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Re: A Tale Of Two Teks (454A CRT Not Lighting Up)

teamlarryohio
 

Sorry about the confuzzlement. K == cathode. It should be the same
as the HV test point. -1960 sounds familiar. Cathode is pin 2, G1
(control grid) is pin 3. The white cap can be popped off the socket
if necessary, but the test point should serve just fine.

Your LV supplies sound good. There's a 2A fuse in the supply line to the
HV supply. Spend some time with the 'crt circuit' schematic in the
manual. That and the circuit description will pretty well explain
how the HV works. I'd wax more verbose, but it's bedtime plus.

Keep us posted.
-ls-

Thomas Simpson <bullet@sc.rr.com> wrote:

The test pins on the LV control board (+12v, -12v, and +75v) all check
out fine. Or is that what you mean?

I cant seem to find a pinout for the jug in the manual here, but by the
K-pin, do you mean one of the holes in the back of the CRT plug? If so,
which one?

I note that the check voltage for the HV power supply is at 1960v. Is
that what I can expect to find at the K-pin?

I am going to have to rig up a HV probe: nothing I have at present will
go over 1.5kV with their standard probes (I have a Simpson 260-7, a RCA
Senior Voltohmyst WV-98C VTVM and a Fluke 8800A that I don't
particularly trust, along with a generic compact DVM).

Sorry for all the newb questions, and thanks for the help.

-Tom


larrys@teamlarry.com wrote:

Thomas Simpson <bullet@sc.rr.com <mailto:bullet%40sc.rr.com>> wrote:

And no, I dont mean the Scale Illumination...that works fine. :- /


I did my minimally-invasive CRT swap-out (which is of course, fairly
invasive no matter what you do) and replaced the bad bearings in the
case fan. I connected up the CRT just as I found the old, shattered one
connected, said a small prayer, and put power to it.
---snip---

Next step is to check the LV supplies. If ok, See if you have any HV
on the K pin of the jug.
-ls-



------------------------------------

Yahoo! Groups Links
Re: A Tale Of Two Teks (454A CRT Not Lighting Up)

Tom Miller <tmiller@...>
 

Hey Tom,

The "K" pin he is talking about is the CRT cathode, pin 2. It should be the about the same as the -1960 volt test point.

For the CRT circuit, see http://manoman.sqhill.com/pdf/tek-454a.pdf for a better copy of the 454A manual. The CRT circuit is on page 271 of the pdf manual. It is schematic 17.

Be careful making up home made high voltage probes. Probably your generic DVM would be the best (and most accurate) to use here. It should have a 10 meg input impedance so a 10x multiplier probe would be a 90 megohm stack (9 - 10 meg, 1/2 watt film resistors). Check the specs on the DVM if you still have them.

I would stay away from the anode high voltage without a real high voltage probe.

HTH,
tom

----- Original Message -----
From: "Thomas Simpson" <bullet@sc.rr.com>
To: <TekScopes@yahoogroups.com>
Sent: Sunday, January 24, 2010 12:47 AM
Subject: Re: [TekScopes] A Tale Of Two Teks (454A CRT Not Lighting Up)


The test pins on the LV control board (+12v, -12v, and +75v) all check
out fine. Or is that what you mean?

I cant seem to find a pinout for the jug in the manual here, but by the
K-pin, do you mean one of the holes in the back of the CRT plug? If so,
which one?

I note that the check voltage for the HV power supply is at 1960v. Is
that what I can expect to find at the K-pin?

I am going to have to rig up a HV probe: nothing I have at present will
go over 1.5kV with their standard probes (I have a Simpson 260-7, a RCA
Senior Voltohmyst WV-98C VTVM and a Fluke 8800A that I don't
particularly trust, along with a generic compact DVM).

Sorry for all the newb questions, and thanks for the help.

-Tom


larrys@teamlarry.com wrote:

Thomas Simpson <bullet@sc.rr.com <mailto:bullet%40sc.rr.com>> wrote:

And no, I dont mean the Scale Illumination...that works fine. :- /


I did my minimally-invasive CRT swap-out (which is of course, fairly
invasive no matter what you do) and replaced the bad bearings in the
case fan. I connected up the CRT just as I found the old, shattered one
connected, said a small prayer, and put power to it.
---snip---

Next step is to check the LV supplies. If ok, See if you have any HV
on the K pin of the jug.
-ls-



------------------------------------

Yahoo! Groups Links
Re: ...Time to do a run of 547/545B HV transformers...

