11A-series plug-in NVRAM replacement: Difference between revisions

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[[11A16]], [[11A32]], [[11A33]], [[11A34]], [[11A52]], [[11A72]] plugin is courtesy of [[John Addis]].
[[11A16]], [[11A32]], [[11A33]], [[11A34]], [[11A52]], [[11A72]] plugin is courtesy of [[John Addis]].



Some portions of John’s procedure do not appear in any Tek manual
==REPLACING NVRAM IN TEKTRONIX 11000 SERIES PLUGINS==
which makes it impossible to permanently recalibrate the plugin after the NVRAM has been replaced
without the information John compiled into this procedure.




An expired battery inside the NVRAM in 11A16, 11A32, 11A33, 11A34, 11A52, 11A72 plugins results in three problems:


A non volatile random access memory (NVRAM) integrated circuit in Tektronix 11000 series plugins
# “Serial Sum” diagnostic failure at turn-on (loss of the plugin’s serial number).  
remembers information such as serial number and control settings. It contains a lithium battery that eventually dies.
# Running calibration routine at every turn on even though the plugin has not been removed from the mainframe.

Rated lifetime is 10 years, but 25-30 years is common. The date code (format: YYWW) indicates when the part was manufactured.
# Failure to retain V/Div, Offset, Probe calibration, etc. after turn off.
When it fails, there are several problems:
# “Serial Sum” diagnostic failure at turn-on (loss of the plugin’s serial number).
# Calibration routine runs at every turn on even though the plugin has not been removed from the mainframe.
# Failure to retain V/Div, Offset, Probe calibration, etc. after power is turned off.
# Serial number is not displayed on screen in Mainframe’s Utility Menu (Select “Ident”)
There may be other failures directly caused by the NVRAM failure, so multiple failure codes should not discourage you.
They may just be lost information from the last probe attached.
These failures should be cleared by recycling the power on the mainframe after replacing the NVRAM.
Other than these failures, the plugin will operate normally once the diagnostic error codes are cleared by exiting the diagnostic screen.
If the oscilloscope shows no failures after Enhanced Calibration, operation is fully calibrated except for transient response in the 11A52.
To avoid these recurring and annoying problems, the NVRAM must be replaced ​and​ the plug in serial number must be written into the NVRAM.
The NVRAM is identified as a Dallas Semiconductor 1220Y and is the tallest, thickest chip on the board. It has 24 pins.
This NVRAM can be replaced with Dallas 1220AD-200, which is currently still in production and will have a battery that should last 25 years.
Unsolder and remove the Dallas NVRAM.
I recommend that the replacement NVRAM be socketed with a Mill-Max 110-41-624-41-001000 socket, available from Mouser Electronics and other suppliers
The procedure to replace the NVRAM and install a serial number is the same for the 11A16, 11A32, 11A33, 11A34, 11A71, and 11A72 plugins,
except for 12 additional constants required by the 11A52.
Note:​ The 12 calibration constants for 11A52 high frequency transient response cannot be set using an 11300 series mainframe.
This is apparently due to a failure of the plugin design group and the 11300 series design group to communicate
in spite of the fact that the two groups were contiguous and had the same manager.
When given a choice, do not use an 11401 main frame for setting the 11A52 high frequency calibration constants
as the 11401 bandwidth is not quite adequate to adjust the 11A52 properly, although you can probably come pretty close.
The DSA601 mainframe can be used as well as the 11402 and 11403.
For all plugins, you must enter a serial number into the NVRAM using an 11000 series mainframe,
a personal computer and either an RS232C cable or GPIB cable connected between them.


