Tektronix 2220 - something not working?

[AppleJuce]

Hey!
I have a problem with the oscilloscope, when I turn it on the screen displays X, none of the buttons work, I did not find anything in the manual that could help me. Also it happens to be random.
Thanks for help!

[shakalnokturn]

I seem to remember a topic on this exact problem on either tektronix Yahoo or Groups.io
I'll have a quick search, but suggest you search yourself just in case...

[shakalnokturn]

Fond the topic by Stewart Barker on Yahoo groups at the time, there was no positive outcome to the X on the display.
It was supposed that it was either an alignment mode for the digital section on the CRT or a way of displaying a fault condition...

Does your scope display this on every startup?

[AppleJuce]

No, this happens randomly, around 7/10 turns on the oscilloscope

[shakalnokturn]

The above mentioned case was the same, kind of random...

If you can find a service manual, otherwise 2221 or 2230 should be close.
Try checking loose jumpers, interconnect and socketed I.C. seating.
Also check PSU voltages/ripple, including locally on the digital board. (Maybe near the more power hungry components, usually the hottest.)

Other things I would look into are squashed logic levels on buses, flaky EPROMS (rewrite a pair on new IC's), finding some something to disconnect that will give you the X every time could also give some clues...

I have a 2230 that I bought cheap and hardly ever use, bought cheap because it had a "display issue" since I have it it has always worked but I can't help think that maybe the 2230 is capable of displaying the X too.