I have a bad and good CRT. I want to swap out BAD CRT with the
(known compatible) good one.

The CRT's HV wires have a special plug/jack into the HV
multiplier (flyback) so there is no flaky splicing to worry with.

The good CRT has (too) short HV wire. The wire does not reach the
HV multiplier (flyback).

I was told that i can carefully cut under silicon blob where HV
wire attaches to CRT and unsolder wire then solder the long one
in place ?yes/no? Then re-cover with silicon.
Let silcon dry/cure (**** completely ****) !!!

Questions :
0. Is this a feasible repair ?
1. What silicon do i buy (from local hardware?) ? is that special
silicon ?
2. Good CRT has 2" copper tape over the silicon blob / HV wire.
a. Do i need to replace this tape ?
b. can i use aluminum tape like for duct work ?
that is the real Aluminum tape with just sticky stuff
(no foam /vinyl/etc)
c. How can i get old piece copper tape to stick back ?
d. Any alternatives to the copper tape ?
3. Any special cleaning or surface prep needed to do this repair?

thanks for any help,
robb

"robb" wrote in message
...
I have a bad and good CRT. I want to swap out BAD CRT with the
(known compatible) good one.

The CRT's HV wires have a special plug/jack into the HV
multiplier (flyback) so there is no flaky splicing to worry with.

The good CRT has (too) short HV wire. The wire does not reach the
HV multiplier (flyback).

I was told that i can carefully cut under silicon blob where HV
wire attaches to CRT and unsolder wire then solder the long one
in place ?yes/no? Then re-cover with silicon.
Let silcon dry/cure (**** completely ****) !!!

Questions :
0. Is this a feasible repair ?
1. What silicon do i buy (from local hardware?) ? is that special
silicon ?
2. Good CRT has 2" copper tape over the silicon blob / HV wire.
a. Do i need to replace this tape ?
b. can i use aluminum tape like for duct work ?
that is the real Aluminum tape with just sticky stuff
(no foam /vinyl/etc)
c. How can i get old piece copper tape to stick back ?
d. Any alternatives to the copper tape ?
3. Any special cleaning or surface prep needed to do this repair?

thanks for any help,
robb



What kind of CRT is this that the wire is soldered on? I've never seen on
that didn't have a metal cup that the wire just clips into, not saying they
don't exist, but I've yet to ever come across one.

The copper tape is used as shielding, you can buy it from a lot of different
places, just do a google search. You ought to be able to stick it back on
with double sided plastic tape if the original adhesive is not reusable.

"James Sweet" wrote in message
news:wZ8kj.2039$5h6.1213@trndny09...

"robb" wrote in message
...

What kind of CRT is this that the wire is soldered on? I've
never seen on
that didn't have a metal cup that the wire just clips into, not
saying they
don't exist, but I've yet to ever come across one.

out of a Tek o-scope

robb

"robb" wrote in message
...

"James Sweet" wrote in message
news:wZ8kj.2039$5h6.1213@trndny09...

"robb" wrote in message
...

What kind of CRT is this that the wire is soldered on? I've
never seen on
that didn't have a metal cup that the wire just clips into, not
saying they
don't exist, but I've yet to ever come across one.

out of a Tek o-scope

robb


Personally, I think that at last initially, I would feel inclined to leave
the factory connection to the good CRT alone, and go down the splicing
route. If you do a really nice job of soldering the two wire tails side by
side with a generous 'blob' of solder to make sure that there are no spikes,
you shouldn't have an intitial problem with corona discharge. When you are
happy with the solder joint, use a piece of insulation sleeve, slit
lengthwise, to cover the join. Before making the soldered joint, slide a
couple of lengths of hetshrink tubing over the lead. When you have your slit
tubing in place over the joint, work a bit of silicon rubber into the slit,
around the joint, then shrink the first piece of tubing over the whole
joint. When that has cooled down, slide the second (slightly longer) piece
over the whole lot.

I have spliced several high voltage wires of various types over the years,
using basically this method, and have never had a problem. And at least if
it doesn't work for you, you've then still got the damage-riskier option of
trying to get a good bond at the actual CRT connection.

Arfa

Meat Plow wrote in
:

On Sat, 19 Jan 2008 10:35:41 +0000, Arfa Daily wrote:


"robb" wrote in message
...

"James Sweet" wrote in message
news:wZ8kj.2039$5h6.1213@trndny09...

"robb" wrote in message
...

