DELL AC power adapter not recognized

29 Dec 2008
Posted by Laptop Junction

Your system will operate slower

After many flying hours with the DELL Latitude D610, suddenly the DELL AC Power adapter stops charging the laptop battery. At startup the laptop beeps and reports the following BIOS message

"Power Adapter not recognized".

"The AC power adapter type cannot be determined. Your system will operate slower and the battery will not charge. Please connect a Dell 90W AC adapter or higher for best system operation."

DELL AC Power adapter can not de determined
The same BIOS message for a DELL Latitude D610

A strange and sudden malfunction that doesn't give a clue whats wrong. There are several variants of this message - the one in the picture comes from a Dell Latitude D610 with BIOS revision A06.

Plugging the same adapter into an identical DELL D610 during startup produces the exact same message. This indicates the problem is probably within the DELL AC Power adapter. However there's more.

Laptop shuts battery charging down

A bit further in time the problem disappeared a few times, and battery charging continued as normal. However in the end the charging stops finally - and the message keeps appearing all the time.

Looking a bit deeper into the problem, it seems the laptop itself shuts down the charging of the battery. The message at the screen during start-up suggests this. The AC power adapter is actually supplying power, the laptop can run on it - no problem there. Also the adapter doesn't seem to be overheating, it has the same 85-105 Fahrenheit (30-40 Celsius) temperature as before.

The BIOS message during startup of the DELL Latitude D610 can be ignored, even turned off by pressing the key indicated. The problem remains however. This indicates there is a BIOS power-on test of the AC adapter during startup.

Worldwide failure pattern

A deeper dig into search engine results reveals a wide spread pattern. The problem seems quite common and most of the resolutions point towards replacement of the AC power adapter.
A few resolutions to this problem found while surfing:

  1. - Call DELL - explain the problem, insist on a free DELL AC power adapter.
  2. - Power-down, remove battery, hold down the On/Off button for more than 10 seconds.
  3. - Check the power leads - specially coming out of the AC adapter, fix if possible.
  4. - Slowly turn the plug into the jack at the back of the laptop, see if it charges again
  5. - Power-on, after the BIOS message, unplug jack, press F1 and immediately replug jack
  6. - Update the BIOS (use with caution - power failure during BIOS update is fatal

None of them worked in this case.

The adapter was 4 years old already, so no warranty.

  DELL PA 1900 02D2 AC power adapter
  The DELL-PA-1900-02D2 AC power adapter

The DELL 3-wire power cord

Looking closer at the power plug, there are actually 3 wire connections. The outside tube, the inside tube and the small pin in the middle. The out and inside of the power plug supply the power for the laptop. The pin in the middle of the power plug has no voltage - it must have a different function.

Connecting a voltage meter to the power plug shows about 20 volts. Tossing the cable & AC adapter wildly doesn't show unstable voltage. If it would, doing the same with the laptop connected WITHOUT a battery would certainly restart the laptop instantly. It didn't either. This rules out shaky power leads, plug and jack.
The small pin in the middle however gives reasons for suspicion

Identification of the AC adapter

Digger deeper into the subject, the function of the small pin in the middle of the power plug seems to be for identification of the AC adapter or power supply. Assuming this is true, either the lead connected to the this small pin is broken or the circuitry connected to the pin is failing.

That leaves either an internal AC adapter problem or a problem related to the POST / BIOS power-up test. Based upon two DELL Latitude D610's reporting the same message, most likely the problem is with the AC power adapter made by Lite-On Technology Corporation in China. The problem is sporadic at first - but gets worse over time.

In a hurry? Read the DELL AC adapter findings.

Inside the DELL AC power adapter

So let's open the casing and have a look. It took a screwdriver and a bit of force to crack open the glued case. It's not designed to be opened, so be careful.

Inside a DELL AC Adapter

Inside there's a typical layout of a switching power supply. What first attracts attention is the 3 wires going to the laptop. 2 of them connect to the PCB directly - one white, the other black. The white one is V+, the black one V-. A naked wire goes into a black blob, a sealed wire comes out to a connection called IC4. This is probably the identification lead for the AC power adapter.

DELL AC Power adapter leads

Measuring all leads quickly reveals the problem. The middle pin of the power plug is not connected to the power supply. Fiddling with the wires shows intermittent connections. It seems the identification lead is broken somewhere in the black "tube shaped" cable  blob close to the power plug.

The quick fix was to clip the wires on both ends and solder them together and tape the results.

DELL AC Adapter not recognisedDELL ID chip diedDELL design failureInside a DELL battery


NOTE :: The broken wire in this case turned out to be a FREAK occurrence. It takes quite a bit of force to break or snap the identification wire. Since this AC adapter was 2nd hand, this could have happened with the previous owner and actually resulted in a broken wire later-on.

DELL AC power adapter fails again

Now there's quite a bit more to this story - so read on. The adapter failed again a few days later - now because of the reason why so many other DELL AC Adapters fail.

inside the DELL PA-1900-02d2 Power Adapter

In any case, DELL has goofed big time with this AC power adapter. Visitor stats of this story reveals that many have the same problem. And the worst of this problem? The AC adapter is actually working, only charging is shut down by the laptop itself.

A deliberate build in "feature" in this case being triggered by a snapped identification wire and later-on by a design fault.

In terms of adapter replacement, with so many refurbished quality laptops on the market, be sure where to put your money on;

DELL AC Power Adapter findings

Based on the findings with the DELL 90 Watt AC Adapter, website search engine phrases & statistics and incoming e-mails, the following sticks out:


1. Failure pattern is wide spread - worldwide

2. When inside warranty, DELL replaces AC Adapter and Motherboard

3. Two failures are top ranked:
        a) ID chip inside the DELL AC power adapter has died
        b) Power jack is loose on the motherboard.

4. Sometimes replacement adapters also fail after a while

5. Motherboard replacements are sometimes unnecessary.

6. Failure pattern indicates a design / manufacturing failure

Here's more about the battery charging design found in DELL D610 Latitude Laptops:

1. Inside the DELL AC Power adapter
2. Inside a DELL D610 Battery - Connector pinout and timing
3. DELL PA-10 and PA-12 AC Power adapters
4. DELL AC Power adapter - ID CHIP DIED
5. DELL AC Power adapter - The power plug
6. Dell Battery Charging System for D5xx and D6xx laptops 

This problem is seen with the DELL 90 Watt AC power adapter with Model number:  PA-1900-02D2 and revision number REV A04. It supplies 19.5 Volts DC by 4.62 Amps and is produced by the Lite-On Technology Corporation in China. 

The DELL 90 Watt AC Adapter is supplied with the following laptops:

DELL Inspiron 1150, 9200, 9300, 9400, 1501, 300m, 500m, 510m, 600m, 600mcr, 630m, 640m, 6000, 6400, 700m, 710m, 8500, 8600, 8600CR

DELL Latitude 100L,D800, D810, D820, D400, 410, D420, D500, D505, D510, D520,D600,D610, D620, X300

DELL Precision M60, M20

The laptop power adapter is known by the following partnumbers:

PA-10, NADP-90KB, PA-1900-02D, PA-1900-02D2, U7809, C2894, 9T215,