Old Heathkit O-11 Smokes.

[Cyber Vagrant]

I picked up an old heathkit O-11 at a garage sale for a few bucks. It
seems to work but makes a slight sizzling sound and after being on for
a few minutes emitts smoke. I think it is the caps in the power
supply. Does anybody know if these units can be rehabed?

 

[Robert Baer]

I picked up an old heathkit O-11 at a garage sale for a few bucks. It
seems to work but makes a slight sizzling sound and after being on for
a few minutes emitts smoke. I think it is the caps in the power
supply. Does anybody know if these units can be rehabed?

Well, sort-of.
One, use your nose and eyes and see if you can locate the stinky part
(do not turn it on).
Usually the electrolytics need either forming or replacement; prolly
too late to try re-forming.
It is possible the problem is in the transformer, which is special -
it has a rather high voltage winding for the CRT, as i remember.
That winding has a tendency to break down, which results in what you
discovered (but ther may be other reasons for the smoke).
If the transformer is definitely the stinky part, then it is a very
good bet that HV winding is bad.
If you took the transformer laminations off, thenyou may get a better
look to find out if that winding is the outer-most one.
If so, then one could replace it, using better materials.
Count the turns per layer for the first 2 or 3 layers, and the number
of layers for the total turns.
You can use thin mylar tape for insulation in place wher paper was
used when you re-wind.
When the transformer in my O-1 when bad, i ordered a replacement
transformer from Heath (the O-1 was a kit still being sold then).
Be advised that this project would be useful only for re-habilitation
for working antique sales or other profitable purposes.
The O-1, while better than a number of the other inexpensive kits and
scopes at that time, you can get far better (used) scopes now for a cost
less than the time involved for restoration.

 

[Cyber Vagrant]

Reforming, that's when you use a variac and warm up the unit at a
lower voltage for a while?

CV

 

[Cyber Vagrant]

The large Astron can cap seems to have leaked. It's rated at 40mfd,
20mfd, 20mfd and 50mfd at 450 ,450, 450 and 300VDC respectively. When
I turned it on, the first and only time. A green dot appeared on the
tube and the controls seemed to affect it properly. Anybody want it
for parts? Make me an offer

 

[Robert Baer]

Reforming, that's when you use a variac and warm up the unit at a
lower voltage for a while?

CV

Aye-Yup!
And crank up slowly.

 

[Watson A.Name - Watt Sun, Dark Remover]

I picked up an old heathkit O-11 at a garage sale for a few bucks. It
seems to work but makes a slight sizzling sound and after being on for
a few minutes emitts smoke. I think it is the caps in the power
supply. Does anybody know if these units can be rehabed?

Some of the caps are over a thousand volts. They're filtering for the
tube's high voltage.

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

 

[Watson A.Name - Watt Sun, Dark Remover]

Well, sort-of.
One, use your nose and eyes and see if you can locate the stinky part
(do not turn it on).
Usually the electrolytics need either forming or replacement; prolly
too late to try re-forming.
It is possible the problem is in the transformer, which is special -
it has a rather high voltage winding for the CRT, as i remember.
That winding has a tendency to break down, which results in what you
discovered (but ther may be other reasons for the smoke).
If the transformer is definitely the stinky part, then it is a very
good bet that HV winding is bad.
If you took the transformer laminations off, thenyou may get a better
look to find out if that winding is the outer-most one.
If so, then one could replace it, using better materials.
Count the turns per layer for the first 2 or 3 layers, and the number
of layers for the total turns.
You can use thin mylar tape for insulation in place wher paper was
used when you re-wind.

I'd stick with paper, if the proper kind is used it would be better
for a transformer that's in hot tube equipment.

When the transformer in my O-1 when bad, i ordered a replacement
transformer from Heath (the O-1 was a kit still being sold then).
Be advised that this project would be useful only for re-habilitation
for working antique sales or other profitable purposes.
The O-1, while better than a number of the other inexpensive kits and
scopes at that time, you can get far better (used) scopes now for a cost
less than the time involved for restoration.

Really. And they won't be using toobs. One thing that could be donw
is if the high V winding is the problem and the rest of the
transformer works okay, then use a tripler or more for the high V.

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

 

[Robert Baer]

I'd stick with paper, if the proper kind is used it would be better
for a transformer that's in hot tube equipment.


Really. And they won't be using toobs. One thing that could be donw
is if the high V winding is the problem and the rest of the
transformer works okay, then use a tripler or more for the high V.

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

The problem is, that there are shorted turns in the transformer -
which will mwke it overheat.
So one should *not* use it!

 

[Michael A. Terrell]

The problem is, that there are shorted turns in the transformer -
which will mwke it overheat.
So one should *not* use it!

I have seen a lot of these old Heath, Eico and RCA tube scopes with a
separate filament transformer added because the insulation was breaking
down in the original transformer, and people used them daily, for years.
--
9 days!


Michael A. Terrell
Central Florida

 

[Robert Baer]

I have seen a lot of these old Heath, Eico and RCA tube scopes with a
separate filament transformer added because the insulation was breaking
down in the original transformer, and people used them daily, for years.
--
9 days!

Michael A. Terrell
Central Florida

The transformer in the Heath supplys everything, and if the CRT HV
winding goes, then it needs replacement or re-winding.

 

[Michael A. Terrell]

The transformer in the Heath supplys everything, and if the CRT HV
winding goes, then it needs replacement or re-winding.

Robert, i have disconnected the separate 6.3 volt winding from the
CRT and replaced it with a separate transformer and had it work quite a
few times. I've done it to Heath, Eico, RCA, and other brands. It
depends on the problems in the original transformer, but its a lot
better than trashing a scope if you don't have another to replace it
with.
--
8 days!


Michael A. Terrell
Central Florida

 

[Robert Baer]

Robert, i have disconnected the separate 6.3 volt winding from the
CRT and replaced it with a separate transformer and had it work quite a
few times. I've done it to Heath, Eico, RCA, and other brands. It
depends on the problems in the original transformer, but its a lot
better than trashing a scope if you don't have another to replace it
with.
--
8 days!

Michael A. Terrell
Central Florida

Well, like i said, there are a number of windings on the power
transformer, and all of the failures i saw and/or experienced were
related to the CRT high voltage winding.
If there was arcing in any of the HV windings, or arc-over to any
other winding, it is not safe to use the transformer without complete
repair/replacement.
Now, if (somehow) a filament winding fails open, *then* your strategy
is acceptable.