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Lenovo Laptop Rectangular Pin Adapter Repaired

By on January 14, 2022
lenovo laptop repair






Got a call from the Customer that his laptop is not charging but when he plugged another adapter laptop is charging. His office is nearby my place so I told him to send the adapter to me so that I can check it. He sent the adapter to me. On primary Voltage testing it is confirmed that adapter is not working there is no Output voltage.

lenovo adapter repair

After taking conformation from him about repair I started diagnosis by visual inspection.

No physical damage found hence I opened the adapter for further inspection.

how to fix lenovo power supply

how to fix and repair lenovo power adapter

On PCB I did not found any damage or burnt mark. So I checked for 20VDC output voltage I found 20V DC on the output terminal where output DC wires are soldered that is confirmed adapter is working but either DC wire or connector is bad.

So I desoldered the wires from PCB and checked continuity. Earthing wire found ok but +ve supply wire is open circuit. So for finding the culprit I segregated the connector. From the wire. It is very complicated job because it is molded in plastic if you damage the connector you cannot complete the job. So eventually I managed to remove the connector safely.

connector  parameter

I found wire soldered intact this adapter is having ID Pin & I found one resistor of 120Ω. Is connected between earthing and ID pin.

I am confused with color code of the resistor. On googled I found different value resistor is used in different wattage adapter.

wattage of resistor

how to fix power adapter

So connector is in perfect condition now culprit is cable. I am not having this type of cable replacement with me. As this cable is having Ferrite Core on both the end of the Cable so I decide to keep the same cable if it is usable. So I connected only cable one by one on mains line for using my contactless line detector to find out the broken wire location.

contactless tester

But this time this trick is failed because due to Electromagnetic interference on shield of this wire around main +ve wire the LED of detector unit is glowing end to end it indicating no breakage of wire. (This Line detector only work where wire is single. may be misguide on twisted wire pair)

I used another trick to find broken wire location i.e. Puncture the cable using sharp needle on various ascending order on the cable.

how to fix power adapter cable

Using this trick I connected one probe of meter on one end and another probe on Needle …..If meter is beeps that means from the end where you connected the probe to this location where Needle is inserted showing continuity and wire is ok. So I started to check from one end which is connected to DC output PIN.

how to test dc output of power adapter

So gradually I am moving ahead on adapter side here in between length of cable I found one location where I did not get the beep.

how to fix power adapter pin

Again I punctured the cable backward direction step by step & testing on different location I found the location where I got the beep so that is the location of broken cable.

I cut the wire on that location just pulled the inner cable with hand and I found the broken wire on my hand it is hardly one inch away from the cut. Checked the continuity again now Wire showing the continuity on both the cut piece.

I joined the cable by soldering and insulating using heat shrink tube.

heatshrink tube

Checked Out Put Voltage on cable meter is showing 20VDC.


Connected the connector:

testing connector after fixing it

Checked Voltage after fixing the connector

connector fixed

Now Adapter is ready for pickup.

This article was prepared for you by Yogesh Panchal who works as a Computer Hardware Engineer in Mumbai India.

P.S- Do you know of any your friends who would benefit from this content that you are reading now? If so, forward this website to your friends or you can invite your friends to subscribe to my newsletter for free in this Link.

Note: You can check his previous repair articles on Battery Eliminator 1.5V To 12V Modification




  1. Y. S. Rao

    January 14, 2022 at 9:31 am

    This type of problem is present with many Lenovo adapters. Lenov adapters are of cheap quality. It is not clear which wire (White or black or shield) is broken.

    • Yogesh Panchal

      January 14, 2022 at 3:38 pm

      Y. S. Rao,
      In this adapter "white wire" is +ve.-ve black wire is covered on white wire as a shield.
      Thanks! for your comment.

  2. Parasuraman S

    January 14, 2022 at 10:11 am

    Vow! What a wonderful fix! Well done!