Chuck Harris <cfharris@...>
 

Hi Morris,

The story as it was told to me by Deane Kidd, was that
the failures started coming in after the epoxy varnished
transformers had been in the field, and were nearing their
intended end-of-life. Tektronix was obliged to replace
failed transformers, and tried to do so, only to find
that the new old stock transformers on their shelves
were bad too.

The made up a run of new transformers, and used them to
replace failures until end-of-life occurred, and then
they breathed a sigh of relief, and went on about their
business.

Clearly they figured out how to make epoxy impregnated
transformers that didn't fail, as is evidenced by all
of the later scopes they made. I have never been able
to find anyone that could tell me what went wrong with
the epoxy, or what they did to solve the problem.

-Chuck Harris

morriso2002 wrote:

Hi Chuck & the gang,
As it happens I have my "new" 547 on the bench and am gradually running through the cal procedure. So far I have had
it running for a couple of hours at a time and there is no sign of the transformer problem. Chuck's post prompted me
to have a closer look at the HVPS. The transformer has obviously been replaced by a previous owner, as the solder
joints to it look non original with rather messy flux residue which you don't see in original Tek joints. The
transformer however looks like genuine Tek article. It has the correct part number and the bobbin and material look
like all the other ones I've seen. On test, the 6AU5 screen voltage stays low and rock solid for a couple of hours
which indicates to me that it's a good 'un.
My question is, did Tek ever issue an improved version of the transformer without the problem? If not, is it safe to
assume that after 40 odd years this one is going to stay OK?? I'm tempted to order one of Chuck's trannies as a spare
but both my 547s are running perfectly at the moment.
Morris
Re: ...Time to do a run of 547/545B HV transformers...

Chuck Harris <cfharris@...>
 

Hi Brian,

My biggest problem with the 549 is I have no jigs
set up to test the final result. HV transformers
can really surprise you sometimes. You think you
are doing everything right, and then something comes
up, like you pull the tape too hard when you are winding
the final protective layer, and the transformers
arc-over.

If you are willing to work with me, and take a little
of the risk, I will try to make one up for you.

As to the price, add some token amount to the price
I listed earlier, and that should suffice.

I'm not in this for the money. I built all of the
gear to wind a couple of transformers for my own
scopes. Bernd Schroeder talked me into making them
available to others.

I really hate to see these fine old scopes sitting on
the shelf wasting away because of such a simple failure.

-Chuck Harris

brianas1948 wrote:

Hi again Chuck , thats good news about the transformer I have . Before you commit serious time to the project it would be a good idea if you can give me an idea of the cost involved . Brian .
--- In TekScopes@yahoogroups.com, Chuck Harris <cfharris@...> wrote:
brianas1948 wrote:
Hi Chuck
Thankyou for responding so soon . As I will have to find a suitable core for this , space might not be that much of a problem . I have had a quick look in my workshop but I cannot find the original core , cant think why its not with the bobbin . The original was potted in epoxy , it developed a short between the 2 x 1000 windings . Hard to track down at first , then it behaved like a shorted turn after being on for a while and killed HV . I have the HV power supply from a 545 -- dont know which version though but it does use the tube rectifiers , not solid state . Would that be a suitable donor core ?
Yes! Any 500 series scope with plugins uses the same core +/- some small variances that just don't matter.
-Chuck Harris
Re: A Tale Of Two Teks (454A CRT Not Lighting Up)

Thomas Simpson <bullet@...>
 

The test pins on the LV control board (+12v, -12v, and +75v) all check out fine. Or is that what you mean?

I cant seem to find a pinout for the jug in the manual here, but by the K-pin, do you mean one of the holes in the back of the CRT plug? If so, which one?

I note that the check voltage for the HV power supply is at 1960v. Is that what I can expect to find at the K-pin?

I am going to have to rig up a HV probe: nothing I have at present will go over 1.5kV with their standard probes (I have a Simpson 260-7, a RCA Senior Voltohmyst WV-98C VTVM and a Fluke 8800A that I don't particularly trust, along with a generic compact DVM).

Sorry for all the newb questions, and thanks for the help.

-Tom


larrys@teamlarry.com wrote:


Thomas Simpson <bullet@sc.rr.com <mailto:bullet%40sc.rr.com>> wrote:

And no, I dont mean the Scale Illumination...that works fine. :- /


I did my minimally-invasive CRT swap-out (which is of course, fairly
invasive no matter what you do) and replaced the bad bearings in the
case fan. I connected up the CRT just as I found the old, shattered one
connected, said a small prayer, and put power to it.
---snip---

Next step is to check the LV supplies. If ok, See if you have any HV
on the K pin of the jug.
-ls-
Re: ...Time to do a run of 547/545B HV transformers...

