Can anyone suggest what might cause NXC100 controller with HP3 robot dropping servo power off now and then? Problems started so that servo power turned on but brakes didn't release everytime. After a while it started giving alarms 4301 (Contactor error) and sometimes alarm 1345  (Safe circuit signal not same (SV)). Now the new problem is that it is dropping servo power off, and there is no alarm, just dropping servo off and brakes on. Sometimes power stays on only few seconds, sometimes few minutes. This new problem makes it impossible to use this robot so now it really needs to be fixed.
I have changed NTU board (because I thought it might be the reason for brakes not releasing) and tried with another teach pendant and cable. I was thinking that could it be power source that is "tired" and voltage drops so that it has no power to keep contactors closed? Or what could it be?