Frank Dresser wrote:
"geojunkie" wrote in message
om...


It's easy to figure how much capacitor leakage would cause an excessive
grid voltage, a reduced screen voltage or plate voltage. It's a simple
ohm's law problem. Don't forget the power leaky bypass capacitors have
to dissapate. Cathode bypasses can get very leaky before causing
problems.

But I'd be surprised if there are any 40+ year old paper caps around
that can meet a fairly loose throw away standard now. Say 1 microamp
per microfarad at it's rated voltage.

What year was your SX 101 made? Mylar caps started showing up around
1960. Even my SW 500 (S 120) had several good quality mylar C-D Black
Cats.

Also, there was an early 60s version of the Sprague Black Beauty which
was paper-mylar rather than paper-oil. The paper-mylar cap was quite
reliable.

Frank Dresser



Here's an excellent way to determine if paper caps should be replaced.
Count the number of caps in the radio and divide by the number of times
you want to go in and re-troubleshoot. If the quotient is equal to or
less than the original number of caps then they should be replaced.

Hope this helps,
Bill

Here's an excellent way to determine if paper caps should be replaced.
Count the number of caps in the radio and divide by the number of times
you want to go in and re-troubleshoot. If the quotient is equal to or
less than the original number of caps then they should be replaced.

Hope this helps,
Bill

Should we be getting vibes you feel strongly about this?

Avery W3AVE
Potomac, Md.

AComarow wrote:
Here's an excellent way to determine if paper caps should be replaced.
Count the number of caps in the radio and divide by the number of times
you want to go in and re-troubleshoot. If the quotient is equal to or
less than the original number of caps then they should be replaced.

Hope this helps,
Bill


Should we be getting vibes you feel strongly about this?

Avery W3AVE
Potomac, Md.

Only vibes, Ave? Maybe I wasn't clear enough!
:-)
Seriously, I question the logic of say encountering 20 caps in a 50-year
old radio and half of them have gone bad and then leaving the other
half. "Bad" is a relative term depending where it is in the circuit and
how much leakage you can tolerate but the fact is that the paper is
slowly deteriorating because of inherent acids and is only gonna get
worse with time.
So, you can replace them now or later. I enjoy replacing caps, and I
restuff the paper ones, and I really don't mind doing so. Might as well
unless you're in it for a business where your time equals money.

-Bill

Only vibes, Ave? Maybe I wasn't clear enough!
:-)
Seriously, I question the logic of say encountering 20 caps in a 50-year
old radio and half of them have gone bad and then leaving the other
half. "Bad" is a relative term depending where it is in the circuit and
how much leakage you can tolerate but the fact is that the paper is
slowly deteriorating because of inherent acids and is only gonna get
worse with time.
So, you can replace them now or later. I enjoy replacing caps, and I
restuff the paper ones, and I really don't mind doing so. Might as well
unless you're in it for a business where your time equals money.

-Bill

I totally agree. Unfortunately, when I start thinking about recapping some of
the old communications receivers I have around and what that would involve, my
inclination is to put it off, and off, and off. Removing the sliding coil
catacomb from an NC-2-40D to get at the caps lurking beneath is one of these
little nightmares--I can take anything out, but putting it back the right way
often challenges my modest mechanical skills. This group probably boasts
hundreds of individuals who rub their hands with glee when they face these
jobs. Me, I'd like a wide-open chassis, please.

Not that this has anything to do with your logic, which is impeccable as
always....

Avery W3AVE
Potomac, Md.

- - Bill - - wrote:

So, you can replace them now or later. I enjoy replacing caps, and I
restuff the paper ones, and I really don't mind doing so. Might as well
unless you're in it for a business where your time equals money.

Where can one learn about the art of 'restuffing' paper caps'? I saved
all the old ones from recapping my SX-100. Maybe I'll restuff them some
day.


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starman wrote:
- - Bill - - wrote:


So, you can replace them now or later. I enjoy replacing caps, and I
restuff the paper ones, and I really don't mind doing so. Might as well
unless you're in it for a business where your time equals money.


Where can one learn about the art of 'restuffing' paper caps'? I saved
all the old ones from recapping my SX-100. Maybe I'll restuff them some
day.

I hope you aren't being facetious and yanking my chain.

