow

On Wed, 22 Sep 2010 17:39:27 +0100, N_Cook wrote:

> Meat Plow <mhywatt@yahoo.com> wrote in message
> news:pan.2010.09.22.15.17.33@hahahahahahahah.nutz.I.am...
>> On Wed, 22 Sep 2010 15:23:05 +0100, N_Cook wrote:
>>
>> > Known history with this , from its purchase in Germany onwards,
>> > including its original set of valves (not in there and used now, but
>> > will test out of curiosity). What are the main potential
>> > safety/reliability issues with an amp of this age? All the cotton
>> > covered wiring looks good but is there some test/procedure more
>> > convincing as to insualting value? Bakelite brittleness in the valve
>> > bases? metallurgical failure of springiness of valve contacts?
>> > Someone modified to 3 core mains cable and made an earth point, for
>> > 240V land, at some point in its history. Numerous caps replaced in
>> > 1991 and 1997 and some carbon R replaced with MO at some point. I've
>> > not checked the main caps yet.
>>
>> No known safety issues other than mains wiring. These were pretty
>> reliable amps. I own a 1970 Showman USA model. Someone tried to turn it
>> into a 100 watt model by replacing the iron and adding two octals to
>> the already blanked out chassis. I ripped all that stuff out and put
>> new output iron in it. It's not worth much but it does sound sweet.
>>
>>
>>
>> --
>> Live Fast, Die Young and Leave a Pretty Corpse
>
>
>
> Closer look and the cotton covering to the wiring between the output
> heaters is "perished", crumbling to dust, and needs replacing. Strange
> having a load of Mullard, Brimar and Z&I Aero valves to test

Since the heater wiring is twisted it would be a good idea to replace if
it is that poor of a state. I don't recall ever seeing the LV wiring in
any Fender of that era in that state and the state of all the wiring is
what I usually inspect first on any P2P wired vintage amp.

--
Live Fast, Die Young and Leave a Pretty Corpse

== 5 of 5 ==
Date: Wed, Sep 22 2010 11:17 am
From: Jeff Layman

On 22/09/2010 17:39, N_Cook wrote:

> Closer look and the cotton covering to the wiring between the output heaters
> is "perished", crumbling to dust, and needs replacing. Strange having a load
> of Mullard, Brimar and Z&I Aero valves to test

Z&I Aero!!! I haven't heard that name for over 40 years. That was when
their shop in Tottenham Court Road was worth visiting, followed by a
stroll to Proops, and then onto Lisle Street. Are there any surplus
places worth visiting today?

--

Jeff

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TOPIC: Music Man Sixty Five
http://groups.google.com/group/sci.electronics.repair/t/b6026a75cd412799?hl=en
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== 1 of 2 ==
Date: Wed, Sep 22 2010 10:13 am
From: "Arfa Daily"

Just had one of these lovely old amps across the bench, and was extremely
surprised to see a plate voltage of 730 on the two 6CA7 / EL34 output
pentodes. That is some serious HT, and I'm sure rather higher than I
remember seeing typically on any similar amps. The problem was low distorted
audio, and was down to an O/C screen (G2) feed resistor. Full normal
operation was restored once this had been replaced. G2 volts were around 360
when it was running normally. The bias was about -36v. I actually looked
this configuration up, and it just falls within the maximum specs for those
tubes, which are quoted at 800v on-load plate voltage max. At this level of
plate, G2 and bias, the quoted max output is 100 watts. That's pretty good
going from a single pair. Most amps from that era used two pair to get that
sort of power.

I guess the name "Sixty Five" relates to this amp's claimed output power,
but even that is PDG from a single pair, given that most amps of a similar
configuration are typically only capable of 30 watts or so.

The output tubes that are in it look quite old, but they are delivering the
goods, and are pretty reasonably balanced, so I am reluctant to recommend
replacement as a standard 'service' option whilst it's in, given the dubious
quality and reliability of many tubes these days, even when running at
relatively low levels of plate voltage up to say 500v. Anybody know much
about these amps ? Not terribly common this side of the pond - or at least
I've not had the pleasure of seeing many from this manufacturer over the
years ...

Arfa

== 2 of 2 ==
Date: Wed, Sep 22 2010 11:35 am
From: Meat Plow

On Wed, 22 Sep 2010 18:13:49 +0100, Arfa Daily wrote:

> Just had one of these lovely old amps across the bench, and was
> extremely surprised to see a plate voltage of 730 on the two 6CA7 / EL34
> output pentodes.

That's what they run em at. What did you need to know about them, I used
to own a 112 combo 65/35 watter. Probably very similar.

--
Live Fast, Die Young and Leave a Pretty Corpse

==============================================================================
TOPIC: Opened laptop battery to replace lithium ion cells (Lenovo X61 tablet
PC) -- Where do I get replacement battery cells?
http://groups.google.com/group/sci.electronics.repair/t/b825f0a2f4a3f913?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Sep 22 2010 10:24 am
From: ng_reader

I give up, what or where is "Mobile Track Power"

>
> I just bought 2 lap top batteries, one for Dell and one for HP. Found them
> at Mobile Track Power. Good warranty and good prices. Why mess with what
> you have? WW
>
>

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