Date   
Re: Tek 2467B

Chuck Harris
 

Hugo Holden did a quick calculation using his logic analyzer,
and the FRAM datasheet, and came up with the following:

Ramtron claims the FM16W08 cells should operate for 10^14 R/W cycles.

The life is apparently related to temperature, and supply voltage.
the 10^12 number is at max temperature, and 5.5V, tek runs the
logic at 5V.

Given that the FRAM is like the old magnetic core memory, in that
reading requires destroying the data bit, and rewriting it, every
read or write cycle wears the FRAM the same.

Hugo calculated that the 2465 accesses RAM at a 100KHz rate, and
that if the same cell was accessed at that rate, 24/7, it would
last 31 years.

Hugo further calculated that at the 6802's 100KHz RAM R/W rate,
operating 5 days per week, and 8 hours per day, it should last
130 years.

Will it? Nobody knows, FRAM's haven't been around very long.

It is a grand experiment that a few of us are doing.

But seriously, your scope needs calibrating every 5-10 years.

-Chuck Harris

Raymond Domp Frank wrote:

On Fri, Oct 12, 2018 at 04:34 PM, Chuck Harris wrote:
Hi Chuck,
You're writing:

99% (hopeless exaggeration) of the NVRAM is not calibration
constants, but rather operating memory for the 6802. That
memory holds stuff like the interrupt pointers, stack, heap,
and data areas for the program.
Knowing the limited number of write cycles that an FRAM is capable of: Have you ever done any calculations or measurements re. the lifetime to be expected for these devices in a 2445(X) or 2465(X)?
Since these devices do not do any wear leveling, results could be worrying/disappointing.

Raymond



Re: 2445A calibration

 

Alas, I don't use my 2465As or 2465s anymore.....gone digital etc.
I keep them as I used to dream of owning them back as an undergrad. Used PDP 11, Commodore 64, Atari ST, Amiga 4000 back in the days along with time shared VAX VMS main frame consoles.
The 24xx still work...and I did do the NVRAM battery backup and recapping the PSU etc...so the cals are OK.
I have all the usual set of 500 series plugins to do the cal.

I do assembly code so I can reverse engineer the code....I started as a 6502 programmer so I should be able to recreate the source, even sold assembly code programmes to Compute's Gazette publishers half a lifetime ago.
I used to rev. engineer 6510 source to modify the ROM code behavior to add new custom features to the BASIC language..
Time is my constraint these days. Plus I am doing a Coursera C and embedded ATMEGA and RASPberry Pi 3, IoT certificate series.
I do PIC 10,12,16 & 18F series assembly code directly and full discrete hardware, electronic design and PCBA manufacture to go with it.

BTW...I have 3, new, SG-504 calibrated heads for sale ....all new units, which I manufacture and calibrate to better specs than the OEM Tek units. They are used for leveled sine wave cals for the 24xx series.

Re: 2445A calibration

Max Vlasov
 

Chuck,

I've noticed too the same weird behavior of the pots on the front panel. It's like the FW value isn't synchronized to the real pot position unless the whole CW-CCW-desired position swing could be made.

Also I'm very reluctant to replace any ICs on the A5 board since it's difficult to find NOS circuits of exactly the same type which are not fake. I just wanted to find the way how to test the multichannel DAC and multichannel ADC at the system level (in terms of performance).
One more thing:
By mistake while in CAL02 I've set the output generator voltage from 0 to 5V square wave instead of requested 0 to 10V and the calibration routine passed this step!
Now I wonder whether the requested "standard calibration signal" must be bipolar?
Maybe 500mV from -250mV to 250mV? 1V from -0.5V to 0.5V and so on?

Could you, please, check on your side the calibration signal amplitude and levels?
I remember that before having TG501 I've tried to pass the CAL01 with the fast pulse generator w/o any success. However, once I've got TG501, the things started to move. Maybe also as you suggested the standard calibration signal is not correct?

Thank you,

All the Best,

Maxim

Re: 155-0004-01 Tektronix Parts

Tom Bowers
 

I have two 576 Curve Tracers. One has everything working perfectly and the
other has readout problems in the Beta display. I have two BAD and one good
155-0004-01 ICs. I know the problem is this part in the defective readout
board because swapping in the U976 part from the good board makes this
board work. The problem follows either of my defective U976 (155-0004-01)
parts. For what it's worth, the two bad 155-0004-01 parts fail
differently. Still looking for a good replacement 155-0004-01 part.
Thanks, Tom Bowers

On Fri, Oct 12, 2018 at 1:41 AM Craig Sawyers <c.sawyers@...>
wrote:

Hi, I'm a new member of this group. My name is Tom Bowers. I have been a
Tektronix fan since the
late 1960s. I own an assortment of instruments and run an electronics
engineering and fabrication
shop from my home. I am looking for a readout decoder for a 576 Curve
Tracer, part number 155-0004-
01. I see a post from about a year ago, but can't figure out how to get
in touch with the person
mentioned (Steve Clark). If someone can provide contact info, or knows
of a source for this part, I
would appreciate the help. Thanks, Tom
Welcome to the group! Is that device missing entirely, or is the one in
your 576 dead?

