Last week Ernie Leimkuhler held a mig welding tutorial at Grant's
place ( Thanks again Grant and ernie!). Ernie told me that the high
voltage caps in the high frequency circuit go bad and it is hard to
find replacements for them. I had noticed that something was dripping
on the floor underneath the Miller Goldstar welder. I searched in
without success for the source of the drips. Then yesterday I found
the source while wiring in an extra relay and receptacle. The relay
connects the receptacle to 115 volts which then powers up the water
cooler for tig welding. The source is the high voltage capacitors.
some kind of oily substance is coming out of them and dripping down
the red phenolic mounting board. Ernie was right, these caps are hard
to find. In fact, using google tonight to find these caps was
fruitless. They are mica capacitors. Can types other than mica be
used? And can they be paralleled to increase the value? Is there a
better type than mica? And finally, does anybody here have some to
sell?
Thanks,
Eric R Snow

Eric R Snow tesnow@whidbeydotcom wrote:
Last week Ernie Leimkuhler held a mig welding tutorial at Grant's
place ( Thanks again Grant and ernie!). Ernie told me that the high
voltage caps in the high frequency circuit go bad and it is hard to
find replacements for them. I had noticed that something was dripping
on the floor underneath the Miller Goldstar welder. I searched in
without success for the source of the drips. Then yesterday I found
the source while wiring in an extra relay and receptacle. The relay
connects the receptacle to 115 volts which then powers up the water
cooler for tig welding. The source is the high voltage capacitors.
some kind of oily substance is coming out of them and dripping down
the red phenolic mounting board. Ernie was right, these caps are hard
to find. In fact, using google tonight to find these caps was
fruitless. They are mica capacitors. Can types other than mica be
used? And can they be paralleled to increase the value? Is there a
better type than mica? And finally, does anybody here have some to
sell?
Thanks,
Eric R Snow

post pics of the caps and any markings on them.

"Eric R Snow" tesnow@whidbeyDOTcom wrote in message
...
Last week Ernie Leimkuhler held a mig welding tutorial at Grant's
place ( Thanks again Grant and ernie!). Ernie told me that the high
voltage caps in the high frequency circuit go bad and it is hard to
find replacements for them. I had noticed that something was dripping
on the floor underneath the Miller Goldstar welder. I searched in
without success for the source of the drips. Then yesterday I found
the source while wiring in an extra relay and receptacle. The relay
connects the receptacle to 115 volts which then powers up the water
cooler for tig welding. The source is the high voltage capacitors.
some kind of oily substance is coming out of them and dripping down
the red phenolic mounting board. Ernie was right, these caps are hard
to find. In fact, using google tonight to find these caps was
fruitless. They are mica capacitors. Can types other than mica be
used? And can they be paralleled to increase the value? Is there a
better type than mica? And finally, does anybody here have some to
sell?
Thanks,
Eric R Snow

I would expect Miller to have the parts available, at least unless the
welder is an antique. It's a big part of why I bought a Miller instead of
an off-shore el-cheapo. That being said, in order to find a suitable
replacement from other sources, you need to know the characteristics of the
capacitor you are trying to replace. And it is more than just the
capacitance and voltage. Many types of capacitors don't take kindly to
being charged backward and, if you put AC across them, they'll literally
explode. Even if they have enough of a DC charge on them that they never
see a reverse polarity, if they have a significant effective series
resistance (ESR), they'll get hot and blow if there is a substantial AC
signal riding on the DC. And this just scratches the surface...

Jerry

On Sun, 16 Oct 2005 03:36:40 GMT, tesnow@whidbeyDOTcom (Eric R Snow)
wrote:

Last week Ernie Leimkuhler held a mig welding tutorial at Grant's
place ( Thanks again Grant and ernie!). Ernie told me that the high
voltage caps in the high frequency circuit go bad and it is hard to
find replacements for them. I had noticed that something was dripping
on the floor underneath the Miller Goldstar welder. I searched in
without success for the source of the drips. Then yesterday I found
the source while wiring in an extra relay and receptacle. The relay
connects the receptacle to 115 volts which then powers up the water
cooler for tig welding. The source is the high voltage capacitors.
some kind of oily substance is coming out of them and dripping down
the red phenolic mounting board. Ernie was right, these caps are hard
to find. In fact, using google tonight to find these caps was
fruitless. They are mica capacitors. Can types other than mica be
used? And can they be paralleled to increase the value? Is there a
better type than mica? And finally, does anybody here have some to
sell?
Thanks,
Eric R Snow

You'll need to know working voltage and capacitance. Then google on
"transmitting mica". High voltage mica caps are routinely used in
radio transmitters. Yes, they can be paralleled to get the required
capacitance. If size, performance and cost are the measures of
"better", I doubt if there's a better cap for this app than mica.

high voltage mica caps aren't hard to find, I have a 30,000 VAC mica cap
sitting here at this moment - it's about 8 inches X 6 inches X 12 inches,
with a 8 inch insulator on top, the case is one terminal, the other is on
top of the insulator.

I suspect your TIG welder needs a lower voltage.

