Date   
Re: 11801 NVRAM

Reginald Beardsley
 

FWIW I set up my 11801 using the internal trigger and feeding a ~100 kHz ramp from my 33622A. By making slight adjustments to the ramp frequency I get a straight line which intersects the graticule all the way across the screen at 5 ps/div and 2 mV/div using 5120 points and at 1 ps/div with 1024 points. The internal timebase is not as stable as the 33622A which, despite not having the high stability option, has *very* little drift relative to a GPSDO from Leo Bodnar.

I'm obviously severely aliased to get a single cycle image of a 100 kHz ramp in a 10 or 50 ps wide window. That corresponds to 10 femtosecond sampling.

If there is a time base correction that was lost I don't see how I can measure it or what effect it might have. The ramp appears dead straight though it jumps around a lot because of the 4 ps jitter of the 11801 clock. By continually fiddling with the ramp frequency I can stop the display for a single sweep with a diagonal line over the full screen from upper right to lower left when collecting 5120 points.

I'm going to puzzle over this while I fix a rather late lunch. But I can't see how there is a significant issue. I should be able to do better getting digits via the GPIB interface and supplying a trigger signal from the 33622A.

As I removed the NVRAM battery to get it to boot before I replaced the NVRAM chip, there's no question that if there were cal data in the NVRAM chip it was lost.

Have Fun!
Reg

Re: 2465 DVS Repair - was; Re: [TekScopes] Wanted; Person to repair Tektronix 2465 DVS

Chuck Harris
 

It should be exactly 0.8Vp-p, with no offset. See the waveform
picture in the manual.

The scope's power on test routing attempts to measure the peaks
of that sine'ish waveform as a verification of the trigger and DAC
circuitry. Your scope is failing this test.

The first digit of the error code can be 0, 2, or 4.

4 means that the positive peak of the sinewave is too positive.

The second digit of the error code can be 0, 1, 2, or 4.

2 means that the negative peak is not negative enough.

That means, your sinewave appears to the controller as being
shifted up in the positive direction.

That is what you want to look for. Since the test signal goes
directly to the trigger chip, and if carefully measured will probably
be just right, the problem has to be that the trigger hybrid's
threshold is not being set correctly.

If your other knobs work ok when you press A/B and dismiss the error
message, the DAC has to be ok.

That leaves a bad MUX, or an opamp with a stuck output. I don't recall
which way a bad capacitor in the Sample gate goes, but you should be
able to see any of these errors, as they will stay stuck all of the
time.

-Chuck Harris

jhalbrecht wrote:

Assuming TP46 is the PCB edge side of R567 It has about 1VAC 60hz maybe a 20 ms dc
offset. It doesn't change as I exit the error message or _fiddle_ with the triggering
adjustments.

- Jeff

On 9/15/2019 6:39 AM, Chuck Harris wrote:
The power inside of the 2465 supplies is pretty dirty from
an RF point of view. It is pretty quiet from a 2x60Hz point
of view.

How can you tell the difference?

The RF noise is composed of sliver thin spikes that ride on
the top and bottom of the supply's DC waveform. They look like
a fuzzy caterpillar.

The 2x60Hz ripple will stand still when the scope is triggered
using the line mode.

Tek recommends you use the scope in bandwidth limit mode for
making these measurements.

The other failure that can happen to cause the Test05 Fail XX
failures is in the MUX and Sample and hold gates that the A5
board uses to feed the threshold signals to the trigger hybrid.

Typically one of three things happens (In approximately the
order of likelihood):

The MUX has an output that gets stuck high, or low (the message
gives a clue), or,

The sample and hold op amp gets stuck high or low, or,
The sample and hold capacitor gets leaky.

Trace back the TLA and TLB signals from the trigger hybrid to
the two sample and hold OPAMPS, and from there to the MUX.

And, it is conceivable that the AC Line signal that is supposed
to go from the power supply to the CHN5 input to the trigger hybrid
could be missing, or stuck... TP46 is your friend.

-Chuck Harris


jhalbrecht wrote:
O.K. tried without success to improve the ripple signal on the DC test points. I
don't have a dedicated ground on the Rigol nor on an old 15mhz B&K I aoso tried. I
tried with the banana clip between the 2464 ground jack and the ground of the test
signal on the rigol and on the outside of a BNC connector on CH2 of the Rigol. I
tried it like that with and without the addition of the probe ground too. Nothing got
me near to what I thought ripple might look like.

Is there any change the DC is that dirty?

I also tried swapping out the U300 trigger hybrid from the 2445 switch and knob
donor. Nope, same error Test 05 Fail 42

- Jeff


On 9/14/2019 4:59 AM, Chuck Harris wrote:
That won't do it!

You must connect a big fat banana plug terminated cable in the
2465's ground jack (near the calibrator) to the equivalent ground
on the front panel of the scope that is measuring the ripple.

Anything less will allow the ground loop current to pass through
the probe's shield, and the current through the probe's shield will
generate tens of millivolts (I2R) of unnecessary ground loop noise
in your signal.

We are dealing with a maximum of a few mv of signal here.

Strap the two scopes' grounds together!

-Chuck Harris


jhalbrecht wrote:
:-) yup. Connected the short ground clip from my probe to the solder ground lug on
the chassis / bnc of ch 1. Also set 20mhz bw filter too.