Craig





Re: 155-0004-01 Tektronix Parts

Bob Albert
 

On Friday, October 12, 2018, 8:41:05 AM PDT, Tom Bowers <pvhengineering@...> wrote:

I have two 576 Curve Tracers. One has everything working perfectly and the
other has readout problems in the Beta display. I have two BAD and one good
155-0004-01 ICs. I know the problem is this part in the defective readout
board because swapping in the U976 part from the good board makes this
board work. The problem follows either of my defective U976 (155-0004-01)
parts. For what it's worth, the two bad 155-0004-01 parts fail
differently.  Still looking for a good replacement 155-0004-01 part.
Thanks,  Tom Bowers

On Fri, Oct 12, 2018 at 1:41 AM Craig Sawyers <c.sawyers@...>
wrote:

Hi, I'm a new member of this group. My name is Tom Bowers. I have been a
Tektronix fan since the
late 1960s. I own an assortment of instruments and run an electronics
engineering and fabrication
shop from my home. I am looking for a readout decoder for a 576 Curve
Tracer, part number 155-0004-
01. I see a post from about a year ago, but can't figure out how to get
in touch with the person
mentioned (Steve Clark). If someone can provide contact info, or knows
of a source for this part, I
would appreciate the help.    Thanks,    Tom
Welcome to the group! Is that device missing entirely, or is the one in
your 576 dead?

Craig





Re: 155-0004-01 Tektronix Parts

Tom Bowers
 

Their web sites shows availability but their checkout system is disabled. I
called the phone number, and was told to enter the info into Ebay, and it
would show up if they still had stock, which they apparently don't. So,
that was a good clue, but another dead end. Thanks, Tom

On Fri, Oct 12, 2018 at 9:59 AM Bob Albert via Groups.Io <bob91343=
yahoo.com@groups.io> wrote:

Does this help?

https://www.surplusselect.com/products/up-to-2-new-tektronix-integrated-circuits-155-0004-01

On Friday, October 12, 2018, 8:41:05 AM PDT, Tom Bowers <
pvhengineering@...> wrote:

I have two 576 Curve Tracers. One has everything working perfectly and the
other has readout problems in the Beta display. I have two BAD and one good
155-0004-01 ICs. I know the problem is this part in the defective readout
board because swapping in the U976 part from the good board makes this
board work. The problem follows either of my defective U976 (155-0004-01)
parts. For what it's worth, the two bad 155-0004-01 parts fail
differently. Still looking for a good replacement 155-0004-01 part.
Thanks, Tom Bowers

On Fri, Oct 12, 2018 at 1:41 AM Craig Sawyers <
c.sawyers@...>
wrote:

Hi, I'm a new member of this group. My name is Tom Bowers. I have been
a
Tektronix fan since the
late 1960s. I own an assortment of instruments and run an electronics
engineering and fabrication
shop from my home. I am looking for a readout decoder for a 576 Curve
Tracer, part number 155-0004-
01. I see a post from about a year ago, but can't figure out how to get
in touch with the person
mentioned (Steve Clark). If someone can provide contact info, or knows
of a source for this part, I
would appreciate the help. Thanks, Tom
Welcome to the group! Is that device missing entirely, or is the one in
your 576 dead?

Craig










Re: Tek 2467B

Chuck Harris
 

OOPS! See typo below:

Chuck Harris wrote:
Hugo Holden did a quick calculation using his logic analyzer,
and the FRAM datasheet, and came up with the following:

Ramtron claims the FM16W08 cells should operate for 10^14 R/W cycles.

The life is apparently related to temperature, and supply voltage.
the 10^12 number is at max temperature, and 5.5V, tek runs the
^
10^14


logic at 5V and much cooler..

Given that the FRAM is like the old magnetic core memory, in that
reading requires destroying the data bit, and rewriting it, every
read or write cycle wears the FRAM the same.

Hugo calculated that the 2465 accesses RAM at a 100KHz rate, and
that if the same cell was accessed at that rate, 24/7, it would
last 31 years.

