Servicing 48 LED Random LED Light
This random running light is one of the products that I deal with in my hobby sales. This was brought to me by a customer after almost an year stating that it was dead. I opened it and after cleaning of cobweb and dirt of dead insects inside, took it up for diagnosis.
On checking with my Analogue Multimeter, I could make out that one resistor was burnt and three LEDs were short. Replaced these. While replacing the LED, we need to follow the R G B written on the board for selecting the correct colour of the LED. Did a thorough retouch of all solder points. Switched on and it worked. As the IC number was not written on the top, I suspected it could be underneath and removed it. It was there on the bottom (one of the cheap Chinese tricks to avoid copying!) You will also notice that the colour code on the resistor is absurd! (I compared the value of the resistor with another new light from my stock and found it to be 33K!)
Looked for datasheet of this IC, but unavailable as expected!
Provided an IC socket and put the IC back.
Assembled the unit back to its original condition and switched on.
These are the components replaced:
So, my satisfaction list lengthened further!
This article was prepared for you by Parasuraman Subramanian from India. He is 69 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:
https://jestineyong.com/crude-drawing-to-find-out-burnt-components-part-number/
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Paul Preston
May 30, 2018 at 11:16 pm
You said you removed the IC but you didn't state the part number. Do you still have the IC part number available?
Parasuraman
May 31, 2018 at 7:32 pm
Kindly zoom and see the image of IC. It's readable.
Robert Calk Jr.
May 31, 2018 at 6:26 am
Good job, Parasuraman.
Robert Calk Jr.
May 31, 2018 at 6:30 am
Oh yeah, I hope our friend Albert doesn't get mad at you for using your VOM. lol
Albert
May 31, 2018 at 7:29 am
Indeed another pro job done Parasuraman. It seems likely that the device with the 5DF2433E still is somehow 'copyprotected' since no datasheet exists and the chip still can't be found anywhere either. Or it is not the correct chipmarking after all?
Parasuraman
May 31, 2018 at 7:33 pm
Possible!
James
May 31, 2018 at 2:16 pm
I thought that was a smoke alarm' :[) lol
Suranga Electronics
May 31, 2018 at 7:38 pm
Good Reair Job Mr,Parasuraman
Michael Ripley
May 31, 2018 at 7:48 pm
The pcb was printed with "30K" under the resistor. Just an observation.
Badly marked IC are very annoying. Very common in automotive ECU and increasingly seeing it on laptop motherboards.
Robert Calk Jr.
June 1, 2018 at 9:29 am
It's also annoying when the PCB and the schematic doesn't match.
Christian Robert Adzic
July 6, 2018 at 9:17 pm
In automotive ecu's a very common labeling is a so called "masking".
Some of masked parts list can be checked here:
http://www.autotronika.pl/files/file/MASK_SETS_by_Autotronika.pdf
Also the same situation on PC mother board, laptops etc...
Hakan
June 1, 2018 at 4:25 pm
Hi why did you use IC SOCKET.. Was the IC damaged..
Parasuraman
June 1, 2018 at 10:33 pm
Because, the PCB tracks were not good quality and I wanted to avoid a resolder in case the IC fails and I have to replace it from salvaged similar lights.
HAKAN
June 2, 2018 at 7:40 pm
Thanks
Christian Robert Adzic
July 6, 2018 at 9:19 pm
Great Job!
The ic could be a uC, maybe some sort of attiny 85 or so.
Checking the circuit could be maybe identify if it is a attiny 85 or so.
In many china tools could be found a uC that family.
Probably also a clone/copy of the original...