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Blown Up 5 Volt USB Charger Repaired

By on January 12, 2021
power adapter repair usb 5 volt

 

 

 

 

 

My very handy nephew, who is a great professional new kitchen installer, brought over about a month ago an EVOLine 230VAC back flip Power outlet Box with now defect 5V USB charger board in it he had to replace at a customer’s house with a brand new EVOLine back flip box. We got no clue what they did with the charger that made it completely blow up. Replacing the old one was the best service he instantly could provide.

After I had removed the charger board from the brought over back flip box, I started examining its components.

Not only the primary MJE13005 HV NPN transistor on the small 5V charger board was now completely short circuited, but also the 2 emitter resistors were gone, including the primary safety inrush resistor fuse to the greatz rectifier was blown. And of course also the tiny sot23-6 controller with smd code ‘67A’ was no longer working. This IC from Melexis is a PWM controller but apparently because this mlx02367A is a special designed ASIC they were not allowed to give any datasheet or info on this chip and even the seller who sold me 50 of them couldn’t provide any information. Not even its function! So I hoped that the ordered chip was the right one, and after I had replaced the old ‘67A’ chip I would soon find out if I was right.

I measured both primary transformer coils with my Blue ring tester, and they looked fine. Also the secondary coil was fine. And on the secondary side of the 5V USB converter board all parts measured fine too. The Lite-on 356T optocoupler was still good, so it was only the primary of the board where parts were destroyed. Below is shown the solder side of this small charger board.

small charger board repair

In previous photo D6 is de greatz diode bridge rectifier, IC1 is the 67A smd component, and in the top right the Liteon optocoupler is present. As we can see emitter resistors R11 and R10 placed in parallel are both open line now. And they needed replacements just as the NPN transistor just above R11. All smd resistors are marked in the EIA-96 code for their values. This is important because else you would easily give the smd resistors completely wrong values! Next photo also shows the now also blown primary safety fuse resistor with code brown,black,black,gold (10 Ohm 5%), that was connected to one of both the ~AC pins of the diode bridge rectifier.

usb charger 5 volt repair

Only just about 2 weeks later the 50 tiny sot 23-6 mlx02367A chips already arrived from the Chinese Aliexpress seller. And I immediately replaced the defect ‘67A’ pwm controller. The defect NPN transistor I already had replaced 2 weeks earlier and was a little bigger than its original was, Why I molded the plastic holder a bit using my hot air station to make some place for the higher replacement NPN, and for the defect emitter resistor I now just used a 3.9 Ohm 5% resistor to be able to test the charger circuit. (the resistor looks a bit burned but that was from another test, not this one!). I hoped for the best and switched on the primary 230V AC voltage with a light bulb in series as protection against any short circuits on the power line that still might occur.

But the light bulb stayed completely off, and to my happy surprise the secondary connected 5V led light started to light up right away. So the mlx02367A chip received indeed was the right PWM controller chip for fixing this 5V USB charger board. So to also check the secondary output voltage I connected an USB tester in between the charger output port and the led light. Next photo shows the component side of this small 5V USB charger board. And following photos after that show the

perfectly working fixed as new 5V charger. The labels and the pcb markings didn’t help to find anything online about this only about 4,2 x 3,5 cm small 5V charger.

how to fix small charger

fixing a small charger

how to fix a broken charger

usb power meter

usb power meter testing

usb 5 volt charger diagram

Of course I previously started by drawing a small circuit with the information from the given board to determine how it worked and above result was a great help. At first it was uncertain if I would be able to find the right replacement PWM controller chip as no datasheet or info was given on this ‘67A’ labelled chip. That according to Melexis was a special designed ASIC and therefore was prohibited from them giving any specs. What is very surprising because they are easily available. And 50 of them did only cost me about 8 dollar/euro free shipping. (So I have 49 of them new ones left!).

About the mentioned EIA-96 resistor code. Following values where found: R1 3014 = 3.01Mohm, R2 2004 = 2Mohm, R3 75R0 = 75 ohm, R4 4754 = 4.75Mohm, R5 0 ohm,

R7 01E = 1Mohm, R9 73B = 5.62Kohm , R13 90B = 8.45Kohm, R10 and R11 defect/unknown,

R19 8252 = 82.5Kohm, R20 3010 = 301 ohm , R21 01B = 1Kohm , R22 58B = 3.92Kohm, R23 561

The Art nr of the mentioned EVOline back flip Wall outlet box with the now fixed USB charger in it is 927 00001 Type 927-1. These power line boxes are completely hidden in a cabinet until they are flipped after which the 2 outlets and the USB charger port show when they are mechanically turned upwards.

Conclusion: Even if there is no datasheet for a component nor any information on the device itself, it is still possible to fix the device without even knowing exactly what component you need.

MLX02367A

50Pcs-MLX02367A-Markering-67A-MLX02367-SOT23-6-Nieuwe-Originele (txt with seller’s advert)

Best tip here is to look on the Aliexpress website to find unknown components with the smd code marking that is given on the component that needs to be replaced. Aliexpress often mentions the exact same smd code and the component it represents! Even if the seller, in this case the friendly

Jiexincheng Microelectronics Store, doesn’t know its function and he neither had any datasheet of the component he sold me!

I am glad that buying new unused original parts in this case was no problem from this trusted seller! And I immediately replied to him that it was indeed the right chip I needed in case other buyers needed that information too. And the seller replied with the text “VICTORY” and told me he had many more parts to sell. No doubt many original parts but maybe also without any datasheet or additional information.

Following some additional photos to complete the information about this device.