Hugo further calculated that at the 6802's 100KHz RAM R/W rate,
operating 5 days per week, and 8 hours per day, it should last
130 years.

Will it? Nobody knows, FRAM's haven't been around very long.

It is a grand experiment that a few of us are doing.

But seriously, your scope needs calibrating every 5-10 years.

-Chuck Harris

Raymond Domp Frank wrote:
On Fri, Oct 12, 2018 at 04:34 PM, Chuck Harris wrote:
Hi Chuck,
You're writing:

99% (hopeless exaggeration) of the NVRAM is not calibration
constants, but rather operating memory for the 6802. That
memory holds stuff like the interrupt pointers, stack, heap,
and data areas for the program.
Knowing the limited number of write cycles that an FRAM is capable of: Have you ever done any calculations or measurements re. the lifetime to be expected for these devices in a 2445(X) or 2465(X)?
Since these devices do not do any wear leveling, results could be worrying/disappointing.

Raymond





Re: 2445A calibration

Chuck Harris
 

The signals from the PG506, while in calibrate voltage
mode are all 0 to whatever positive volts... not bipolar.

The calibration routine CAL02 does *n0t* always tell you
about an out of range condition. Sometimes it waits until
the next time you cycle power.

I have been burned by that "feature" from time-to-time.

-Chuck Harris

Max Vlasov via Groups.Io wrote:
Chuck,
...
One more thing:
By mistake while in CAL02 I've set the output generator voltage from 0 to 5V square wave instead of requested 0 to 10V and the calibration routine passed this step!
Now I wonder whether the requested "standard calibration signal" must be bipolar?
Maybe 500mV from -250mV to 250mV? 1V from -0.5V to 0.5V and so on?

Could you, please, check on your side the calibration signal amplitude and levels?
I remember that before having TG501 I've tried to pass the CAL01 with the fast pulse generator w/o any success. However, once I've got TG501, the things started to move. Maybe also as you suggested the standard calibration signal is not correct?

Thank you,

All the Best,

Maxim



Free to a good home - again :-)

 

Dear All,

Free to a good home, to be collected in Cirencester UK. 7704A 4 slot
mainframe. It lights up but the intensity is playing up a bit so some TLC
is required. I do not have the time to progress this so it's got to go as
part of my big tidy up. I can probably find a service manual to go with it.



Kind regards



Robin Birch

Re: 2445A calibration

Chuck Harris
 

Not that it matters much, but Tektronix used the 68B02
microprocessor here, rather than the 6502. They are both
substantially similar, and there are quite good assemblers
and disassemblers available in opensource.

Usually when I started a new project, I would write a
simple monitor program in assembly that blinked some LED's,
did rudimentary self testing, and allowed me to fiddle with
the various hardware elements of the embedded design. I would
then build on that monitor to allow it to handle all of the
necessary housekeeping for a launch into "C", and the real
coding would commence.

There are a lot of us here that could do the job, time and
interest seem to be the limiting factors.

I am certain that somewhere on the A5 board there is an
unused input and output bit that could be easily tapped to
allow a software uart to run...doesn't need to be fancy.


OBTW, I can vouch for Ancel's SG504 heads. They are very
functional replacements for the original SG504 leveling
heads at a very fair price. I would have preferred a higher
quality male BNC connector, mine is already showing signs of
wear... and a latching connector for the control/power cable,
but that would certainly have raised the price.

-Chuck Harris

Ancel wrote:

Alas, I don't use my 2465As or 2465s anymore.....gone digital etc.
I keep them as I used to dream of owning them back as an undergrad. Used PDP 11, Commodore 64, Atari ST, Amiga 4000 back in the days along with time shared VAX VMS main frame consoles.
The 24xx still work...and I did do the NVRAM battery backup and recapping the PSU etc...so the cals are OK.
I have all the usual set of 500 series plugins to do the cal.

I do assembly code so I can reverse engineer the code....I started as a 6502 programmer so I should be able to recreate the source, even sold assembly code programmes to Compute's Gazette publishers half a lifetime ago.
I used to rev. engineer 6510 source to modify the ROM code behavior to add new custom features to the BASIC language..
Time is my constraint these days. Plus I am doing a Coursera C and embedded ATMEGA and RASPberry Pi 3, IoT certificate series.
I do PIC 10,12,16 & 18F series assembly code directly and full discrete hardware, electronic design and PCBA manufacture to go with it.

BTW...I have 3, new, SG-504 calibrated heads for sale ....all new units, which I manufacture and calibrate to better specs than the OEM Tek units. They are used for leveled sine wave cals for the 24xx series.

