Date   
Re: vintageTEK museum releases Replaceable Parts Registry (RPR)

Dave Brown
 

The link is now on Manuals, Catalogs, and Other Publications > Reference Materials.
Dave

Re: 2445A calibration

Chuck Harris
 

Harvey White wrote:
The state of LA disassembler probes never reached a point where useful
work could be done, and are in fact a tantalizing way of wasting money.
It seems like it should be possible, was sold as the software engineers
panacea, but it never is.
There are some situations where the LA can be of use, but mostly for
tracking specific events under specific conditions, IMHO.
Indeed, but I find that the LA disassemblers are problematic. It is difficult
to tell with a piplined processor whether the memory reads you are processing
are reading data, or reading instructions. Without a probe specific to the
processor that can make those determinations, you are just looking at
data translated to assembler mnemonics... not useful. The 8086 was the first
commonly used microprocessor to suffer this problem... and solution. Intel
included extra pads that brought out pipeline tracking information for emulators
and logic analyzers.

Tracking specific events under specific conditions is where a LA shines.

The largest problem is that the disassembler probes for given microprocessors
always lags the deployment of those microprocessors, and the fast evolution of
new processors means that the art is always running away from your investment
in probes.
Now for the 6800 and such, you could find the most up-to-date probe,
so that becomes less of a factor for that generation of processors,
I'd think.
Possibly, most of the older processor's pods have been long since scrapped,
but some are certain to still exist.

I just ditched some 6502, Z80, and 8085 emulators... They probably are still
available from the recycler if anyone is interested.



A far better way of understanding an assembly program is to use a
good disassembler, that allows you to use your own labels for data and
jump addresses, and it is generally free. Plus, the software interface to
the hardware processors is surprisingly slow to change, and simple and
cheap to adapt.
Hmmm, got one for the 6800 series? I have core images...
A couple, actually. Sourceforge, and github are littered with them,
particularly the 6809, which is an upfeatured 6802 used in the automotive
industry.

PHK, Poul-Henning Kamp wrote a nice one that actually analyzes the code
by executing it. He used it to disassemble the code in some HP counters.

...

IIRC, the 6802 did more integration of the RAM into the processor. I
think that the DM5010 uses one as well
Tek tended to use the 68B02, which is a 6802 without the internal RAM.

-Chuck Harris

Re: 2445A calibration

Harvey White
 

On Sat, 13 Oct 2018 16:05:14 -0400, you wrote:

Harvey White wrote:
<snip>
The largest problem is that the disassembler probes for given microprocessors
always lags the deployment of those microprocessors, and the fast evolution of
new processors means that the art is always running away from your investment
in probes.
Now for the 6800 and such, you could find the most up-to-date probe,
so that becomes less of a factor for that generation of processors,
I'd think.
Possibly, most of the older processor's pods have been long since scrapped,
but some are certain to still exist.

I just ditched some 6502, Z80, and 8085 emulators... They probably are still
available from the recycler if anyone is interested.
I probably would have liked the ones for the 8085 and the 6502, just
because. Every once and while, I need to look at some of those old
ones. Right now it's the 6802 that I need to look at.



A far better way of understanding an assembly program is to use a
good disassembler, that allows you to use your own labels for data and
jump addresses, and it is generally free. Plus, the software interface to
the hardware processors is surprisingly slow to change, and simple and
cheap to adapt.
Hmmm, got one for the 6800 series? I have core images...
A couple, actually. Sourceforge, and github are littered with them,
particularly the 6809, which is an upfeatured 6802 used in the automotive
industry.
I found a few, they want DOS.

I have one that I wrote that runs under windows and is gui driven.


PHK, Poul-Henning Kamp wrote a nice one that actually analyzes the code
by executing it. He used it to disassemble the code in some HP counters.
Hmmm, some people want money for those things, not that I begrudge him
the income, but I tend to go to open source.

That's what mine does, although I get tired of writing tools to make
tools....



