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).

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

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

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.

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!

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!

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

Chuck,

I have been reading all these posts about these transformers. Mine is

BTW, I would GLADLY pay $200 for another new transformer or a custom

Thanks!

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

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

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

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