Dell PA-10 ac adapter center pin

Discussion in 'Dell' started by RobertKahle, Dec 7, 2007.

  1. RobertKahle

    RobertKahle Guest

    I've been looking around a lot to see if anyone had any information
    about this but came up with nill...So I investigated it myself for
    anyone out there that may be interested in what that center pin really
    does. For those of you that think I don't know my butt from a hole in
    the ground and feel like leaving any messages against what I did I'm
    not asking for pointless opinions here so take them elsewhere. There
    was a need for it to be reverse engineered and I did it. Enough
    ranting lets get on to the beef of the post.

    I too was wondering what this third center pin is about. No voltage
    present to it, no resistance, no capacitance; got me wondering what
    kinda surprise did Dell put in the power supply that they don't want
    us to know about. So curiosity got the best of me and I very carefully
    pried the glued case apart.

    Standard switching power supply, but then near where the wire enters
    the case and is soldered to the circuit board resides a small TO-92
    device. First thought was maybe a transistor that sinks a certain
    current upon attachment but after further inquiry, only two leads were
    connected. This led me to reverse engineering this small circuit. It
    turns out theres a 131 ohm resistor in series with the center pin wire
    of the DC connecter and one pin of the 'mystery device' and then there
    is a reverse biased diode going to ground. The other pin that is
    connected of said device is also connected to ground (by reverse
    biased I mean that the diode will only conduct if a positive voltage
    were applied to the ground connection of the power supply and a
    negative (ground) were connected to the center pin of the DC power
    connector. This lead me to deducing, because of the series resistor,
    that this diode was a zener of currently unknown breakdown voltage.

    The next step was to determine the true identity of the 'mystery
    device.' The part number read "Dallas 2501 (then a date code)." Dallas
    being dallas semiconductor (aka Maxim IC). A search yielded only a
    very incomplete datasheet refering me to the DS2502 which is a 1kbit
    one-wire EPROM version. The "2501" was a DS2501 of 512 bit data space.
    The datasheet gives specifications to a max programming voltage after
    EPROM write instruction of 12V. This means to protect the device from
    overvoltage this zener diode connected to the pins must be a 12V zener
    and the sereis resistor being a current limiter protecting the diode
    in the event that the inner barrel and center pin were to come into

    The DS2502 and 2501 (1kbit and 512 bit respectively) use Dallas Semi.
    1-Wire (R) communication protocol. It gets its power from the data
    line and when the data line is low a diode protected capacitor supplys
    power for its logic circuits, Parasite Power. This means that to
    communicate with the DS2502/1 one only needs two lines, a data line
    (logic high idle state) and ground. The power to the data/power line
    is supplied by the master through a 5k ohm resistor for short cable

    Hope anyone reading this that wants to make his/her own power
    converter finds this information usefull (insert disclaimer here; ie.
    use this information at your own risk, I am not to be held responsible
    if someone else's equipment gets fried b/c of poor design, I only
    described how it works and make no claims to it being my own design
    giving rights of design and operation to Dell and/or LiteOn (written
    on power brick) and any other engineering firm/company/manufacturer
    that was involved in the design of the motherboard, power brick and
    any other associated equipment, etc.)
    RobertKahle, Dec 7, 2007
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  2. RobertKahle

    RobertKahle Guest

    New update....since my last post on this subject I've written a
    firmware for a microcontroller to read the memory chip in these power
    supplies...this is the eeprom dump from it

    002100: 11 17 E1 6C 02 00 00 C2 ...l....
    002110: 44 45 4C 4C 30 30 41 43 DELL00AC
    002118: 30 39 30 31 39 35 30 34 09019504
    002120: 36 43 4E 30 44 46 32 36 6CN0DF26
    002128: 36 37 31 36 31 35 36 32 67161562
    002130: D0 FF FF FF FF FF FF FF ........
    002138: 41 30 30 85 90 FF FF FF A00.....
    002140: FF FF FF FF FF FF FF FF ........
    002148: FF FF FF FF FF FF FF FF ........
    002150: FF FF FF FF EA FF FF FF ........
    002158: FF