...

IIRC, the 6802 did more integration of the RAM into the processor. I
think that the DM5010 uses one as well
Tek tended to use the 68B02, which is a 6802 without the internal RAM.
The one in the DM5010 isn't, I think, and actually has internal RAM.
For analysis cases, all it does (of course) is to change the location
of some of the RAM.

Harvey


-Chuck Harris


Re: 7000-series power-hungry plug-ins

tinkera123
 

Okay, understand that now. I have played with/built many linear supplies, but none with much protection circuitry.
Thank you, Chuck.
Cheers,
Ian

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

Re: 2445A calibration

Chuck Harris
 

There are many disassemblers that actually emulate the target
code to determine the exact way it operates... all in software.

CAL01 doesn't have much to do with CAL02.

Which attenuator settings give you the RANGE error when running
CAL02?

-Chuck Harris

maxim.vlasov@... wrote:

Chuck,

I've been using all sorts of LAs since the beginning of 90s in the reverse engineering for the systems with scarse or no technical documentation. Simply at the start I had my own home built machine initially based on Intel FlexLogic ICs (they had the fastest clock rate in 1993) then switching to Altera FLEX/APEX families. Then at the beginning of 2000s HP/Agilent LAs with a deep memory became available at the bargain prices. I talk mainly about the arcade machine HW (as this role goes I analyze the chipset architecture in details and re-produce its functional analogues for the FPGA/semicustom IP implementation) which are not the simple uP based HW (Tek is a such example). So, I know something about the reverse engineering bringing the concrete examples ;))

Everyone in the embedded "professional" hacking knows IDA. This is not a panacea as a cross-platform disassembler, but almost and certainly the best of all. But since there is a lot's of the dynamic code in the FW (especially when ppl translating from C++), which can't be analyzed statically (by the disassembler), this runtime can be only analyzed on the working maching by using the LA even without any built-in inverse assembler. So the synergy of both are required to understand the code architecture. Getting the architecture, control and data flow and symbolizing the source is the most important steps. Also we shouldn't forget that the source can be actually compiled by not a very optimal compiler generating the spagetty code.
From all the above, the current example (Tek 6802 base platform) is quite simple, HW is all documented and it can be analyzed statically. But due to the code volume superimposing the calls will be necessary and there the LA will be undispensable.
Back to the oscilloscope, I've got 2445a CAL01 re-calibrated. This time I got it right (digital scopes unfortunately are quite useless). Still CAL02 gives the LIMIT error. But what I also noticed is that when I put the time cursors to the 1st and 11st vertical line the displayed frequency/period gives the precise value in seconds. However, it seems that when I just put them one division apart or a few, then I do have the error in the displayed delta T. Negative if both cursors are to the left from the center and positive when both to the right. It seems like there is a problem with the DAC linearity or something in its path.
IMHO this kind of error then hits back in CAL02.

What do you think?

Thank you again and all the Best,

Maxim

Re: 2445A calibration

Chuck Harris
 

PHK is an open source legend. His disassembler is available
for free on github.

PHK wrote the NTP routines for openbsd.

-Chuck Harris

Harvey White wrote:
On Sat, 13 Oct 2018 16:05:14 -0400, you wrote:
...

PHK, Poul-Henning Kamp wrote a nice one that actually analyzes the code
by executing it. He used it to disassemble the code in some HP counters.
Hmmm, some people want money for those things, not that I begrudge him
the income, but I tend to go to open source.

That's what mine does, although I get tired of writing tools to make
tools....



...

IIRC, the 6802 did more integration of the RAM into the processor. I
think that the DM5010 uses one as well
Tek tended to use the 68B02, which is a 6802 without the internal RAM.
The one in the DM5010 isn't, I think, and actually has internal RAM.
For analysis cases, all it does (of course) is to change the location
of some of the RAM.