    • Yogesh Panchal

      January 14, 2022 at 3:38 pm

      Thank you! Sir

    • Tito Kanshulu

      January 16, 2022 at 8:14 pm

      Nice article Yogesh, and very educative

      • Yogesh Panchal

        January 17, 2022 at 3:14 pm

        Tito Kanshulu
        Thank you!

  3. Tayo

    January 14, 2022 at 12:16 pm

    Very good article. As a rule of thumb I almost always check the wires and connectors for continuity FIRST before I start poking around with the internals and components. Most of the housing/cases and connectors these days are sealed and bonded in a way that if you take them apart, even with care, its impossible to put them back together neatly and cleanly. Luckily if you have time you can order a replacement cord/connector from Aliexpress for a very low price and slice the new cable unto the old one. I did this just this week.

    • Yogesh Panchal

      January 14, 2022 at 3:43 pm

      you are right But ordering Pin Connector is always doubtful because of various size and diameter.

  4. Albert van Bemmelen

    January 14, 2022 at 1:35 pm

    The needle poking trick is the easiest way to find the broken wire spot. Using a contactless line detector never helped me to solve such problems. Good to know that Lenovo power adapters and these connectors often cause problems. Thanks for sharing.

  5. Imoudu Onwumah

    January 14, 2022 at 2:44 pm

    I have just learnt another method of detecting broken wire-use of needle. Thanks for sharing.

    • Yogesh Panchal

      January 15, 2022 at 11:35 pm

      Your Welcome!Imoudu Onwumah

  6. Yogesh Panchal

    January 14, 2022 at 3:43 pm

    Thanks! Albert

  7. Lee

    January 14, 2022 at 7:10 pm

    I recently had Lenovo laptop for repair that was not powering on.
    It also had a broken rectangular connector that some one had tried to repair and unfixable.
    The internal cable connecting the power had broken wires and was unrepairable so i corded an new power brick and internal cable fro E-bay and that fixed it.

    • Yogesh Panchal

      January 15, 2022 at 11:37 pm

      Congratulations! for fix and saving original adapter.

  8. Humberto

    January 15, 2022 at 12:24 am

    I´ve really enjoyed reading this article, good job Yogesh. Congratulations.

    • Yogesh Panchal

      January 15, 2022 at 11:37 pm

      Thanks! Bro

  9. Waleed Rishmawi

    January 15, 2022 at 2:49 pm

    good article, thanks for sharing. I usually use the beebing test on my voltmeter but in your situation you were getting the ghost voltage which means, the meter is reading voltage yet there is no voltage present. I find it very usefull in this case to use a tone checker. connect a tone generator to one end of the cable and the other device to check with the tone disappears in the cable. have a blessed day

  10. Yogesh Panchal

    January 15, 2022 at 11:44 pm

    You are Right Waleed, Tone Generator is very handy tool to find exact cable in bunch of cables mainly used for tracing Network cables which are not labeled one to one.


    January 17, 2022 at 10:51 am

    Very interesting detailed solution given to the problem, that would have ordinarily cost the owner buying a new laptop charger.
    Thanks for your patience and your step by step follow up until solution is given.

  12. Yogesh Panchal

    January 17, 2022 at 3:17 pm

    Thank you! Sir.

  13. Rajesh

    May 15, 2022 at 12:00 am

    Could you confirm the resistance in other adaptors like 135 watt. My Adaptor output is fine. Checked the resistance it 1K. But still not able to charge the laptop. I bought another compatible adaptor and it is able to charge the laptop

    Please help

  14. Imran uddin

    March 20, 2023 at 4:43 am

    Is this work for Thinkpad T460s??

  15. Alexandru Bondoc

    April 11, 2023 at 4:08 pm

    Hello! First of all, very good article and very good job repairing the charging adapter. I am looking forward on repairing my own adapter which has a bad connector that only charges in some twisted position. Bad news is that I only found in a local store a 90W replacement cable while my adapter has 170W so I need to replace just the connector and also switch the resistance. Could you give me some guidance about how to remove the black plastic protection on the connector?


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