- Jeff


On 9/13/2019 9:11 PM, Chuck Harris wrote:
While doing the ripple measurement, you must connect the
grounds between the 2465 and the testing scope.

-Chuck Harris

jhalbrecht wrote:
Before trying the hybrid swap I got a bit more familiar with my 2465 by
testing the
voltages on J119 and comparing to table 5-1 in the adjustment procedure.

I used a Keithley 2000 Multimeter and a Rigol DS1054z oscilloscope with the extra
options enabled.

The measurements looked solid and stable well withing the published tolerances.

However I'm not confident on my procedures for measuring ripple. It seemed more
like
stray noise basically at 120Hz I tried with the Keithley on AC and the Rigol
with AC
coupling. All the ripple appeared well below 100mv but for instance on pin 6, 12
and
5 that exceeds the 15mv spec as well as the 10mv spec for pin 1.

Before actually physically swapping the trigger hybrid are there any other test
suggestions to try first?


- Jeff

On 9/12/2019 11:11 AM, Chuck Harris wrote:
Hi Jeff,

Usually, when I see Test05, Fail XX, and it isn't the A5 board
of a late model 2465B, it is due to a bad trigger hybrid. Try
removing one from one of your 2445's, and put it into your DVS.
I would bet it will fix the problem.

Note: Seat the chip by hand, making sure it goes all the way
to the PCB. Then while holding it, put nuts on diagonal corners,
and snug them finger tight. Then put on the other two nuts.

Tightness doesn't improve the contacts, it just breaks the board
and studs. No more than 1/8T beyond contact. Just enough to
make the lock washer grab, no more.

Do measure the power supply's voltages and ripple. Don't tweak
any adjustments, unless you want to do a complete recalibration.

The capacitors are almost certainly dead by now... especially
if the fan is stopped, or sluggish from lack of lubrication.

-Chuck Harris

jhalbrecht wrote:
I got the paddle switch out of the donor without incident.

Chuck and group,

Perhaps I could check some voltages on the 2465 dvs (original / first model) A5
board
next in an attempt to solve the "Test 05 Fail 42' triggering problem before
digging
into replacing the paddle switch into the 2465 switch board assembly.

- Jeff






Re: Tek 576 Curve Tracer HV Transformer winding

Chuck Harris
 

Just remember the ferrite is a ceramic mixture,
so it was once heated much hotter than your oven
will ever go.

Good gloves so you don't burn yourself, don't worry
about the winding. Soak it in the oven, and then
remove it and with two hands give the top half and
the bottom half a twist, like you were removing a
jar lid.

If that doesn't work, up the temperature.

If you break it, don't cry. A drop of thin crazy
glue, and carefully aligning it back together, and
you will never know you did it... electrically.

A dry trial fit is a good idea, and a little compressed
air to remove any extra bits of ferrite sand that may
be in the way of a good fit.

-Chuck Harris

Mlynch001 wrote:

John,

I will try this again at a higher temp. You are very certainly right about this. I have not done any “practice” since I don’t have anything to practice on. I guess this is my “practice” piece? I’m going to cut the rest of the coil off and then go from there. I appreciate Chuck’s offer, but I really feel the need to try to do this on my own. I may break the core, I may be successful or, in the end, I may give up and send it to Chuck. If I break these ferrite cores, I may come crying to Chuck or others for a replacement set. I appreciate your advice and insight. One way or the other, I will get this thing fixed. It is a shame that one stupid part has disabled an otherwise functioning instrument. Before it “cuts off”, it works beautifully.

Sincerely

Re: 2465 DVS Repair - was; Re: [TekScopes] Wanted; Person to repair Tektronix 2465 DVS

jhalbrecht
 

Assuming TP46 is the PCB edge side of R567 It has about 1VAC 60hz maybe a 20 ms dc offset. It doesn't change as I exit the error message or _fiddle_ with the triggering adjustments.

 - Jeff

On 9/15/2019 6:39 AM, Chuck Harris wrote:
The power inside of the 2465 supplies is pretty dirty from
an RF point of view. It is pretty quiet from a 2x60Hz point
of view.

How can you tell the difference?

The RF noise is composed of sliver thin spikes that ride on
the top and bottom of the supply's DC waveform. They look like
a fuzzy caterpillar.

The 2x60Hz ripple will stand still when the scope is triggered
using the line mode.

Tek recommends you use the scope in bandwidth limit mode for
making these measurements.

The other failure that can happen to cause the Test05 Fail XX
failures is in the MUX and Sample and hold gates that the A5
board uses to feed the threshold signals to the trigger hybrid.

Typically one of three things happens (In approximately the
order of likelihood):

The MUX has an output that gets stuck high, or low (the message
gives a clue), or,

The sample and hold op amp gets stuck high or low, or,
The sample and hold capacitor gets leaky.

Trace back the TLA and TLB signals from the trigger hybrid to
the two sample and hold OPAMPS, and from there to the MUX.

And, it is conceivable that the AC Line signal that is supposed
to go from the power supply to the CHN5 input to the trigger hybrid
could be missing, or stuck... TP46 is your friend.