Harvey


-Chuck Harris





Re: 7000-series power-hungry plug-ins

Chuck Harris
 

If you have ever used a 7805, or LM309, LM319, or LM340, ... you
have already used current foldback.

-Chuck Harris

tinkera123 wrote:

Okay, understand that now. I have played with/built many linear supplies, but none with much protection circuitry.
Thank you, Chuck.
Cheers,
Ian

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

Re: 2445A calibration

Chuck Harris
 

Hi Maxim,

The normalizer is just a resistor and a trimmer capacitor
in parallel, but in series with the center conductors of
a male and a female BNC connector. It is built in a little
Pomona box.

You can do the same thing with a scope probe, using the
probe's trimmer capacitor to square up the waveform on
one channel, and the C205 to square it up on the other.

I doubt it needs adjustment, assuming that you haven't moved
it already.

That CAL03 throws a LIMIT on CH3 and 4 makes me even more
certain that your problem is your generator.

-Chuck Harris

maxim.vlasov@... wrote:

Chuck,

I read again the input capacitance adjustment procedure for CH1/CH2. I have no 15pF normalizer and the high voltage calibration generator.

I can observe that when 1 MOhm input on the scope is selected, the square waveform signal delivered by the BNC cable has a visible overshoot on the rising edge. So, likely the C105 & C205 have to be adjusted too. I wonder if this overshoot could potentially contribute to the CAL02 LIMIT problem on the channel 1 & 2.
However, when calibration CAL03 routing with other channels 3 & 4 the scope also throws the LIMIT error.

Thank you,

Maxim

Re: 2465B Blue Screen Filter - 378-0270-00

Miklos Koncz
 

Hi Victor,

Please, reserve me also 2 pieces of blue filter!

You can contact me at kmiklos at vnet.hu.

Thanks

Miklos

Re: 2445A calibration

maxim.vlasov@...
 

To be more concrete I've thrown to IDA the 2465a ROM files. 160-3302-09 & 160-3303-09 are the part number downloaded from here:
http://w140.com/tekwiki/wiki/ROM_images

The code structure is quite interesting. The bank switching routines are in the first 2K RAM working area. I've quickly found the voltage reference setting routine:
https://groups.io/g/TekScopes/photo/74577/22?p=Name,,,20,1,20,0

See the comments in the code. The 0xAC=172d code thrown in the DAC sets the reference voltage of 1.36V:
1ma*(4095-172)*4/4096=3831uA. Solving for x=TP2421 voltage:
x*14.2KOhm/13.0KOhm + 681Ohm*(4095-172)*0.004A/4096 = -x
x=(4095-172)*0.004A/4096*681Ohm/(1Ohm+14200Ohm/13000Ohm) = -1.247V

The above assumes that the DAC is calibrated for the 1mA reference current.

Here are some other examples of the DAC and the counter access:
https://groups.io/g/TekScopes/photo/74577/21?p=Name,,,20,1,20,0
https://groups.io/g/TekScopes/photo/74577/20?p=Name,,,20,1,20,0

The code is complex in structure due to the ugly banking implementation. There are similar sections in all four 32K ROM pages. DAC is accessed all over the place in byte fashion and also by direct 16 bit X or even S register store. The DAC work area in the first 2K of RAM is also used heavily and many locations are duplicated.

If completely stuck, then I'll try tracing the LIMIT error, but looking just at the ADC routine complexity (uses almost 200 bytes of various runtime data to do the conditional branching) likely it will consume all the time for several months...

Re: 2445A calibration

maxim.vlasov@...
 

Thank you, Chuck,

I haven't touched the capacitors yet. I've tried all 3 AWGs and got the same result. CAL01 had to run again this time with 7834a, since the steps with the extenal DSO scope were not aligned correctly. Now it's fine, but still LIMIT error. I'll try using the high resolution HDO6034 scope at work to check the AWG output before connecting to 2445a in CAL02. But I can assume that it will be fine since all the equipement at work is fresh out the calibration lab.