    at memory address 2130, D0, is a CRC (8-bit, x^8+x^5+x^4+1 polynomial)
    of address locations 2110 - 212F that was calculated by the DS2501 as
    the data was read in by the bus master.
    I was unable to get any useful data after 213C but then it read a byte
    at location 2155. The cause of this is unknown and there was no valid
    CRC calculated...this is still under investigation.
    As far as the memory dump....Dell (manu.), 00 I'm guessing is an
    identifier, AC describing what type of adapter, 0 another identifier,
    195046 being 19.5 volts and 4.6 amps. From CN to 62 this is the
    product identification number found on the barcode and A00 is the
    revision code 00 being the important part b/c I obtained a second 90
    watt power supply and it too and an 'A' appended before the numerical
    portion of the revision number.

    Hope anyone reading this finds the information useful.

    (Same as before insert disclaimer here....)
    RobertKahle, Dec 14, 2007
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  3. RobertKahle

    RobertKahle Guest

    After doing some detective work and general head scratching I rewrote
    the firmware to read the whole memory space instead of a page at a
    time, this let me gain access to all the information (consecutive
    addresses throughout) allowing me to find that the whole barcode
    number is stored on the DS2501 followed by the revision number. The
    following is the memory dump from the 12F683's internal EEPROM....

    002100: 11 36 14 6D 02 00 00 B8 .6.m.... = ROM
    002108: F3 FF FF FF FF FF FF 00 ........ = STATUS
    002110: C3 FF FF FF FF FF FF FF ........ = STATUS CRC (=C3)
    002118: 44 45 4C 4C 30 30 41 43 DELL00AC = Start of page 0
    002120: 30 39 30 31 39 35 30 34 09019504
    002128: 36 43 4E 30 43 38 30 32 6CN0C802
    002130: 33 34 38 36 36 31 36 31 34866161 = End of page 0
    002138: 52 32 33 48 38 41 30 33 R23H8A03 = Start of page 1
    002140: 4D 7C FF FF FF FF FF FF M|......
    002148: FF FF FF FF FF FF FF FF ........
    002150: FF FF FF FF FF FF FF FF ........ = End of page 1
    002158: FF FF FF FF FF FF FF FF ........

    So here we have the first line being the ROM. 11 is the family code,
    the serial number is: 0000026D1436 and B8 is the hardcoded CRC reality
    check byte
    The next line is the EPROM status register. The first byte is the code
    protection bits (bits 0-3) and memory usage map (bits 4-7, reserved
    for TMEX) the next 4 are page redirection bytes, bytes 6 and 7 are
    maintained clear/unprogrammed and byte 8 is programmed to 00 at the
    factory. C3 is the CRC computed by the DS2501, this was checked by
    using the program I wrote in windows for computing the CRC
    (x^8+x^5+x^4+1), and was determined to be valid. The next five lines
    are the actual data space information. Dell is the manufacturer, 0 is
    a field identifier, AC is the type of adapter, 090 is the wattage
    rating (my thought is that it allows for 99+ watt power adapters),
    195046 is the nominal voltage rating (19.5 Volts) followed by the
    nominal current rating adjusted to one decimal place (4.6 Amps). From
    C to H8 is the barcode number of the power adapter and A03 is the
    revision of the power adapter. 4D7C is an end of information
    identifier as I have found this on another adapter I own. The one
    thing I was unsuccessful in acquiring was the computed CRC at the end
    of the data space that the memory chip is supposed to send as a 65th
    byte (which is sent at the end of the data space, this was assumed to
    be the same communication protocol as is used for the DS2502).

    Again I hope this helps answer any inquiries anyone may have as to the
    actual data stored in the memory chip.

    I'll be happy to answer any technical questions anyone may have about
    this. Please only technical questions, I am not offering design
    services and any inquiries of that type will be immediately ignored
    and any additional blocked permanetly if I so deem them to be a

    (insert additional lenghty disclaimers here...)
    RobertKahle, Dec 19, 2007
  4. RobertKahle

    ejay Guest

    Hi there, I have a PA-10 adapter which I accidentally damaged by
    shorting the inner barrel with the centre pin. I have dismantled the
    adapter and unsoldered the Dallas 2501 IC. Do you know how/where to get
    this replacement part?

