01-05-2018 08:24 AM
Mock me if you like, , but... Figured I would share, so others might benefit?
There are a few flavours of AC Power issue out there (some bad 170W Power Supplies, some Lenovo Battery Manager issues, etc.), but if you are greeted with the warning on your W520, and are using a true 170W Power Supply, stop and check the Power Supply plug connection IN to the dock.
I know sounds ridiculous, but... First, given the slotted construction of the 170W Power Supply connector, NEVER force anything! But, once you've lined that up, are sure and slid it in to the dock, at that point, make SURE that it's really fully seated in to the connector! PUSH it to ensure!
I've been having the issue, and finally realized, on my setup, there is an extra "hump" you have to push the connector past. (How long have I had this machine? FACEPALM!) If you plug it in, it will work, but give errors and be problematic on charging. Once you FULLY plug it in, that problem goes away.
I think it's a function of the middle pin not being fully and properly seated - so a test was failing (making it think it was a 90W supply?).
And a PS for folks:
The original dock for the W520 was the "4338-30U (eSATA)", 170W.
I can report that the "4338-35U (USB 3.0)", 170W DOES in fact work with the W520.
Sadly (as I expected), no, you don't get another USB 3.0 port on the back of the dock. It de-rates to a USB 2.0 port, but that port does work - so 7 USB 2.0 ports on the dock itself. (This is a chipset limitation of the W520 - think that was changed with the W530?) So you only still get the two USB 3.0 ports on the side the of laptop itself, but that newer dock will work for you. My sound had turned MONO, so I got a replacement to sort that.
Oh, and if you look around for the "4338-35U" - be aware, there are lots of sellers that are VERY confused by that. The 35U absolutely is the 170W part needed. But you will see many listings confusing it with the 90W USB 3.0 version (4338-15U), or list the 15U as a 170W solution - it's not.
11-15-2018 04:48 AM
To expand on this reply. The 4337 docking station works with the W500. Most sellers of this docking station advertise that it works with the W520. But read the FINEprintwith the asterisk. The 4337 ONLY works with the W520 / W530 TWO processor laptops. The 4338 works with the W520 / W530 QUAD processor. I learned this distinction the hard way.