What is the meaning of ULU? Topic was: 7000-series power-hungry plug-ins

 

On behalf of all of us thank you Håkan once again.

Of course I know what Fold Back Current Limiting is. In its simplest terms it is a circuit that prevents you from burning up a valuable instrument while you are tinkering around inside it with a screwdriver or other metal tool. One of Murphy Law's guarantees that the more careful you are, the more catastrophic the damage you will cause. Fold back Current Limiting is designed to sacrifice active devices such as transistors and ICs in order to protect the fast blow fuse from stress.

"tinkera123" also asked what the acronym ULU meant. I was hoping someone would explain it. The specific sentence it is used in doesn't give much to go on:
"Some suggestions for the wiring interface to the ULU are offered."
This is followed by 5 suggestions.

From the suggestions it sounds like they are talking about a Device Under Test but the well-known acronym for this is DUT. Some companies use Unit Under Test or UUT.

So far no one has offered an explanation for ULU. I can't think of anything that fits those letters and there are very few ULU acronyms.

The closest I could up with is Unit Under Load which might mean a set of standard load resistors attached to a male connector that plugs into the backplane and loads the power supply enough to draw the maximum amount of power from each supply that the slot should be able to supply. But a Unit Under Load would be UUL. As anyone who plays Scrabble knows, the order of the letters can be really important.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
tinkera123
Sent: Friday, October 12, 2018 3:34 PM
Subject: Re: [TekScopes] 7000-series power-hungry plug-ins

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.


--
Dennis Tillman W7PF
TekScopes Moderator

Re: 2445A calibration

Harvey White
 

On Sat, 13 Oct 2018 18:45:03 -0400, you wrote:

PHK is an open source legend. His disassembler is available
for free on github.
THe internet is being particularly obtuse tonight, or at least
duckduckgo is...

Have a name I should look for? Perhaps that'll help.

Sorry, and thanks.

Harvey



PHK wrote the NTP routines for openbsd.

-Chuck Harris

Harvey White wrote:
On Sat, 13 Oct 2018 16:05:14 -0400, you wrote:
...

PHK, Poul-Henning Kamp wrote a nice one that actually analyzes the code
by executing it. He used it to disassemble the code in some HP counters.
Hmmm, some people want money for those things, not that I begrudge him
the income, but I tend to go to open source.

That's what mine does, although I get tired of writing tools to make
tools....



...

IIRC, the 6802 did more integration of the RAM into the processor. I
think that the DM5010 uses one as well
Tek tended to use the 68B02, which is a 6802 without the internal RAM.
The one in the DM5010 isn't, I think, and actually has internal RAM.
For analysis cases, all it does (of course) is to change the location
of some of the RAM.

Harvey


-Chuck Harris






Re: What is the meaning of ULU? Topic was: 7000-series power-hungry plug-ins

Renée
 

I love the definition of "Fold Back Current Limiting " ...Dennis you are so right, the fuse always survives...LMAO....thanks I needed that...
Renée, K6FSB

On 2018-10-13 05:49 PM, Dennis Tillman W7PF wrote:
On behalf of all of us thank you Håkan once again.

Of course I know what Fold Back Current Limiting is. In its simplest terms it is a circuit that prevents you from burning up a valuable instrument while you are tinkering around inside it with a screwdriver or other metal tool. One of Murphy Law's guarantees that the more careful you are, the more catastrophic the damage you will cause. Fold back Current Limiting is designed to sacrifice active devices such as transistors and ICs in order to protect the fast blow fuse from stress.

"tinkera123" also asked what the acronym ULU meant. I was hoping someone would explain it. The specific sentence it is used in doesn't give much to go on:
"Some suggestions for the wiring interface to the ULU are offered."
This is followed by 5 suggestions.

From the suggestions it sounds like they are talking about a Device Under Test but the well-known acronym for this is DUT. Some companies use Unit Under Test or UUT.
So far no one has offered an explanation for ULU. I can't think of anything that fits those letters and there are very few ULU acronyms.