There may be other failures directly caused by the NVRAM,
==WRITING THE SERIAL NUMBER INTO NVRAM==
so multiple failures should not discourage you.
IMPORTANT: Both 11400 main frame and plugin jumpers need to be installed to write the serial numbers
or the 11A52 high frequency calibration constants into NVRAM.
The 11300 series mainframes do not have a “Cal Lock” jumper but still allow the serial number to be written.
The relevant plugin jumper is J611, (J400 on 11A71).
For writing the plugin serial number and the 11A52 calibration constants, J611 needs to be in the “horizontal position”.
(In the 11A71, this is the two pins toward the instrument top.)
For normal operation the jumper is set to the “vertical position” (bottom in 11A71).
The mainframe jumper on 11400 series mainframes is located on the large bottom board in the front of the instrument.
Remove the mainframe bottom cover.
The jumper, labeled “Cal Lock”, is located about 1” away from the board’s (left to right) center on the CRT side of the instrument
and centered in the front to back dimension of the bottom board. There are just two pins,
there is no third pin to hold the jumper during normal operation.
If the jumper is missing, one has to be stolen from some two pin shorting socket,
preferably from another instrument such as a plugin not in use. You may also use an alligator clip. Be careful.
Establish communications between the mainframe and a personal computer with GPIB or an RS232 port
using either Hypertext support (Win XP or earlier) or a modem capable of RS-232-C support.
For Hyperterminal on Win XP and earlier Windows computers: START > All Programs > Accessories > Communications > Hyper Terminal.
Use a normal RS-232-C cable. Do not use a Null Modem cable.
The 11403A I have is set to the following
* Baudrate: 19200
* Echo: On
* Stop bits: 1
* Parity: Even
* Flag: Hard
* Delay: 0
* EOL String: CR/LF Verbose: On Debug: On
Some PC modems may need a lower baudrate (​e.g.​ 4800 or less).
Whichever baudrate you choose must be the same in both the computer and the mainframe.
Into the computer, type: UID? LEF then hit ENTER if the plugin is in the left hole, UID? CEN or UID? RIG if the plug in is in one of the other two holes.
The mainframe should respond with the serial number of the plugin located in the specified hole.
If you have replaced the NVRAM, if the number returned is not the serial number of the instrument,  
or it is gibberish, you will have to enter a serial number.
To query the serial number:
UID? LEF​ returns the Left plugin serial number UID? CEN​ returns the Center plugin serial number UID? RIG​ returns the Right plugin serial number


Note: the 11A52 is a special case in that the high frequency response (a single pot per channel in the 11A32 and 11A34)
UID? MAI​ returns the Mainframe serial number
is instead encoded in 12 calibration constants (six per channel).
Examples to enter the serial number:
These are lost in the 11A52 along with the serial number, instrument settings, and probe settings at last turn off.
UID LEF:“B010525”
UID CEN:“B061532”
UID RIG:“B120518”
UID means User IDentification. Use the serial number for your plugin printed on the top plugin rail. Notice that there is no space between : and ​“
The full words, ​LEFT​, ​CENTER​, or ​RIGHT​ are also acceptable in place of LEF, CEN or RIG.
You can check that the serial number is correct by pressing the mainframe front panel “UTILITY” button and touching the “Ident” part of the screen.
All the installed plugin serial numbers and firmware versions should be shown.
If your plugin is anything except an 11A52, you are done. Replace the jumpers to their original postions.
The mainframe will read the new serial number and invoke calibration at the next turn on.
11A52 HIGH FREQUENCY CALIBRATION CONSTANTS
The 11A32 and 11A34 use a single pot per channel to manually set the high frequency transient response.
The 11A71 and 11A72, I think, have all manual transient response adjustments.
The 11A52 does not use pots for high frequency adjust.
Instead, the two high frequency adjustment voltages (one per channel) are driven by the D/A converter (digital to analog converter),
S/H (sample and hold) farm, and processor. The voltage is set differently by the processor for each channel and for each of the M377 step gains:
50mV/div, 20mV/div, 10mV/div, 5mV/div, 2mV/div, and 1mV/div to optimize transient response.
With a bad or unprogrammed NVRAM, the 11A52 fails ​HFadj Cksum​ at turn on and the high frequency transient response will be poor
unless these 12 additional calibration constants (cal constants) are all set correctly.  
The information for the voltages is held along with the other cal constants in the NVRAM.
The 11A52 CH 1 cal constants known to me are:
* 1: unknown
* 2: unknown
* 3: unknown
* 4: unknown
* 5: unknown
* 6: unknown
* 7: VAR Gain characterization? 8: VAR Gain characterization? 9: VAR Gain characterization?
* 10: VAR Gain characterization? 11: Off Centering?
* 12: Off Centering?
* 13: 1 mV dc balance
* 14: 2 mV dc balance
* 15: 5 mV dc balance
* 16: 10 mV dc balance
* 17: 20 mV dc balance
* 18: 50 mV dc balance
* 26: VAR Gain sensitivity
* 28: 1 mV/div gain
* 29: 2 mV/div gain
* 30: 5 mV/div gain
* 31: 10 mV/div gain
* 32: 20 mV/div gain
* 33: 50 mV/div gain
* 34: X1 atten gain
* 35: X10 atten gain
* 36: X100 atten gain (probably just the other X10 attenuator as two X10 attenuators are cascaded)
* 37: 100 MHz BWL gain (20MHz BWL gain is the reference setting)
* 38: Full BWL gain (20MHz BWL gain is the reference setting)
* 39: OFFSET X100 attn gain
* 40: OFFSET X10 attn gain
* 53: HFAdj at 1mV/div (11A52 only) (HFAdj means High Frequency Adjust)
* 54: HFAdj at 2mV/div (11A52 only)
* 55: HFAdj at 5mV/div (11A52 only)
* 56: HFAdj at 10mV/div (11A52 only)
* 57: HFAdj at 20mV/div (11A52 only)
* 58: HFAdj at 50mV/div (11A52 only)




