I've old (year 1993) Nichiyu FBZ25PL-55BC-470M electric forklift. After start it's working perfectly only about 1 minute and then it will shut down functions and stop operating. When the error occurs the numbers in display are dimming slowly and then finally are not visible at all. After that only steering works. Then after 10-15 minutes waiting it works again the same one minute operating time.

Could it be fault in circuit board (PB84-46)? There is three red leds on the board: leds P5 and P12 are on (bright) all the time and when the fault occurs the third led STP will turn on. I'm very grateful if someone can guide me to fix the problem.