DeWalt charger unstable?

Deterioration of lacquer on a transformer / inductor in the switching power supply?

You could use the old TV repairman's standard fix, toothpicks and Ambroid glue to keep the windings from shifting. Used to do that with flyback tranformers when they got too annoying.

Stan

In a past life, I troubleshot switch mode supplies for a living. This symptom is more consistent with deterioration of filter component(s) in the feedback loop, though I do see a *lot* of elastomer gunk surrounding a couple filter inductors and other parts on the PCB. This uses a custom Zilog chip, (the 4448 AKA B&D1999XRL) on a board made by Delta, the power supply folks.

I don't see any documentation for this on the net and it's faster to toss it and buy a Makita, though I'm tempted to draw a schematic for it. :)

--Winston

Yes, but I'd be happier if the feedback loop was not oscillating like that. I see they put a cheapo 1 uF lytic right next to the MOSFET pass element. What'll you wager it is no longer a 1 uF low - ESR lytic? :)

--Winston

So don't sit there whining about it! Go get a new cap and plug in your soldering station.

And a little whine is a good thing - When it stops whining, it's done cooking - and you didn't even need to walk over and check on it.

Or it stopped whining too early because it went into "Hot Pack Shutdown" or Power Line Fault (usually the 12V truck charger, it doesn't like the starter motor droop) and you DO need to check on it.

-->--

Ay ay, Sir! :)

Mine can't decide which mode it is in. Sometimes it doesn't even start whining when charging. Sometimes the oscillation is in step with the flashing 'charge' light. Sometimes it stops whining at end of charge, sometimes it continues.

Lost an alternator that way. Next time I jump someone's battery, I am borrowing all their car keys. (Grumble)