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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]]. | ||
==REPLACING NVRAM IN TEKTRONIX 11000 SERIES PLUGINS== | |||
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. | ||
# | 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 | 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 | ==WRITING THE SERIAL NUMBER INTO NVRAM== | ||
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 | |||
UID? MAI returns the Mainframe serial number | |||
Examples to enter the serial number: | |||
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) | |||
All cal constants for Channel 2 are 128 higher. | |||
For example, CH 2 HFAdj at 50mV/div is cal constant 186. | |||
Except for the 11A52 HFAdj cal constants, you will not have to set any of these numbers. | |||
They are all set by the calibration cycle. | |||
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 | Transient response for the plugin must be set for the 1mV to 50mV/div settings on each channel. | ||
The 11A52 reuses the 10mV, 20mV and 50mV settings for 100mV through 10V. | |||
1mV/div, 2mV/div and 5mV/div are used only on those sensitive settings. | |||
To clear the HFAdj chksum error, and obtain good high frequency/transient response, | |||
The | you must enter all six cal constants for each channel. | ||
and | ==11A52 HIGH FREQUENCY CALIBRATION CONSTANT COMMANDS== | ||
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. | |||
== ADDENDUM: PROGRAMMING THE 11K SERIES PLUGINS REMOTELY== | |||
Knowledge of these commands is not necessary for replacement of the NVRAM or 11A52 high frequency calibration constants. | |||
The | 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. | |||
There is a space after the channel number, but none after the colon. The commands are not case sensitive. | |||
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. | |||
John Addis Rev February 13, 2019 | |||
[[Category:Repair issues]] | [[Category:Repair issues]] |