On the left on next photos the original smaller 13005 now replaced bad npn transistor is shown and on the right the EVOline inside turn mechanism with the two 230VAC earthed power outlets.

smd 13005 transistor

Below the turned upwards EVOline flipbox with USB charger port plus both 230VAC outlets.

how to fix 5 volt usb charger

Next photo shows the complete back flip box inside with the now fixed 5V USB charger board on the right.

how to repair 5 volt usb charger

Other online websites provided wrong information about the mlx02367A telling that the mlx02367A was some type of thyristor chip. And yet another website sold these chips second hand (already used) which no doubt was also the complete wrong information! So don’t get confused in your search for the right part(s)!




I am very glad that the charger board in this rather expensive and special EVOline back flip device is fixed and again at almost no cost!

So even if the manufacturer of a chip doesn’t want to provide any help in any way there is a very good chance you still will be able to repair your device following the given search method!

albert from netherlands

Albert van Bemmelen, Weert, The Netherlands.

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Note: You can read his previous repair article in the below link:

https://jestineyong.com/raspberry-pi-5-volt-3-amp-adapter-repaired/

 

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14 Comments

  1. Andrew F. Ali

    January 12, 2021 at 9:11 pm

    Great work!!!!!

    Likes(2)Dislikes(0)
    • Albert van Bemmelen

      January 13, 2021 at 1:53 am

      Thanks Andrew! You maybe better also watch my next article on Jestine's blog. Because after this repair I found a very interesting way on how to test these smaller smps adapters even without connecting these to the dangerous 230VAC power lines!

      Likes(4)Dislikes(0)
      • Alena Patterson

        January 13, 2021 at 9:25 pm

        Looking forward to learn this new trick

        Likes(2)Dislikes(0)
  2. Parasuraman S

    January 12, 2021 at 9:53 pm

    A tough challenge taken up, but completed successfully! Shows your caliber, grit and determination to complete a job taken up! Hat's off!

    Likes(2)Dislikes(1)
    • Albert van Bemmelen

      January 13, 2021 at 2:05 am

      I humbly put your always appreciative comment in my growing satisfaction bag Parasuraman LOL! Also read my reply to above post from Andrew because after this repair I found a very interesting way to test these small smps power adapters without dangerous 230V AC power line connection and even without the commonly used safety Light Blub!

      Likes(1)Dislikes(0)
  3. Gassan Ali

    January 13, 2021 at 1:59 am

    When Albert posts an article, I barely understand half of it not because his writing is bad but merely because of the depth of his explanation and lack of technical knowledge on my part, and for this reason, Albert has become a person that I highly appreciate without understanding him much. The repair is great anyway. The extra tips given on how to find the right part from Aliexpress is truly valuable bonus. I'm bying components form Aliexpress every month. Just the general stuff like resistors, capacitors, diodes, pots, fused, and many more, with great hope of opening my own electronics components shop someday.

    Likes(3)Dislikes(0)
    • Albert van Bemmelen

      January 13, 2021 at 1:44 pm

      Thank you for your kind reply Gassan. Like you I am also a frequent buyer on Aliexpress too, and for the older parts I less often use eBay. Also because the only electronics shop in town can't deliver most parts I look for. Like the for this article repair needed mlx02367A sot23-6 PWM controller that they for sure never could have provided. Anyway I wish you all success in starting your own business one day! In my town we sure could use a few larger electronic shops!

      Likes(3)Dislikes(0)
  4. Mark

    January 13, 2021 at 5:55 am

    Well done Albert,
    Could it have been damaged due to a lightning strike?

    Likes(1)Dislikes(0)
    • Albert van Bemmelen

      January 13, 2021 at 1:14 pm

      It could have been a lightning strike Mark. I however think that it was the smaller original used 13005 NPN transistor that short circuited somehow likely causing a high current through both mlx02367A PWM controller and the 10 Ohm inrush safety resistor that obviously destroyed them both? The new replaced 13005 transistor is not a original used smaller smd component that hopefully protects the charger from this happening again.

      Likes(1)Dislikes(0)
  5. Yogesh Panchal

    January 14, 2021 at 5:26 pm

    Albert,
    Making stagewise diagram is always useful to understand the working of the section.Here 67A PWM IC is taking feedback signal from opto and supplying it to the switching section....and you can easily trace the culprit.

    Likes(1)Dislikes(0)
    • Albert van Bemmelen

      January 14, 2021 at 6:06 pm

      Indeed Yogesh, but a datasheet of the missing specs of the mlx02367A would have made it so much easier!

      Likes(0)Dislikes(0)
  6. boijke

    January 15, 2021 at 12:59 am

    goed bezig albert
    =================
    well done albert

    Likes(1)Dislikes(0)
  7. Albert van Bemmelen

    January 15, 2021 at 1:45 pm

    Bedankt Frans! (en de altijd gezellige weekend broodje eten uitjes!!)
    ================
    Thanks Frans! (and the always nice weekend trips to eat a meal somewhere!!)

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  8. Michel Janssen

    April 6, 2021 at 9:27 pm

    Goedemiddag Mr. van Bemmelen,

    Bedankt voor de fijne tips, zelf was ik privé met een Bosch batterijlader aan het worstelen met hetzelfde Melexis ic die het liet afweten. De transistor TSC13003 en 10 ohm weerstand zijn natuurlijk ook naar het hiernamaals.
    Indien u een paar van deze ic-tjes zou willen verkopen dan ben ik natuurlijk geïnteresseerd.
    Dank bij voorbaat, met vriendelijke groeten,
    Michel.
    ====================================

    Good afternoon Mr. van Bemmelen,

    Thanks for the great tips, I was privately struggling with a Bosch battery charger with the same Melexis ic that failed. The transistor TSC13003 and 10 ohm resistor are of course also to the afterlife.
    If you would like to sell a few of these ICs then I am of course interested.
    Thanks in advance, best regards,
    Michel.

    Likes(0)Dislikes(0)

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