Hi Group,

So I thought I'd re-cap my Sherwood S8000 amp/FM. Ha Ha Ha. I discovered
that all three transformers have nice HV sleeving over the wires, but the
sleeving starts at about 1/4" outside the transformer! The old insulation
underneath is gone, and the wires are bare exiting the transformers. The
bare wiring has turned green, and one wire just fell off by moving it around
a little to remove a capacitor. Looks like all three transformers need to be
partially rebuilt with new wires attached to the enamel covered windings. I
have got a few ideas of how to carry this out, but I wonder if any in the
group has it fresh in their minds how to best accomplish this task. Looks
like many a restoration job to a vintage amp will need this treatment. I am
not looking forward to this :-(

Jim

"Jim Candela" wrote in message
om...
: Hi Group,
:
: So I thought I'd re-cap my Sherwood S8000 amp/FM. Ha Ha Ha. I
discovered
: that all three transformers have nice HV sleeving over the wires, but the
: sleeving starts at about 1/4" outside the transformer! The old insulation
: underneath is gone, and the wires are bare exiting the transformers. The
: bare wiring has turned green, and one wire just fell off by moving it
around
: a little to remove a capacitor. Looks like all three transformers need to
be
: partially rebuilt with new wires attached to the enamel covered windings.
I
: have got a few ideas of how to carry this out, but I wonder if any in the
: group has it fresh in their minds how to best accomplish this task. Looks
: like many a restoration job to a vintage amp will need this treatment. I
am
: not looking forward to this :-(
:
: Jim
:
Hehe, hope you didn't buy monster-speakercable for this baby to 'mprove da
sound.
Wow, corroded through copper wire, you must be living tucked in between the
sea and a
bunch of heavy industry charcoal burning plants! Sorry, no usefull comments
'bout the
transformer,
Cheers,
Rudy

Art Student : If it's technical, can it be Art ?
Anthro Student : If it's mostly technical, can it be Black Art ?
Homer Simpson : If it's a grey day, it's a Great Day to Fart !

"Ruud Broens" wrote in message
...

"Jim Candela" wrote in message
om...
: Hi Group,
:
: So I thought I'd re-cap my Sherwood S8000 amp/FM. Ha Ha Ha. I
discovered
: that all three transformers have nice HV sleeving over the wires, but
the
: sleeving starts at about 1/4" outside the transformer! The old
insulation
: underneath is gone, and the wires are bare exiting the transformers. The
: bare wiring has turned green, and one wire just fell off by moving it
around
: a little to remove a capacitor. Looks like all three transformers need
to
be
: partially rebuilt with new wires attached to the enamel covered
windings.
I
: have got a few ideas of how to carry this out, but I wonder if any in
the
: group has it fresh in their minds how to best accomplish this task.
Looks
: like many a restoration job to a vintage amp will need this treatment. I
am
: not looking forward to this :-(
:
: Jim
:
Hehe, hope you didn't buy monster-speakercable for this baby to 'mprove da
sound.
Wow, corroded through copper wire, you must be living tucked in between
the
sea and a
bunch of heavy industry charcoal burning plants! Sorry, no usefull
comments
'bout the
transformer,
Cheers,
Rudy


Rudy,

I guess it is somewhat my fault. I let this thing run about 5 hours /
week for 20 years without fiddling with it one bit. The ventilation was
poor, so it cooked itself yet never failed. Quite a bit of wiring needs to
be replaced besides what I mentioned. This will take some time, but should
be worth the effort. I can see a nice little DC fan blowing across the
7868's held behind the unit with some long 3" standoffs. I bought eight
Sylvania 7868's in 1983, and the first 4 are still good, and the others are
still in the box NOS. I added bias pots for each output tube, and set the
idle current to about 25 ma per tube. After 20 years they were still set
pretty close to that!

Jim

"Jim Candela" wrote in message
om...
Hi Group,

So I thought I'd re-cap my Sherwood S8000 amp/FM. Ha Ha Ha. I
discovered
that all three transformers have nice HV sleeving over the wires, but the
sleeving starts at about 1/4" outside the transformer! The old insulation
underneath is gone, and the wires are bare exiting the transformers. The
bare wiring has turned green, and one wire just fell off by moving it
around
a little to remove a capacitor. Looks like all three transformers need to
be
partially rebuilt with new wires attached to the enamel covered windings.
I
have got a few ideas of how to carry this out, but I wonder if any in the
group has it fresh in their minds how to best accomplish this task. Looks
like many a restoration job to a vintage amp will need this treatment. I
am
not looking forward to this :-(

Jim

Update:

The transformer was worse than I thought. I had to tear into it. The audio
output transformers are in the same sad state. Sigh!

See link below.

http://pages.prodigy.net/jcandela/Sherwood_S8000/

Questions:

1. The old potting material is mostly gone, hard, and brittle. If I
attach wires as is will it work, or flameout from internal arcing?

