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Servicing Romai Power Bank 10400mAh

By on February 12, 2018
how to fix and repair power bank romai










repair power bank

My mobile Power Bank, another Chinese make, which is only about 2 years old, started giving troubles.  It does not take load sometimes and charging LED goes off on its own even though mobile is not fully charged.  So, I opened this power bank for the first time, being my first power bank service.

The two covers at the top and bottom will have to be pried open, as these are stuck with gum. Then we can see a black cover with fitting screws on one side. Then we need to push the battery to take out the control board along with the battery.

how to fix power bank

Here are the pictures of the board.  The 14 pin Li-ION battery charge control IC (output) is obliterated, so I have no idea what is the IC number!  A cheap way for a manufacturer to do, to avoid copying their circuit! The Positive supply is coming to Pin 9 and ground goes to pins 10 and 14. I tried combing the web for a similar 14 Pin IC, giving various combinations for search, with no useful result.  (If any of you know the IC number, please do let me know. There is a possibility that the number is there on the bottom of the IC. But I do not want to remove the IC just for this sake.)

how to repair power bank

how to fix and repair power bank


There is a temperature sensor connected to the battery:

battery power bank bad

The DC-DC Converter IC number is FP6276, and here is the link for its datasheet,

Now, for the observations and remedial actions taken (at last)!

I observed that the input from battery as well as the output to mobile connector were quite normal. I checked the push to on switch and it was also ok. There was no dirt collection, as the unit was completely sealed. Could not find any fungus or other corrosions. So, just retouched all the solder joints. Cleaned and lubricated the USB socket and mobile connecting socket. That is all what I did for servicing this unit. Connected my mobile and left for charging, before closing the covers of the Power Bank. It was charging well, and no auto off problems was also noticed. So, ‘reversed’ the opening process. Since the top and bottom covers have sticky gum on it, it got fastened by itself and there was no need for me to apply Fevibond.

Thus completed the service, the missing IC number still gnawing my heart!

This article was prepared for you by Parasuraman Subramanian from India. He is 68 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. Aziz

    February 12, 2018 at 6:07 pm

    Thank you. Very good

  2. Albert van Bemmelen

    February 12, 2018 at 7:07 pm

    I do not know if I can help you to find that 14 pin IC Parasuraman but I do know that most of these Powerbanks only give 1 or 2 Amps out. Those boards can be found on Aliexpress here:,searchweb201602_1_10152_10151_10065_10344_10068_10342_10325_10546_10343_10340_10548_10341_10084_10083_10618_10304_10307_10313_10059_10534_100031_10103_10626_10625_10624_10623_10622_10621_10620_10142,searchweb201603_38,ppcSwitch_4&algo_expid=24e1b525-c6f0-4fc7-9440-f735fc4f3c69-0&algo_pvid=24e1b525-c6f0-4fc7-9440-f735fc4f3c69&priceBeautifyAB=0

    The 10400 mAh description on the Powerbank likely only gives the capacity of the Powerbank and not the maximum Amperage its able to give. Also because charging and discharging needs to be controlled and watched by the protective board. And those Aliexpress boards also use 14 pins ICs without showing any type marking.

  3. Kerry Koppert

    February 12, 2018 at 7:21 pm

    Seems to me the batteries are the most expensive part, a new power bank minus the batteries is under $3.00

  4. Andrew F. Ali

    February 12, 2018 at 10:54 pm

    Good job, Parasuraman.
    I have found that the only thing that can go wrong with these power banks are that the batteries. The chemicals dissociate and so the battery do not hold charge anymore. Great work.

  5. Robert Calk

    February 13, 2018 at 1:35 am

    Good job Parasuraman. I see the MC numbers laser etched off all the time now. Even my little cheap crystal checker has the MC numbers laser etched!

  6. eng abdelhamied

    February 13, 2018 at 8:29 am

    most of power bank have currenr sense resistor in thier design intended fo control charging and cut off circuit in no load (mobile) also it wiil be determine the minimum and maxmum power that delivers to load so you can see if the load is lowering in its power value after a while from connecting the power bankn to load it will be goining to off

  7. Yogesh Panchal

    February 13, 2018 at 2:47 pm

    Good Job! Sir.

  8. Suranga Electronics

    February 14, 2018 at 12:26 am

    Good Service !

  9. dilmildps

    February 16, 2018 at 11:51 pm

    Thank you for all your beautiful inspirations


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