Chuck Harris <cfharris@...>
 

Hi Victor,

I suppose I could. I'll have to bring my camera down when I
do my next run.

-Chuck Harris

victor.silva wrote:

Chuck,
Can you take a photo record of the process? Or maybe you have one already. This would be great knowledge to pass on
to others.
Thanks, Victor
Re: ...Time to do a run of 547/545B HV transformers...

Chuck Harris <cfharris@...>
 

Hi Victor,

There is a picture of the finished result in the photos section
of this group. I think I labeled it CFHC-120-0308, or something
like that.

I spent a lot of time making the coil winding machine, and developing
a method of making the transformers. And a fair bit of research went
into figuring out the best formula for the wax, and building up a
reliable wax impregnation system.

Then there are the test jigs I built to verify that the transformer
will survive running full tilt in a broken 547 HV supply. When
the 12AU7 regulator tube fails, or is left out of the circuit, the
6AU5 turns the HV up full tilt, and it can put out double the
normal operating voltage.

There are several guys out there that are using the finished product,
and if they are so inclined, they can tell you the good, the bad, and
the ugly about my work.

-Chuck Harris

victor.silva wrote:

WOW, from your description I want to get just to put in a display case, sounds like you do beautiful work Chuck. If
only I had a 545B to use it in.
--Victor
Re: A Tale Of Two Teks (454A CRT Not Lighting Up)

teamlarryohio
 

Thomas Simpson <bullet@sc.rr.com> wrote:

And no, I dont mean the Scale Illumination...that works fine. :- /


I did my minimally-invasive CRT swap-out (which is of course, fairly
invasive no matter what you do) and replaced the bad bearings in the
case fan. I connected up the CRT just as I found the old, shattered one
connected, said a small prayer, and put power to it.
---snip---

Next step is to check the LV supplies. If ok, See if you have any HV
on the K pin of the jug.
-ls-
Re: ...Time to do a run of 547/545B HV transformers...

victor.silva
 

Chuck,

Can you take a photo record of the process? Or maybe you have one already. This would be great knowledge to pass on to others.

Thanks,
Victor
A Tale Of Two Teks (454A CRT Not Lighting Up)

Thomas Simpson <bullet@...>
 

And no, I dont mean the Scale Illumination...that works fine. :- /


I did my minimally-invasive CRT swap-out (which is of course, fairly invasive no matter what you do) and replaced the bad bearings in the case fan. I connected up the CRT just as I found the old, shattered one connected, said a small prayer, and put power to it.

All of the front panel lights did what front panel lights are supposed to do. The "A Sweep Trig'd" light flickered unevenly and the fan spun with a reassuring "woosh!". A faint buzzing sound emanated from the rear of the case. Something related to the HV, no doubt. Could be normal, for all I know. Seems to be. No smoke or open flames, which is a victory unto itself.

I configured all the switches to their nominal positions per the manual.

The only thing missing? Any evidence of a trace. Or a dot. Or so much as a flicker of anything on the CRT. :- /

And no, the Beam Finder did not live up to it's name, though the 20mHz bandwidth limiter produced a nice little relay-like click somewhere in the machine.

The Circuit Isolation Troubleshooting Chart would seem to indicate that the next things to try would be the various outputs of the power supply and then voltages at various points on various control boards. If none of that works, the next indicated thing to do is "check CRT circuit". I cant seem to find a procedure for that in the manual.

Any ideas on this last point, or any other.

Thanks;

-Tom
Re: NV ram in 2465B

victor.silva
 

Stan,

I replied to you in another thread concerning 2465 Cal.
I do have multiple pulse heads, not only the 015-0311-00 (made for the CG551AP, but does work with the CG5011), I also have the 015-0611-01 pulse head.

My favorite calibrators to work with are the CG5011/SG5030. Beautiful equipment and it makes calibration so easy. I also have a TM506 fully loaded with the previous generation calibration plug-ins: SG503, SG504, TG501A, PG506A. I don't keep these officially calibrated like I do the CG5011/SG5030, so I don't normally use them for the scopes I sell. I can't justify calibration expense for the TM506 and TM5006 equipment, when just the TM5006 series calibrators are all I need.

