notebook ac adapter pulsing

M

mynick

Guest
The notebook probably will not boot because the adapter output is
oscilating approx +/-0.5v
the output pi filter capacitors and inductor seem ok and there is same
pulsing in front of it -any ideas what may be the cause?There
are:nec2501 LK837-?,TL431c-regulator, fch200.. double diode,10n60
power mos
thanks
 
mynick wrote:
The notebook probably will not boot because the adapter output is
oscilating approx +/-0.5v
the output pi filter capacitors and inductor seem ok and there is same
pulsing in front of it -any ideas what may be the cause?There
are:nec2501 LK837-?,TL431c-regulator, fch200.. double diode,10n60
power mos
thanks
Click to expand...
Look at the feedback loop on the adapter.
 
On Wed, 8 Dec 2010 10:06:50 -0800 (PST), mynick <anglomont@yahoo.com>
wrote:

The notebook probably will not boot because the adapter output is
oscilating approx +/-0.5v
the output pi filter capacitors and inductor seem ok and there is same
pulsing in front of it -any ideas what may be the cause?There
are:nec2501 LK837-?,TL431c-regulator, fch200.. double diode,10n60
power mos
thanks
Click to expand...

If it pulses with no load on it, the problem is most likely an
electrolytic cap in the primary circuit. If it only pulses with a
load on it, there could be a short in the notebook. Chuck
 
On Dec 9, 2:37 pm, Chuck <c...@deja.net> wrote:
On Wed, 8 Dec 2010 10:06:50 -0800 (PST), mynick <anglom...@yahoo.com
wrote:

The notebook probably will not boot because the adapter output is
oscilating approx +/-0.5v
the output pi filter capacitors and inductor seem ok and there is same
pulsing in front of it -any ideas what may be the cause?There
are:nec2501 LK837-?,TL431c-regulator, fch200.. double diode,10n60
power mos
thanks

If it pulses with no load on it, the problem is most likely an
electrolytic cap in the primary circuit.  If it only pulses with a
load on it, there could be a short in the notebook.  Chuck
Click to expand...

Thank you both
besides pulsing you can hear clicking in same rhytm,probably from
transformer since lk837 seems to be optocoupler.
With (non notebook) load output goes down to few volts!!There is also
a controller chip but cannot see which is it
How do you check that real big electolytic capacitor
 
On Thu, 9 Dec 2010 11:46:05 -0800 (PST), mynick <anglomont@yahoo.com>
wrote:

On Dec 9, 2:37 pm, Chuck <c...@deja.net> wrote:
On Wed, 8 Dec 2010 10:06:50 -0800 (PST), mynick <anglom...@yahoo.com
wrote:

The notebook probably will not boot because the adapter output is
oscilating approx +/-0.5v
the output pi filter capacitors and inductor seem ok and there is same
pulsing in front of it -any ideas what may be the cause?There
are:nec2501 LK837-?,TL431c-regulator, fch200.. double diode,10n60
power mos
thanks

If it pulses with no load on it, the problem is most likely an
electrolytic cap in the primary circuit.  If it only pulses with a
load on it, there could be a short in the notebook.  Chuck


Thank you both
besides pulsing you can hear clicking in same rhytm,probably from
transformer since lk837 seems to be optocoupler.
With (non notebook) load output goes down to few volts!!There is also
a controller chip but cannot see which is it
How do you check that real big electolytic capacitor
The easiest way to check electrolytic capacitors is with an ESR meter.
Click to expand...
However, you could try replacing caps between 1 and 100 mfd in this
supply. Chuck
 
On Dec 10, 2:17 pm, Chuck <c...@deja.net> wrote:
On Thu, 9 Dec 2010 11:46:05 -0800 (PST), mynick <anglom...@yahoo.com
wrote:



On Dec 9, 2:37 pm, Chuck <c...@deja.net> wrote:
On Wed, 8 Dec 2010 10:06:50 -0800 (PST), mynick <anglom...@yahoo.com
wrote:

The notebook probably will not boot because the adapter output is
oscilating approx +/-0.5v
the output pi filter capacitors and inductor seem ok and there is same
pulsing in front of it -any ideas what may be the cause?There
are:nec2501 LK837-?,TL431c-regulator, fch200.. double diode,10n60
power mos
thanks

If it pulses with no load on it, the problem is most likely an
electrolytic cap in the primary circuit. If it only pulses with a
load on it, there could be a short in the notebook. Chuck

Thank you both
besides pulsing you can hear clicking in same rhytm,probably from
transformer since lk837 seems to be optocoupler.
With (non notebook) load output goes down to few volts!!There is also
a controller chip but cannot see which is it
How do you check that real big electolytic capacitor

The easiest way to check electrolytic capacitors is with an ESR meter.
However, you could try replacing caps between 1 and 100 mfd in this
supply. Chuck
Click to expand...
Ok thanks however the pwm controller is ob2269
(http://www.datasheet4u.com/download.php?id=624217)but the 19v circuit
is similar to the one shown typical application:(
 
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