Using an older power adapter with a new T42

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dansthink · #1 Post by **dansthink** » Tue Feb 14, 2006 8:58 am

Hi, I have an older power adapter meant for a Thinkpad 570e that I'd like to use with my T42. When plugging it in today, I noticed that the battery takes about 33% longer to charge with this older adapter. The specs are the same except the output: 2.2 amps vs. 4.5A. Physically it fits just perfect. Not being an EE myself, I would imagine this is why the T42 takes longer to charge with the old adapter. But if I don't care about charge time, is this otherwise hurting my T42 over the long-run?

hoya · #2 Post by **hoya** » Tue Feb 14, 2006 10:45 am

You can buy a brand new T42 AC Adapter (72 watt) on Amazon for about $35. I would recommend going that route.
http://www.amazon.com/gp/product/B00006 ... 9?n=172282

Website · #3 Post by **tfflivemb2** » Tue Feb 14, 2006 11:02 am

I really wouldn't recommend using anything less than a 72watt power supply on your machine. Using the lower Amp'd power supplies can cause power issues on your system, including damage to the system board. Take a quick breeze through the T2x series forum and you will see what I am talking about.

There is a great post on here, which uses an excellent analogy to explain this: http://forum.thinkpads.com/viewtopic.ph ... wer+supply

laz · #4 Post by **laz** » Tue Feb 14, 2006 11:48 am

Since lenovo sells a 56W power supply, I can't imagine that it would damage the system. Otherwise they'd get lots of service requests because of a product they reccomend for TPs.

Website · #5 Post by **tfflivemb2** » Tue Feb 14, 2006 12:10 pm

Yes, Lenovo sells the 56W adapter, However, the T42 requires a 72W adapter because it uses more power. The 56W is for older systems like the 570E that the OP mentioned.

Using a 56W adapter on a T42 might work for a little while, but extended use will most certainly damage the mainboard and/or the battery.

This is why a lot of T2x users that have purchased T30 batteries for their systems, should be using a 72W adapter. Those that haven't, including someone that I just sold a T23 to, now have problems. The guy that I just sold a T23 to, bought a 56W for his house since it was only $12, and left the 72W at work. It is now sitting on my desk because it will not power on.

dansthink · #6 Post by **dansthink** » Tue Feb 14, 2006 2:13 pm

OK, enough said, I'll use the correct power supply. The reaosn I was doing this was because my old PS for the 570E partially broke in that a piece of the end broke off and made it loose when plugged in. Since I have a dock for my T42, the somewhat lose end wouldn't be a big deal. But the 570 lives on my couch, is moved all the time and has no working battery--not a good recipe for a loose power supply. Maybe I'll snip off the ends and swap them with each other. Nothing wrong with that, right?

I know that $35 to buy a new PS isn't a lot, but my wife gives birth to our first baby in two weeks and money is really tight!

Thanks for the info.

Website · #7 Post by **tfflivemb2** » Tue Feb 14, 2006 6:39 pm

Did you not get a 72W adapter with your T42?

You can most likely find them a lot cheaper on eBay if you are interested.

I'm not quite sure what you mean about the alterations to the power supples.

hoya · #8 Post by **hoya** » Wed Feb 15, 2006 9:53 am

interesting note on Lenovo's site about customers using the wrong AC Adapter with a system and subsequently frying the system board:

http://www-307.ibm.com/pc/support/site. ... MIGR-55458

dansthink · #9 Post by **dansthink** » Wed Feb 15, 2006 11:30 am

tfflivemb2 wrote:I'm not quite sure what you mean about the alterations to the power supples.

I just want to swap the coaxial ends so that the partailly broken one lives on my new power adapter that powers the T42 (via the dock) instead of the one that powers the 570E. That way i get the right power specs into each system, but I have a snug fit on the laptop that needs it.

hoya · #10 Post by **hoya** » Wed Feb 15, 2006 12:13 pm

dansthink wrote: I know that $35 to buy a new PS isn't a lot, but my wife gives birth to our first baby in two weeks and money is really tight!

how about $16 shipped for brand new genuine IBM? I've bought from this guy and had no trouble at all:

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 6849981525

#11 Post by **jdhurst** » Wed Feb 15, 2006 12:46 pm

These threads keep popping up. Please remember two principles:

1. Ohms law V = IR
2. You cannot push power, only pull it.

So by putting in a smaller adapter, the ThinkPad pulls more power through it which can damage the ThinkPad from undervoltage and damage the adapter from overamperage.

For safety's sake and for the sake of your expensive computer, please use only the correct adapter, no matter what other people say will work.
... JD Hurst

Using an older power adapter with a new T42

Using an older power adapter with a new T42

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