HP "Smart(ass)" power bricks

[Behemot]

I've just found about these "Smart" power bricks for HP laptops and (especially) docking stations but there's still lot of questions, has anybody more insight on this?

It seems there is a line of these smart bricks which are intended for docking stations, 693709-001 and 609941-001. They talk digitally over the center pin, without that the docking station does not work, even though the laptop does. Also these docks are no longer fed from the laptop (as old, e. g. NX5000 did - it worked with power from whichever side).

I also found that the best for dock are 120W PSUs while with (some) 90W it supposedly works too, but a message appears regularly that some stuff may not work cause of weak PSU etc.

Now my question is, there are also older 120W bricks like 317188-001, 350221-001, 393945-001. Possibly many more 90W too. Do they also talk over the enter pin, or they are two-pole only and will not work with the dock? I got dozens of docking stations but if an overpriced/hard-to-get 120W brick is needed for them, I might as well scrap them, nobody will buy that.

[Behemot]

Re: HP "Smart(ass)" power bricks

Solved it. It seems there is only simple voltage-level logics, so when there is some certain minimum voltage (not sure what), it opens some tiny FET and that in turn enables all the VRM drivers etc.

It is possible that depending on the exact voltage, the port replicator detects what power the brick is and tells the laptop to generate the message if it is too low, dunno. But definitelly just putting a kilo-ohm resistor across the voltage input and the center pin (did this directly on the dock board) makes it work with every power brick, incl. non-HP with the correct size adapter.

[ala_borbe]

Re: HP "Smart(ass)" power bricks

to mimic 90w power adaptor put 100k resitor from plus to middle pin on any power brick, not only hp but any and you have 3 pin power supply... no communication as far as i know (dell does communication on middle pin). for 120w maybe you need lower resistance resistor... works 100%

[Behemot]

Re: HP "Smart(ass)" power bricks

Works with 1k, I've also read about 10k. So I guess anything in between

Once it was enough to just charge the FET gate by connecting the two poles with a finger so it indeed could be also very high resistance. Did not manage to repeat that again though, lol.

[piernov]

Re: HP "Smart(ass)" power bricks

Never really got into it but I've observed lower voltages on the center pin on newer platform. The center pin is usually clamped on the board with zener diodes between ground and a power rail, and then goes to the EC. The EC probably has an ADC to measure the voltage and enable power rails (and report back to the BIOS).
On Dell there is a one-wire ROM inside the power brick. You can buy them already programmed on Aliexpress and either solder it on the board or inside the power brick. You can use an older HP power brick for Dell, the barrel plug (thick one) is the same.

[Behemot]

Re: HP "Smart(ass)" power bricks

If it is connected, older 65W HP bricks only have 2 wires.

I knew there is that digital crap in Dell, that's what I was afraid too with this, fortunatelly it is not the case. Still, thanks for the info about the boards, could come in handy. Still rather repair original brick than buying these aftermarket El Cheapo craps which will set you on fire.

[piernov]

Re: HP "Smart(ass)" power bricks

I know of 3 different HP power jacks at least. The very old one that was pretty standard at that time, barrel plug without center pin (may have a yellow tip), acer uses the same, found on P4 laptops for example. The old one which is a large barrel plug with center pin, found on C2D laptops. The newer one, smaller barrel plug with center pin (may have a blue tip) found on current series of laptop.

Dell has been using the large barrel plug with center pin for a very long time.

[Behemot]

Re: HP "Smart(ass)" power bricks

Old 4.8/1.7 was used with Pentium M systems too. The smaller one currently in use is likely to make them 14" very thin, The Chinese (Lenovo) claim that's why they had to make that rectangular thing.

[dfragx]

Re: HP "Smart(ass)" power bricks

Just opened an original 65W charger that i really needed fixed, after looking, it uses a simple resistor of 383Koms to the 19V. After replicating this with a bench PSU at 19V + ~390k, the laptop will work and charge perfectly. Laptop Is one of those that are "picky" with the charger it will not power even with full 19V on middle pin, only when the resistor is placed, hope this helps someone

[Behemot]

Re: HP "Smart(ass)" power bricks

I've entountered interesting thing recently. Usually use adapters of the most usual 5.5/2.5mm connector from the collection Avacom sells (local seller of such stuff), so far they always worked. But now I've encountered that with one, I think 65W brick, it worked, but during FullHD video playback, the 6730b sound was heavily lagging, often dropping off alltogether. Identified the brick as the culprit. Gonna take 90W brick next time to check!

[Behemot]

Re: HP "Smart(ass)" power bricks

Wanted to moddify another dock to use in second place with the same laptop, so far using 10k and 2k4 resistor makes it throttle to 133-266 MHz!!! I've upgraded to P9700 since which would explain this change in behaviour too. So one must most likely really mimic the correct resistance. I can confirm measuring on 65W brick it is those 383k.

ADD// 100k resistor did the trick, now works with 65W and 120W bricks so it's safe to asume it will also work with 90W brick and around 90W-ish two-wire bricks using an adapter. Remember that when dealing with docking stations, the effective value will vary depending on which brick you use as you connect those two resistors in parallel (if you want to put the resistor directly on the dock power jack)

So far the observed resistance is:

- 65W brick: 383k
- 90W brick: 100k (acording to ala_borbe)
- 120W brick: 220k