What kind of CRT is this that the wire is soldered on? I've
never seen on
that didn't have a metal cup that the wire just clips into, not
saying they
don't exist, but I've yet to ever come across one.

out of a Tek o-scope

ever since TEK began making their own CRTs with the ceramic bell,they have
affixed the anode lead to the CRT bell.
I've seen maybe one failure of that joint in my 21.5 years
there.Usually,it's because some customer tried to measure the anode V by
digging under the silicone rubber seal.




robb


Personally, I think that at last initially, I would feel inclined to
leave the factory connection to the good CRT alone, and go down the
splicing route. If you do a really nice job of soldering the two wire
tails side by side with a generous 'blob' of solder to make sure that
there are no spikes, you shouldn't have an intitial problem with
corona discharge. When you are happy with the solder joint, use a
piece of insulation sleeve, slit lengthwise, to cover the join.
Before making the soldered joint, slide a couple of lengths of
hetshrink tubing over the lead. When you have your slit tubing in
place over the joint, work a bit of silicon rubber into the slit,
around the joint, then shrink the first piece of tubing over the
whole joint. When that has cooled down, slide the second (slightly
longer) piece over the whole lot.

I have spliced several high voltage wires of various types over the
years, using basically this method, and have never had a problem. And
at least if it doesn't work for you, you've then still got the
damage-riskier option of trying to get a good bond at the actual CRT
connection.


The OP wants to be careful with splicing in a scope. I reckon that any
point in the HV lead that is not contiguous might have the possibility
of generating some RFI which could have consequences when measuring
delicate signals. I'll assume this is also the reason the anode cap is
taped over with copper.



While at TEK,I had to splice a few 634 monitor anode leads,and we used a
silicone rubber tubing to go over the soldered splice,then heatshrink over
that to keep it in place. 10KV or more has a way of finding any pinhole or
leakage path and making arcs,carbonizing a better path,etc.

But I missed the reason WHY the OP wants to splice the CRT anode lead.

--
Jim Yanik
jyanik
at
kua.net

"Jim Yanik" wrote in message
...
While at TEK,I had to splice a few 634 monitor anode leads,and
we used a
silicone rubber tubing to go over the soldered splice,then
heatshrink over
that to keep it in place. 10KV or more has a way of finding any
pinhole or
leakage path and making arcs,carbonizing a better path,etc.

But I missed the reason WHY the OP wants to splice the CRT
anode lead.

--
Jim Yanik
jyanik

Hello Jim,

OP here. The reason ....
I want to replace a BAD CRT with compatible GOOD one.
The GOOD CRT has an HV lead that is too short.

The HV Anode Plug will not reach the socket on the HV multiplier
that is sitting inside the PS. It is about 1.5 '' to short with
HV lead pulled taught.

I read that one can cut the CRT anode silicon cover , unsolder
the long lead and then solder long lead to GOOD CRT and then
recover with silicon.

I am asking ...
1. is this possible or feasible ?
2. What silicon do i use (from local hardware store) ? "RTV" is
not there just %100 silicon sealer
3. is there any special surface prep to perform ?
4. What can i do to replace or re-glue the 2" copper tape that
was covering the silcon anode mount point ?

and any other ideas i did not list,
robb

"robb" wrote in message
...

"Jim Yanik" wrote in message
...
While at TEK,I had to splice a few 634 monitor anode leads,and
we used a
silicone rubber tubing to go over the soldered splice,then
heatshrink over
that to keep it in place. 10KV or more has a way of finding any
pinhole or
leakage path and making arcs,carbonizing a better path,etc.

But I missed the reason WHY the OP wants to splice the CRT
anode lead.

--
Jim Yanik
jyanik

Hello Jim,

OP here. The reason ....
I want to replace a BAD CRT with compatible GOOD one.
The GOOD CRT has an HV lead that is too short.

The HV Anode Plug will not reach the socket on the HV multiplier
that is sitting inside the PS. It is about 1.5 '' to short with
HV lead pulled taught.

I read that one can cut the CRT anode silicon cover , unsolder
the long lead and then solder long lead to GOOD CRT and then
recover with silicon.

I am asking ...
1. is this possible or feasible ?
2. What silicon do i use (from local hardware store) ? "RTV" is
not there just %100 silicon sealer
3. is there any special surface prep to perform ?
4. What can i do to replace or re-glue the 2" copper tape that
was covering the silcon anode mount point ?

and any other ideas i did not list,
robb


Well for the foil tape you might be able to use aluminum foil tape which is
for air duct work. They sell it at most hardware stores. Well at least it is
common here in the US, don't know about the rest of the world since HVAC
isn't as common other places.

