DC Adapter Tip

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jrv331 · #1 Post by **jrv331** » Thu Sep 20, 2007 7:18 am

Im looking to by a DC adapter for my A31 and see that most of the universal ones come with several tips numbered s1-s7 . Not all tips are color coded.Does anyone know what tip the A31 takes?
Thanks
John

tom lightbody · #2 Post by **tom lightbody** » Thu Sep 20, 2007 10:41 am

with aftermarket DC adapter you are risking your
thinkpad: fuses have been blown. I suggest you look
around for an IBM 72 watt ac/dc combo power adapter pn
22P9003. There also are several other 16v from IBM, some
DC only. 22P7091.

#3 Post by **rkawakami** » Thu Sep 20, 2007 11:51 am

I'd second that suggestion (getting a genuine IBM AC/DC combo adapter), however, to answer your question in a way:

5.5mm outside diameter, 2.5mm inside diameter, center positive

jrv331 · #4 Post by **jrv331** » Thu Sep 20, 2007 12:37 pm

Thanks for the part numbers. I was looking at the combo unit and got to thinking - I have the genuine AC adapter, can I just go out and buy the three sided DC power cord and use that? Kind of looks like what the combo unit is.
Thanks
John

jrv331 · #5 Post by **jrv331** » Thu Sep 20, 2007 12:39 pm

Sorry for the second post, I thought the idea behind the fuse was that it would blow before causing harm to the computer.
John

#6 Post by **rkawakami** » Thu Sep 20, 2007 12:47 pm

The AC/DC combo adapter has TWO input power cords and jacks: a regular 2-wire AC cord and a 4-pin DIN style DC cord (ending in the usual cigarette lighter plug). You can't use a regular AC adapter unless you get what's called a power inverter. That changes the 12V DC from your car to 110V AC. You then plug your normal Thinkpad AC adapter into that. As a bonus, you could use the power inverter to power other (small) AC equipment.

And yes the fuse may protect your system but transistors and ICs have a nasty habit of blowing up first so that they end up saving the fuse!

#7 Post by **carbon_unit** » Thu Sep 20, 2007 1:03 pm

rkawakami wrote:(snip) a 4-pin DIN style DC cord (ending in the usual cigarette lighter plug). (snip)

Ray, do you have a part number for this item or do you know where I can find one? I have an ac/dc/ combo adapter but no dc cord.

jrv331 · #8 Post by **jrv331** » Thu Sep 20, 2007 1:06 pm

I actually have two heavy duty power inverters that use on trips for the kids games. I didn't think it would be a good idea for use with a computer? Any special kind?
Thanks
John

#9 Post by **rkawakami** » Thu Sep 20, 2007 2:14 pm

carbon_unit wrote:Ray, do you have a part number for this item or do you know where I can find one?

Unfortunately, no. The AC cord comes with an FRU sticker attached but the DC cord does not appear to have any identifying marks. The only thing I have recently noted about this cord is this:

http://www.kawakami-ca.com/images/ibm_dc_cable.jpg

It's the end of the cord which plugs into the combo adapter. The other end is the cigarette lighter adapter into which the Enpower (?) plug fits in. I'm in the same boat as you since I believe I'm missing two such cords. I have found them on eBay but they are quite rare by themselves. Some of the combo adapters being offered are missing the DC cord.

@jrv331: No, not really. The inverter you use should be rated for more power than what you are trying to run. For something as small as a 72 watt combo adapter, a 150 watt inverter should suffice. I have a Power2Go L03040 which is rated for 140 watts. Your heavy duty inverter may be more than that. If the inverter delivers a "dirty" AC signal (not exactly a sine-wave 60hz), the regular AC adapter should still be able to generate a nice steady 16VDC.

jrv331 · #10 Post by **jrv331** » Thu Sep 20, 2007 3:48 pm

Thanks for the help, you save me a few bucks here. I have a 300w and a 600w inverter. I used to power a tv/vcr combo back in the day for long road trips. Now its a PS3.
Great forum
John

Robbyrobot · #11 Post by **Robbyrobot** » Fri Sep 21, 2007 3:36 am

I thought the idea behind the fuse was that it would blow before causing harm to the computer.

That's generally true, but even if were true all the time (Ray mentioned some exceptions), the Thinkpad fuses are on the mainboard and by no means so easy to replace - or even find in some cases.

dogtag1968 · #12 Post by **dogtag1968** » Sat Sep 29, 2007 11:02 am

I use a Targus Universal ac adapter on my R40, and the #4 tip is recommended. The same tip is recommended for use with their Auto/Air adapter.
The same tip works on my T22 & R30

DC Adapter Tip

DC Adapter Tip

DC Adapter Tip

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