Mica has particular dielectric benefits in certain frequency bands - and oil
dripping out is not a real problem, jsut remove the cap, refill with oil and
seal it again. use mineral oil if you can't find capacitor oil.


" They are mica capacitors. Can types other than mica be
used? And can they be paralleled to increase the value? Is there a
better type than mica? And finally, does anybody here have some to
sell?
Thanks,
Eric R Snow

"william_b_noble" wrote in message
news:1129443990.371761fa123e7cca0b6df5fa678f46c1@t eranews...
high voltage mica caps aren't hard to find, I have a 30,000 VAC mica cap
sitting here at this moment - it's about 8 inches X 6 inches X 12 inches,
with a 8 inch insulator on top, the case is one terminal, the other is on
top of the insulator.

I suspect your TIG welder needs a lower voltage.

Mica has particular dielectric benefits in certain frequency bands - and
oil dripping out is not a real problem, jsut remove the cap, refill with
oil and seal it again. use mineral oil if you can't find capacitor oil.

Just make sure it's oil in there, not PCB. What vintage is the machine?

regards,

John

On Sun, 16 Oct 2005 03:36:40 GMT, tesnow@whidbeyDOTcom (Eric R Snow)
wrote:

Last week Ernie Leimkuhler held a mig welding tutorial at Grant's
place ( Thanks again Grant and ernie!). Ernie told me that the high
voltage caps in the high frequency circuit go bad and it is hard to
find replacements for them. I had noticed that something was dripping
on the floor underneath the Miller Goldstar welder. I searched in
without success for the source of the drips. Then yesterday I found
the source while wiring in an extra relay and receptacle. The relay
connects the receptacle to 115 volts which then powers up the water
cooler for tig welding. The source is the high voltage capacitors.
some kind of oily substance is coming out of them and dripping down
the red phenolic mounting board. Ernie was right, these caps are hard
to find. In fact, using google tonight to find these caps was
fruitless. They are mica capacitors. Can types other than mica be
used? And can they be paralleled to increase the value? Is there a
better type than mica? And finally, does anybody here have some to
sell?
Thanks,
Eric R Snow

Oh oh....Now Erics place is a Hazmat site. PCBs...Run Erick Run!!1


G


http://www.arcowelder.com/

Call and ask for Dennis. Tell him Gunner refered you. Id be surprised
if he didnt have some good used ones kicking around

Gunner

"Pax Americana is a philosophy. Hardly an empire.
Making sure other people play nice and dont kill each other (and us)
off in job lots is hardly empire building, particularly when you give
them self determination under "play nice" rules.

Think of it as having your older brother knock the **** out of you
for torturing the cat." Gunner

On Sat, 15 Oct 2005 23:26:26 -0700, "william_b_noble"
wrote:

high voltage mica caps aren't hard to find, I have a 30,000 VAC mica cap
sitting here at this moment - it's about 8 inches X 6 inches X 12 inches,
with a 8 inch insulator on top, the case is one terminal, the other is on
top of the insulator.

I suspect your TIG welder needs a lower voltage.

Mica has particular dielectric benefits in certain frequency bands - and oil
dripping out is not a real problem, jsut remove the cap, refill with oil and
seal it again. use mineral oil if you can't find capacitor oil.


Capacitor oil kinda sounds like skyhooks and file grease. I'm sure
it's not. I'll look for it and try to see why the things are leaking.
Will oil loss make the capacitance lower?
Eric
" They are mica capacitors. Can types other than mica be
used? And can they be paralleled to increase the value? Is there a
better type than mica? And finally, does anybody here have some to
sell?
Thanks,
Eric R Snow

On Sun, 16 Oct 2005 19:11:32 +1000, "john johnson"
wrote:


"william_b_noble" wrote in message
news:1129443990.371761fa123e7cca0b6df5fa678f46c1@ teranews...
high voltage mica caps aren't hard to find, I have a 30,000 VAC mica cap
sitting here at this moment - it's about 8 inches X 6 inches X 12 inches,
with a 8 inch insulator on top, the case is one terminal, the other is on
top of the insulator.

I suspect your TIG welder needs a lower voltage.

Mica has particular dielectric benefits in certain frequency bands - and
oil dripping out is not a real problem, jsut remove the cap, refill with
oil and seal it again. use mineral oil if you can't find capacitor oil.

Just make sure it's oil in there, not PCB. What vintage is the machine?

regards,

John

The machine was built in the early seventies. Were PCBs used then? I
think they were. If they are leaking PCBs then wouldn't the best fix
be just re-filling with non PCB oil and sealing them? I could take
them to the county as hazmat but then they would have to deal with
them.
ERS

john johnson wrote:

Just make sure it's oil in there, not PCB. What vintage is the machine?

regards,

John

Mmmmmmmmmmmm! IMO, nothing beats PCB's spread on a ritz cracker :-)

On Sun, 16 Oct 2005 22:19:19 +0000 (UTC), Cydrome Leader
wrote:

Eric R Snow wrote:
On Sat, 15 Oct 2005 23:26:26 -0700, "william_b_noble"
wrote:

high voltage mica caps aren't hard to find, I have a 30,000 VAC mica cap
sitting here at this moment - it's about 8 inches X 6 inches X 12 inches,
with a 8 inch insulator on top, the case is one terminal, the other is on
top of the insulator.