    Can you also describe how you were able to read/write to the 2501? What
    eeprom reader did you use? It would be awesome if you can provide the
    details necessary to program up one of these ICs so that I can obtain a
    replacement and get my adapter working properly again.

    BTW, when the Dallas 2501 chip is damaged, the laptop (in this case a
    Inspiron 8500) runs OK off mains power, but the battery won't charge.
    The BIOS also complains about not knowing what type of adapter it is,
    with the message "The AC Power Adapter type cannot be determined. This
    will prevent optimal system performance".

    Thanks for your assistance

    No thank you to Dell for making such easily broken products. Why can't
    you guys at Dell design your systems to use a normal AC adapter without
    the need for silly detection circuits?

    'Ejay' (
    ejay, Jan 27, 2008
  5. RobertKahle

    msnyder19 Guest


    Thanks for effort on this, my PA10 cord got frayed and looks like the
    brief short took out the DS2105. I opened up the power supply and I do
    not see the Zener and resistor internal to the supply maybe they moved
    that circuitry into the laptop. In my PA10 the DS2105 appears to be
    wired without any supply to it atleast internal to the power supply.

    The Zener that you mentioned was it internal to the power supply or
    did you trace it to within you laptop?

    msnyder19, Jan 27, 2008
  6. RobertKahle

    ejay Guest

    Mine didn't appear to have the zener anywhere. The center pin of the
    barrel plug was wired straight to one of the pins of the DS2105. So the
    IC has no protection whatsoever, be it from overvoltage or static

    I'm also curious if anyone has found a way to bypass this problem.
    Conceivable methods might include modifications to the motherboard, or a
    hacked BIOS. Let me know if you have a solution.

    'Ejay' (
    ejay, Jan 28, 2008
  7. RobertKahle

    msnyder19 Guest

    I think the easiest solution is to get a sample from Dallas of their
    1Kbit eprom, program it with the dump that Robert's shown above and
    see if it works, I have ordered a sample and will try this out, will
    report back If it works. I broke down and bought a replacement adapter
    it seems ebay has them for around $ 20, but would still like to get my
    original working again, pretty sneaky of Dell to do this but I guess
    they will just claim they were trying to ensure that bad adapters do
    not harm the battery :)
    msnyder19, Jan 31, 2008
  8. RobertKahle

    ejay Guest

    Having obtained the component, how would you go about programming it? Is
    it possible to use a modified EEPROM programmer? Or would a simple
    homebrew circuit to interface to a serial/parallel port do?

    Would be nice if Robert could explain in detail how he did it.

    I'm sure there are heaps of Dell adapters out there that have suffered
    the same fate. It's very rare for an incorrect adapter to 'harm' a
    battery anyway - the onboard charging circuitry knows how full the
    battery is, and will apply the charge accordingly. Not to mention the
    proprietary plug, which basically precludes the use of any other
    adapter, so it's not a scheme to protect the battery - but rather a way
    for Dell to screw the customers for more $$ when the adapters break.

    'Ejay' (
    ejay, Feb 1, 2008
  9. RobertKahle

    BillW50 Guest

    In Christopher Muto typed on Mon, 04 Jan 2010 16:54:46 -0500:
    Well that is a tip-off for sure. But if it doesn't, it doesn't mean it
    isn't the jack itself or the solder connections to the board. As
    sometimes the jack can break (and it is still can be solid as a rock) or
    a solder connection or something... and no amount of wiggling will make
    it work for some of them.
    BillW50, Jan 4, 2010
  10. RobertKahle

    MZB Guest


    Can you elaborate. Lately, my Inspiron does switch from battery to AC when I
    jiggle the chord a bit.
    What does that indicate?

    Is it easy to fix?

