OSCILLOSCPE TESLA BM566A PROBLEM

[BEHnam]

HI
I have an old Tesla BM566A oscilloscope.
it works some years without any problem. yesterday I tried to see a signal but it shows nothing! even zero line.
I'm sure that display is working because when I push "beam finder" button it works correctly.
I opened the case cover and in first I found no problem like capacitors crack.
anyone can guide me how to fix the problem?

[vidi]

Hello,

I'm afraid I cannot help you directly, but if you need schematics, layouts, .. they are available at:
http://www.telehistoria.org/index.php?option=com_content&view=article&id=151&Itemid=595&jsmallfib=1&dir=JSROOT/Meracie_Pristroje/Ceskoslovenske/Tesla/BM566a_Osciloskop#filePageTop
with description in Czech, Russian and English.

[BEHnam]

thanks for your replay.
schematics is not useful at this time because I have no idea which unit cause the problem.