2. Should I vacuum impregnate it with varnish? If so, what kind?

3. As for a bakeout afterward, how long, and at what temperature?

4. Should I just junk the whole project, buy a $99.00 solid state
amp/tuner, unsubscribe, and go on with my life? :-)

Regards,
Jim

Jim Candela wrote:
[...]

Update:

The transformer was worse than I thought. I had to tear into it. The audio
output transformers are in the same sad state. Sigh!

See link below.

http://pages.prodigy.net/jcandela/Sherwood_S8000/

Questions:

1. The old potting material is mostly gone, hard, and brittle. If I
attach wires as is will it work, or flameout from internal arcing?

Doesn't look too bad after your cleanup, I'd bend the wires back towards
the coil (so they won't run into the bells) and trim back to about 1 cm
(1/2"), and attach new leads; then cover with several layers of shrink
wrap. That should work out fine, presuming that the transformer worked
originally.

The wires will all be pointing in the wrong direction now, of course, so
you'll have to bend them back 180 degrees (or whatever) to bring them
out through the openings in the bells. Perhaps needless to say, leave
yourself long runs of wire so you don't have to splice into them
afterwards.

I'd also suggest installing new bolts, preferably hardened. These have
little radial lines cast into the head, the more lines the harder it is.
Three should be fine. You can find these at industrial supply houses
(not the usual hardware store). Then torque the living daylights out of
them.

2. Should I vacuum impregnate it with varnish? If so, what kind?

3. As for a bakeout afterward, how long, and at what temperature?

I'll leave those two Q's to others (such as Patrick Turner) who do such
things routinely....

4. Should I just junk the whole project, buy a $99.00 solid state
amp/tuner, unsubscribe, and go on with my life? :-)

[Beaker voice] Nonononono-no!

Cheers,
Fred
--
+--------------------------------------------+
| Music: http://www3.telus.net/dogstarmusic/ |
| Projects: http://dogstar.dantimax.dk |
+--------------------------------------------+

The transformer was worse than I thought. I had to tear into it. The audio
output transformers are in the same sad state. Sigh!

See link below.

http://pages.prodigy.net/jcandela/Sherwood_S8000/

Questions:

1. The old potting material is mostly gone, hard, and brittle. If I
attach wires as is will it work, or flameout from internal arcing?


That should work (attaching new wires to the stubs). Internal arcing is
unlikely, even with
cracks in the potting. Only thing is that when you attach new wires
(using heat shrink), you
might not be able to fit the bell onto the transformer all the way. I'd
just use some washers
or spacers to hold the bell a small distance from the core to accomidate
the wires. I figure
that you will need to fold the splice area over onto the body of the
windings, and loop the new
wire to the exit holes of the bell. I doubt that the splices will fit
the exit holes directly.

Jim,

Sorry about your Sherwood. I've redone a couple of them. One that didn't
make it was stripped and my neighbor has the output trannies. I think I
threw the rest of the chassis away with the IF cans. ;-(

Based upon what you describe it may be best to cut your losses. Sell it on
eBay and say it needs work . . . You should get enough $$ to buy a Sansui
500A. The 500A is similar to the 1000A but less power (it has Nuvistors in
the front end like it's big brother). It uses 7189A tubes or the Russian
replacements (if you add a wire or two to the sockets).

The Sansui has a better FM section than the Sherwood. Includes AM, too.
And you can recap it until your heart's content, 'cause all of those little
gray coupling caps will have to go!

Good luck . . .

- Jon

From: "Jim Candela"
Organization: SBC http://yahoo.sbc.com
Newsgroups: rec.audio.tubes
Date: Wed, 29 Oct 2003 03:34:02 GMT
Subject: Sherwood S8000 Restoration Saga


"Jim Candela" wrote in message
om...
Hi Group,

So I thought I'd re-cap my Sherwood S8000 amp/FM. Ha Ha Ha. I
discovered
that all three transformers have nice HV sleeving over the wires, but the
sleeving starts at about 1/4" outside the transformer! The old insulation
underneath is gone, and the wires are bare exiting the transformers. The
bare wiring has turned green, and one wire just fell off by moving it
around
a little to remove a capacitor. Looks like all three transformers need to
be
partially rebuilt with new wires attached to the enamel covered windings.
I
have got a few ideas of how to carry this out, but I wonder if any in the
group has it fresh in their minds how to best accomplish this task. Looks
like many a restoration job to a vintage amp will need this treatment. I
am
not looking forward to this :-(

Jim

Update:

The transformer was worse than I thought. I had to tear into it. The audio
output transformers are in the same sad state. Sigh!

See link below.

http://pages.prodigy.net/jcandela/Sherwood_S8000/

Questions:

1. The old potting material is mostly gone, hard, and brittle. If I
attach wires as is will it work, or flameout from internal arcing?

2. Should I vacuum impregnate it with varnish? If so, what kind?

3. As for a bakeout afterward, how long, and at what temperature?

4. Should I just junk the whole project, buy a $99.00 solid state
amp/tuner, unsubscribe, and go on with my life? :-)

Regards,
Jim