I suspect your TIG welder needs a lower voltage.

Mica has particular dielectric benefits in certain frequency bands - and oil
dripping out is not a real problem, jsut remove the cap, refill with oil and
seal it again. use mineral oil if you can't find capacitor oil.


Capacitor oil kinda sounds like skyhooks and file grease. I'm sure
it's not. I'll look for it and try to see why the things are leaking.
Will oil loss make the capacitance lower?

Pics and part numbers.

I deal with high voltage capacitors and would love
to help, but you need to provide info on the part itself.
I thought I'd already posted a message concerning pics in the dropbox.
I will be taking pics tomorrow and posting them in the dropbox. In the
meantime here's the info on the capacitor:
GAMO TYPE
MICA CAP
Miller Electric P/N 31-602
And from the manual:
Capacitor, mica .002 uf 6000 volt
The capacitors themselves have places on them for Amps, Volts, MFD,
but these spaces are blank. I hope the info above will help.
Thanks,
eric

On Sun, 16 Oct 2005 18:29:24 -0400, Joseph Gwinn
wrote:

In article ,
Eric R Snow wrote:

On Sat, 15 Oct 2005 23:26:26 -0700, "william_b_noble"
wrote:

high voltage mica caps aren't hard to find, I have a 30,000 VAC mica cap
sitting here at this moment - it's about 8 inches X 6 inches X 12 inches,
with a 8 inch insulator on top, the case is one terminal, the other is on
top of the insulator.

I suspect your TIG welder needs a lower voltage.

Mica has particular dielectric benefits in certain frequency bands - and oil
dripping out is not a real problem, jsut remove the cap, refill with oil and
seal it again. use mineral oil if you can't find capacitor oil.


Capacitor oil kinda sounds like skyhooks and file grease. I'm sure
it's not. I'll look for it and try to see why the things are leaking.
Will oil loss make the capacitance lower?

No. The oil is to prevent flashover within the case, and to cool the
mica, which does the heavy lifting. Flashover within a capacitor in a
welder may destroy the capacitor, so I'd make sure there is enough oil
in the capacitor case.

Joe Gwinn
The oil has been leaking for a long time. I thought it was something
else. If flashover occurs will it act like a short? And would this
prevent any high frequency at all? I ask because the high frequency is
weak and always has been. But it is there. The spark gaps work. But
every Goldstar machine I've used has been the same. Maybe they all
have defective caps. On Lincoln machines you could see purple sparks
emanating from the tip of the tungsten and dissipating into the air.
But Miller Goldstar machines I've used never would do that.
Eric

Eric
" They are mica capacitors. Can types other than mica be
used? And can they be paralleled to increase the value? Is there a
better type than mica? And finally, does anybody here have some to
sell?
Thanks,
Eric R Snow

Eric R Snow wrote:

On Sat, 15 Oct 2005 23:26:26 -0700, "william_b_noble"
wrote:

high voltage mica caps aren't hard to find, I have a 30,000 VAC mica cap
sitting here at this moment - it's about 8 inches X 6 inches X 12 inches,
with a 8 inch insulator on top, the case is one terminal, the other is on
top of the insulator.

I suspect your TIG welder needs a lower voltage.

Mica has particular dielectric benefits in certain frequency bands - and oil
dripping out is not a real problem, jsut remove the cap, refill with oil and
seal it again. use mineral oil if you can't find capacitor oil.


Capacitor oil kinda sounds like skyhooks and file grease. I'm sure
it's not. I'll look for it and try to see why the things are leaking.
Will oil loss make the capacitance lower?
Eric
" They are mica capacitors. Can types other than mica be
used? And can they be paralleled to increase the value? Is there a
better type than mica? And finally, does anybody here have some to
sell?
Thanks,
Eric R Snow



Here is a site with hv mica caps. I would use this one:
CFT) 224M356 .001 µF (dual) 10 kv 1-1/8" x 1-7/8" 9.00

IF it is a dual cap you can parallel it to get the .002 uf that you
need. The cap is rated at 10 kv which is just the voltage rating. A
higher rating will work the same.


http://www.surplussales.com/Capacito...misctrans.html



John

Eric R Snow wrote:
On Sun, 16 Oct 2005 22:19:19 +0000 (UTC), Cydrome Leader
wrote:

Eric R Snow wrote:
On Sat, 15 Oct 2005 23:26:26 -0700, "william_b_noble"
wrote:

high voltage mica caps aren't hard to find, I have a 30,000 VAC mica cap
sitting here at this moment - it's about 8 inches X 6 inches X 12 inches,
with a 8 inch insulator on top, the case is one terminal, the other is on
top of the insulator.

I suspect your TIG welder needs a lower voltage.

Mica has particular dielectric benefits in certain frequency bands - and oil
dripping out is not a real problem, jsut remove the cap, refill with oil and
seal it again. use mineral oil if you can't find capacitor oil.