    MZB, Jan 5, 2010
  11. RobertKahle

    BillW50 Guest

    In Christopher Muto typed on Mon, 04 Jan 2010 22:36:53 -0500:
    I always wondered why some genius hasn't made fake batteries with a jack
    on them. For those that use their laptops on AC alone, I figure this
    would be a gold mine for somebody. Even adding a power regulator inside
    (since the AC adapter voltage is higher than the battery) shouldn't be
    too costly. After all, you can buy AC adapters for 10 bucks or less on

    Another solution is if your laptop can handle a docking station. Well
    there you go. No power jack required. <grin>
    BillW50, Jan 5, 2010
  12. RobertKahle

    MZB Guest

    Thanks Chris.

    So far, it has not been a problem. But I suspect it will get worse over
    I don't think it is the chord.

    This Inspiron 2200 (much maligned by many on the newsgroup) has worked
    flawlessly for me for about 7 years. When it gets worse, I'll buy a new

    I also have an Acer netbook which I like a lot.

    MZB, Jan 5, 2010
  13. RobertKahle

    kajander Guest

    kajander, Apr 19, 2011
  14. RobertKahle


    Jun 3, 2011
    Likes Received:
    OP thanks for posting! I've always wondered what exactly the center "smart" pin is doing. I don't have access to the right equipment to play around with this kind of stuff anymore.
    DJ_Fixalot, Jun 3, 2011
  15. Robert Kahle's 2007 post was all I needed to hack the adapter. Using a
    8 pin microchip 10f220, I wrote the following code. It's the .HEX I
    you want the source PM me.


    The code aint pretty, but it works.

    This sends a fake 90W signal to the mobo to make it think a dell adapte
    is connected. I needed it because I'm off grid and I only have 24VDC.
    I step this down t 18V and use the PIC to fool the mobo. Been good fo
    9 months now.

    You'll need an old plug to connect to the laptop and you'll need t
    identify +, - and signal (centre) pin.
    Connect 18V into the laptop. The centre pin of the goes to pin 3 of th
    Put a ge diode anode on pin 3, cathode k on pin 2.
    Put 0v on pin 7. 330n cap pin 2 to pin 7. You get about 2.5V on pin 2
    which is just enough to power the PIC. The PIC waits about 200ms an
    then sends the message when requested by the mobo. There is so littl
    current sent by the mobo that you can barely light a LED, so only use
    DVM and dont connect anything else!

    I've tested it on 2 d610 and 1 d600. Flawless!

    You'll need a good grasp of electronics to make sense of this, not t
    mention programming PICs. I'm not selling these and dont intend to.

    Usual disclaimers apply
    artful_bodger, Sep 22, 2011
  16. RobertKahle

    gsabovic Guest

    It would be nice to see source code of Artful_bodgers PA-10 PIC emulator, so it could be possible to make one with different PIC.
    P.S. I don`t know how to send PM to Artful_bodger
    gsabovic, Sep 13, 2012
  17. After reading what Robert Kahle had found I was inspired to write my own code to read the chip in dell power supplies. I happen to have a few power supplies so I read them all and came up with the following data:

    Summery of strings from my power supplies:
    MFG- ?? PS -W- -V- -A- --------SerialNumber-------- CRC-16
    DELL 00 AC 150 195 077 CN-0J408P-48661-228-1U2D-A02 0x9447
    DELL 00 AC 090 195 046 CN-0J62H3-71615-04N-49C3-A01 0xA76D
    ..... 00 AC 090 195 046 CN-0C2894-48661-475-6PD3-A02 0xD533
    DELL 00 AC 090 195 046 CN-09T215-71615-41U-3355-L03 0x2564
    DELL 00 AC 065 195 033 CN-05U092-71615-464-0220-A03 0xEF29
    DELL 00 AC 065 195 033 CN-0F7970-71615-55G-02AB-A00 0x7DAB

    Robert had it all right except for the last two digits which I have verified are a CRC16 of the previous 40 bytes.
    Notes: The top supply above is 150 watts proving Robert right about the three digits. The third line is very interesting as the first four digits arenulls instead of "DELL". The CRC16 is either not valid or calculated different. But my laptops don't care!