-Chuck Harris


jhalbrecht wrote:
O.K. tried without success to improve the ripple signal on the DC test points. I
don't have a dedicated ground on the Rigol nor on an old 15mhz B&K I aoso tried. I
tried with the banana clip between the 2464 ground jack and the ground of the test
signal on the rigol and on the outside of a BNC connector on CH2 of the Rigol. I
tried it like that with and without the addition of the probe ground too. Nothing got
me near to what I thought ripple might look like.

Is there any change the DC is that dirty?

I also tried swapping out the U300 trigger hybrid from the 2445 switch and knob
donor. Nope, same error Test 05 Fail 42

- Jeff


On 9/14/2019 4:59 AM, Chuck Harris wrote:
That won't do it!

You must connect a big fat banana plug terminated cable in the
2465's ground jack (near the calibrator) to the equivalent ground
on the front panel of the scope that is measuring the ripple.

Anything less will allow the ground loop current to pass through
the probe's shield, and the current through the probe's shield will
generate tens of millivolts (I2R) of unnecessary ground loop noise
in your signal.

We are dealing with a maximum of a few mv of signal here.

Strap the two scopes' grounds together!

-Chuck Harris


jhalbrecht wrote:
:-) yup. Connected the short ground clip from my probe to the solder ground lug on
the chassis / bnc of ch 1. Also set 20mhz bw filter too.

- Jeff


On 9/13/2019 9:11 PM, Chuck Harris wrote:
While doing the ripple measurement, you must connect the
grounds between the 2465 and the testing scope.

-Chuck Harris

jhalbrecht wrote:
Before trying the hybrid swap I got a bit more familiar with my 2465 by testing the
voltages on J119 and comparing to table 5-1 in the adjustment procedure.

I used a Keithley 2000 Multimeter and a Rigol DS1054z oscilloscope with the extra
options enabled.

The measurements looked solid and stable well withing the published tolerances.

However I'm not confident on my procedures for measuring ripple. It seemed more
like
stray noise basically at 120Hz I tried with the Keithley on AC and the Rigol
with AC
coupling. All the ripple appeared well below 100mv but for instance on pin 6, 12
and
5 that exceeds the 15mv spec as well as the 10mv spec for pin 1.

Before actually physically swapping the trigger hybrid are there any other test
suggestions to try first?


- Jeff

On 9/12/2019 11:11 AM, Chuck Harris wrote:
Hi Jeff,

Usually, when I see Test05, Fail XX, and it isn't the A5 board
of a late model 2465B, it is due to a bad trigger hybrid. Try
removing one from one of your 2445's, and put it into your DVS.
I would bet it will fix the problem.

Note: Seat the chip by hand, making sure it goes all the way
to the PCB. Then while holding it, put nuts on diagonal corners,
and snug them finger tight. Then put on the other two nuts.

Tightness doesn't improve the contacts, it just breaks the board
and studs. No more than 1/8T beyond contact. Just enough to
make the lock washer grab, no more.

Do measure the power supply's voltages and ripple. Don't tweak
any adjustments, unless you want to do a complete recalibration.

The capacitors are almost certainly dead by now... especially
if the fan is stopped, or sluggish from lack of lubrication.

-Chuck Harris

jhalbrecht wrote:
I got the paddle switch out of the donor without incident.

Chuck and group,

Perhaps I could check some voltages on the 2465 dvs (original / first model) A5
board
next in an attempt to solve the "Test 05 Fail 42' triggering problem before
digging
into replacing the paddle switch into the 2465 switch board assembly.

- Jeff



Re: Tek 576 Curve Tracer HV Transformer winding

ykochcal
 

There are practice cores in most old electronics, which are everywhere
around here if you look.

In particular Old PC power supplies typically have one of similar size but
the wrong orientation.

I am under the opinion that if you break the core it may still be useable.
They have by design a fair gap in the center leg.
If you break the core you will most lily break off one side of the E
Then you just need to break the other side to match (that happened to me
anyway).
Then glue back together with very slow epoxy using a machinist vise and
clamp to keep it square while squeezing it so the gap is as small as
possible.

I ended up with a gap in each leg that I thought was about less then 20% or
so of the gap in the center.

The core seemed to work well, but after awhile that attempt failed due to a
short. I think that I did not put in added space when the winding went from
two wires to one at the end of the coil which doubled the voltage difference
per layer.

Haven't tried to rewind after that attempt
John

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
Mlynch001
Sent: Sunday, September 15, 2019 10:51 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tek 576 Curve Tracer HV Transformer winding

John,

I will try this again at a higher temp. You are very certainly right about
this. I have not done any "practice" since I don't have anything to
practice on. I guess this is my "practice" piece? I'm going to cut the
rest of the coil off and then go from there. I appreciate Chuck's offer,
but I really feel the need to try to do this on my own. I may break the
core, I may be successful or, in the end, I may give up and send it to
Chuck. If I break these ferrite cores, I may come crying to Chuck or others
for a replacement set. I appreciate your advice and insight. One way or
the other, I will get this thing fixed. It is a shame that one stupid part
has disabled an otherwise functioning instrument. Before it "cuts off", it
works beautifully.

Sincerely

--
Michael Lynch
Dardanelle, AR

Re: From 2014: Tektronix Announces Winner of Europe’s Oldest Working Oscilloscope Contest

Dave Daniel
 

Yes, after perusing my copy of "Oscilloscope Development, 1943-57" by Peter D. Hiscocks, I realize that one cannot beat a 511 as the earliest 'Tektronix 'scope.

