On Fri, 05 Oct 2012 21:19:00 -0700, Jeff Liebermann
wrote:

On Fri, 05 Oct 2012 20:10:55 -0500, legg wrote:

This DeWalt 9116 charger has had battery packs forced into it
repeatedly and strongly enough to crease-open board foil in the area
and crack R49 ntc thermistor in half. The thermistor chip fragment
remaining in the R49 half-package still measures ~77K, but standard
values suggest this should be sloser to either 13K, 25K, 37K or 120K
at room temperature.

So what's the correct normal R49 value for replacement?

Dunno. I couldn't find a schematic. Easiest way is probably to find
an identical charger and measure the resistance.

This might be interesting and possibly useful:
http://dewaltownersgroup.com/index.php?topic=869.0

As a result of the physical damage, other parts are also damaged, but
I believe these have been fairly easy to track down, identify and
replace.

I see DeWalt chargers at the local used tool dealer for about $20. Not
sure which model but it looks similar. It's always easier to repair
something when you have a working unit available with which to
compare.

I've already accessed the images - this version is a later revision
with slightly different artwork and a completely different controller
(higher pin count, wider body). The area around R49 and other
temperature sensors is the same. The charger model has been recalled
and revised a couple of times - has different voltage versions with
the same part number, it seems.

An unreadable schematic off the web assists in identifying functions
of most parts in the power train and drive cctry. Have been working on
switchers for some decades, so this section offers few surprises. I
can probably get function with a fixed value here, but am looking for
confirmation for a correct repair.

This thing and it's exploded electrolytic picked off the floor at a
work site. Cracked board looks like original fault, but much damage
resulting.....no working unit for comparison. Just hope the controller
section is as carefully partitioned as schematic suggests - no reason
to fail unless chip supply(and program memory) also got scrambled.

RL