Dell PA-10 ac adapter center pin
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 contact. 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 lengths. 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.) |
Dell PA-10 ac adapter center pin
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....) |
Dell PA-10 ac adapter center pin
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 nuisance. (insert additional lenghty disclaimers here...) |
Dell PA-10 ac adapter center pin
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 PS 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' (http://ejay.com.au) |
Dell PA-10 ac adapter center pin
Robert,
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? Thanks Mike |
Dell PA-10 ac adapter center pin
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 electricity. 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' (http://ejay.com.au) |
Dell PA-10 ac adapter center pin
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 :-) On Jan 28, 7:49*am, ejay wrote: Mine didn't appear to have the zener anywhere. Thecenterpinof 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 electricity. 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' (http://ejay.com.au) |
Dell PA-10 ac adapter center pin
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' (http://ejay.com.au) |
Dell PA-10 ac adapter center pin
My PA10 works intermittently. Anyone managed to repair it or do I need to buy a replacement?:mad: |
Dell PA-10 ac adapter center pin
phoenix wrote:
My PA10 works intermittently. Anyone managed to repair it or do I need to buy a replacement?:mad: are you sure the problem is the adapter and not the computer? it is a common and unfortunate problem with many model laptops that the connector in the computer becomes loose and so has poor contact with the system board. a simple test of this condition is jiggle the plug on the computer end while it is inserted into the laptop and watch to see if it switches between battery and ac power. this should be covered under warranty or there are many shops that will re solder the ac jack back on the system board for a flat fee. depending on the age of the system it may not be worth the expense. having said that, genuine dell pa10 adapters can be had from ebay for about $20 delivered. clone "for dell" adapters can be had on ebay for close to $10 delivered but they are junk and will not be as durable or long lasting. |
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