These are the result of a failed battery inside the NVRAM (U801).
All cal constants for Channel 2 are 128 higher.
"Serial Sum" error code is a check on the integrity of the NVRAM part.
For example, CH 2 HFAdj at 50mV/div is cal constant 186.
The information stored there is the plugin’s calibration settings, the last control settings,
Except for the 11A52 HFAdj cal constants, you will ​not​ have to set any of these numbers.
and the serial number, which the mainframe interrogates to determine
They are all set by the calibration cycle.
if that plugin was the last one residing in that plugin slot (LEFT, CENTER, or RIGHT).


They are reset at turn on (with a new NVRAM, or a change in plugin location)  
or whenever you press Enhanced Accuracy, assuming the instrument has warmed up.  
All of this is very automatic and should not be of concern to you.
You do, however, have to set the serial number of the plugin in the NVRAM. See above.
SETTING THE TWELVE 11A52 CALIBRATION CONSTANTS
For optimum transient response in the 11A52, every M377 preamplifier gain setting sensitivity has a different HFAdj associated with it.
For example, 58 is for CH1 (​i.e.​ input 1) at 50mV/div. 184 is for CH2 at 10mV/div. See the Table below for a full list.
The random number assigned when the NVRAM is replaced will result in bad transient response, particularly from 10mV/div to 10V/div.
The effect is seen in frequencies above 100MHz and for about the first two nanoseconds of the transient response.


The NVRAM is identified as a Dallas Semiconductor 1220Y and is the tallest, thickest chip on the board, 24 pins.
Transient response for the plugin must be set for the 1mV to 50mV/div settings on each channel.
The internal battery is not 
rechargeable even if you could get to it.
The 11A52 reuses the 10mV, 20mV and 50mV settings for 100mV through 10V.
One of mine is still working 29 years after manufacture without failing.
1mV/div, 2mV/div and 5mV/div are used only on those sensitive settings.
A replacement part is available on the internet (DS1220Y-200 works).
To clear the HFAdj chksum error, and obtain good high frequency/transient response,  
The date code (format: YYWW) indicates when the part was manufactured
you must enter all six cal constants for each channel.
and was originally stated to last at least 10 years after that date.  
==11A52 HIGH FREQUENCY CALIBRATION CONSTANT COMMANDS==
I have found DS1220Y-200s on the internet with a 1503 date code (third week in 2015).


