2467B TEST 04 FAIL 02


Thomas Voshell
 

My 2467B >B052xxx suffered two nasties! (The processor board caps exploded and subsequently ate up some of the copper traces near them underneath the solder mask layer. (tough to see)
Also my sram backup died. I was able to get a new recent date code SRAM and it works ok but no cal data now. Also I was able to clean up the cap mess and replace the crummy electrolytic caps with tantalum caps.
I went thru the tek "ADJUSTMENT PROCEDURE" and set everything I could: the really fast horizontal cal's I didn't have gear for. I approximated the top end and pressed the trigger coupling button. I was able to program everything else, or so I thought, but now I am getting a cal limit error TEST 04 FAIL 02. Since the procedure is quite lengthy, with a lot of steps stored, it would be great to know which step of which cal is out of limit.

Is there a way to determine which cal/step is responsible for the error?

All responses are welcome, Thanks
TomV


Chuck Harris <cfharris@...>
 

Sadly, there is no sanctioned way of telling what step
has failed.

You can tell with unsanctioned methods by reading the
NVRAM, and looking at the data bits. The location and
layout of the calibration data is only loosely described
in the maintenance section of the manual. There are 170
14 bit calibration constants in the NVRAM. Each of those
constants has its own checksum, and status bits to tell
if it is in or out of range. All left to us as a mystery
by tektronix.

If you look at the calibration data using the EXER02 function
in the calibration/test menu, you will see each of the
256 RAM locations you can read has the format:

AA DDDD P, where "AA" is the address, "DDDD" is the hex
data for the constant, of which 14 bits are valid, and P is
the parity bit X is even, blank is odd.

The actual locations of this data in the NVRAM have been
found and discussed by others on this group.

I meant one day to take a virgin NVRAM, and read it after
every step of the calibration routine is completed, and
to note the differences in the calibration section of the
NVRAM. I will probably never do so, because I, well, I have
a life, and I just don't care that much....

However, there is nothing stopping one of you from doing
the heavy lifting. I would suggest using what is called
an EPROM emulator, or RAM emulator to save wear on the
NVRAM socket. There will be at least 170 times the data
after a calibration step needs to be compared with the
"virgin" NVRAM data.

Please note that the NVRAM has only 170 calibration constants,
and the entire rest of the NVRAM is used as program storage,
and as a result, is reset every time you fire up the scope.

This is your task should you choose to accept it, good luck
with it! International fame and no fortune await!

-Chuck Harris

tvoshell@cableone.net wrote:

My 2467B >B052xxx suffered two nasties! (The processor board caps exploded and subsequently ate up some of the copper traces near them underneath the solder mask layer. (tough to see)
Also my sram backup died. I was able to get a new recent date code SRAM and it works ok but no cal data now. Also I was able to clean up the cap mess and replace the crummy electrolytic caps with tantalum caps.
I went thru the tek "ADJUSTMENT PROCEDURE" and set everything I could: the really fast horizontal cal's I didn't have gear for. I approximated the top end and pressed the trigger coupling button. I was able to program everything else, or so I thought, but now I am getting a cal limit error TEST 04 FAIL 02. Since the procedure is quite lengthy, with a lot of steps stored, it would be great to know which step of which cal is out of limit.

Is there a way to determine which cal/step is responsible for the error?

All responses are welcome, Thanks
TomV






Jean-Paul
 

Tom V

the steps are divided into sections and each type of CAl is independent of the other sections.

Certain steps near the end require a very precise and symmetric test wave in both amplitude and frequency.

If you dont generate that précise signal, the CAL of that step will fail.

I think Chuck will recall previous discussions, but I forgot which CAL it was, perhaps the HOR.

It was the only step that is is so picky.

Jon


Thomas Voshell
 

Thanks Jon & Chuck,

I have made some progress: Now I am passing my cals. It helps a lot to have marker signals of an appropriate amplitude for the routines to sample.
Now I have another issue that was waiting for me all along. I am getting a “CT TEST 81 FAIL 03” . I believe CT means Confidence Test but I am not sure. Regardless, I am not finding the meaning of 81 with 03.

Does anyone have an idea about this one?

I cannot seem to find any info about 80 series CT tests.


