Discussion:
Zenith Transoceanic questions - capacitors, etc.
(too old to reply)
Chuck Brockway
2006-02-20 00:49:54 UTC
Hello everyone. I'm new to this group and I need to tap into the
wealth of knowledge here!

I'm working on an 8G005, chassis 8C40T. The best way to describe its
condition is that is appears to have been in a fire. The chassis, e.g.
the I.F. cans has a dark greyish discoloration that doesn't come off
except with sandpaper. The coils all have a dark color, almost black.
On the other hand, the cabinet, knobs, etc. don't show any strange
damage. Components underneath appear normal, but there seems to
excessive brittleness in insulation, etc. I should say I have very
little experience as to what is "normal." Any thoughts?

Here's my real question. The multi-section capacitor values on the
cans don't seem to agree with the schematic:

No. Can mark Schematic
C30 20 40
C31 20 20
C32 200 10
C33 40 200
C34 40 40

I think that C30-C32 are in one can, C33-C34 in another. Am I
misreading something, or is there some explanation for this? I'm
assuming I should stick to the schematic.

Chuck
Mark Oppat
2006-02-20 04:47:24 UTC
there were a few versions of the 8G005. There was the suffix Z, Z1 and Z2 I
think.

anyways, your numbers match but are shuffled except one 20 is 10mfd in the
second column.

stick with the 20 (22mfd today), or jump up to 33mfd which in the 160v
rating is more common. I carry all these in radial lead caps which are the
only ones you can fit under that chassis mostly.

Mark Oppat
Post by Chuck Brockway
Hello everyone. I'm new to this group and I need to tap into the
wealth of knowledge here!
I'm working on an 8G005, chassis 8C40T. The best way to describe its
condition is that is appears to have been in a fire. The chassis, e.g.
the I.F. cans has a dark greyish discoloration that doesn't come off
except with sandpaper. The coils all have a dark color, almost black.
On the other hand, the cabinet, knobs, etc. don't show any strange
damage. Components underneath appear normal, but there seems to
excessive brittleness in insulation, etc. I should say I have very
little experience as to what is "normal." Any thoughts?
Here's my real question. The multi-section capacitor values on the
No. Can mark Schematic
C30 20 40
C31 20 20
C32 200 10
C33 40 200
C34 40 40
I think that C30-C32 are in one can, C33-C34 in another. Am I
misreading something, or is there some explanation for this? I'm
assuming I should stick to the schematic.
Chuck
Gordon Richmond
2006-02-20 04:25:30 UTC
Hello Chuck,

I'm in the midst of an 8G005 resto myself, so I have the schematic
here in the computer.

It showsC30, C31, and C32 as being in one can, and acting as the
filter network for the 117Z3 rectifier tube. That agreed with what I
found in my set. I've re-stuffed that filter can. It's 30,30, 10 uF.

C33 and C34 share another can. 40 uF and 200 uF. The 40 uF is at 150
WV, if I remember right and acts as screen bypass cap for the output
tubes. The 200 is at 25 volts, I think, and serves as a filter for the
filament string. I've acquired the necessary caps, but have not yet
restuffed the can, although I did get it open. With those
cardboard-sleeved 'lytic cans, I simply rolled them under the blade of
a pocket knife, just above the bottom rim (once I slipped the
cardboard sleeve off, of course). The cardboard sleeve comes off the
can easily if you warm it for a few minutes in an oven or with a hot
air gun to soften the tar inside it. Once the can is severed, you can
easily remove and dispose of the guts. I use a drill press to drill a
1/16" hole through the fiber disc adjacent to each solder lug, and
feed the leads of the new caps out that way. The cardboard sleeve can
be re-attached to the base rim of the cap with a little glue. Once
done, this repair is quite invisible from the top, and one would have
to look quite closely at the underside to spot it.

A lot of the wiring in my set has rubber insulation. Some of the
rubber has become so brittle, it simply shatters and falls off the
wire. Other pieces of wire, the rubber is still supple. Darned if I
know why. I just adopted a policy of changing out the crispy critters,
and leaving the supple ones be.

Hope this helps,

Gordon Richmond
Brenda Ann
2006-02-20 04:39:24 UTC
"Gordon Richmond" <***@telusplanet.net> wrote in message news:***@4ax.com...
The 200 is at 25 volts, I think, and serves as a filter for the
Post by Gordon Richmond
filament string.
Without looking at the schematic I can't be 100% certain, but I believe it's
actually the cathode bypass capacitor (suppose it would look like it might
be filament filtering)
Paul P
2006-02-21 14:29:58 UTC
Post by Gordon Richmond
The 200 is at 25 volts, I think, and serves as a filter for the
Post by Gordon Richmond
filament string.
Without looking at the schematic I can't be 100% certain, but I believe
it's actually the cathode bypass capacitor (suppose it would look like it
might be filament filtering)
And............The Filament have it!


Brenda,

FYI - According to the R520/URR manual (army version with the complete
component function descriptions) the low voltage section of 45D, of the 4
section can cap is for the filaments. R50 C45 I think is the same cap to
the 8G005 being referenced.

Schematic at http://www.transoceanic.nostalgiaair.org/520urr.htm. I have
used this manual as a troubleshooting aid for other TOs. Very informative
document! Large pdf but informative.