The closest I could up with is Unit Under Load which might mean a set of standard load resistors attached to a male connector that plugs into the backplane and loads the power supply enough to draw the maximum amount of power from each supply that the slot should be able to supply. But a Unit Under Load would be UUL. As anyone who plays Scrabble knows, the order of the letters can be really important.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
tinkera123
Sent: Friday, October 12, 2018 3:34 PM
Subject: Re: [TekScopes] 7000-series power-hungry plug-ins

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: What is the meaning of ULU? Topic was: 7000-series power-hungry plug-ins

Harvey White
 

On Sat, 13 Oct 2018 19:32:21 -0700, you wrote:

I love the definition of "Fold Back Current Limiting " ...Dennis you are
so right, the fuse always survives...LMAO....thanks I needed that...
Renée, K6FSB
What happens in a technical sense is that the circuit is set up with a
(much lower) short circuit current limit. When the overcurrent
happens, the circuit "folds back" to the point where the maximum
current is the foldback limit. To get it to reset, you generally turn
power off and reapply power.

There's a particular setup in the uA723 regulator (yeah, old
nomenclature) that is available for that.

An example would be that you have a 5 volt supply at 1.5 amps,
foldback to 300 ma.

Voltage is reduced, of course, to maintain that maximum current.

The old data sheets for the UA723 would show that circuit. A nice
thing is that these regulators show up in Tektronix equipment.

and I *think* that a suitable quote runs something like this:

Fuse: an inexpensive part designed to fail to protect a circuit; is
always protected by an extremely expensive part that will fail first
in order to protect the 25 cent fuse.

Harvey




On 2018-10-13 05:49 PM, Dennis Tillman W7PF wrote:
On behalf of all of us thank you Håkan once again.

Of course I know what Fold Back Current Limiting is. In its simplest terms it is a circuit that prevents you from burning up a valuable instrument while you are tinkering around inside it with a screwdriver or other metal tool. One of Murphy Law's guarantees that the more careful you are, the more catastrophic the damage you will cause. Fold back Current Limiting is designed to sacrifice active devices such as transistors and ICs in order to protect the fast blow fuse from stress.

"tinkera123" also asked what the acronym ULU meant. I was hoping someone would explain it. The specific sentence it is used in doesn't give much to go on:
"Some suggestions for the wiring interface to the ULU are offered."
This is followed by 5 suggestions.

From the suggestions it sounds like they are talking about a Device Under Test but the well-known acronym for this is DUT. Some companies use Unit Under Test or UUT.
So far no one has offered an explanation for ULU. I can't think of anything that fits those letters and there are very few ULU acronyms.

The closest I could up with is Unit Under Load which might mean a set of standard load resistors attached to a male connector that plugs into the backplane and loads the power supply enough to draw the maximum amount of power from each supply that the slot should be able to supply. But a Unit Under Load would be UUL. As anyone who plays Scrabble knows, the order of the letters can be really important.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
tinkera123
Sent: Friday, October 12, 2018 3:34 PM
Subject: Re: [TekScopes] 7000-series power-hungry plug-ins

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

Chuck Harris
 

You could try:

<https://github.com/bsdphk/PyRevEng>

-Chuck Harris

Harvey White wrote:

On Sat, 13 Oct 2018 18:45:03 -0400, you wrote:

PHK is an open source legend. His disassembler is available
for free on github.
THe internet is being particularly obtuse tonight, or at least
duckduckgo is...

Have a name I should look for? Perhaps that'll help.

Sorry, and thanks.

Harvey

Re: 468 horizontal jitter

skv1958@...
 