Capacitor oil kinda sounds like skyhooks and file grease. I'm sure
it's not. I'll look for it and try to see why the things are leaking.
Will oil loss make the capacitance lower?

Pics and part numbers.

I deal with high voltage capacitors and would love
to help, but you need to provide info on the part itself.
I thought I'd already posted a message concerning pics in the dropbox.
I will be taking pics tomorrow and posting them in the dropbox. In the
meantime here's the info on the capacitor:
GAMO TYPE
MICA CAP
Miller Electric P/N 31-602
And from the manual:
Capacitor, mica .002 uf 6000 volt

The physical case sounds really large for such a capacitor, especially a
mica one.

Induction heater polypropylene caps might be an acceptable replacement.

Does anybody know what frequenecy these welders operate at, and possible
RMS current levels these caps see?

Size alone and that these are mica says you're going to need a AC rated,
probably RF duty cap. No bathtub cap or filter cap will work.

Eric R Snow wrote:

On Sun, 16 Oct 2005 19:11:32 +1000, "john johnson"
wrote:


"william_b_noble" wrote in message
news:1129443990.371761fa123e7cca0b6df5fa678f46c1@ teranews...
high voltage mica caps aren't hard to find, I have a 30,000 VAC mica cap
sitting here at this moment - it's about 8 inches X 6 inches X 12 inches,
with a 8 inch insulator on top, the case is one terminal, the other is on
top of the insulator.

I suspect your TIG welder needs a lower voltage.

Mica has particular dielectric benefits in certain frequency bands - and
oil dripping out is not a real problem, jsut remove the cap, refill with
oil and seal it again. use mineral oil if you can't find capacitor oil.

Just make sure it's oil in there, not PCB. What vintage is the machine?

regards,

John

The machine was built in the early seventies. Were PCBs used then? I
think they were. If they are leaking PCBs then wouldn't the best fix
be just re-filling with non PCB oil and sealing them? I could take
them to the county as hazmat but then they would have to deal with
them.
ERS

It the cap does not have "no PCBs" printed on it than it can be assumed
to contain PCBs which means you've got a bit of a problem on your hands
if it leaked.

Pete C.

Eric R Snow wrote:

On Sun, 16 Oct 2005 19:11:32 +1000, "john johnson"
wrote:


"william_b_noble" wrote in message
news:1129443990.371761fa123e7cca0b6df5fa678f46c1@ teranews...
high voltage mica caps aren't hard to find, I have a 30,000 VAC mica cap
sitting here at this moment - it's about 8 inches X 6 inches X 12 inches,
with a 8 inch insulator on top, the case is one terminal, the other is on
top of the insulator.

I suspect your TIG welder needs a lower voltage.

Mica has particular dielectric benefits in certain frequency bands - and
oil dripping out is not a real problem, jsut remove the cap, refill with
oil and seal it again. use mineral oil if you can't find capacitor oil.

Just make sure it's oil in there, not PCB. What vintage is the machine?

regards,

John

The machine was built in the early seventies. Were PCBs used then? I
think they were. If they are leaking PCBs then wouldn't the best fix
be just re-filling with non PCB oil and sealing them? I could take
them to the county as hazmat but then they would have to deal with
them.
ERS

The following might be of use:

http://www.epa.gov/opptintr/pcb/

Pete C.

Pete C. wrote:
Eric R Snow wrote:

On Sun, 16 Oct 2005 19:11:32 +1000, "john johnson"
wrote:


"william_b_noble" wrote in message
news:1129443990.371761fa123e7cca0b6df5fa678f46c1@ teranews...
high voltage mica caps aren't hard to find, I have a 30,000 VAC mica cap
sitting here at this moment - it's about 8 inches X 6 inches X 12 inches,
with a 8 inch insulator on top, the case is one terminal, the other is on
top of the insulator.

I suspect your TIG welder needs a lower voltage.

Mica has particular dielectric benefits in certain frequency bands - and
oil dripping out is not a real problem, jsut remove the cap, refill with
oil and seal it again. use mineral oil if you can't find capacitor oil.

Just make sure it's oil in there, not PCB. What vintage is the machine?

regards,

John

The machine was built in the early seventies. Were PCBs used then? I
think they were. If they are leaking PCBs then wouldn't the best fix
be just re-filling with non PCB oil and sealing them? I could take
them to the county as hazmat but then they would have to deal with
them.
ERS

It the cap does not have "no PCBs" printed on it than it can be assumed
to contain PCBs which means you've got a bit of a problem on your hands
if it leaked.

You could also assume it's full of gold, but that's wrong too.

Eric R Snow wrote:

The oil has been leaking for a long time. I thought it was something
else. If flashover occurs will it act like a short? And would this
prevent any high frequency at all? I ask because the high frequency is
weak and always has been. But it is there. The spark gaps work. But
every Goldstar machine I've used has been the same. Maybe they all
have defective caps. On Lincoln machines you could see purple sparks
emanating from the tip of the tungsten and dissipating into the air.


