New unibody power adapters don't work with older 17 inch notebooks

I had the power adapter from my son's new Unibody MBP - it's the one where the adapter goes ninety degrees from the connector instead of plugging straight in. I tried it on my old Penryn MBP and it would not give me any lights or charge. I tried the adapter on my daughter's older Merom MBP and it work with no problems. So it appears this is one case where the adapter for one doesn't work on all of the others.

BTW, I just used my daughter's adapter for power.

 

Strange, my Unibody MBP adapter works with my cousin's Penryn MBP no problem. I really don't think that there would be a charger that is incompatible with older models, it's not apple's style. (With the exception of the PowerBooks)

 

you didn't mention sizes there much.... don't mix up any of the 65 to 85 watt adapter differences...

 

Looking at the OP's signature, I believe all the 15" and 17" MBPs have come with 85W adapters?

Also, I know there is no "right-way up" on the mag-safe connectors. But on occasion, I've plugged mine and the charging light wouldn't come on. And the only thing that would get it to work was/is unplugging it and flipping it over. Could be worth a try.

 

They are all 85 Watt adapters. I tried the adapter both ways. The new adapter worked on older 15 inch MBPs but not on my 17 inch. We have six or seven adapters for four computers now with three MBPs in full-time use. The additional adapters is so that we don't have to carry the adapters with us.

 

I read on apples sites for older MBP's you have to remove the battery, hold power button for 10 seconds, put battery back in, power on, then put on the new power cord and it will work. Dont ask my why ppl just say this works.

 

Sounds plausible. Both my son's and daughter's MBPs have had motherboard replacements after I bought my 17 inch MBP and something could have been updated on the motherboards after I bought mine.

 

Finally had a chance to try the workaround as I needed to use my son's adapter in his apartment. I will bring one of the old spares down to the apartment tomorrow. So the workaround is to remove the battery. It works after that.

From reading on the web, it appears that you need to do the workaround if you go back and forth between new and old adapters. I guess that isn't too bad. I have three adapters that I use in the places where I am most often and never carry adapters around with me unless traveling.

 

I've been using a 65 watt adapter with my MBP Unibody for the last month. Its the adapter I bought to test an old SR Macbook.

 

I'm installing a new firmware update from Apple to fix this problem.

I won't get a chance to test it for a while as it's at my son's apartment. Hopefully all will be well.