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Dry Solder Caused ‘No Light’ In Mr.Light Emergency Light

By on June 11, 2020
how to fix emergency light

how to repair and fix emergency light

Make and Model : Mr.Light – Mr.X10

Complaint reported: Dead

Trouble shooting and rectification done: Opened the light by removing the screws from the rear, cleaned the inside and observed a lot of dry solder on the board, though this was reported to be only a few months old. As there were no component failures on cold testing, I just did the dry solder patching up. When the light was charged, the battery got charged and the light worked very well. Even the auto switch on when the power goes off was checked, the very purpose of emergency light. Mission accomplished and satisfaction got collected.

Here are a few pictures:

smd board dry joints

emergency light parts

emergency light circuit board

how to service emergency light

This article was prepared for you by Parasuraman Subramanian from India. He is 70 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.

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You may check on his previous repair article below:



  1. Albert van Bemmelen

    June 11, 2020 at 8:56 pm

    Good result of course but hardly a difficult job compared to your usual higher level of repair.

    • Parasuraman S

      June 12, 2020 at 2:53 pm

      Many thanks! Yes, a few such easy to do jobs do pop in!

  2. Henrique J. G. Ulbrich

    June 11, 2020 at 10:59 pm

    Thanks for sharing, dear Parasuraman. The problem with such type of gadgets is quite often with the battery. I have two Chinese headlights put aside due to a silly reason: end of useful life of the battery. It´s a 4 V lead acid one, a kind of "white fly". When I tried to buy another, they told me that such a kind of battery is not found. Not only in my city but, following a further research, I´ve found out this occurs throughout my country (Brazil). Perhaps this is the situation in many countries, if not all. For me, this resembles a situation of a car that must be thrown away when the fuel tank becomes empty. This means: the Chinese laughing at our face. How long?

    • Parasuraman S

      June 12, 2020 at 2:56 pm

      Yes, mainly these come with battery problems. You could have used 3 1.2V NC rechargeable cells in place of the 4V. I did this modification in one Chinese light, because of short life of batteries. In yet another, I even used 4 such rechargeable cells. Many thanks for your detailed input!

      • Henrique J. G. Ulbrich

        June 13, 2020 at 1:06 am

        Thanks for the suggestion, Parasuraman. I had already thought about this possibility, although with some doubts: the rating of charge is different among different batteries. But considering these systems use a kind of trickle charger, and as being transformerless they act as a constant current device, it becomes clear that it works. I´ll try it. You encouraged me, thanks a lot.

        • Parasuraman S

          June 14, 2020 at 9:08 pm

          Yes, you should give it a try!

  3. Gregory B

    June 11, 2020 at 11:38 pm

    Nice job ... the company that made that unit needs better quality control of their products

    • Parasuraman S

      June 12, 2020 at 2:56 pm

      Many thanks! I was surprised that a company like that is neglecting quality in their products!

  4. Tayo

    June 12, 2020 at 1:36 am

    This is actually a very interesting case Parasuraman. This circuit board looks terribly manufactured. The amount of excess solder is puzzling. Even someone doing by hand in a manufacturing setting would not be so inefficient. Could the poor manufacturing (workmanship and probably the grade of solder used) be the cause of this unit developing dry solder joints?

    • Parasuraman S

      June 12, 2020 at 2:59 pm

      My assumption is that poor quality of solder could be the cause. The soldering was also not having the shine it should have when fresh. Anyhow, we know what to look for in these Mr lights and may be their other products! Many thanks for your feedback and comments!

      • Henrique J. G. Ulbrich

        June 13, 2020 at 1:15 am

        I am surprised due to the fact that it is a German product. The German industry is known as a high-quality one. I now very well German products - I worked for one famous German manufactures for 21 years!. It´s hard to believe that this is a German product.

        • Parasuraman S

          June 13, 2020 at 11:17 pm

          Could have been made elsewhere! Or another Chinese product! In fact, I myself was surprised to see this!

  5. Humberto

    June 12, 2020 at 10:52 am

    Another device saved by you, congrats.

    • Parasuraman S

      June 13, 2020 at 11:18 pm

      Many thanks!

  6. nkokana

    June 12, 2020 at 2:49 pm

    some times the repair article would give u hard time. I was repairing one amp with no power.i had to replace a power cap since the voltage that was there was lower than 3volts dc since it should have been 16volts DC.after changing the power cap nothing changed even after disconnecting all the output know , I changed all the bridge diodes even when they were all reading well. guess what power, power resumed and the speaker was live again.

    • Parasuraman S

      June 13, 2020 at 11:21 pm

      Yes sometimes, the bridge rectifier will behave like that and there is only one way, just replace it. Good job there! Thanks for sharing!

  7. Gaurav

    October 27, 2020 at 11:02 pm

    I have the same led. Resistor got rusted out and broke. I tries to connect directly without resistor and also tried with the rusted resistor. It didn't work. The battery and led alone are working but now working when connected to board

    • G

      October 27, 2020 at 11:03 pm

      *not working when connected to the board


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