How can I use a small 90W power adapter with a ThinkPad W530?

The following is what seems to be the simplest solution. I have tried this myself and it seems to be working fine, but I can't myself judge whether there are any problems with it.

User Tamazerd posted this solution on the Lenovo discussion forum:

I used a small jump wire from a kit i had but anything will do. Just make sure it wont short against anything else!

I located where the middle pin of the power-plug is connected to the motherboard (blue cable) and used the jump wire to bridge it with one of the ground/negative ones (black).

This works good for me so far. The only problem i can see with this is if the computer now thinks that all adapters are 135W ones, even the 170W adapter. This is something i havent been able to check.

WARNING: Modifying electric equipment might be dangerous! Do this on your own risk and only if you know what you are doing.