Hi, I am a new comer in the forum with little experience, but I have tried fixing various problems my old 465B had. It's channel 1 had jitter, the trace vertically changing position at random, by about half a division, with or without signal being applied. I could see edges of the rise or fall and the edges we're fast. I suspected a semiconductor device initially, but finally I traced the problem to vertical centering pot on vertical preamplifier board, a Bourns 3352. Replacing the pot cured the problem. In fact almost all other problems of the scope were traced to failed or failing pots of same family. I have replaced 11 pots so far, and 6 more are suspected on trigger generator board. Surprisingly, other brand pots are all fine. Do look around for failing pots. May be this is of some help for your problem.

Shailendra

Re: 468 horizontal jitter

Brendan
 

On Sat, Oct 13, 2018 at 10:38 AM, lop pol wrote:

I'm working on my second 468 and I noticed some horizontal jitter.

On Sat, Oct 13, 2018 at 09:51 AM, Jeff Urban wrote:


In case you haven't, it is important to check if it is a centering problem
or
a triggering problem. Even in auto or free run it is still triggered, so if
it
is the problem could be all the way back at the ramp generator.

If the trace itself is moving and not the sweep (I hope you got that...)
then
I would more look for hash on a PS line somewhere. Of course that applies to
the ramp generator as well but different PS legs of course.
Thanks Jeff.
There is jitter on the A gate out with no input just a free running trace. I
had to put my 465 in 10x to see it but it does match the jitter on the 468.
So... This looks like its going to be a fun one to figure out.
Q181 on the sweep and z axis board was not seated properly. I have no idea how it happened. I have never messed around inside but the base was bent instead of seated. Looking at the schematic I can't tell how that could cause the trace jitter though. The base is connected to ground. So far it seems to be working correctly though. I also installed the EPROMs and images from the Vintage Tek museum. Boards fit correctly and so far so good.

Re: 2445A calibration

Harvey White
 

On Sat, 13 Oct 2018 23:11:02 -0400, you wrote:

You could try:

<https://github.com/bsdphk/PyRevEng>
Thanks, downloading and I will evaluate it.

Wouldn't have thought of that one. Mine's written in Lazarus Pascal,
which is my preferred "goto" for windows style programming.

For microprocessors (ARM), it's C (because a certain company does not
generate a C++ project at all).

Harvey


-Chuck Harris

Harvey White wrote:
On Sat, 13 Oct 2018 18:45:03 -0400, you wrote:

PHK is an open source legend. His disassembler is available
for free on github.
THe internet is being particularly obtuse tonight, or at least
duckduckgo is...

Have a name I should look for? Perhaps that'll help.

Sorry, and thanks.

Harvey

Re: 2445A calibration

maxim.vlasov@...
 

After the code disassembly, seeing that the FW writes 0xAC to the DAC for the U2521 channel 0, the reference voltage on TP2421 is supposed to be 1.24692V
but I measure TP2421=-1.2524V, which is 4392ppm lower. I wonder how accurate it supposed to be.

Try to socket tomorrow U2420 and measure the resistors R2422, R2421, R2521 & R2520 separately.

One way of attack would be by using the Logic Analyzer to find the corresponding to CAL02 routine code and understand it in the details (I'm moving forward with IDA disassembly).

The other - a bit more simplistic - by using the LA to decode/demultiplex the digital sequence at the input of the DAC and multiplexers. It's assumed that in the static o-scope operation, the levels produced by the multichannel DAC are static. Hence, I could compare the code written to the DAC and the de-mulitplexer against the voltage setting at the output. For that there is Agilent 16702a+16534a+16710a setup on my bench. However, I believe that once the voltage settings will be proven static after de-multiplexing, the high resolution voltmeter will be required to find whether the output corresponds to the input digital settings.

Also even more interesting exercise can be done to analyze the performance of the multichannel successive approximation ADC. I try connecting the LA to the DAC, U2510 comparator output (to be socketed too) or even the port 3 input buffer U2220 and the multiplexer controls for U2401, U2601 & U2501. Again, assuming that the input to the ADC at the runtime is static for some signals, use those to find the end of conversion value (also this would help understanding the successive approximation FW routine).