Query examples
CCAL? 58
RCAL? 58
RCAL? 186
LCAL? 56
Command examples
CHC1 SENS:.05
CHR2 SENS:5E-2
Description
Returns present value of cal constant 58 of the center plugin. 58 is the cal constant for CH 1 (​i.e.​ input 1) at 50mV/div HFAdj pin in volts delivered to the M377 (165-2129-xx) preamplifier.
Add 128 to 58 = 186 to get CH 2 at 50mV/div.
Returns Cal constant 58 for the Right plugin (CH1, 50mV/div) Returns Cal constant 186 for the Right plugin (CH2, 50mV/div) Returns Cal constant 56 for the Left plugin (CH1, 10mV/div)
Description
Sets the Channel 1 of the Center plugin to 50mV/div.
CH means Channel, or input. C1 means Center plugin hole, CH1 (​i.e.​ input 1).
Sets the Channel 2 of the Right plugin to 50mV/div.  
As you can see, scientific notation works as well as fixed point
To adjust transient response of Channel 1 of the center plugin at 50mV/div, use a TD pulser to observe transient response.  
Set the CH 1 V/div to 50mV/div using either the mainframe front panel control (easier) or by using the computer interface (takes time).  
Query the present value of cal constant 58:
CCA? 58 The value should be between -1 and +1.
Adjust the transient response by changing the value between -1 and +1 by typing in a
voltage. The ​effect will be observed only at the oscilloscope’s faster sweep speeds,​ i.e.​ 2ns/div. ​
More positive numbers increase the transient response peaking.
Important:​ When changing the HFAdj cal settings, the 11A52 processor has to actually invoke that cal constant in order to make the voltage change.
This means that when you, for example, set the CH 1 transient response for 50mV/div by changing cal constant 58,
you must then manually select a different V/div setting (​e.g.​ 20mV/div)
and then return to 50mV/div to see the cal constant and transient response change actually take place.
CCAL 58:-.4 Sets CH1 HFAdj to -0.4V at 50mV/div for the Center plugin RCAL 185:4E-1 Sets CH2 HFAdj to 0.4V at 20mV/div for the plugin in the Right
plugin compartment.
Adjust the 1mV/div to 50mV/div transient responses for both channels.
You must use an appropriate coaxial attenuator between the TD pulser and the 11A52 input to be sure the signal remains entirely on screen.  
2mV/div and 1mV/div are slower than the other sensitivities,
and the adjustment will have less effect at these sensitivities.
A setting of +1V will not be uncommon at 1mV/div and 2mV/div.
==DEFLECTION FACTORS AND ASSOCIATED ADDRESS TABLE==
Deflection Factor
50mV/div 20mV/div 10mV/div
5mV/div 2mV/div 1mV/div
That should do it.
CH1 Cal Address
    58
    57
    56
    55
    54
    53
CH2 Cal Address
    186
    185
    184
    183
    182
    181
  Return the plugin disconnected state.
J611 jumper to the
vertical position. Return the mainframe Cal Lock jumper to the
With 12 new HFAdj cal constants and a new serial number, the instrument will probably come up without errors.
If there are probe related errors,
they can be eliminated by putting a level 2 probe
(one which tells the plugin its offset and attenuation ratio with a small pin next to the BNC connector)  
on the front panel with the instrument running and then removing it.
Simply recycling the power or shorting the probe ring may also do this.
You can check that the serial number is correct by pressing the mainframe front panel “UTILITY” button and touching the “Ident” part of the screen.
All the installed plugin serial numbers and firmware versions should be shown.


The part is soldered into the board.  
== ADDENDUM: PROGRAMMING THE 11K SERIES PLUGINS REMOTELY==
After removing the DS1220Y, I suggest soldering a socket into the board and installing the replacement part in the socket.
Knowledge of these commands is not necessary for replacement of the NVRAM or 11A52 high frequency calibration constants.
The 24 pin socket is Mill-Max 110-41-624-41-001000.
They are given here as a quick tutorial.
Programming the 11A32, 34, 52, and 72 is fairly straight forward. Sending the mainframe the following example commands has the following result.  
The 11A71 and 11A72 do not respond to BW or IMP commands as they do not have changeable bandwidth or input impedance.




I have successfully programmed the serial number into my 11A32 using an NVRAM purchased for $7.50 from China.
There is a space after the channel number, but none after the colon. The commands are not case sensitive.  
Reprogramming the serial number is necessary to prevent the plugin from going through a calibration cycle at every turn on.
The 11A33 does not have a channel 2, just two inputs. The 11A32, 11A52 and 11A72 do not have a channel 3 or channel 4.
Any legitimate serial number will work,but I suggest you program the serial number printed on the top rail of the plugin.
That is what Tektronix did.




The plugin service manual tells you how to reprogram the serial number, BUT THAT DOES NOT WORK BECAUSE IT IS INCOMPLETE.


