The problem is:
I have taken out the master PCB A16B-1010-0041/04A, then installed it back. After turning power on, display brought up the following:
The first string: FS10T9A
The second string: ROM TEST:END
The third string: RAM TEST:
There is no response after pushing any key. During test the 7-segment LED displays consequently 9,8,7,4. After that letter E appears. And tape reader reels rotate all the time What could happened?