When I was much younger, I had a Dumont 'scope that was given to me by an uncle who worked for Fisher Scientific. It did not have calibrated amplifier controls, which, at age 11 or so, confused me. I do not remember the model of that 'scope and I have wondered for years how old it was.

The original 511 was made available in 1948.

DaveD

On 9/15/2019 9:56 AM, Chuck Harris wrote:
The 310 is close, but no cigar.

The 511 was the original Tek scope, the 511AD was a
later refined model, with a distributed vertical amplifier.

My working (?) 513D is probably older than Alan's 511AD.

I give it a ? because although I went over it completely
about 30 years ago, it has the selenium rectifiers, which
tend to turn into insulators.

According to Stan G's book:

511 last catalog 1952
511AD last catalog 1955
513 last catalog 1953
513D last catalog 1953

310 last catalog 1958
310A last catalod 1971

-Chuck Harris

Dave Daniel wrote:
Hmmm.. I have (and had back in 2014) a working 310.

As cool as an MDO would be, and not that I want a 'scope that I can't repair when
(not if) it breaks, but there have to be hundreds of owners of vintage Tektronix
'scopes out there that own working 'scopes that are older than the 511 cited in the
post, Europe or not.

I don't recall hearing of this "contest". It is weird that it did not come to light
while it was in progress. Does anyone have any information about the the contest itself?

DaveD

Re: AM700

 

Hi,
Wow! I waiting for your flash image very happy. Do you know if this flash simm are commercial type?
In this days I continued capacitors check, I find some through hole capacitors that just start leak (green oxide on leg and smell when desolder).
I am start to change all capacitors before is to late.

Re: 11801 NVRAM

Reginald Beardsley
 

I'm very interested in how to derive and store the correction terms. There has been discussion of a command to write them, but it appeared not to work when attempted IIRC.

It would be very helpful to know where they are stored in the NVRAM. I've got a programmer, but no idea where to put the data.

My Keysight 33622A is specified as <1 ps jitter. That's less than the 4 ps jitter specified for the 11801. I think I'll play with that a bit and see if I can persuade the 11801 to tell me what the uncalibrated errors are.

Having just built a GPIB-USB adapter using an Uno and AR488 I think I need to read the programming manual for my 11801 to see if I can get digits out via the GPIB port. That would allow removing the NVRAM one time to load the correction values.

Have Fun!
Reg

Re: Tek 576 Curve Tracer HV Transformer winding

Mlynch001
 

John,

I will try this again at a higher temp. You are very certainly right about this. I have not done any “practice” since I don’t have anything to practice on. I guess this is my “practice” piece? I’m going to cut the rest of the coil off and then go from there. I appreciate Chuck’s offer, but I really feel the need to try to do this on my own. I may break the core, I may be successful or, in the end, I may give up and send it to Chuck. If I break these ferrite cores, I may come crying to Chuck or others for a replacement set. I appreciate your advice and insight. One way or the other, I will get this thing fixed. It is a shame that one stupid part has disabled an otherwise functioning instrument. Before it “cuts off”, it works beautifully.

Sincerely

--
Michael Lynch
Dardanelle, AR

Re: Tek 576 Curve Tracer HV Transformer winding

ykochcal
 

I have split a number of transformers, A few thoughts

1, You should take Chuck up on the offer

2, But how are you getting the number 260F? oven dials can be way off and
the temp inside an oven can very considerably depending where you measure


I found the epoxy strength has a fairly quick transition, so its possible
that it's not hot enough.

Also a transformer cools very quickly and gets strong again so I would have
gloves, open oven, grab and give a quick twist, if it did not split, back in
and add a few more degrees.

I would call the move a shearing twist.

I too was a bit hesitant then practiced on some old power supply and TV
cores to get the hang of it, although clearly different epoxies are used
that break at different temps.

John

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Chuck
Harris
Sent: Sunday, September 15, 2019 7:08 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tek 576 Curve Tracer HV Transformer winding

Michael,

The cores are universal among tekscopes.

I have never had one stick like you are describing. Epoxy
just isn't that good.

Send it to me, and I will remove it. If, in my zeal I should
happen to break it, I will send you another core.

I have two examples of the 576 EHT right on my desk, one black,
and one brown. Both were removed in the way I described.

-Chuck Harris

Mlynch001 wrote:
Chuck,

I have been reading all these posts about these transformers. Mine is
definitely bad and I need to attempt to rewind. People are all saying "no
problem, just heat them up and pull them apart". Well this is not working
for me. The bobbin and windings are loose on the core, they are not the
problem. The problem is that the core halves on my 576 HV Transformer are
stuck tight and I mean TIGHT! I have heated for an hour @ 260F, hot enough
that the epoxy just peeled off the windings, but those 2 halves of the core
are not budging. It is like they are welded or silver soldered. I can see
the split between the two halves of the core, but I'll be darned if they
will come apart. I have put some small chips in the cores, so I stopped
trying for now. The winding part does not scare me, but breaking the only
cores that I have scares the crap out of me. Any Ideas?

BTW, I would GLADLY pay $200 for another new transformer or a custom
rewind of the old one.

Thanks!

Re: 2465 DVS Repair - was; Re: [TekScopes] Wanted; Person to repair Tektronix 2465 DVS

Tony Fleming
 

Very well and detail explanation!
Thank you Chuck.

