SMD Regulator IC Found Open In OLSENMARK OMR1239
MAKE AND MODEL: OLSENMARK MODEL OMR 1239 USB RADIO
COMPLAINT REPORTED: DEAD
TROUBLESHOOTING AND RECTIFICATION DONE: Opened, dismantled and cleaned the set thoroughly. Applied power externally to check upto which stage the power was reaching. Noticed that it was reaching to pin one of SMD regulator IC which had a marking ‘54FK.’ Searched the web and came to know that it was a 2.8V regulator IC. As this part was not available in the market, I replaced it with AMS1117 – 2.5V SMD IC. As the positions of the pins were different, drilled three holes on the board where 54BK was, and fit the AMS1117 from the top, ensuring that the input, ground and output was in position.
Powered the set again and noticed that the Radio and USB were working very well. The point .3V difference did not matter at all! (It struck me now while writing this article that I could have added a diode to the ground to boost .5V in the output!) Did patch up of all the solder joints on the boards after replacing all the electrolytic capacitors as a routine preventive maintenance. Assembled the boards back and let it run for many hours using all its functions and ensured that it was working very well. Mission accomplished and satisfaction got added!
HERE ARE A FEW PICTURES:
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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