Thanks,
-TomV


Jean-Paul
 

Hello, CT référence to Counter Timer option, see separate Options manual, I think on BAMA archive or TEK WIKI.

The self test menu has a separate test for CTT.

Often the fail is related to U500 the the Trigger hybrides

Bon Chance


Jon


Chuck Harris <cfharris@...>
 

The counter timer option is very complex, but trivial to
calibrate... if you have the right equipment.

First, Test 81 ERR 03 indicates two errors exist:

ERR01 and ERR02. ERR03 is a binary SUM of the error flags.

ERR01 means Delay Offset constant Board Tests out of range
ERR02 means Clock Frequency constant out of limit.

This is what happens when the NVRAM loses its data... which
you already know happened to your scope.

The adjustment procedure calls for an extended accuracy TG501,
and uses it to trigger a pulse generator that is set to make an
accurate 0.5us wide pulse... Thus turning the 1MHz glitch pulses
from the TG501 into a 1Vp-p into 50 ohms square wave...

OK, if you say so....

First, the extended accuracy TG501's aren't all that accurate,
and are rare as hen's teeth. And second, there is no need for
the signal even to be a square wave, as it is just feeding the
scope's trigger hybrid, which is only looking for zero crossings.

I use my GPS disciplined Rb lab standard to feed the EXT REF
on a HP3336B synthesized sine wave level generator set to 1MHz,
with a 1Vp-p 50 ohm output. The 3336B is set to generate a very
low distortion sine wave, and the scope's trigger hybrid knows how
to find its zero crossings, which is all the CTT can see anyway.

The calibration sequence is: plug the sine wave into CH1, enter
CT CAL 81, and press the upper trigger COUPLING button when it
asks you to, and then the A/B TRIG to exit after it is done.

-Chuck Harris


Thomas Voshell wrote:

Thanks Jon & Chuck,

I have made some progress: Now I am passing my cals. It helps a lot to have marker signals of an appropriate amplitude for the routines to sample.
Now I have another issue that was waiting for me all along. I am getting a “CT TEST 81 FAIL 03” . I believe CT means Confidence Test but I am not sure. Regardless, I am not finding the meaning of 81 with 03.

Does anyone have an idea about this one?

I cannot seem to find any info about 80 series CT tests.


Thanks,
-TomV






Jean-Paul
 

Chuck, perfect information as always, and very useful to those who suffer with an ornery CTS option.

Bon Journee,

Jon


Michael W. Lynch
 

Chuck,

An enlightening explanation, as always. As a point of education for me, is the "Extended Accuracy TG501" an instrument with Option1, the 5MhZ temp compensated Oscillator?

--
Michael Lynch
Dardanelle, AR


Chuck Harris <cfharris@...>
 

Yes, that is the one. They are out there, but really not
all that stable, and certainly overkill for the usual timing
calibration of scopes.

Anyway, my major point was they went to an awful lit of work
to make a square wave, when all they needed was some zero
crossings. A sine wave will do.

-Chuck Harris

Michael W. Lynch via groups.io wrote:

Chuck,

An enlightening explanation, as always. As a point of education for me, is the "Extended Accuracy TG501" an instrument with Option1, the 5MhZ temp compensated Oscillator?


Michael W. Lynch
 

On Sun, Feb 21, 2021 at 02:40 PM, Chuck Harris wrote:


Anyway, my major point was they went to an awful lit of work
to make a square wave, when all they needed was some zero
crossings. A sine wave will do.
Chuck,

Yes, I understood your point about the sine wave. That all made perfect sense to me. I am actually starting to understand some of this stuff.

Although I do not own a 2465 series instrument, I find your comments about calibration are always helpful. What I took from this was a method to pair the TG501 and any one of a number of PG50x Pulse generators to obtain other more useful and desirable signal characteristics. I might just start looking for a 2465 as a "project".

Funny part about this, and what caught my eye was you saying that these Option 1 TG501's were "rare as hens teeth". I have three TG501's, and all are Option 1 and they all work. I even built a 4th "Option 1" unit from a "junk parts" box that I bought and which I later sold on E-bay.

Thanks for the verification!

Sincerely,

--
Michael Lynch
Dardanelle, AR