On Sun, Sep 15, 2019 at 8:39 AM Chuck Harris <cfharris@...> wrote:

The power inside of the 2465 supplies is pretty dirty from
an RF point of view. It is pretty quiet from a 2x60Hz point
of view.

How can you tell the difference?

The RF noise is composed of sliver thin spikes that ride on
the top and bottom of the supply's DC waveform. They look like
a fuzzy caterpillar.

The 2x60Hz ripple will stand still when the scope is triggered
using the line mode.

Tek recommends you use the scope in bandwidth limit mode for
making these measurements.

The other failure that can happen to cause the Test05 Fail XX
failures is in the MUX and Sample and hold gates that the A5
board uses to feed the threshold signals to the trigger hybrid.

Typically one of three things happens (In approximately the
order of likelihood):

The MUX has an output that gets stuck high, or low (the message
gives a clue), or,

The sample and hold op amp gets stuck high or low, or,
The sample and hold capacitor gets leaky.

Trace back the TLA and TLB signals from the trigger hybrid to
the two sample and hold OPAMPS, and from there to the MUX.

And, it is conceivable that the AC Line signal that is supposed
to go from the power supply to the CHN5 input to the trigger hybrid
could be missing, or stuck... TP46 is your friend.

-Chuck Harris


jhalbrecht wrote:
O.K. tried without success to improve the ripple signal on the DC test
points. I
don't have a dedicated ground on the Rigol nor on an old 15mhz B&K I
aoso tried. I
tried with the banana clip between the 2464 ground jack and the ground
of the test
signal on the rigol and on the outside of a BNC connector on CH2 of the
Rigol. I
tried it like that with and without the addition of the probe ground
too. Nothing got
me near to what I thought ripple might look like.

Is there any change the DC is that dirty?

I also tried swapping out the U300 trigger hybrid from the 2445 switch
and knob
donor. Nope, same error Test 05 Fail 42

- Jeff


On 9/14/2019 4:59 AM, Chuck Harris wrote:
That won't do it!

You must connect a big fat banana plug terminated cable in the
2465's ground jack (near the calibrator) to the equivalent ground
on the front panel of the scope that is measuring the ripple.

Anything less will allow the ground loop current to pass through
the probe's shield, and the current through the probe's shield will
generate tens of millivolts (I2R) of unnecessary ground loop noise
in your signal.

We are dealing with a maximum of a few mv of signal here.

Strap the two scopes' grounds together!

-Chuck Harris


jhalbrecht wrote:
:-) yup. Connected the short ground clip from my probe to the solder
ground lug on
the chassis / bnc of ch 1. Also set 20mhz bw filter too.

- Jeff


On 9/13/2019 9:11 PM, Chuck Harris wrote:
While doing the ripple measurement, you must connect the
grounds between the 2465 and the testing scope.

-Chuck Harris

jhalbrecht wrote:
Before trying the hybrid swap I got a bit more familiar with my 2465
by testing the
voltages on J119 and comparing to table 5-1 in the adjustment
procedure.

I used a Keithley 2000 Multimeter and a Rigol DS1054z oscilloscope
with the extra
options enabled.

The measurements looked solid and stable well withing the published
tolerances.

However I'm not confident on my procedures for measuring ripple. It
seemed more
like
stray noise basically at 120Hz I tried with the Keithley on AC and
the Rigol
with AC
coupling. All the ripple appeared well below 100mv but for instance
on pin 6, 12
and
5 that exceeds the 15mv spec as well as the 10mv spec for pin 1.

Before actually physically swapping the trigger hybrid are there any
other test
suggestions to try first?


- Jeff

On 9/12/2019 11:11 AM, Chuck Harris wrote:
Hi Jeff,

Usually, when I see Test05, Fail XX, and it isn't the A5 board
of a late model 2465B, it is due to a bad trigger hybrid. Try
removing one from one of your 2445's, and put it into your DVS.
I would bet it will fix the problem.

Note: Seat the chip by hand, making sure it goes all the way
to the PCB. Then while holding it, put nuts on diagonal corners,
and snug them finger tight. Then put on the other two nuts.

Tightness doesn't improve the contacts, it just breaks the board
and studs. No more than 1/8T beyond contact. Just enough to
make the lock washer grab, no more.

Do measure the power supply's voltages and ripple. Don't tweak
any adjustments, unless you want to do a complete recalibration.

The capacitors are almost certainly dead by now... especially
if the fan is stopped, or sluggish from lack of lubrication.

-Chuck Harris

jhalbrecht wrote:
I got the paddle switch out of the donor without incident.

Chuck and group,

Perhaps I could check some voltages on the 2465 dvs (original /
first model) A5
board
next in an attempt to solve the "Test 05 Fail 42' triggering
problem before
digging
into replacing the paddle switch into the 2465 switch board
assembly.

- Jeff








Re: Tek 576 Curve Tracer HV Transformer winding

Michael W. Lynch
 

Chuck,

Leave it to me to have the “odd ball” of the group. I have seen many others that look the same or very similar. I may take you up on your offer and contact you off list for an address.

Sincerely,

Michael Lynch

From My I-Phone

mlynch003@...

479-477-1115

On Sep 15, 2019, at 9:08 AM, Chuck Harris <cfharris@...> wrote:

Michael,

The cores are universal among tekscopes.

