Restored A Rat Spoiled National SG250W Two-In-One
This set belonged to one of my close friends and he brought it to me for a possible restoration. According to him, it was lying in the attic. I saw the carry bag had a hole underneath which looked like a rat made one. I removed the top cover, which had no screws. I was shocked to see that almost all wires inside were cut by the mischievous rat or rats! Just see a couple of the several pictures that I took:
Though I tried my best to fetch a service manual of this set, it was not available even for purchase!
(In case any of you can help me get one just for my reference and record for future use, if and when found necessary, kindly provide a link in your comments!) After doing a thorough cleaning of inside, I dismantled the set totally:
Reconnected the cut wires of the transformer and in other sections by scraping and soldering the cut ends. Replaced the mains cord as it was damaged very badly. Covered the wires with sleeves, wherever the wires were not cut, but had the protective insulation scraped off. Did a dry solder patch up on the main board. Changed a few capacitors which were found to be leaking or ESR out. Cleaned and lubricated Mechanism. Changed the worn out pinch roller. Fixed a belt as it was found missing. Cleaned and lubricated control switches and recording switch. Then connected the boards externally and gave an external audio in to check working of the amplifier. It was working very well to my amazement:
Found that in the Radio mode, there was crackling noises in all bands. Checked for any defective components in the board and also replaced all electrolytic caps on it, including the one board fit vertically, housing the IC LA3350. I removed this board and the IC and after checking for any defective component in it, I concluded that the culprit was the IC itself. As this was not available in the local market, sent out by SOS through whatsup group and located a supplier in Mumbai.
Placed order and paid. Bought two ICs as a buffer in case of failure again. The Radio was working perfectly after replacement of the IC. As the dial cord was also cut by the rat, I did a fresh cording following the printed dotted lines on the Radio Board:
Then fixed the internal antenna coil properly, as this was also cut and torn from its fixture. I did it in my own way, taking into account of the space constraint.
The set was assembled back to its original condition and tested on Radio, Audio in and Tape for several hours and found to be working perfectly well.
I have skipped detailing and many snaps of a few routine work done on the set to ensure brevity. Another very difficult mission accomplished after spending several hours, because of which the satisfaction was more than happy to jump into the collection bag! Here are the pictures of the defective components replaced:
Special notes: (1) Do not allow dejection to grow within the mind whenever you see a set of this nature. Take it as another chance of different kind. What will you do, it if it was your own set? Think that way and start restoration. (2) Patience and tolerance alone can bring results in such a hectic work and remember that doing something impossible will serve as an energy booster.
(3) Bear it in mind that there is a solution for every problem we face and a cool and calm approach alone can help us find the right ways for accomplishment. (4) Panic blocks intellectual thoughts and solutions and grows lethargy and laziness in us.
This article was prepared for you by Parasuraman Subramanian from India. He is 72 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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