What I meant by "in the service manual is there is a list of required equipment for Calibration/Verification. Substitution can be made as long as the substituted equipment can perform the same function as the original. In my opinion the CG551AP with its slewed markers below 10ns cannot be used in place of a TG501A or CG5011.

I am an EE in nuclear power plant control systems. I am currently on assignment in Taiwan helping to bring up a new plant. It's been some time since I've worked on any of my Tek equipment in my home lab.

--Victor

--- In TekScopes@yahoogroups.com, "Stan & Patricia Griffiths" <w7ni@...> wrote:

Hi Victor,



You are correct that I have never tried to calibrate a 2465, A, or B since I
have never even touched one that I can recall. Yes, I worked in TM500
Marketing and marketed the CG551AP but 2465 Marketing was an entirely
different group and I really have no idea what they meant in the words used
in the service manual.



Unfortunately, I have no access to either a 2465 nor a CG551AP so I can't
try it to see why it won't work. I just can't imagine why it won't work . .
.



Also, I retired from Tek at the end of 1989 and did nothing but sell
spectrum analyzers from 1979 through 1989 and was far from 2465s and
CG551APs.




Stan

_____

From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com] On Behalf
Of victor.silva
Sent: Wednesday, January 20, 2010 2:41 AM
To: TekScopes@yahoogroups.com
Subject: [TekScopes] Re: NV ram in 2465B





Stan,

I perfectly understand slewed markers. I stand by what I said.
The CG551AP has never been called out in an 2465, 2465A or 2465B service
manual. I have all three: TG501A, CG551AP and CG5011 in my possession, the
CG5011 can perfectly replace the TG501(A). In my opinion the CG551AP cannot
be used to calibrate a 2465(B) or if possible it will be very, very
difficult and would possibly produce questionable results.

One possible error I did make was calling the horizontal CAL 01 steps 28,
30, 33, 34 a transient response adjustment. Although the 2465B service
manual states, set the time marker to 2ns and ADJ TRANS RESP (R802). So I
maybe you can define what Tek meant by this statement since you worked in
their marketing department. Maybe when Tek says transient response, they
mean something else here?

In any case applying slewed edges markers to steps 17 and above in the CAL
01 procedure will be completely confusing.

I begin to wonder if you have actually ever done a 2465B calibration from
the statements you have made.

Regards,
Victor Silva

--- In TekScopes@yahoogrou <mailto:TekScopes%40yahoogroups.com> ps.com,
"Stan & Patricia Griffiths" <w7ni@> wrote:

I don't know why you think you can't use a CG551AP to do the timing
adjustments and checks on a 2465. I think that is exactly what it was made
for.



It sounds like maybe you don't really understand the "slewed edge", how it
works, and what it is used for. I will try to explain it here. The slewed
edge is used for timing checks and adjustments on the fastest sweep
speeds.
It is not used for adjusting the high frequency transient response of the
vertical amplifier. The slewed edge consists of a series of very
accurately
spaced "edges", space accurately "in time" from the CG551AP Trigger Output
pulse. A scope display of it will consist of 10 or 12 accurately spaced
transitions. The BIG advantage of the slewed edge is that you can get a
display that allows you to check very fast sweep speeds (as fast as 0.4ns
per division) without having to have a vertical amplifier with a bandwidth
higher than about 100 MHz. This is really important in a large company
calibration lab where you may be calibrating a 7104 with a 7B92A (as fast
as
10ns per division) in the horizontal and have only a 7A18 (75 MHz)
vertical
plugin available.



For checking vertical transient response, you must have the Pulse Head
(015-0311-01) which is a standard accessory included with the CG551AP.
(CG551AP Option 02 DELETED the Pulse Head.) Since the Pulse Head is a
plug-in accessory, it can easily get separated from the CG551AP, never to
be
found again. I suspect you do not have the Pulse Head for your CG551AP and
you will need to get one if you are going to use the CG551AP to check and
adjust vertical amplifier transient response.



I hope this clears up some of the confusion. I worked in TM500 Marketing
at
Tek when the CG551AP was introduced and it was my project to introduce it
to
the world. It was a LONG time ago but I remember it well.



If you still have some questions about how to use it, please ask and I
will
try to help.



Stan Griffiths







_____

From: TekScopes@yahoogrou <mailto:TekScopes%40yahoogroups.com> ps.com
[mailto:TekScopes@yahoogrou <mailto:TekScopes%40yahoogroups.com> ps.com] On
Behalf
Of David C. Partridge
Sent: Monday, January 18, 2010 5:22 AM
To: TekScopes@yahoogrou <mailto:TekScopes%40yahoogroups.com> ps.com
Subject: RE: [TekScopes] Re: NV ram in 2465B





Victor,

I've not had to do a 2465 cal before now. If one can't use a CG551AP to
calibrate the timing, what is the weapon of choice? I don't really want to
have to buy a CG5011 and TM5000 frame to put it in (not that I wouldn't
*like* to have them, just a money shortage).