I have never had one stick like you are describing. Epoxy
just isn't that good.

Send it to me, and I will remove it. If, in my zeal I should
happen to break it, I will send you another core.

I have two examples of the 576 EHT right on my desk, one black,
and one brown. Both were removed in the way I described.

-Chuck Harris

Mlynch001 wrote:
Chuck,

I have been reading all these posts about these transformers. Mine is definitely bad and I need to attempt to rewind. People are all saying "no problem, just heat them up and pull them apart". Well this is not working for me. The bobbin and windings are loose on the core, they are not the problem. The problem is that the core halves on my 576 HV Transformer are stuck tight and I mean TIGHT! I have heated for an hour @ 260F, hot enough that the epoxy just peeled off the windings, but those 2 halves of the core are not budging. It is like they are welded or silver soldered. I can see the split between the two halves of the core, but I'll be darned if they will come apart. I have put some small chips in the cores, so I stopped trying for now. The winding part does not scare me, but breaking the only cores that I have scares the crap out of me. Any Ideas?

BTW, I would GLADLY pay $200 for another new transformer or a custom rewind of the old one.

Thanks!

Re: Tek 576 Curve Tracer HV Transformer winding

Chuck Harris
 

Michael,

The cores are universal among tekscopes.

I have never had one stick like you are describing. Epoxy
just isn't that good.

Send it to me, and I will remove it. If, in my zeal I should
happen to break it, I will send you another core.

I have two examples of the 576 EHT right on my desk, one black,
and one brown. Both were removed in the way I described.

-Chuck Harris

Mlynch001 wrote:

Chuck,

I have been reading all these posts about these transformers. Mine is definitely bad and I need to attempt to rewind. People are all saying "no problem, just heat them up and pull them apart". Well this is not working for me. The bobbin and windings are loose on the core, they are not the problem. The problem is that the core halves on my 576 HV Transformer are stuck tight and I mean TIGHT! I have heated for an hour @ 260F, hot enough that the epoxy just peeled off the windings, but those 2 halves of the core are not budging. It is like they are welded or silver soldered. I can see the split between the two halves of the core, but I'll be darned if they will come apart. I have put some small chips in the cores, so I stopped trying for now. The winding part does not scare me, but breaking the only cores that I have scares the crap out of me. Any Ideas?

BTW, I would GLADLY pay $200 for another new transformer or a custom rewind of the old one.

Thanks!

Re: Thermal Insulator question

Chuck Harris
 

Be careful here!

Sometimes, the screw passes through the heatsink to a
socket, and the screw is the electrical connection to
the tab. Other times the screw screws into the heatsink,
and must be isolated from the tab.

Be sure what your situation is. The schematic may be a
more clear indication of the need for isolation.

-Chuck Harris

Mlynch001 wrote:

Chuck,

The 577 has one such nylon collar. It is not difficult to overlook or lose this item. I nearly left the collar off while re-assembling my 577. The first two transistors (Q766 and Q788) from the bottom have a mica and do not require the addition of the nylon insulator collar. The next IC above them (U732) has a mica insulator and the nylon collar under the head of the screw. Finally the very top IC (U722) has neither the mica insulator or the nylon collar. The mica insulators are very thin and difficult to see under some circumstances. I double checked the "mechanical parts" section of the manual, just to be sure I was not missing something.

Re: From 2014: Tektronix Announces Winner of Europe’s Oldest Working Oscilloscope Contest

Chuck Harris
 

The 310 is close, but no cigar.

The 511 was the original Tek scope, the 511AD was a
later refined model, with a distributed vertical amplifier.

My working (?) 513D is probably older than Alan's 511AD.

I give it a ? because although I went over it completely
about 30 years ago, it has the selenium rectifiers, which
tend to turn into insulators.

According to Stan G's book:

511 last catalog 1952
511AD last catalog 1955
513 last catalog 1953
513D last catalog 1953

310 last catalog 1958
310A last catalod 1971

-Chuck Harris

Dave Daniel wrote:

Hmmm.. I have (and had back in 2014) a working 310.

As cool as an MDO would be, and not that I want a 'scope that I can't repair when
(not if) it breaks, but there have to be hundreds of owners of vintage Tektronix
'scopes out there that own working 'scopes that are older than the 511 cited in the
post, Europe or not.

I don't recall hearing of this "contest". It is weird that it did not come to light
while it was in progress. Does anyone have any information about the the contest itself?

DaveD

Re: 2465 DVS Repair - was; Re: [TekScopes] Wanted; Person to repair Tektronix 2465 DVS

Chuck Harris
 

The power inside of the 2465 supplies is pretty dirty from
an RF point of view. It is pretty quiet from a 2x60Hz point
of view.

How can you tell the difference?

The RF noise is composed of sliver thin spikes that ride on
the top and bottom of the supply's DC waveform. They look like
a fuzzy caterpillar.

The 2x60Hz ripple will stand still when the scope is triggered
using the line mode.

Tek recommends you use the scope in bandwidth limit mode for
making these measurements.

The other failure that can happen to cause the Test05 Fail XX
failures is in the MUX and Sample and hold gates that the A5
board uses to feed the threshold signals to the trigger hybrid.

