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Tektronix 2440 Oscilloscope Repaired- Part 4
Here are the previous article:
Today I opened the already completely repaired 2440 Tektronix Oscilloscope again to try and fix some of the remaining FAIL errors. (FAILs which were mentioned in the already published 2440 Repair articles part 1 to 3)
I wanted to start with the 3000 FAIL concerning the U664 SRAM on the A12 Board. So I checked the Boards with U664 , and U424A by touching all components with my fingers for hot spots again. And I was trying to test some of the signals on U664 with Probe Channel 1. But to my surprice at Start-Up/Powering Up the 2440 Tektronix Memory Scope, all of the 3000 Fails had gone.
Something had changed because a 6000 FAIL message “ CKSUM NVRAM* ” had added itself to the FAIL list. And that part has not been there before and could mean an empty Lithium Battery problem.
And because my previous message at address 3000 had gone I took another try in Fixing the remaining errors by the Scope’s Built-In Self Diagnostics. But I first closed the Oscilloscope again, so the FAN could effectively keep all components from over-heating.
After a 10 minute or so warming up time with the Oscilloscope case closed (when the warming up first warning on screen disappears from the screen the warming up period is complete) the SELF CAL routine can be started by first pressing the MENU OFF/EXTENDED FUNCTIONS button. (like explained in the previous 2440 repair articles).
And after some time RUNNING, the PASS message appeared above the SELF CAL choice on the screen.
And next I did the same with running the SELF DIAG choice on the screen. And to my happy surprise also this test had automatically PASSed itself after RUNNING.
So when I now startup the 2440 Scope by pressing the ON/OFF Button, the “running self test” message only briefly shows on the screen, after which every Diagnostic Test comes up being all PASSed.
And the Tektronix Scope has completely fixed and Calibrated itself!
Following photos prove that the 2440 is completely working as it was since 1988.
On previous photos the SELF CAL diagnostic has passed. (I better wait until the scope gets Warmed up before continueing with the SELF DIAG. By pressing the button under that text on the screen.
Photo above clearly proves what a great piece of Hardware Tektronix really is!
I just saved myself $600 dollar on Calibration Costs by letting the Scope run its own Built-In Diagnostic!!
Next photos show that the 2440 Oscilloscope is ready to read the signals on Channel 1 and Channel 2.
I earned my Coffee break and placed my cup on the sturdy Tektronix Machine.
This concludes my Tektronix 2440 Memory Oscilloscope repair. And my good friend Frans now has to buy a pair of 300MHz Probes because that is the only thing he didn’t get with this previous Defect but now magnificent instrument.
So to you all… buy or repair such a great Tektronix Oscilloscope. If I can do it so can you!
This 500MS/s 300MHz Tektronix Scope can still easily compete with todays oscilloscopes after almost 30 years !
Albert van Bemmelen, Weert, The Netherlands.
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