No kidding! When I first started learning to use my Lincoln Square-Wave
TIG 300, I was actually WELDING with HF only. I never got the electrodes
close enough for the main welding current to flow! That was awesome that
it could melt thin metal just with the HF! Under the right conditions, I
can get 1", sometimes even 1.5" arcs from the HF, it looks just like those
plasma globe things. (After an hour of fooling around, I discovered the
main welding current by squeezing the finger control more, getting the
electrode closer, and getting a real arc to develop.) But, clearly, there
is NOTHING wrong with my HF generator.

I know that the HF system is the reason many TIG welders get junked
or converted to stick-only. The main transformer is generally very
robust, but the caps, HV transformer and spark gaps all need to be
maintained.

Jon

Cydrome Leader wrote:

Pete C. wrote:
Eric R Snow wrote:

On Sun, 16 Oct 2005 19:11:32 +1000, "john johnson"
wrote:


"william_b_noble" wrote in message
news:1129443990.371761fa123e7cca0b6df5fa678f46c1@ teranews...
high voltage mica caps aren't hard to find, I have a 30,000 VAC mica cap
sitting here at this moment - it's about 8 inches X 6 inches X 12 inches,
with a 8 inch insulator on top, the case is one terminal, the other is on
top of the insulator.

I suspect your TIG welder needs a lower voltage.

Mica has particular dielectric benefits in certain frequency bands - and
oil dripping out is not a real problem, jsut remove the cap, refill with
oil and seal it again. use mineral oil if you can't find capacitor oil.

Just make sure it's oil in there, not PCB. What vintage is the machine?

regards,

John

The machine was built in the early seventies. Were PCBs used then? I
think they were. If they are leaking PCBs then wouldn't the best fix
be just re-filling with non PCB oil and sealing them? I could take
them to the county as hazmat but then they would have to deal with
them.
ERS

It the cap does not have "no PCBs" printed on it than it can be assumed
to contain PCBs which means you've got a bit of a problem on your hands
if it leaked.

You could also assume it's full of gold, but that's wrong too.

I believe that all fluorescent ballasts, oil filled capacitors and oil
filled transformers manufactured since the ban on PCBs are required by
law to state "no PCBs". Presumably there may have been some transition
period where non-PCB units may not have been marked, but it should be a
reasonably safe assumption that if it doesn't say "no PCBs" it likely
has some level of PCBs.

From: http://www.epa.gov/opptintr/pcb/2003pt761.txt

[63 FR 35443, June 29, 1998]

Subpart C--Marking of PCBs and PCB Items

Sec. 761.40 Marking requirements.

(g) Each large low voltage capacitor, each small capacitor normally
used in alternating current circuits, and each fluorescent light ballast
manufactured (``manufactured'', for purposes of this sentence, means
built) between July 1, 1978 and July 1, 1998 that do not contain PCBs
shall be marked by the manufacturer at the time of manufacture with the
statement, ``No PCBs''. The mark shall be of similar durability and
readability as other marking that indicate electrical information, part
numbers, or the manufacturer's name. For purposes of this paragraph
marking requirement only is applicable to items built domestically or
abroad after June 30, 1978.



Pete C.

On Sun, 16 Oct 2005 15:49:54 -0700, Eric R Snow
wrote:

On Sun, 16 Oct 2005 22:19:19 +0000 (UTC), Cydrome Leader
wrote:

Eric R Snow wrote:
On Sat, 15 Oct 2005 23:26:26 -0700, "william_b_noble"
wrote:

high voltage mica caps aren't hard to find, I have a 30,000 VAC mica cap
sitting here at this moment - it's about 8 inches X 6 inches X 12 inches,
with a 8 inch insulator on top, the case is one terminal, the other is on
top of the insulator.

I suspect your TIG welder needs a lower voltage.

Mica has particular dielectric benefits in certain frequency bands - and oil
dripping out is not a real problem, jsut remove the cap, refill with oil and
seal it again. use mineral oil if you can't find capacitor oil.


Capacitor oil kinda sounds like skyhooks and file grease. I'm sure
it's not. I'll look for it and try to see why the things are leaking.
Will oil loss make the capacitance lower?

Pics and part numbers.

I deal with high voltage capacitors and would love
to help, but you need to provide info on the part itself.
I thought I'd already posted a message concerning pics in the dropbox.
I will be taking pics tomorrow and posting them in the dropbox. In the
meantime here's the info on the capacitor:
GAMO TYPE
MICA CAP
Miller Electric P/N 31-602
And from the manual:
Capacitor, mica .002 uf 6000 volt
The capacitors themselves have places on them for Amps, Volts, MFD,
but these spaces are blank. I hope the info above will help.
Thanks,
eric

See if you can find a place that services electronic air cleaners --
the kind that go into the furnace. Those have 6KV to 10KV caps in
the .001 to .002 uF range. Two mfrs are Honeywell and Trion. I
used to know a lot of guys at HON but that was a while ago now.

TV sets used to have 500 pF (.0005 uF) 20KV "doorknob" caps.

Here is a surplus place that has transmitting micas, 2000 pF (.002
uF) 6KV for $99. (Ow!)
http://www.surplussales.com/Capacito...ansP-ECap.html

Transmitting micas are much more robust than you need because they're
made to handle high RF currents. However, they certainly would work.

