Two Resistors Found Open In 5V 3A AC-DC Power Adapter
Model and Make: Nagano 5V 3A AC Adapter Model SQ15W5P-11
Problem reported: Dead
Observation: A lot of dry solder. Fuse was intact. TL431 SMD in the secondary side was burst.
Trouble shooting and rectification done: Checked the SMPS transformer with Blue Ring Tester and found all LEDs lit up indicating that there was no short in primary or secondary. Used Blue ESR Meter to check electrolytic capacitors and did not find any caps abnormal. (To know how useful a Blue Ring tester and Blue ESR Meter are and to buy, kindly see links http://www.electronicrepairguide.com/blueringtesterresult.html http://www.electronicrepairguide.com/esrmeter.html ) Did cold test of all components on the primary and secondary. Found two SMD resistors were open in the secondary section. Replaced it with normal resistors. Also replaced TL431 fixing it from the top. Looked for any more defective components in primary and secondary. Did not find any. Did a thorough dry solder patch up.
Result: Adapter worked fine adding satisfaction to my collection.
Here are some pictures:
Note: Sorry, forgot to click the component side of the PCB.
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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