Paul. :~)

Paul P
2006-02-20 06:42:02 UTC
If it helps I have documented my personal experiences with the TO caps here:
http://www.ppinyot.com/transoceanic/transoceanic.htm with details here:
http://www.ppinyot.com/Restoration/Capacitors.htm. The site's links page
has great TO sites of others.

I picked up this conversation mind stream. So I may have missed other
contributors and your original question. Lots of great people and help here
on this board!!

Welcome aboard,
Paul
Post by Gordon Richmond
Hello Chuck,
I'm in the midst of an 8G005 resto myself, so I have the schematic
here in the computer.
It showsC30, C31, and C32 as being in one can, and acting as the
filter network for the 117Z3 rectifier tube. That agreed with what I
found in my set. I've re-stuffed that filter can. It's 30,30, 10 uF.
C33 and C34 share another can. 40 uF and 200 uF. The 40 uF is at 150
WV, if I remember right and acts as screen bypass cap for the output
tubes. The 200 is at 25 volts, I think, and serves as a filter for the
filament string. I've acquired the necessary caps, but have not yet
restuffed the can, although I did get it open. With those
cardboard-sleeved 'lytic cans, I simply rolled them under the blade of
a pocket knife, just above the bottom rim (once I slipped the
cardboard sleeve off, of course). The cardboard sleeve comes off the
can easily if you warm it for a few minutes in an oven or with a hot
air gun to soften the tar inside it. Once the can is severed, you can
easily remove and dispose of the guts. I use a drill press to drill a
1/16" hole through the fiber disc adjacent to each solder lug, and
feed the leads of the new caps out that way. The cardboard sleeve can
be re-attached to the base rim of the cap with a little glue. Once
done, this repair is quite invisible from the top, and one would have
to look quite closely at the underside to spot it.
A lot of the wiring in my set has rubber insulation. Some of the
rubber has become so brittle, it simply shatters and falls off the
wire. Other pieces of wire, the rubber is still supple. Darned if I
know why. I just adopted a policy of changing out the crispy critters,
and leaving the supple ones be.
Hope this helps,
Gordon Richmond
Shawn K
2006-02-20 04:37:30 UTC
Post by Chuck Brockway
Hello everyone. I'm new to this group and I need to tap into the
wealth of knowledge here!
Well Hello, and welcome to the group! Everyone is "new" at some point in
time....
Post by Chuck Brockway
I'm working on an 8G005, chassis 8C40T. The best way to describe its
condition is that is appears to have been in a fire. The chassis, e.g.
the I.F. cans has a dark greyish discoloration that doesn't come off
except with sandpaper. The coils all have a dark color, almost black.
On the other hand, the cabinet, knobs, etc. don't show any strange
damage. Components underneath appear normal, but there seems to
excessive brittleness in insulation, etc. I should say I have very
little experience as to what is "normal." Any thoughts?
First, is there any burn marks on the wooden shelf that the radio sits
on in the cabinet? If there has been a fire, the shelf will be burnt. I
have had one R-520 that had that problem. Second, I had a quick look at
my 8G005YBT chassis, the coils are very dark on mine, and the insulation
on the wiring is VERY brittle. This is common on the 8G's (7G605 as
well), the rubber insulation just breaks down with time.
Post by Chuck Brockway
Here's my real question. The multi-section capacitor values on the
No. Can mark Schematic
C30 20 40
C31 20 20
C32 200 10
C33 40 200
C34 40 40
I think that C30-C32 are in one can, C33-C34 in another. Am I
misreading something, or is there some explanation for this? I'm
assuming I should stick to the schematic.
You are correct, C30, C31, and C32 are in one can, located by the
speaker, C33 and C34 are in another can, located by the tuning cap. Does
it look like these may have been changed sometime in the past? If intend
to replace them (a very good idea), go with the values listed on the
schematic.

I hope that this helps you out with your restoration...
--
Shawn K
www.thisoldradio.com
Chuck Brockway
2006-02-20 18:57:37 UTC
Great help! Thank you.

It doesn't appear that the cans have been changed out. One can says
Aerovox, the other some name I don't recognize. Would the originals
have said Zenith?

I'll definitely be replacing them, and I'm planning to use the
schematic values unless there's some reason to use the can values. The
major difference is the 200 MFD on the schematic vs. 40 MFD on the can.

Chuck
Shawn K
2006-02-21 06:02:02 UTC
Post by Chuck Brockway
Great help! Thank you.
It doesn't appear that the cans have been changed out. One can says
Aerovox, the other some name I don't recognize. Would the originals
have said Zenith?
Both of the caps on my chassis have Zenith stamped into the black
cardboard covers.
--
Shawn K
www.thisoldradio.com
Peter Wieck
2006-02-21 12:43:44 UTC
Zenith made no paper or electrolytic capacitors or tubes of their own.
They purchased capacitors in job-lots from various suppliers including
at one time or another all the well-known favorites. Early Zenith
radios usually had the makers's names on them, as they became larger,
they had the makers install their name and part-numbers. But on
occasion, and in the same type radio there may be (factory) mix & match
as there may have been a shortfall in branded parts, requiring Zenith
to use unbranded (generic) parts until an order came in. All of their
radio tubes were made by Sylvania and rebranded for Zenith. Unlike the
two other "majors", Philco and RCA, Zenith was not nearly so vertically
integrated an organization.

Peter Wieck
Wyncote, PA