Cornell-Dubilier (CDE) makes a mica paper cap, partnumber:
KVX10S222K0T001 that is an .0022 uF 10KV cap. Here is a list of CDE
distributors:
http://www.cde.com/distributors/distsites.htm

Here is a selection of 10 mica doorknob caps on ebay:
http://tinyurl.com/d7a2y

No telling what the values will be, but they'll all be at least 10KV
and you probably can parallel some of them to get close to 2000 pF
(.002 uF).

Pete C. wrote:
Cydrome Leader wrote:

Pete C. wrote:
Eric R Snow wrote:

On Sun, 16 Oct 2005 19:11:32 +1000, "john johnson"
wrote:


"william_b_noble" wrote in message
news:1129443990.371761fa123e7cca0b6df5fa678f46c1@ teranews...
high voltage mica caps aren't hard to find, I have a 30,000 VAC mica cap
sitting here at this moment - it's about 8 inches X 6 inches X 12 inches,
with a 8 inch insulator on top, the case is one terminal, the other is on
top of the insulator.

I suspect your TIG welder needs a lower voltage.

Mica has particular dielectric benefits in certain frequency bands - and
oil dripping out is not a real problem, jsut remove the cap, refill with
oil and seal it again. use mineral oil if you can't find capacitor oil.

Just make sure it's oil in there, not PCB. What vintage is the machine?

regards,

John

The machine was built in the early seventies. Were PCBs used then? I
think they were. If they are leaking PCBs then wouldn't the best fix
be just re-filling with non PCB oil and sealing them? I could take
them to the county as hazmat but then they would have to deal with
them.
ERS

It the cap does not have "no PCBs" printed on it than it can be assumed
to contain PCBs which means you've got a bit of a problem on your hands
if it leaked.

You could also assume it's full of gold, but that's wrong too.

I believe that all fluorescent ballasts, oil filled capacitors and oil
filled transformers manufactured since the ban on PCBs are required by
law to state "no PCBs". Presumably there may have been some transition
period where non-PCB units may not have been marked, but it should be a
reasonably safe assumption that if it doesn't say "no PCBs" it likely
has some level of PCBs.


That's really backwards reasoning, and quite wrong too.

On Mon, 17 Oct 2005 00:39:48 +0000 (UTC), Cydrome Leader
wrote:

The physical case sounds really large for such a capacitor, especially a
mica one.

Induction heater polypropylene caps might be an acceptable replacement.

Does anybody know what frequenecy these welders operate at, and possible
RMS current levels these caps see?

The freq is typically somewhere between 1 and 8 MHz. You can
figure the RMS current from the voltage level and freq. That rating
would be very conservative because it's basically like a Marconi spark
xmtr rather than a CW-excited tank at the operative freq.

Cydrome Leader wrote:

Pete C. wrote:
Cydrome Leader wrote:

Pete C. wrote:
Eric R Snow wrote:

On Sun, 16 Oct 2005 19:11:32 +1000, "john johnson"
wrote:


"william_b_noble" wrote in message
news:1129443990.371761fa123e7cca0b6df5fa678f46c1@ teranews...
high voltage mica caps aren't hard to find, I have a 30,000 VAC mica cap
sitting here at this moment - it's about 8 inches X 6 inches X 12 inches,
with a 8 inch insulator on top, the case is one terminal, the other is on
top of the insulator.

I suspect your TIG welder needs a lower voltage.

Mica has particular dielectric benefits in certain frequency bands - and
oil dripping out is not a real problem, jsut remove the cap, refill with
oil and seal it again. use mineral oil if you can't find capacitor oil.

Just make sure it's oil in there, not PCB. What vintage is the machine?

regards,

John

The machine was built in the early seventies. Were PCBs used then? I
think they were. If they are leaking PCBs then wouldn't the best fix
be just re-filling with non PCB oil and sealing them? I could take
them to the county as hazmat but then they would have to deal with
them.
ERS

It the cap does not have "no PCBs" printed on it than it can be assumed
to contain PCBs which means you've got a bit of a problem on your hands
if it leaked.

You could also assume it's full of gold, but that's wrong too.

I believe that all fluorescent ballasts, oil filled capacitors and oil
filled transformers manufactured since the ban on PCBs are required by
law to state "no PCBs". Presumably there may have been some transition
period where non-PCB units may not have been marked, but it should be a
reasonably safe assumption that if it doesn't say "no PCBs" it likely
has some level of PCBs.

That's really backwards reasoning, and quite wrong too.

Wrong eh? I guess you didn't read the federal law section I included
that mandates the marking of all non-PCB ballasts and capacitors
manufactured domestically or abroad after June 30th 1978? Here, I'll
include it again:

From: http://www.epa.gov/opptintr/pcb/2003pt761.txt

[63 FR 35443, June 29, 1998]

Subpart C--Marking of PCBs and PCB Items

Sec. 761.40 Marking requirements.

