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.
Good luck!
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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Josh
April 21, 2022 at 11:34 pm
That is very impressive.A lot of work and it looks like you enjoyed it.
Parasuraman S
April 22, 2022 at 2:37 pm
Yes, enjoyed it very much! But I forgot to thank the rat/s! (LOL)
Ajay Kumar
April 21, 2022 at 11:48 pm
Excellent Sir. Happy to see the restoration/ repair of an obsolete audio system!
Parasuraman S
April 22, 2022 at 2:37 pm
Many thanks for your comments!
Ajay Kumar
April 21, 2022 at 11:48 pm
Happy to see the restoration/ repair of an obsolete audio system!
Parasuraman S
April 22, 2022 at 2:38 pm
Many thanks for your comments! (Though it is repeated)
Albert van Bemmelen
April 22, 2022 at 2:41 am
Let's hope that after this splendid restoration the little rascals no longer are interested in destroying this time consuming repair.
Parasuraman S
April 22, 2022 at 2:38 pm
LOL! Yes, let us hope so!
Anil Kumar V K
April 22, 2022 at 2:38 pm
old is gold,thanks for sharing
Parasuraman Subramanian
April 22, 2022 at 9:15 pm
Many thanks!
Yogesh Panchal
April 23, 2022 at 2:13 pm
Sir,
Definitely you got "Booster Dose" for Patience and tolerance you had spent;after reviving the equipment.
Parasuraman Subramanian
April 25, 2022 at 12:51 am
Many thanks for the boosting comments!
Waleed Rishmawi
April 23, 2022 at 2:50 pm
another great repair success. Yes, rats chew on everything; when I was living in basement before we moved to our house, I had this problem of rats chewing up cables. power, audio, anything they can chew on, they chew on... thanks for sharing.
Parasuraman Subramanian
April 25, 2022 at 12:52 am
Yes, they sharpen the teeth for better biting! Many thanks for your comments!
jai Etwaroo
April 24, 2022 at 10:37 pm
Job well done Parasuraman , Complex repair and restoration .
Parasuraman S
April 29, 2022 at 2:07 pm
Many thanks!
Biju
May 2, 2022 at 6:25 pm
Sir, I am an electronics hobbyist and i frequently follow your post. I have a tape deck BPL/Sanyo. C12MKII model. Which i repaired earlier due to the FM section not working. Now the tape deck have some issues and the belt is broken. I have seen you fix this type of vintage record players. From where i can find suitable belts. Thank you
jai Etwaroo
May 8, 2022 at 8:46 am
Nice job Parasuraman, very detail and intricate repair.
Jenefer
December 18, 2023 at 7:16 pm
Can we get the SG250w National radio spare parts of the Radio.
Hazem Najjar
July 3, 2024 at 6:37 pm
greeting , i have the same stereo National SG-250W ... the problem is radio channels are not clear , how i can fix it