Typically one of three things happens (In approximately the
order of likelihood):

The MUX has an output that gets stuck high, or low (the message
gives a clue), or,

The sample and hold op amp gets stuck high or low, or,
The sample and hold capacitor gets leaky.

Trace back the TLA and TLB signals from the trigger hybrid to
the two sample and hold OPAMPS, and from there to the MUX.

And, it is conceivable that the AC Line signal that is supposed
to go from the power supply to the CHN5 input to the trigger hybrid
could be missing, or stuck... TP46 is your friend.

-Chuck Harris


jhalbrecht wrote:

O.K. tried without success to improve the ripple signal on the DC test points. I
don't have a dedicated ground on the Rigol nor on an old 15mhz B&K I aoso tried. I
tried with the banana clip between the 2464 ground jack and the ground of the test
signal on the rigol and on the outside of a BNC connector on CH2 of the Rigol. I
tried it like that with and without the addition of the probe ground too. Nothing got
me near to what I thought ripple might look like.

Is there any change the DC is that dirty?

I also tried swapping out the U300 trigger hybrid from the 2445 switch and knob
donor. Nope, same error Test 05 Fail 42

- Jeff


On 9/14/2019 4:59 AM, Chuck Harris wrote:
That won't do it!

You must connect a big fat banana plug terminated cable in the
2465's ground jack (near the calibrator) to the equivalent ground
on the front panel of the scope that is measuring the ripple.

Anything less will allow the ground loop current to pass through
the probe's shield, and the current through the probe's shield will
generate tens of millivolts (I2R) of unnecessary ground loop noise
in your signal.

We are dealing with a maximum of a few mv of signal here.

Strap the two scopes' grounds together!

-Chuck Harris


jhalbrecht wrote:
:-) yup. Connected the short ground clip from my probe to the solder ground lug on
the chassis / bnc of ch 1. Also set 20mhz bw filter too.

- Jeff


On 9/13/2019 9:11 PM, Chuck Harris wrote:
While doing the ripple measurement, you must connect the
grounds between the 2465 and the testing scope.

-Chuck Harris

jhalbrecht wrote:
Before trying the hybrid swap I got a bit more familiar with my 2465 by testing the
voltages on J119 and comparing to table 5-1 in the adjustment procedure.

I used a Keithley 2000 Multimeter and a Rigol DS1054z oscilloscope with the extra
options enabled.

The measurements looked solid and stable well withing the published tolerances.

However I'm not confident on my procedures for measuring ripple. It seemed more
like
stray noise basically at 120Hz I tried with the Keithley on AC and the Rigol
with AC
coupling. All the ripple appeared well below 100mv but for instance on pin 6, 12
and
5 that exceeds the 15mv spec as well as the 10mv spec for pin 1.

Before actually physically swapping the trigger hybrid are there any other test
suggestions to try first?


- Jeff

On 9/12/2019 11:11 AM, Chuck Harris wrote:
Hi Jeff,

Usually, when I see Test05, Fail XX, and it isn't the A5 board
of a late model 2465B, it is due to a bad trigger hybrid. Try
removing one from one of your 2445's, and put it into your DVS.
I would bet it will fix the problem.

Note: Seat the chip by hand, making sure it goes all the way
to the PCB. Then while holding it, put nuts on diagonal corners,
and snug them finger tight. Then put on the other two nuts.

Tightness doesn't improve the contacts, it just breaks the board
and studs. No more than 1/8T beyond contact. Just enough to
make the lock washer grab, no more.

Do measure the power supply's voltages and ripple. Don't tweak
any adjustments, unless you want to do a complete recalibration.

The capacitors are almost certainly dead by now... especially
if the fan is stopped, or sluggish from lack of lubrication.

-Chuck Harris

jhalbrecht wrote:
I got the paddle switch out of the donor without incident.

Chuck and group,

Perhaps I could check some voltages on the 2465 dvs (original / first model) A5
board
next in an attempt to solve the "Test 05 Fail 42' triggering problem before
digging
into replacing the paddle switch into the 2465 switch board assembly.

- Jeff






Re: Thermal Insulator question

Chuck Harris
 

Thermal Conductivity
--------------------

Mica = 0.75W/mK
Silicone/fiberglass = 1.3-3.0W/mK

The unit of thermal conductivity is Watts per milliKelvin temperature rise.

So, higher W/mK is better conductivity.

Dielectric Strength
-------------------

Silicone/fiberglass dielectric strength is typically 300-400V/mil.
Mica dielectric strength is typically 5000KV/inch, or 5000V/mil.

Where 1 mil = 0.001 inch.

Mica was used at first because it was all we had. Later advances in
material science brought us the silicone-fiberglass composites, and
their improvement in thermal transfer. In addition, the incompressibility
of silicone rubber, and its tendency to flow, improves thermal contact
with irregular surfaces. The silicone rubber flows into the voids.

Mica's biggest advantages are very high dielectric strength and very
high temperature capability.

Silicone/fiberglass pads biggest advantages are ease of use, and
high thermal conductivity.

Thermal greases, such as silicone grease, or the white zinc-oxide/
silicone greases, are used to fill any air gaps between the device being
cooled, and the heatsink. The zinc-oxide was added to silicone grease
because it has a slightly better thermal conductivity. In some applications,
beryllium oxide ceramic powder, silver powder, or ??? powder is added to
silicone grease improve thermal conductivity even more.

