I have a problem with a TOP227 which is behaving strangely in a piece of medical equipment.
After being life tested for a considerable period with no problems the unit was left switched off for about a month. When it was then switched on the PSU failed to start. The supply rail was measured as 320V. The TOPSWITCH was changed and the unit operated normally. To investigate this I fitted the failed device into another power supply, where it started up and seemed to behave without fault.As it is important to understand any failures I fitted the device back into the original equipment; where it again operates correctly. The rise on the control pin appears normal, so I can see no cause for the original failure.I wondered if anyone had any ideas on this? The capacitor on the control pin is a 47u tantalum, rated at 16V.