(g) Each large low voltage capacitor, each small capacitor normally
used in alternating current circuits, and each fluorescent light ballast
manufactured (``manufactured'', for purposes of this sentence, means
built) between July 1, 1978 and July 1, 1998 that do not contain PCBs
shall be marked by the manufacturer at the time of manufacture with the
statement, ``No PCBs''. The mark shall be of similar durability and
readability as other marking that indicate electrical information, part
numbers, or the manufacturer's name. For purposes of this paragraph
marking requirement only is applicable to items built domestically or
abroad after June 30, 1978.


So, once again, if you have an oil filled AC capacitor that is not
marked "No PCBs" per federal law, it likely contains PCBs.

It would appear the the OP should take a look at the EPA info regarding
decontamination for his shop.

Pete C.

According to Pete C. :
Cydrome Leader wrote:

[ ... ]

That's really backwards reasoning, and quite wrong too.

Wrong eh? I guess you didn't read the federal law section I included
that mandates the marking of all non-PCB ballasts and capacitors
manufactured domestically or abroad after June 30th 1978? Here, I'll
include it again:

As I read what is quoted below, it would appear that any
manufactured *after* July 1 1998 (e.g. for about the past seven years)
new capacitors and ballasts are no longer required to be so marked. (I
presume that they are thinking that all are out of service by now -- or
will be so by the time these recent capacitors look old enough to be
questioned.

But beside that -- capacitors manufactured *before* June 30th
1978 (again from what you quoted below) are not required to be so
marked, and not all capacitors made prior to that date *would* have
PCBs.

From: http://www.epa.gov/opptintr/pcb/2003pt761.txt

[63 FR 35443, June 29, 1998]

Subpart C--Marking of PCBs and PCB Items

Sec. 761.40 Marking requirements.

(g) Each large low voltage capacitor, each small capacitor normally
used in alternating current circuits, and each fluorescent light ballast
manufactured (``manufactured'', for purposes of this sentence, means
built) between July 1, 1978 and July 1, 1998 that do not contain PCBs
shall be marked by the manufacturer at the time of manufacture with the
statement, ``No PCBs''. The mark shall be of similar durability and
readability as other marking that indicate electrical information, part
numbers, or the manufacturer's name. For purposes of this paragraph
marking requirement only is applicable to items built domestically or
abroad after June 30, 1978.


So, once again, if you have an oil filled AC capacitor that is not
marked "No PCBs" per federal law, it likely contains PCBs.

Unless it was manufactured after July 1, 1998, or possibly if it
was manufactured before July 1 1978 and did not happen to use PCBs.

It would appear the the OP should take a look at the EPA info regarding
decontamination for his shop.

He should at least take steps to see whether what it leaking
*is* PCBs.

When was the welder in which this capacitor was installed
manufactured? That may have been covered earlier, but I do not remember
it, and with my current news server, backtracking the threads often
fails.

Enjoy,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

"DoN. Nichols" wrote:

According to Pete C. :
Cydrome Leader wrote:

[ ... ]

That's really backwards reasoning, and quite wrong too.

Wrong eh? I guess you didn't read the federal law section I included
that mandates the marking of all non-PCB ballasts and capacitors
manufactured domestically or abroad after June 30th 1978? Here, I'll
include it again:

As I read what is quoted below, it would appear that any
manufactured *after* July 1 1998 (e.g. for about the past seven years)
new capacitors and ballasts are no longer required to be so marked. (I
presume that they are thinking that all are out of service by now -- or
will be so by the time these recent capacitors look old enough to be
questioned.

Quite possible it expired and also quite possible manufacturers have
continued to mark "No PCBs".


But beside that -- capacitors manufactured *before* June 30th
1978 (again from what you quoted below) are not required to be so
marked, and not all capacitors made prior to that date *would* have
PCBs.

The marking law corresponds with the marking law. There is a strong
probability that older non-marked capacitors do contain some level of
PCBs. The gist of the law overall is that non marked capacitors are to
be considered guilty until proven innocent as more likely than not they
will be found guilty.


From: http://www.epa.gov/opptintr/pcb/2003pt761.txt

[63 FR 35443, June 29, 1998]

Subpart C--Marking of PCBs and PCB Items

Sec. 761.40 Marking requirements.

(g) Each large low voltage capacitor, each small capacitor normally
used in alternating current circuits, and each fluorescent light ballast
manufactured (``manufactured'', for purposes of this sentence, means
built) between July 1, 1978 and July 1, 1998 that do not contain PCBs
shall be marked by the manufacturer at the time of manufacture with the
statement, ``No PCBs''. The mark shall be of similar durability and
readability as other marking that indicate electrical information, part
numbers, or the manufacturer's name. For purposes of this paragraph
marking requirement only is applicable to items built domestically or
abroad after June 30, 1978.


So, once again, if you have an oil filled AC capacitor that is not
marked "No PCBs" per federal law, it likely contains PCBs.

Unless it was manufactured after July 1, 1998, or possibly if it
was manufactured before July 1 1978 and did not happen to use PCBs.

Not sure what percentage of capacitors manufactured prior to the ban
were non-PCB. PCBs were pretty pervasive back then, likely only a year
or so before the ban that any significant quantities of non-PCB
capacitors were produced, also likely that those were marked No-PCBs as
well since the law appears to have been in development from sometime in
1976 and I'd expect manufacturers were following it closely to see what
would happen.