Thanks
Dave

-----Original Message-----
From: TekScopes@yahoogrou <mailto:TekScopes%40yahoogroups.com> ps.com
[mailto:TekScopes@yahoogrou <mailto:TekScopes%40yahoogroups.com> ps.com]
On
Behalf
Of victor.silva
Sent: 18 January 2010 08:29
To: TekScopes@yahoogrou <mailto:TekScopes%40yahoogroups.com> ps.com
Subject: [TekScopes] Re: NV ram in 2465B

I don't see how a CG551AP can be used. The slewed markers at the high
frequencies will make it very difficult to tell which marker is the
correct
one for the high frequency adjustment.

To get rid of a 04 02 error you should be able to blow through the tests
in
about 15 minutes. Remember you're not really calibrating it, you just want
to get through the steps. If finishing all the CAL steps (in 15 min.) gets
rid of the 04 02 error then you can redo the Cal more carefully.

--Victor
Re: ...Time to do a run of 547/545B HV transformers...

victor.silva
 

WOW, from your description I want to get just to put in a display case, sounds like you do beautiful work Chuck. If only I had a 545B to use it in.

--Victor
Re: NV ram in 2465B

victor.silva
 

Well it does have four input channels. Really I wouldn't consider this a shortcoming, there aren't many times where most people would need to view four signals and need an external trigger.

This is a portable after all.

--Victor

--- In TekScopes@yahoogroups.com, "Stan & Patricia Griffiths" <w7ni@...> wrote:

WOW! You are right! Never having actually touched a 2465, I did not
realize that it did not have an External Trigger input. I have NEVER seen a
scope without this feature and, yes, it is essential to use external
triggering with the CG551AP slewed edge. Yep, it won't work! I consider
that a serious shortcoming of the 2465 series. There are a lot of useful
measurements that depend on the ability to trigger from an external source.
Guess you just can't make them with a 2465 . . .



Stan



_____
Re: NV ram in 2465B

victor.silva
 

Stan,

The 2465~2465B analog series have an automated steps CAL01 through CAL09 in firmware. Changes in how these steps operate, such as "select Channel 3 as the trigger source" cannot be made.

The step is started and you must conform to the instructions and inputs as coded in the firmware. Adding a signal input to Channel 3 will be ignored and cannot be changed. When the scope is in a CAL step it ignores front panel controls except the ones it is expecting.

Unless you can get Tek to give us new firmware for the 2465B?

--Victor

--- In TekScopes@yahoogroups.com, "Stan & Patricia Griffiths" <w7ni@...> wrote:

Hi Tom,



After giving this some more thought, I think there IS a way to use the
slewed edge with the 2465 series.



Even though there is no input on the front panel labeled "External Trigger
In", you can apply the slewed edge to, say, Channel 1 and apply the CG551AP
trigger output to, say, Channel 3 and select Channel 3 as the trigger source
for the 2465. Essentially, you would be using Channel 3 as an "External
Trigger Input". I can't try it since I have neither a CG551AP nor any of
the 2465 series. Maybe you could try it and tell me if it works or not . .
.



Stan
Re: NV ram in 2465B

teamlarryohio
 

"Stan & Patricia Griffiths" <w7ni@easystreet.net> wrote:
Even though there is no input on the front panel labeled "External Trigger
In", you can apply the slewed edge to, say, Channel 1 and apply the CG551AP
trigger output to, say, Channel 3 and select Channel 3 as the trigger source
for the 2465. Essentially, you would be using Channel 3 as an "External
Trigger Input". I can't try it since I have neither a CG551AP nor any of
the 2465 series. Maybe you could try it and tell me if it works or not . .
.
Stan, I'm pretty sure that would be an effective way to do it. Ch 3 + 4
are very limited compared to 1 + 2, so why not?
-ls-
Re: NV ram in 2465B

Stan & Patricia Griffiths
 

Hi Tom,

 

After giving this some more thought, I think there IS a way to use the slewed edge with the 2465 series.

