Converter In-Rush Thermistors etc, UPDATE -4
UPDATE on 17 Nov, Update 2 on 22 Nov, Update 3 on 16 Jan 14, Update 4 on 19 Oct 14. --------------- In a recent thread there was mention of how you can wreck your gizmo (in my case a converter) ...
Forum Discussion
Hi BLF,
I have had an oppertunity to repair as many as 20 to 30 converters over the last couple of years.
90% of the failures have been the input side 250Vdc 1,000ufd caps (typically there are at least three in parallel). Most switching converters ingest the 115VAC then with a full wave bridge rectifier get about 160VDC on the input side of the switching supply.
Yes from what I have seen plugging and unplugging the source AC supply has contributed to the failures. That said many were defective caps in the first place. I would venture a guess that your thermister was previous to the bridge rectifier on the AC side of things. Surge currents do strange things and are NEVER any good for electronics devices.
I have had an oppertunity to repair as many as 20 to 30 converters over the last couple of years.
90% of the failures have been the input side 250Vdc 1,000ufd caps (typically there are at least three in parallel). Most switching converters ingest the 115VAC then with a full wave bridge rectifier get about 160VDC on the input side of the switching supply.
Yes from what I have seen plugging and unplugging the source AC supply has contributed to the failures. That said many were defective caps in the first place. I would venture a guess that your thermister was previous to the bridge rectifier on the AC side of things. Surge currents do strange things and are NEVER any good for electronics devices.