It would appear the the OP should take a look at the EPA info regarding
decontamination for his shop.

He should at least take steps to see whether what it leaking
*is* PCBs.

Certainly a good idea to investigate further. Presumably the cap can be
bagged and sent to a lab.


When was the welder in which this capacitor was installed
manufactured? That may have been covered earlier, but I do not remember
it, and with my current news server, backtracking the threads often
fails.

A specific date was not given, only a 70s vintage which would put it in
the right timeframe for PCBs.

Pete C.

Pete C. wrote:
Cydrome Leader wrote:

Pete C. wrote:
Cydrome Leader wrote:

Pete C. wrote:
Eric R Snow wrote:

On Sun, 16 Oct 2005 19:11:32 +1000, "john johnson"
wrote:


"william_b_noble" wrote in message
news:1129443990.371761fa123e7cca0b6df5fa678f46c1@ teranews...
high voltage mica caps aren't hard to find, I have a 30,000 VAC mica cap
sitting here at this moment - it's about 8 inches X 6 inches X 12 inches,
with a 8 inch insulator on top, the case is one terminal, the other is on
top of the insulator.

I suspect your TIG welder needs a lower voltage.

Mica has particular dielectric benefits in certain frequency bands - and
oil dripping out is not a real problem, jsut remove the cap, refill with
oil and seal it again. use mineral oil if you can't find capacitor oil.

Just make sure it's oil in there, not PCB. What vintage is the machine?

regards,

John

The machine was built in the early seventies. Were PCBs used then? I
think they were. If they are leaking PCBs then wouldn't the best fix
be just re-filling with non PCB oil and sealing them? I could take
them to the county as hazmat but then they would have to deal with
them.
ERS

It the cap does not have "no PCBs" printed on it than it can be assumed
to contain PCBs which means you've got a bit of a problem on your hands
if it leaked.

You could also assume it's full of gold, but that's wrong too.

I believe that all fluorescent ballasts, oil filled capacitors and oil
filled transformers manufactured since the ban on PCBs are required by
law to state "no PCBs". Presumably there may have been some transition
period where non-PCB units may not have been marked, but it should be a
reasonably safe assumption that if it doesn't say "no PCBs" it likely
has some level of PCBs.

That's really backwards reasoning, and quite wrong too.

Wrong eh? I guess you didn't read the federal law section I included
that mandates the marking of all non-PCB ballasts and capacitors
manufactured domestically or abroad after June 30th 1978? Here, I'll
include it again:

Yes, I stand corrected. The original post was from a man looking for a new
lighting ballast for his shoplight, and not a capacitor from a welder.


From: http://www.epa.gov/opptintr/pcb/2003pt761.txt

[63 FR 35443, June 29, 1998]

Subpart C--Marking of PCBs and PCB Items

Sec. 761.40 Marking requirements.

(g) Each large low voltage capacitor, each small capacitor normally
used in alternating current circuits, and each fluorescent light ballast
manufactured (``manufactured'', for purposes of this sentence, means
built) between July 1, 1978 and July 1, 1998 that do not contain PCBs
shall be marked by the manufacturer at the time of manufacture with the
statement, ``No PCBs''. The mark shall be of similar durability and
readability as other marking that indicate electrical information, part
numbers, or the manufacturer's name. For purposes of this paragraph
marking requirement only is applicable to items built domestically or
abroad after June 30, 1978.


So, once again, if you have an oil filled AC capacitor that is not
marked "No PCBs" per federal law, it likely contains PCBs.

It would appear the the OP should take a look at the EPA info regarding
decontamination for his shop.

Pete C.

Don Foreman wrote:
On Mon, 17 Oct 2005 00:39:48 +0000 (UTC), Cydrome Leader
wrote:

The physical case sounds really large for such a capacitor, especially a
mica one.

Induction heater polypropylene caps might be an acceptable replacement.

Does anybody know what frequenecy these welders operate at, and possible
RMS current levels these caps see?

The freq is typically somewhere between 1 and 8 MHz. You can
figure the RMS current from the voltage level and freq. That rating
would be very conservative because it's basically like a Marconi spark
xmtr rather than a CW-excited tank at the operative freq.

I just dug up two old Cornell Dublier mica transmitting caps. Each is
rated 0.004uF at 12kV and 22A @ 3MHz. Used in series they would provide
the correct capacitance of 0.002uF and should be quite suitable for 6kV
use. They would fit into an approximately 6" cube box each.

Remove the MUNGE from my email address to contact me directly for more
info.

Ignoramus27736 wrote:
Just wanted to say something, possibly unrelated. To the person
looking for mica caps, first check if they are indeed bad. They should
show infinite resistance when unplugged. You can also try charging
them with low voltage, and see if you get a spark in a screwdriver
test.

You're not going to get any sparks off a 0.002uF cap charged to low
voltages.


The reason why I am saying this is that I also was dismayed to find
that HF was not working in my welder. It turned out, simply, that it
was wired for a remote arc starter. I rewired it for the local starter
and it all works.

i