Its really quite easy to do although a bit messy and tedious and its
much easier to do a whole batch at one time rather than one off.
A heat-gun is the best way to unload the old casing. Dig out the 1/8"
or so of wax at each end and save it. Caveat here is that some brands
use an epoxy type filler on the ends. Apply heat for maybe 20-30
seconds, use gloves/rags/whatever and grab one lead and yank it out.
Most often the lead alone will come out (that tells you something about
the crappo internal connection integrity). So try the other end. Same
thing may happen.
So use a screwdriver or something to poke the guts out of the cardboard
tube. If its still warm it should push right thru.
If you need extra long leads chop short one lead of the new cap and
solder on an appropriate amount of wire so that the connection will be
hidden inside the original tube.
Install the new cap in the cardboard tube and squirt in some hot melt
glue at one end. Let that cool enough so as to not run and do the other
side. Fill to almost full.
Once its all cooled and settled, take some of the original chunks of wax
you saved in the first step...place on the end and use an old soldering
pencil to melt it around to replicate the end seal.
Done deal.
The aesthetics of just how clean you want the exterior are up to you.
You can smooth out the grubby old wax with the heat gun or clean it up
with WD-40 or a combination of the two.
Its an addictive part of restoration. After you've done it a couple of
times and see the nice original looking results with the comfort of
knowing those caps aren't going to crap out in your lifetime you'll
never go back to plain old yellow caps or orange drops or other
"glo-brite" colors that look so inappropriate underneath an old chassis.
HTH,
-Bill

- - Bill - - wrote:

starman wrote:
- - Bill - - wrote:


So, you can replace them now or later. I enjoy replacing caps, and I
restuff the paper ones, and I really don't mind doing so. Might as well
unless you're in it for a business where your time equals money.


Where can one learn about the art of 'restuffing' paper caps'? I saved
all the old ones from recapping my SX-100. Maybe I'll restuff them some
day.

I hope you aren't being facetious and yanking my chain.

Its really quite easy to do although a bit messy and tedious and its
much easier to do a whole batch at one time rather than one off.
A heat-gun is the best way to unload the old casing. Dig out the 1/8"
or so of wax at each end and save it. Caveat here is that some brands
use an epoxy type filler on the ends. Apply heat for maybe 20-30
seconds, use gloves/rags/whatever and grab one lead and yank it out.
Most often the lead alone will come out (that tells you something about
the crappo internal connection integrity). So try the other end. Same
thing may happen.
So use a screwdriver or something to poke the guts out of the cardboard
tube. If its still warm it should push right thru.
If you need extra long leads chop short one lead of the new cap and
solder on an appropriate amount of wire so that the connection will be
hidden inside the original tube.
Install the new cap in the cardboard tube and squirt in some hot melt
glue at one end. Let that cool enough so as to not run and do the other
side. Fill to almost full.
Once its all cooled and settled, take some of the original chunks of wax
you saved in the first step...place on the end and use an old soldering
pencil to melt it around to replicate the end seal.
Done deal.
The aesthetics of just how clean you want the exterior are up to you.
You can smooth out the grubby old wax with the heat gun or clean it up
with WD-40 or a combination of the two.
Its an addictive part of restoration. After you've done it a couple of
times and see the nice original looking results with the comfort of
knowing those caps aren't going to crap out in your lifetime you'll
never go back to plain old yellow caps or orange drops or other
"glo-brite" colors that look so inappropriate underneath an old chassis.
HTH,
-Bill

My query was genuine. I've never considered the possibility of putting
new cap's inside the old casings, at least not for paper ones. I have
experimented with gutting and refilling the large electrolytic cans.
Thanks for the tips.


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"starman" wrote in message
...
- - Bill - - wrote:

So, you can replace them now or later. I enjoy replacing caps, and I
restuff the paper ones, and I really don't mind doing so. Might as well
unless you're in it for a business where your time equals money.

Where can one learn about the art of 'restuffing' paper caps'? I saved
all the old ones from recapping my SX-100. Maybe I'll restuff them some
day.


The Early Television web site has details for retaining the "look" of the
original paper capacitor components -- but using modern components.

http://www.earlytelevision.org/capreplace.html

w9gb

starman wrote:

- - Bill - - wrote:


So, you can replace them now or later. I enjoy replacing caps, and I
restuff the paper ones, and I really don't mind doing so. Might as well
unless you're in it for a business where your time equals money.


Where can one learn about the art of 'restuffing' paper caps'? I saved
all the old ones from recapping my SX-100. Maybe I'll restuff them some
day.

It isn't hard, use a heat gun to soften up the old wax, then with pliers
pull the old cap out of the tube by the lead (hold the hot tube with a
shop towel). If the lead comes off without pulling out the insides, you
can use something like a piece of dowel rod to push the insides out. Put
the new cap in the tube and use hot glue to seal it up. You can get
colored glue sticks that will look much like the old wax.