Hello, I recently changed the motherboard of my dell 640m with a used one. Everything works well but it doesnt charge with the power adapter...When I plug it to the laptop, the small yellow led on the adapter turns off but when I unplug it, it turns back on... Perhaps, it works well with the battery. I tried the power adapter on my other dell laptop and it works perfecly. i would really aprreciate if someone can help me with that matter... Thank you

THE BOTTOM OF SOME DELLS
THE STICKER LABEL THERE SHOWS
65w, on the label.
one I just looked at shows.
if this GPU screen, use 65w
if this GPU screen is advanced GPU use 100w.?
just turn over the laptop\
and read the sticker,

the power pack you have can be bad wrong
wrong and way to week wattage rated.
reading pack only gets 2 packs wrong,dig?
some PCs have 3 pack choices for 3 major options in your PC you have not disclosed. THE BOTTOM OF SOME DELLS THE STICKER LABEL THERE SHOWS 65w, on the label. one I just looked at shows. if this GPU screen, use 65w if this GPU screen is advanced GPU use 100w.? just turn over the laptop\ and read the sticker, the power pack you have can be bad wrong wrong and way to week wattage rated. reading pack only gets 2 packs wrong,dig? some PCs have 3 pack choices for 3 major options in your PC you have not disclosed.

1 milltionth bad battery today world wide
who'd have thunk it? 1 milltionth bad battery today world wide who'd have thunk it?

yes all laptops made run power packs from
as low as 35watts, (new) to older as hight as 150 watts, mine is 240w. and needs that because the
the processor on mine (fast i7) sucks 50 watts an the GPU near the same due the ultra fast GPU option in mine/
each PC has sub model number (laptops)
that tells a technician what options are in this PC. and the power pack size is based on that set of facts and that alone.! (called a power budget)
what is needs is covered in his matching manual on his unstated PC. (but i cant find it)
or the bottom sticker of laptob bottom case
shows watts clear as day,LOOK here first.

only dell can answers watts min.
if not bottom of pc sticker.
here is there page , under power errors
read this quote. only the full service tag on all PCs made tells a real tech what is needed
and the OP did not post those key facts
so ask Dell this. we are not dell;.
if you bought the PC with wrong pack on it reading the label now is DAFFY duck bad.


"Dell laptop PCs may use either a 65W (Watt), 90W, 130W, 180W or 240W AC adapter. For optimal performance, use the AC adapter that came with the Dell laptop PC. AC adapter's wattage information is printed on the label which is located at the bottom of the AC adapter."

off hand a 90w should do it. about 5 Amps
if guessing guess large, 130w would be plenty.
i see dell lost the spec page on this PC
i see the largest pack ever sold for this PC is 130w. (lost in the sands of time)

you can ask on dell.com rel forum
be super wise to do ,known the documents are lost in the support page
btw, fixya has zero documents here.
zero, we can use rabbit in hat trick here. yes all laptops made run power packs from as low as 35watts, (new) to older as hight as 150 watts, mine is 240w. and needs that because the the processor on mine (fast i7) sucks 50 watts an the GPU near the same due the ultra fast GPU option in mine/ each PC has sub model number (laptops) that tells a technician what options are in this PC. and the power pack size is based on that set of facts and that alone.! (called a power budget) what is needs is covered in his matching manual on his unstated PC. (but i cant find it) or the bottom sticker of laptob bottom case shows watts clear as day,LOOK here first. only dell can answers watts min. if not bottom of pc sticker. here is there page , under power errors read this quote. only the full service tag on all PCs made tells a real tech what is needed and the OP did not post those key facts so ask Dell this. we are not dell;. if you bought the PC with wrong pack on it reading the label now is DAFFY duck bad. "Dell laptop PCs may use either a 65W (Watt), 90W, 130W, 180W or 240W AC adapter. For optimal performance, use the AC adapter that came with the Dell laptop PC. AC adapter's wattage information is printed on the label which is located at the bottom of the AC adapter." off hand a 90w should do it. about 5 Amps if guessing guess large, 130w would be plenty. i see dell lost the spec page on this PC i see the largest pack ever sold for this PC is 130w. (lost in the sands of time) you can ask on dell.com rel forum be super wise to do ,known the documents are lost in the support page btw, fixya has zero documents here. zero, we can use rabbit in hat trick here.

THIS PC HAS MANY MOTHERBOARD OPTIONS
EVEN 10 CHOICES PER COUNTRY
WE CANT GUESS WHAT SUB MODEL YOU HAVE.OK?
AND MATTERS
the fasted one sucks the most watts (power)
this old. ok, the GPU and CPU has wide choices new,and varies greatly,
called power needs
and higher is ways better.
and the pack runs cooler and lasts LONGER too. THIS PC HAS MANY MOTHERBOARD OPTIONS EVEN 10 CHOICES PER COUNTRY WE CANT GUESS WHAT SUB MODEL YOU HAVE.OK? AND MATTERS the fasted one sucks the most watts (power) this old. ok, the GPU and CPU has wide choices new,and varies greatly, called power needs and higher is ways better. and the pack runs cooler and lasts LONGER too.