    Full read of device summarized on line 1 (150 Watt,DS2502 chip)
    ROM data bytes are: Family[1], Address[6], and CRC[1]
    09 1A 3A 0B 38 00 00 0E CRC is valid.
    Chip = DS2502, 1024b Add-Only Memory
    EPROM Status bytes are:
    FF FF FF FF FF FF FF 00 CRC:9C is valid.
    EPROM Data is:
    0000: 44 45 4C 4C 30 30 41 43 31 35 30 31 39 35 30 37
    D E L L 0 0 A C 1 5 0 1 9 5 0 7
    0010: 37 43 4E 30 4A 34 30 38 50 34 38 36 36 31 32 32
    7 C N 0 J 4 0 8 P 4 8 6 6 1 2 2
    0020: 38 31 55 32 44 41 30 32 47 94 FF FF FF FF FF FF
    8 1 U 2 D A 0 2 G . . . . . . .
    . . . . . . . . . . . . . . . .
    . . . . . . . . . . . . . . . .
    . . . . . . . . . . . . . . . .
    . . . . . . . . . . . . . . . .
    . . . . . . . . . . . . . . . .
    Entire EEPROM CRC: 1B is valid.
    Calculated CRC16: 9447 on first 40 bytes of EPROM is a match.

    Full read of device summarized on line 3. 90 Watt, old DS2501 chip, ** invalid 16bit CRC **, first 4 bytes do not say "DELL"!:
    ROM data bytes are: Family[1], Address[6], and CRC[1]
    11 54 DB 98 00 00 00 E7 CRC is valid.
    Chip = DS2501, 512b Add-Only Memory
    EPROM Status bytes are:
    F3 FF FF FF FF FF FF 00 CRC:9C is valid.
    EPROM Data is:
    0000: 00 00 00 00 30 30 41 43 30 39 30 31 39 35 30 34
    . . . . 0 0 A C 0 9 0 1 9 5 0 4
    0010: 36 43 4E 30 43 32 38 39 34 34 38 36 36 31 34 37
    6 C N 0 C 2 8 9 4 4 8 6 6 1 4 7
    0020: 35 36 50 44 33 41 30 32 33 D5 FF FF FF FF FF FF
    5 6 P D 3 A 0 2 3 . . . . . . .
    . . . . . . . . . . . . . . . .
    Invalid EPROM data CRC: FF Calculated CRC:57
    Calculated CRC16: F3E4 on first 40 bytes of EPROM is NOT a match!

    Hope this helps you.
    I wrote the reader program for an arduino so it should be easy for anyone who wants to use it.
, Dec 9, 2012
  18. Respected Robert !
    I have accidently shorted the centeral pin with the inner barel of my PA-10and now this adapter is not working.
    Kindly guide me to resolve this problem because i am am very much interested to repair this myself!

    Impatiently waiting for your reply!
    abdullaharif18, Mar 6, 2013
  19. RobertKahle

    Mike S. Guest

    You may need a lot of patience; after 5 years it is doubtful that the
    original posters of this message thread are still reading the topic.
    Mike S., Mar 7, 2013
  20. RobertKahle

    lopez.werner Guest

    Dear Artful_bodger and Robert Kahle:

    It seems like I'm forced to go with your solution using the pic10F220 or reflashing the DS2502 and to practice my forgotten skills in programing withmy PICkit 2. I needed the mentioned modification because a Dell D600 has problem with the DC jack and USB ports. So I bought a Docking Station whichseems to be happy only with the PA-10 Geniune Chinese PS which I don't have. I opened another suitable Dell PS model ADP-90FB modded using the plug connector from a PA-12 and connected the DS2502 on it. The D600 is able to charge and works fine if I turned ON the laptop,let it pass all posts, and then plug the Docking. With this last process it results the Docking stationbypassed its Power(turned off) and obviously not USB's or other Docking hardware is working.

    So now after I explained my scenario please let me know the a suitable solution : a working Ds2502 firmware and instructions to load the program;
    or a little schematic for the Pic10f220 on its VDD power supply(wanted to be sure the GE diode is detecting and rectifying some induced signals to produce the start up Vcc which is later taking from the output port pin #3).

    Best Regards

    lopez.werner, Mar 14, 2013
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