V-Guard Electronic Voltage Stabilizer Restored
This voltage stabilizer used by a family friend widow for her fridge was brought to me with the complaint that there was no output indication and the Fridge did not get on.
As per my usual practice, I opened the device and subjected it to a thorough cleaning. Following is the inside picture:
The first thing what one should do in servicing an old stabilizer such as this, is to replace all the electrolytic caps. No need to check these even. Just replace them. After that, I checked the active and passive components. The potentiometer was rusted.
After measuring the stationary value, I replaced it with an equivalent one, adjusting it to the original setting. One transistor was found leaky, as a result of which the output on LED was burnt. I also replaced the Zener diode as a routine. Then gave a 100W bulb as load and applied power. The output voltage was stable. So closed the device and kept it ready for pick up by customer.
Mission accomplished and added to the satisfaction collection bag.
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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You may check on his previous article on Customer Demanded Replacement Of All Caps In Cambridge CD Player CD6!
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Waleed Rishmawi
August 19, 2023 at 12:46 pm
Good job my friend and thanks for sharing. I am very sure you enjoyed getting this one repaired…( the amount of the capacitors involved). Have a blessed day
Parasuraman S
August 19, 2023 at 3:16 pm
Ha! Ha! Many thanks for your comments, dear friend!
Albert van Bemmelen
August 19, 2023 at 1:50 pm
Another interesting article about these AC voltage stabilizers that however are completely unknown in my country, and surrounding countries. In this case a 500VA x cos phi AC V-Guard (or about 500 Watt).
These devices always draw my interest because of their protective character on safely feeding through the power line AC voltage. Why I am interested in finding a complete circuit for such a device. Just in case I ever need it.
Parasuraman S
August 19, 2023 at 3:18 pm
These VSs are quite old. The latest ones come with a microcontroller program and if there is a software issue, it has to be taken to the company only! Many thanks for your comments and interest!
Yogesh Panchal
August 20, 2023 at 12:25 am
Good Job!Sir
Parasuraman S
August 20, 2023 at 1:21 pm
Many thanks!