oscilloscope problems

Make sure it's not just HF noise that looks like defocussing.

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Thanks for the replies, the model is:

Iwatsu - SS 7636 350Mhz 4 channel

Its not the leads-the whole display is like it (including the numerical display for 'time div' etc.)

As for when it happens...it was fine until the other day, and when it was on it suddenly went like it. ever since its been the same.

thanks!

Sounds like it's probably the HV/focus section (never seeing an Iwatsu myself). Got a user or service manual with a schematic & voltage test points? You might just get away with inspecting the electrolytics for leaking goo/browned/stretched plastic covering & replacing them. Check for any overheated (browned /charred) resistors, & maybe any overheated/lifted/cracked traces on the board.

***Be very, very careful with the anode lead/HV section though!!*** If it's too expensive to fix, Ebay it like everyone else! ;-) G'Luck!