John Addis Rev February 13, 2019
 
The well-kept secret is that a mainframe J450 (Cal Lock) Jumper on the time base board
on the bottom of the mainframe needs to be installed in order to program the plugin.
It is not like they tell you where to find a spare jumper to do this, no, they will, however, sell you one.
Or, you can borrow one from an unused plugin if you happen to know that the jumper is a short.
You can also jump the pins with alligator clips.  Be careful!


 
So both the plugin and mainframe need jumpers installed to program the plugin serial number.
The mainframe SN can be programmed without a plugin, if you have a spare jumper someplace.


 
NEITHER the plugin manual NOR the mainframe manual makes any statement (that I have found)
to the effect that BOTH INSTRUMENTS have to have jumpers installed to program the plugin serial number.


 
Here is what you do:


 
Remove the bottom panel of the mainframe.
On the board closest to the front panel (Time Base board), locate J450 labeled “CAL-LOCK”. This is hard to find.
It is near the center of the board, about 1” toward the rear of center and 1.5” away from the CRT side.
See Fig 3-15 if you have a manual. Short these two pins together with a jumper of some sort.
J450 is probably the name on all 11K mainframes.
 


In the plugin, remove the left side panel, remove and rotate the J611 jumper on the plugin
from vertical (normal) position to horizontal position, and re-install. Install the plugin in the mainframe.
(I used the center hole, and the commands below assume you used the center hole.
If not, substitute RIGHT or LEFT for CENTER in the following instructions.)


 
Connect either a GPIB or an RS232 cable between the mainframe real panel and a computer.
In the case of an RS232, you will have to have a cable capable of mating to both ends
(RS232, or computer COM port connectors varied over time, but they all work).
 

I recommend setting the 11K mainframe RS-232-C settings as follows:
 
<pre>


Baud Rate: 19,200
Parity: EVEN
EOL String: CR/LF
Echo: ON Flagging: HARD
Verbose: ON
Stop bits: 1
Delay: 0
Debug: ON
</pre>
 
Some COM ports will not support 19,200 speed.  
Just use a much slower speed on both the computer and the mainframe.


 
If you are using GPIB, you are on your own.
 


To connect the computer to the mainframe, I used HyperTerminal, a free program on any Windows XP computer
(START > All Programs > Accessories > Communications > HyperTerminal).
I set the HyperTerminal options (Baud rate, Parity, etc.) to match that on the oscilloscope mainframe
(Utilities button > Page to Utility 2 Menu > RS-232-C).
HyperTerm is not free on Windows versions after XP but any serial communications program will work.
See [http://helpdeskgeek.com/windows-7/windows-7-hyperterminal http://helpdeskgeek.com/windows-7/windows-7-hyperterminal]
for some alternative suggestions.


 
You can check that this is working by typing in any legitimate (probably case sensitive) command:
<pre>
UID? MAIN
UID? CENTER
UID? RIGHT
CHL1 IMP:50
CHR4 IMP:1E6
CHC2 SENS: 0.1
CHR2 BW:1E6
</pre>
CH means CHannel.
The letter following CH specifies the plugin hole you are using L, C, or R.  LEF, RIG, and CEN are also acceptable.
The number following L, C, or R is the channel number.  Once this is all working (answering in English),
type in the following command to program the serial number:

UID CENTER:″B010200″
where you substitute the serial number on the top rail of your plugin for B010200 and LEFT or RIGHT for CENTER as appropriate.
No space between the colon and the  double quotation mark.


 
You can use all the same commands using GPIB.


 
The response on the computer should be OK.
Check that the scope identifies the plugin serial number.
 
Mission accomplished, unless you have an 11A52, and that is the subject of another article.
 


Remove the CAL-LOCK jumper from the mainframe.
Reinstall the plugin jumper in the vertical position.
 


And you are done. You can confirm the serial number and the firmware version on the mainframe (Utility button > Page 1 > Ident).
 
Turn the mainframe off and restart.  If there are probe error codes, they can be cleared by installing a probe.
11A52s will still have an "HFAdj Cksum" or similar error code.
The transient response on the 11A52 will not be correct until new constants are installed.  See elsewhere.


 
NOTE: John did this from memory so he hopes it is all correct.


 
Dennis Tillman W7PF




[[Category:Repair issues]]
[[Category:Repair issues]]
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