Re: 2445A calibration

Max Vlasov
 

Thank you, Chuck, for clarifying that the calibrator output is 0V to requested level positive 1KHz.

Then it seems that I've done nothing wrong till now. But was defeated by LIMIT problem. I'll try checking the power supply ripple again making sure that everything is nominal. But the trimmed voltages stay where they are. I doubt that the ripple would be beyond the spec (the power supply and A5 board were re-capped).
Also have adjusted the vertical readout jitter. Minimizing it slightly affected the vertical gain (like you have stated before).
The only thing which I haven't done so far was the variable caps on attenuators for the channel 1/2.

I wouldn't think that the problem is with the hybrids, since the amplification and scaling is working.

Maxim

Re: Tek 2467B

 

On Fri, Oct 12, 2018 at 05:20 PM, Chuck Harris wrote:


Hugo Holden did a quick calculation using his logic analyzer,
and the FRAM datasheet, and came up with the following:
Thanks for that, Chuck

Raymond

Re: Tek 2467B

John Ferguson
 

Here is a link to Dr. Holden's very interesting and informative article on this subject:

http://worldphaco.com/uploads/TEKTRONIX_2465b_OSCILLOSCOPE_CALIBRATION___REPOWERING_THE_DS1225.pdf

Re: 2445A calibration

Craig Cramb
 

So I would guess that what you are meaning is the internal switch in the PG506 needs to be set to DC instead of Square Wave.

Re: 2445A calibration

 

On Sat, Oct 13, 2018 at 12:22 AM, Craig Cramb wrote:
Hi Craig,

So I would guess that what you are meaning is the internal switch in the PG506
needs to be set to DC instead of Square Wave.
This is in response to.....?

Raymond

Re: 7000-series power-hungry plug-ins

tinkera123
 

Regarding this pdf of 7000 series currents ..... I am unfamiliar with the terms Foldback currents and ULU.
Can some-one please explain??

-Chuck Harris

PS, thanks to Håkan for the 7904 power supply capacity note.

Re: 2445A calibration

Craig Cramb
 

The signals from the PG506, while in calibrate voltage
mode are all 0 to whatever positive volts... not bipolar.

The calibration routine CAL02 does *n0t* always tell you
about an out of range condition. Sometimes it waits until
the next time you cycle power.

I have been burned by that "feature" from time-to-time.

-Chuck Harris

Re: 7000-series power-hungry plug-ins

Chuck Harris
 

In regulated supplies, there are often over current protection
circuits that are used in lieu of fuses. These circuits reduce
the voltage from the power supply in an attempt to reduce the
current, and the power dissipation, to something that the supply
can safely survive. This is called current foldback.

The Tektronix power supplies for the most part all have this
capability.

-Chuck Harris

tinkera123 wrote:

Regarding this pdf of 7000 series currents ..... I am unfamiliar with the terms Foldback currents and ULU.
Can some-one please explain??


-Chuck Harris

PS, thanks to Håkan for the 7904 power supply capacity note.


Re: 2445A calibration

 

Hi Craig,
So is this:

So I would guess that what you are meaning is the internal switch in the PG506
needs to be set to DC instead of Square Wave.
in response to this:

The signals from the PG506, while in calibrate voltage
mode are all 0 to whatever positive volts... not bipolar.
?
The voltage calibration output signal from the PG506 normally pulsates (as a square wave) between 0V and the amplitude as set, at about 1 kHz.
The "DC" setting of the PG506, which BTW is available as an external push button on some units, changes the square wave to a steady DC level at the set level.

Raymond

Re: 2445A calibration

Chuck Harris
 

Not everyone sees a chain of all of the messages that have ever
existed on the groups server, when they see your message.

I am one of those someones, as are most everyone on this group
that gets the messages delivered by email.

To prevent confusion, most of us leave a snippet of the message
we are responding to quoted with our message... see below.

To do this, there is a button on the web editor for groups.io
that looks like a ["] If you click on it, the entire message
you are responding to will be "quoted" in your message buffer.

Then, you can delete the excess, and save just enough so that
others can get the gist of the thread, and know what you are
talking about.

As to the switch in the PG506, I wasn't aware that there was one,
but regardless, the calibration instructions for the 2465 call for
a unipolar waveform that is ground referenced.

-Chuck Harris

Craig Cramb wrote:

The signals from the PG506, while in calibrate voltage
mode are all 0 to whatever positive volts... not bipolar.

The calibration routine CAL02 does *n0t* always tell you
about an out of range condition. Sometimes it waits until
the next time you cycle power.

I have been burned by that "feature" from time-to-time.

-Chuck Harris