Dell charger model fa65ne1-00 with sense wire?

[Solve]

I sold an class-d amp to a friend and he had an 19v Dell laptop SMPS with three wires and I just told him to skip one wire and it sounds very bad.
Then I learned it's an sense wire could he connect it to +?
I thinking it dropping the ampere or voltage?
Dell charger model fa65ne1-00

 

[gerhard]

It is not a sense wire in the usual way. It gives no feedback to the regulator.
The PS tells the laptop how much power it can supply and the laptop will
either not even boot ( my Dell Precision on a generic PS with only + and -),
run at reduced speed ( same D.P on the PS of a college's Inspiron) or it
will run normally on its own 240 W supply. Yeah, "portable workstation"

I think the power class is encoded with a resistor to GND in the PS, but
I'm not sure.

cheers, Gerhard

 

[Solve]

Ok, so just make it the easy way from my not DIY friend to skip this and buy another SMPS I think.
Thanks Gerhard!

 

[gerhard]

Probably you can simply ignore that wire. It's worth a try.
After all, there must be power initially, or the Laptop could
not even check if it is enough.

 

[Solve]

Probably you can simply ignore that wire. It's worth a try.
After all, there must be power initially, or the Laptop could
not even check if it is enough.

Yes maybe, I trying to support him on distance but he say is sounds good from USB DAC headphone jack out but RCA to amp just bad.
That start me thinking about the sense wire.
And if I was unclear, the sense wire is not connected.

 

[sgrossklass]

You're probably looking for the problem on the wrong end of the power supply. This smells like classic ground loop to me. I think I've seen Dell power supplies both with secondary-side ground bonded to PE hard and with a more Thinkpad-style connection (1 kOhm || whatever capacitor). Accordingly, your results may vary depending on source.

To confirm this theory, use the amplifier with a floating (battery-operated) source such as a phone or DAP. If that sounds fine, it's very likely to be a ground loop. If not, no idea what else it could be, other than a bad amp or supply or wrong polarity.

 

[Mooly]

The 'third wire' on Dell PSU's is normally connected to a Dallas Semiconductor ? ROM type chip that contains pre-programmed info on the PSU specs. These are read at boot by the laptop and if the details are incorrect then the laptop runs at a reduced performance.

 

[Solve]

Thanks for answers my friend got an new PSU
and everything works fine.