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I have come across similar problems with several 902 adapters. It seems that after a year or two's service the reservoir/smoothing capacitors following the rectifiers become electrically and sometimes physically "leaky".
If left powered up the adapters continue working but if switched off or subject to a power cut they may fail to "wake up" showing various patterns of LED flashing, dim LEDs or even none at all.
Sometimes leaving them powered up for a time will re-awaken them but usually it's a sign of terminal (sorry about the pun  ) failure.
All of the ones I've opened up with failure symptoms have had several power supply board capacitors showing signs of distress, ranging from bulging cans to electrolyte leakage.
It is possible to replace these components, preferably with 'long life' types, though it is not a job to be undertaken unless one is well versed in the black art of wielding a soldering iron. Sadly the PCBs have been assembled with lead-free solder making a tricky job even more difficult.
Thus far I've repaired four 902s successfully at a cost of about £3 and 30 to 45 minutes work for each one.
UPDATE 26/12/2015
Yesterday the 'Master' adapter that I bought new in August 2012 failed, showing a single red LED which could not be reset, it was also quite cool; both symptoms suggestive of a PSU failure.
It having been powered-up constantly for over 12 months I suspected that it had suffered the classic 902 failure. When I opened it up I found that six of the electrolytic capacitors on the power PCB were bulging slightly, confirming my diagnosis.
Having a spare adapter left from my previous repairs I simply swapped the plug-in PCB from the failed adapter to the spare one which powered up and worked OK.
Sadly it looks as though the design and/or component specification of the 902 model destine it to premature failure. |
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2-12-2019 05:07:38