 

Even though there is no input on the front panel labeled “External Trigger In”, you can apply the slewed edge to, say, Channel 1 and apply the CG551AP trigger output to, say, Channel 3 and select Channel 3 as the trigger source for the 2465.  Essentially, you would be using Channel 3 as an “External Trigger Input”.  I can’t try it since I have neither a CG551AP nor any of the 2465 series.  Maybe you could try it and tell me if it works or not . . .

 

Stan

 

From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Tom Miller
Sent: Wednesday, January 20, 2010 4:43 AM
To: TekScopes@...
Subject: Re: [TekScopes] Re: NV ram in 2465B

 

 

Hello Stan,

 

You said

 

 "The slewed edge consists of a series of very accurately
> spaced "edges", space accurately "in time" from the CG551AP Trigger Output
> pulse. A scope display of it will consist of 10 or 12 accurately spaced
> transitions. The BIG advantage of the slewed edge is that you can get a
> display that allows you to check very fast sweep speeds (as fast as 0.4ns
> per division) without having to have a vertical amplifier with a bandwidth
> higher than about 100 MHz. This is really important in a large company
> calibration lab where you may be calibrating a 7104 with a 7B92A (as fast as
> 10ns per division) in the horizontal and have only a 7A18 (75 MHz) vertical
> plugin available."

 

The problem is there is no provision, on the 24XX series, to apply the sync

signal (Trigger Output) during the calibration step. Those edges are not displayed. At

least when I try it. I need to go to another source for the fast markers.

 

 

 

 

Regards,

Tom

 

 
Washing a 547

Morris Odell
 

Hi all,

I have posted some pics of washing & testing my latest 547 in an album called Tek547_wash.

Enjoy!

Morris
Re: ...Time to do a run of 547/545B HV transformers...

Brian
 

Hi again Chuck , thats good news about the transformer I have . Before you commit serious time to the project it would be a good idea if you can give me an idea of the cost involved .
Brian .

--- In TekScopes@yahoogroups.com, Chuck Harris <cfharris@...> wrote:

brianas1948 wrote:
Hi Chuck

Thankyou for responding so soon . As I will have to find a suitable core for this , space might not be that much of a
problem . I have had a quick look in my workshop but I cannot find the original core , cant think why its not with
the bobbin . The original was potted in epoxy , it developed a short between the 2 x 1000 windings . Hard to track
down at first , then it behaved like a shorted turn after being on for a while and killed HV . I have the HV power
supply from a 545 -- dont know which version though but it does use the tube rectifiers , not solid state . Would
that be a suitable donor core ?
Yes! Any 500 series scope with plugins uses the same core +/- some
small variances that just don't matter.

-Chuck Harris
Re: ...Time to do a run of 547/545B HV transformers...

Morris Odell
 

Hi Chuck & the gang,

As it happens I have my "new" 547 on the bench and am gradually running through the cal procedure. So far I have had it running for a couple of hours at a time and there is no sign of the transformer problem. Chuck's post prompted me to have a closer look at the HVPS. The transformer has obviously been replaced by a previous owner, as the solder joints to it look non original with rather messy flux residue which you don't see in original Tek joints. The transformer however looks like genuine Tek article. It has the correct part number and the bobbin and material look like all the other ones I've seen. On test, the 6AU5 screen voltage stays low and rock solid for a couple of hours which indicates to me that it's a good 'un.

My question is, did Tek ever issue an improved version of the transformer without the problem? If not, is it safe to assume that after 40 odd years this one is going to stay OK?? I'm tempted to order one of Chuck's trannies as a spare but both my 547s are running perfectly at the moment.

Morris

--- In TekScopes@yahoogroups.com, Chuck Harris <cfharris@...> wrote:

Hi Gang!

A good friend has urged me to make one of my world renowned
545B/547 replacement HV transformers for him. If I'm going to
start up the production line for one transformer, I might as well
do ten.
Re: ...Time to do a run of 547/545B HV transformers...

Chuck Harris <cfharris@...>
 

brianas1948 wrote:
Hi Chuck
Thankyou for responding so soon . As I will have to find a suitable core for this , space might not be that much of a
problem . I have had a quick look in my workshop but I cannot find the original core , cant think why its not with
the bobbin . The original was potted in epoxy , it developed a short between the 2 x 1000 windings . Hard to track
down at first , then it behaved like a shorted turn after being on for a while and killed HV . I have the HV power
supply from a 545 -- dont know which version though but it does use the tube rectifiers , not solid state . Would
that be a suitable donor core ?
Yes! Any 500 series scope with plugins uses the same core +/- some
small variances that just don't matter.

-Chuck Harris
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