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Fixing a Tektronix 2246


Snekers
 

Hi all! New to groups, so bear with me if I’ve messed up something.

I have a Tektronix 2246 with some very strange symptoms, it’d be great if I
could have some help diagnosing it. Basically, all I have is a flat trace,
no response from signals and no text on the top or bottom to indicate
voltage. That is, unless, I press the menu keys that pop up the previous
measurements, voltmeter, etc. if I press those, the display works.

So far, I’ve:
-checked the voltage rails, all spot on
-looked around for faulty components
-replaced a leaking capacitor on the psu, even though the voltage was fine
-tried every combination of the front panel buttons/knobs

How would I go about finding the issue? Any help would be appreciated.

-Liam


Snekers
 

Well I’ll be dipped, it turned out that one end of the main delay line was loose and was preventing the vertical circuit from working. If anyone ever has similar symptoms, check for that!


tekscopegroup@...
 

While you are inside the scope, or at least put it on your to do list (along with a full recap of the power supply as well) might want to visually check all the MB2501 fast recovery rectifier diodes (17 in total) on the power supply board, and replace the ones with ZM or ZS marked on them as it is a well known problem that they get leaky over time and will cause problems. This is a very common failure scenario for the 2245/6/7A/52 scopes. I replaced them all in my 2247A with MUR160 diodes from Mouser (PN 821-MUR160).


Snekers
 

Thanks for the info! I’ll put that on my list if I ever have a psu issue.