DeWalt charger unstable?
 

My DW9118 charger emits a loud ~10 KHz audible tone
when charging a battery. It didn't use to do that.
Anybody else have one of these?

--Winston

DeWalt charger unstable?
 

Winston wrote:

My DW9118 charger emits a loud ~10 KHz audible tone
when charging a battery. It didn't use to do that.
Anybody else have one of these?

--Winston

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

DeWalt charger unstable?
 

On Wednesday, July 25, 2012 7:42:42 AM UTC-6, Winston wrote:
My DW9118 charger emits a loud ~10 KHz audible tone
when charging a battery. It didn't use to do that.
Anybody else have one of these?

--Winston

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

DeWalt charger unstable?
 

On Wed, 25 Jul 2012 09:28:06 -0500, Pete C. wrote:

Winston wrote:

My DW9118 charger emits a loud ~10 KHz audible tone when charging a
battery. It didn't use to do that. Anybody else have one of these?

--Winston

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

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

DeWalt charger unstable?
 

On Wed, 25 Jul 2012 08:32:57 -0700, stans4 wrote:

On Wednesday, July 25, 2012 7:42:42 AM UTC-6, Winston wrote:
My DW9118 charger emits a loud ~10 KHz audible tone when charging a
battery. It didn't use to do that. Anybody else have one of
these?

--Winston

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.

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

DeWalt charger unstable?
 

Winston wrote:

On Wed, 25 Jul 2012 09:28:06 -0500, Pete C. wrote:

Winston wrote:

My DW9118 charger emits a loud ~10 KHz audible tone when charging a
battery. It didn't use to do that. Anybody else have one of these?

--Winston

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

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. :)


http://www.thecapking.com/whatwestock.html is where I buy some of my low
ESR electrolytics. The rest are bought from Digikey.

DeWalt charger unstable?
 

On 25 Jul 2012 16:27:31 GMT, Winston wrote:
On Wed, 25 Jul 2012 08:32:57 -0700, stans4 wrote:
On Wednesday, July 25, 2012 7:42:42 AM UTC-6, Winston wrote:

My DW9118 charger emits a loud ~10 KHz audible tone when charging a
battery. It didn't use to do that. Anybody else have one of
these?

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.

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? :)

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.

-- Bruce --

DeWalt charger unstable?
 

On Wed, 25 Jul 2012 10:59:50 -0700, Bruce L. Bergman (munged human
readable) wrote:

On 25 Jul 2012 16:27:31 GMT, Winston wrote:
On Wed, 25 Jul 2012 08:32:57 -0700, stans4 wrote:
On Wednesday, July 25, 2012 7:42:42 AM UTC-6, Winston wrote:

My DW9118 charger emits a loud ~10 KHz audible tone when charging a
battery. It didn't use to do that. Anybody else have one of
these?

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.

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? :)

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

Ay ay, Sir! :)

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.

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.

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.

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

-- Bruce --