Rule of thumb: The higher the thermal conductivity, the lower the electrical
resistance. IF you want super high thermal conductivity, bolt the device
directly to the heatsink.

-Chuck Harris

Dale H. Cook wrote:

As a rule I use silicone thermal pads only when heat dissipation needs are relatively
low. For more demanding applications for devices with isolated mounting I use thermal
compound, and for those without isolated mounting I use isolation bushings, mica, and
thermal compound. For most applications I use GC Type Z-9 zinc oxide-silicone
compound. For those rare occasions when bleed must be minimized I use GC Type 44
non-silicone compound. For the most demanding applications where heat transfer must
be maximized, such as with power MOSFETs in broadcast transmitters, I use Aavid
Thermalcote 249G compound, which has exceptional thermal conductivity (about four
times that of common zinc oxide-silicone compound) and is used by the top
manufacturer of AM and FM broadcast transmitters. I'm glad I don't buy it in five
gallon buckets as they do - it is expensive enough in small quantities ($10 for a one
ounce tube at Mouser).

Re: From 2014: Tektronix Announces Winner of Europe’s Oldest Working Oscilloscope Contest

Dave Seiter
 

Did the contest apply to only Tek scopes?  Sadly, my 511A and 514AD don't work (The HV assemblies (I think) on both are dead- both had puddles of melted stuff around the assembly just above the main chassis-if my memory is correct).   I cleaned them up, but never went further. I was waiting until I knew more before attempting anything.
I think my DeForrest Training scope is the oldest I have that works.  The father of some good friends built it as a young man in the midwest many years ago.
-Dave
On Saturday, September 14, 2019, 11:26:14 PM PDT, Dennis Tillman W7PF <@Dennis_Tillman_W7PF> wrote:

Re: 11801 NVRAM

Albert Otten
 

/
/ The challenge would be how to iteratively adjust the NVram constants without removing the NVram chips a thousand times. I don't know of any GPIB way / to SET the value of each NVram cal constant, maybe there's some tribal knowledge regarding that ??
/

Perhaps you haven't seen this message https://groups.io/g/TekScopes/message/159274 and the previous ones in that topic?
Albert

Re: From 2014: Tektronix Announces Winner of Europe’s Oldest Working Oscilloscope Contest

 

Hi Jamie,
AFAIK Alan Ainslie is alive and well since he posted a message this past May but since he receives TekScopes in full digest form he may not be aware of this until tomorrow.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jamie Ostrowski
Sent: Saturday, September 14, 2019 7:59 PM

Does anyone know if there are any photos of Alan Ainslie's Tek oscilloscope collection? I read he had around 400 of them. It would be a pity if a collection of that size were not photographed! I was unable to find anything.

On Sat, Sep 14, 2019 at 8:37 PM Dave Daniel <kc0wjn@...> wrote:

Hmmm.. I have (and had back in 2014) a working 310.

As cool as an MDO would be, and not that I want a 'scope that I can't
repair when (not if) it breaks, but there have to be hundreds of
owners of vintage Tektronix 'scopes out there that own working 'scopes
that are older than the 511 cited in the post, Europe or not.

I don't recall hearing of this "contest". It is weird that it did not
come to light while it was in progress. Does anyone have any
information about the the contest itself?

DaveD


On 9/14/2019 6:43 PM, Dennis Tillman W7PF wrote:
Craig Sawyers found this announcement from 2014 by accident. It was
never mentioned on TekScopes prior to today.
Alan is a member of TekScopes and his prize was an MDO4000 Series
Mixed
Domain Oscilloscope worth €20,700.

Dennis Tillman W7PF

---
Tektronix Announces Winner of Europe’s Oldest Working Oscilloscope
Contest
Oldest Working Tektronix Oscilloscope, Wins the Newest

BRACKNELL, UK - May 2014 - Tektronix, a leading manufacturer of
oscilloscopes, announced the winner of their competition to find the
oldest working oscilloscope in Europe - the winner, chosen from 240
entries, was Alan Ainslie, from Farnham in the UK, with his Model
511AD manufactured in 1951. He won an MDO4000 Series Mixed Domain
Oscilloscope worth €20,700, one of the newest oscilloscopes in the Tektronix portfolio.

Alan is a lifelong user and enthusiastic collector of Tektronix
oscilloscopes, and currently numbers around 400 in his collection,
believed to be the largest outside the USA. "The great thing about
Tektronix", he said, "is their solid heritage and their passion for
what they do, they have always been head and shoulders in advance of
everyone else." Alan is currently building a museum to house his
collection, and the 511AD will take pride of place.

In his spare time, Alan is also involved in teaching and helping
students to understand the basics of engineering, he cited Tektronix
primers and product manuals as leading sources of information and
context to help the students.

"I'm delighted to have won the MDO4000, not just because I'm an avid
fan
and collector of Tektronix oscilloscopes, but also because it will
help in my current job which involves streaming audio over IP,
particularly when used with the Ethernet, PCI and USB.2 modules."

Mikael Näsström, Tektronix EMEA Marketing Director, presented Mr.
Ainslie with his prize. He commented, "We've come a long way since the
511AD. After sixty-five years and over 700 patents, we're proud that
we are still leading the market in technology, innovation and great products."










--
Dennis Tillman W7PF
TekScopes Moderator