IBM Power Adapter PA-1121-071 16V 7.5A Used with CF-51 MK3

Discussion in 'Panasonic' started by PeteB77, Oct 25, 2017.

  1. PeteB77

    PeteB77 Notebook Consultant

    Reputations:
    23
    Messages:
    205
    Likes Received:
    13
    Trophy Points:
    31
    The CF-51 MK3 calls for a 15.6V 8A power adapter that is rather expensive at $25 or more
    from the usual places.
    It is noted in the CF-51 FAQ that the IBM 16V 7.5A adapter will work but you have to cut off
    the connector and solder on the correct one. I found this adapter under part number PA-1121-071
    is correct and are plentiful for $10 BO shipped even as low as $7.50:
    https://i.ebayimg.com/images/g/cYIAAOSwVlVZ5y3T/s-l1600.jpg
    I bought one a while back and finally got around to putting on the correct connector. Many sellers
    provide pictures where you can see the date code, mine is 2005 but I've seen as old as 2003 try
    to get one that is not too old since the caps degrade over time.
    I cut off the IBM connector and found that the cable is shielded with the shield being the negative
    and the center (looks like 16ga or bigger) wire is positive. I thought it would be easiest to solder
    wires together and use heat shrink over the splice so I bought this adapter on ebay:
    5.5mm x 2.5mm Right Angle DC Power Cable Male Plug Connector Adapter
    https://i.ebayimg.com/images/g/uBIAAOSw8L9Z4CRQ/s-l1600.jpg

    I found that the wire is too thin on the above connector but am trying it for now anyway.
    Make sure that the center is positive and of course check your work with a meter.
    This one measures 16.5V no load on a Fluke meter. 16.3V with a 2 amp load. This is a bit
    high but within about 5% so probably okay. 15.6 *1.05 = 16.38V

    Been using it for about an hour now and it works fine. This IBM adapter is HUGE by the way.
    Runs cool with low draw at least.

    If anyone knows of a better 5.5mm connector please post it here.
     
  2. toughasnails

    toughasnails Toughbook Moderator Moderator

    Reputations:
    1,927
    Messages:
    5,697
    Likes Received:
    840
    Trophy Points:
    281
    Did you also see my warning in the FAQ about the IBM power supply ? I fried two of my 51"s and the batteries. Not sure which model I was using but they do work fine on my CF-19 and 30.


    I've used the IBM power supply (16V/4.5A) successfully to power my CF-51P, but be very aware that running a power supply that far above its ratings may very well start a fire. Please be careful, and don't leave your non-standard setup unattended!

    UPDATE....The IBM power supply will power the 51 and charge the battery but not both at the same time. The power supply will get very very hot. On my 51MK3 the charge light was going off and on while the 51 was running but when it was off the charge light would stay on and charge the battery.
     
    Last edited: Oct 25, 2017
  3. CWB32

    CWB32 Need parts for my flying saucer.

    Reputations:
    179
    Messages:
    1,565
    Likes Received:
    410
    Trophy Points:
    101
    that 7.5 amp supply will pretty much loaf along until it is called upon to charge the battery full tilt .
    as long as you have a genuine panasonic/ibm/lenovo brick , it will hold up .
    most of the after market supplies are the pits and built as cheap as possible .

    the best life/physical integrity of the power cable to the machine is had by changing out the entire cord .
    these can be obtained from a decent supplier or from dead power supplies .
    the molded ends are hard to beat .
    i have had some luck by using stepped sizes/placement of heat shrink tubing ...
    keeping the power cable from kinking is the key .
    a radius bend will hold up for a long time .

    it is not unusual to have the cable go bad on these supplies ...
    not because they are cheap but because the power supply itself is used for years and years .
     
  4. PeteB77

    PeteB77 Notebook Consultant

    Reputations:
    23
    Messages:
    205
    Likes Received:
    13
    Trophy Points:
    31
    I thought that the issue was using a 4.5A supply on a unit that requires 8A under worst case
    conditions. Did you ever try the 7.5A IBM supply?
     
  5. Shawn

    Shawn Crackpot Search Ninja and Options Whore

    Reputations:
    1,425
    Messages:
    6,807
    Likes Received:
    1,119
    Trophy Points:
    331
    I personally have never had a problem using IBM 7.5a supplies once I replaced the cable.
    I have spliced the ends before, but I now prefer to open the supply and solder on an entire new cable. That makes for a much cleaner looking job.
    Finding a replacement cable that is heavy gauge can be challenging.
     
  6. PeteB77

    PeteB77 Notebook Consultant

    Reputations:
    23
    Messages:
    205
    Likes Received:
    13
    Trophy Points:
    31
    Thanks Shawn, very good to know.
    I found a cable, it is an old Linksys 5V 2.5A power adapter for the very old blue
    Linksys routers from before they went to 12V. Cable looks like a standard 18 ga
    extension cord. You'd think being so old they'd go for a few bucks used but they
    are around $8 on ebay which I'm not going to pay, will just buy an actual Panasonic.
    I have one and will probably just cut off that cable and solder it on by opening the
    supply - thanks for the tip.
     
Loading...

Share This Page