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11A-series plug-in NVRAM replacement: Difference between revisions
11A-series plug-in NVRAM replacement (view source)
Revision as of 00:32, 15 April 2017
, 15 April 2017category
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An expired battery inside the NVRAM in 11A16, 11A32, 11A33, 11A34, 11A52, 11A72 plugins results in three problems:
| An expired battery inside the NVRAM in 11A16, 11A32, 11A33, 11A34, 11A52, 11A72 plugins results in three problems:
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# “Serial Sum” diagnostic failure at turn-on (loss of the plugin’s serial number). | |||
# Running calibration routine at every turn on even though the plugin has not been removed from the mainframe.
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# Failure to retain V/Div, Offset, Probe calibration, etc. after turn off. | |||
There may be other failures directly caused by the NVRAM, | There may be other failures directly caused by the NVRAM, | ||
so multiple failures should not discourage you. | so multiple failures should not discourage you. | ||
Note: the 11A52 is a special case in that the high frequency response | Note: the 11A52 is a special case in that the high frequency response(a single pot pre channel in the 11A32 and 11A34) | ||
(a single pot pre channel in the 11A32 and 11A34) | |||
is instead encoded in 12 calibration constants (six per channel). | is instead encoded in 12 calibration constants (six per channel). | ||
These are lost in the 11A52 along with the serial number, instrument settings, and probe settings at last turn off. | These are lost in the 11A52 along with the serial number, instrument settings, and probe settings at last turn off. | ||
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The NVRAM is identified as a Dallas Semiconductor 1220Y and is the tallest, thickest chip on the board, 24 pins. | The NVRAM is identified as a Dallas Semiconductor 1220Y and is the tallest, thickest chip on the board, 24 pins. | ||
The internal battery is | The internal battery is not
rechargeable even if you could get to it. | ||
One of mine is still working 29 years after manufacture without failing. | One of mine is still working 29 years after manufacture without failing. | ||
A replacement part is available on the internet (DS1220Y-200 works). | A replacement part is available on the internet (DS1220Y-200 works). | ||
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I have successfully programmed the serial number into my 11A32 using an NVRAM purchased for $7.50 from China. |
I have successfully programmed the serial number into my 11A32 using an NVRAM purchased for $7.50 from China. | ||
Reprogramming the serial number is necessary to prevent the plugin from going through a calibration cycle at every turn on. | Reprogramming the serial number is necessary to prevent the plugin from going through a calibration cycle at every turn on. | ||
Any legitimate serial number will work, | Any legitimate serial number will work,but I suggest you program the serial number printed on the top rail of the plugin. | ||
but I suggest you program the serial number printed on the top rail of the plugin. That is what Tektronix did.
| 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.
| The plugin service manual tells you how to reprogram the serial number, BUT THAT DOES NOT WORK BECAUSE IT IS INCOMPLETE.
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Remove the bottom panel of the mainframe. | Remove the bottom panel of the mainframe. | ||
On the board closest to the front panel (Time Base board), locate J450 labeled “CAL-LOCK”. | On the board closest to the front panel (Time Base board), locate J450 labeled “CAL-LOCK”. This is hard to find. | ||
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. | ||
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. | See Fig 3-15 if you have a manual. Short these two pins together with a jumper of some sort. | ||
Short these two pins together with a jumper of some sort. | |||
J450 is probably the name on all 11K mainframes. | J450 is probably the name on all 11K mainframes. | ||
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Dennis Tillman W7PF | Dennis Tillman W7PF | ||
[[Category:Repair issues]] | |||