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Device repair and troubleshooting help for the E1-571 model of Acer Aspire laptop computers.

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Power cable doesn't work

Hi!

I have an Acer Aspire E1-521.

It was always very slow but one day suddenly it won't power on: the power indicator as the power button was blinking blue.

I have tried to:

1. change power outlet: as before

2. power on without battery: no sign

3. check the power adapter: 19V, ok

4. press the power button  for 60s without battery and power adapter, wait a few minutes, power on with battery and power adapter: as before

5. power on without RAM: as before

6. disassembly the notebook and check the CMOS battery: 2.95V, ok

7. replace the battery: It powers on! But doesn’t charge (and it discharge itself, powered off during the night… is there a short circuit that drains current?)

8. check another time the power adapter: -19V (with the minus! WT*!)

9. replace the power adapter: nothing…

Can the inverted polarity of the charger (is it possible?) destroys my charging circuits? They seem integrated in the motherboard. How I can repair the laptop?

Thank you in advance!

Updates

  1. check for continuity in DC-in cable: ok

@jayeff The old power adapter is not original, it is Kraun “Universal Notebook Power Adapter 90W Home Plus“ and yes, it has the polarity symbol with center positive.

The new one is DTK DL90W shows 19V.

OMG I found why power adapter has reverse voltage! The generic connector was mounted in the wrong way!

The motherboard is Q5WT6 LA-8531P rev 2.0 but I can find schematics only for rev 0.3.

It is a little complex for me, I know the simplest reverse current protection circuits is a single diode but no more. (Transistors scare me ;D )

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Maybe the charging port needs replacing?

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@aactech I have to check it!

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Hi!

I finally bought a new mother board from Aliexpress for 45€.

Now everything is working like a charm, thank for your support!

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Hi @enricorox ,

Open the laptop and disconnect the DC-In cable from the motherboard and then use an Ohmmeter to check for continuity between the jack and the cable connector tied to it.

It is not uncommon for the jack to fail internally, usually the centre pin connection breaks off. If it is faulty it cannot be repaired, it has to be replaced

Update (02/14/2020)

Hi @enricorox ,

That shows that there is a -ve voltage on the centre connector of the plug

There should be no -ve symbol with the measurement with the leads connected as they are.

Is the adapter the original one that came with the laptop?

Here’s an image taken from this link for an adapter for an Acer E1-521.

It shows that the DC output is +ve in the centre of the plug and -ve on the outside of the plug.

Does your adapter show the same symbol for the output?

Block Image

(click on image to enlarge for better viewing).

Does the other adapter you tried ( “9. replace the power adapter: nothing… “) show the voltage correctly i.e. 19V DC and not -19V DC when measured the same way?

If so then perhaps the laptop doesn’t have reverse voltage protection and the input circuit has been damaged.

Try searching online for a schematic of the motherboard. Search for (Insert motherboard’s “board” number) schematic and check if there’s one available that will help to find the components on the board that may have been damaged

Update (02/15/2020)

Hi @enricorox ,

It may be that there is no difference between the motherboard Revisions as far as this part of the circuit is concerned. Worth a look anyway.

It’s a bit too complicated for me too but maybe you can check if there are components PQ6, PQ7 PQ8, PQ10, PQ14A & PQ14B around the VIN point as shown in the circuit. If so perhaps they may show signs of physical damage

Components usually show a reading of some sort when using an Ohmmeter (reverse the leads and test ‘both ways”) so if any are testing either a dead short circuit or an open circuit they may be suspect. Take them out of circuit by unsoldering them and test them again out of circuit. Don’t forget to disconnect the battery from the motherboard when testing with an Ohmmeter;-)

Here’s the part of the circuit that I’m talking about, although you’ve probably already been here.

Block Image

Click on image to enlarge for better viewing)

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Thank you, I will check this saturday!

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The little DC cable is ok!

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Do you know if the hard drive works? A lot of laptops that aren’t properly designed to ignore dead drives and hang the BIOS - it’s somewhat common for ASUS and Acer to hang due to the BIOS not being designed to be resilient to drive failure like most other laptops. Most laptops ignore the dead hard drive and PXE boot or complain about boot media. See if you can boot without the hard drive installed - if it boots, the drive has an issue and it’s a boot hanging BIOS.

The RAM/WiFi/HD bay has a similar design to the Asus machines (usually Clevo for mainstream/Sager for ROG), so they likely come from the same ODM and the problem was inherited by Asus.

If that doesn’t fix it, I would change the jack as @jayeff suggested and if that fails, the motherboard is dead - likely a BGA failure or fried components. The problem is BGA failures are rabbitholes for end users and board repair can be difficult to trace down the fault.

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With the new battery it boot up to Windows, but I don't know if there are strange hardware errors in the hdd

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@enricorox If it doesn't have boot issues, the drive is fine.

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