Mike

"robb" wrote in
:


"Jim Yanik" wrote in message
...
While at TEK,I had to splice a few 634 monitor anode leads,and
we used a
silicone rubber tubing to go over the soldered splice,then
heatshrink over
that to keep it in place. 10KV or more has a way of finding any
pinhole or
leakage path and making arcs,carbonizing a better path,etc.

But I missed the reason WHY the OP wants to splice the CRT
anode lead.

--
Jim Yanik
jyanik

Hello Jim,

OP here. The reason ....
I want to replace a BAD CRT with compatible GOOD one.
The GOOD CRT has an HV lead that is too short.

The HV Anode Plug will not reach the socket on the HV multiplier
that is sitting inside the PS. It is about 1.5 '' to short with
HV lead pulled taught.

I read that one can cut the CRT anode silicon cover , unsolder
the long lead and then solder long lead to GOOD CRT and then
recover with silicon.

I am asking ...
1. is this possible or feasible ?
2. What silicon do i use (from local hardware store) ? "RTV" is
not there just %100 silicon sealer
3. is there any special surface prep to perform ?
4. What can i do to replace or re-glue the 2" copper tape that
was covering the silcon anode mount point ?

and any other ideas i did not list,
robb


I'm afraid I don't have any answers to those questions.Sorry.

--
Jim Yanik
jyanik
at
kua.net

"Meat Plow" wrote in message
...
On Sat, 19 Jan 2008 10:35:41 +0000, Arfa Daily wrote:


"robb" wrote in message
...

"James Sweet" wrote in message
news:wZ8kj.2039$5h6.1213@trndny09...

"robb" wrote in message
...

What kind of CRT is this that the wire is soldered on? I've
never seen on
that didn't have a metal cup that the wire just clips into, not
saying they
don't exist, but I've yet to ever come across one.

out of a Tek o-scope

robb


Personally, I think that at last initially, I would feel inclined to
leave
the factory connection to the good CRT alone, and go down the splicing
route. If you do a really nice job of soldering the two wire tails side
by
side with a generous 'blob' of solder to make sure that there are no
spikes,
you shouldn't have an intitial problem with corona discharge. When you
are
happy with the solder joint, use a piece of insulation sleeve, slit
lengthwise, to cover the join. Before making the soldered joint, slide a
couple of lengths of hetshrink tubing over the lead. When you have your
slit
tubing in place over the joint, work a bit of silicon rubber into the
slit,
around the joint, then shrink the first piece of tubing over the whole
joint. When that has cooled down, slide the second (slightly longer)
piece
over the whole lot.

I have spliced several high voltage wires of various types over the
years,
using basically this method, and have never had a problem. And at least
if
it doesn't work for you, you've then still got the damage-riskier option
of
trying to get a good bond at the actual CRT connection.


The OP wants to be careful with splicing in a scope. I reckon that any
point in the HV lead that is not contiguous might have the possibility of
generating some RFI which could have consequences when measuring delicate
signals. I'll assume this is also the reason the anode cap is taped over
with copper.


The only way that I can see it generating any RFI, is if the joint is not
good enough to be corona-free. Based on what Jim says at the bottom of the
thread, removing the lead from the actual CRT does not seem to be the 'done
thing' - so I'm guessing that there must be a reason for that. Based on that
assumption, I would still think that it was better to at least try to do a
good job on a splice initially, rather than risk 'doing a job' on the new
CRT that left it useless. I would have thought that there is just as much
potential to do a joint at the CRT end that corona'd and generated RFI as
there is of having the same happen at a splice - yes ?

Arfa

I am asking ...
1. is this possible or feasible ?
2. What silicon do i use (from local hardware store) ? "RTV" is
not there just %100 silicon sealer
3. is there any special surface prep to perform ?
4. What can i do to replace or re-glue the 2" copper tape that
was covering the silcon anode mount point ?



Personally I would probably splice the wire then carefully cover the splice
with silicone, let it cure, and slide heatshrink over that. If the
connection on the CRT is easy to get to, then solder it there. Cover it with
ordinary *clear silicone*, not colored, not latex. Let it cure for 48 hours
before applying power. For the copper tape, any number of glues will work,
contact cement, spray adhesive, double sided tape, etc.