Shorted Zener Diode Found In Voltage Stabilizer
This is a voltage stabilizer that is in use for my Fridge. It had failed a couple of years back and that time, it was due to dry solder and I solved it and also replaced the electrolytic capacitors, since the ESRs were in the brim. My wife reported that the Fridge was not on and when I went and checked up, there was no output from the voltage stabilizer, even though there was input. I connected the Fridge directly and it was found working well. So brought the stabilizer for troubleshooting to my workshop.
As usual, the first job is external and internal cleaning, which I did quickly. Removed the PCB and found that there was no dry solder.
The stabilizer has two PCBs, one for its power supply, which housed the rectifier diodes, smoothing capacitor and 12V regulator IC. The next board was the buck/boost section, which had two relays. The relay was getting on when switched on, indicating that the primary power supply and the relay driver circuit was working alright.
As you can see, the soldering was still intact.
I checked the semiconductors as well as the passive components and found only one 9.1V Zener leaky.
Replaced it, gave power connection and checked the outputs. The LED was lit and the output was present.
Reassembled the unit and connected it to the Fridge and found it to be working perfectly well. My wife was happy that I could fix it so soon!
Another service added to my satisfaction list, with ‘double’ effect!
This article was prepared for you by Parasuraman Subramanian from India. He is 69 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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