Power Cord Found Powdered And Shorted In VINVERTH Emergency Light Model VARNA LED
This emergency light belonged to a widow living alone and was brought to me with the complaint that the charging light and green light both are not getting on. I opened the lamp and looked for the trouble maker. The power cord was found open with its non-conducting coating spilling over powder. Just see the condition.
This exposes the poor quality of wire used and though I have seen this happening in many appliances which draw high current, I never expected this in an Emergency Light. The fuse, rated 1.5A was blown.
I replaced the power cord and fuse. The power supply was of SMPS type, switching done by a tiny SMD IC, which you can see from the following pictures:
I did a thorough retouch of the board and applied power and I was glad to see the red LED lit up, indicating that charging was taking place. The battery was good and did not require a replacement.
The light was having two modes; one normal and another extra bright, apart from the off position. I applied lubricant in the switch and operated it several times to enable self-cleaning of the contacts. In off position, the charging would take place, but the light will not get on when the power goes, whereas it will in the other two modes. I saw transistor circuit controlling the battery charging level and cut off. Altogether it was a good lamp, except for the poor quality of mains cord, without which I would not have got this work!
So, thanks to the company! (LOL) I forgot to click some more snaps of the lamp in lit condition and battery. Anyhow, mission accomplished very easily collecting satisfaction to the kitty.
This article was prepared for you by Parasuraman Subramanian from India. He is 74 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.
Please give a support by clicking on the social buttons below. Your feedback on the post is welcome. Please leave it in the comments.
P.S-If you enjoyed reading this, click here to subscribe to my blog (free subscription). That way, you’ll never miss a post. You can also forward this website link to your friends and colleagues-thanks!
You may check on his previous article on Lightning Blowing Relay Contact Was Found In V-Guard Voltage Stabilizer
(46)Dislikes
(0)
9 Comments
Leave a Reply
Waleed Rishmawi
May 18, 2024 at 5:20 pm
good job on the repair. yes cords get damaged all the time. I wish all repairs are this easy. thanks for sharing and have a blessed day
Parasuraman S
May 18, 2024 at 5:22 pm
Many thanks, dear friend!
Yogesh Panchal
May 18, 2024 at 5:33 pm
Good Job! Sir
Parasuraman S
May 19, 2024 at 10:52 am
Many thanks, dear!
Albert van Bemmelen
May 18, 2024 at 6:47 pm
In these cases I always would like to know what tiny pwm chip was used here? Or what smd marking that chip was given which sadly can't be seen by zooming on the photos. But it apparently still uses a power mosfet to drive the smps transformer with.
Imoudu.O
May 19, 2024 at 3:01 am
.......and cut off,do you mean you disengage the battery charging circuit?
Parasuraman S
May 23, 2024 at 5:58 pm
That is an over charge protection circuit. It cuts off the charge once the battery has reached its full limit. Many thanks for your enquiry and comments!
Albert van Bemmelen
May 22, 2024 at 2:59 am
Any chance that you know what smd controller chip it was that is used? The photos sadly do not show any marking when zoomed in. But apparently that pwm controller also drives a mosfet to power the primary of the smps transformer with.
Parasuraman S
May 23, 2024 at 6:09 pm
Yes U1 is the PWM controller. Unfortunately, I did not make a note of its number. The mosfet is a through hole type and found soldered from the top. The top picture shows it. Again, the number was not noted. As the circuit was working, I did not bother to pay much attention to such details. Thanks for your keen and expert observation and comments!