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Dry Solder And Bad Capacitors Caused Refrigerator Stabilizer To Go Dead

By on November 7, 2020
Dry Solder And Bad Capacitors Caused Refrigerator  Stabilizer To Go Dead







voltage stabilizer repair

This voltage Stabilizer belonged to a family friend and was brought to me stating that it did not work. When I checked it up, the complaint was correct as no output was coming. There is a voltage meter which can be connected to input or output through a selector switch. Then when we press the indicator switch, it will show the reading. However, the needle was getting stuck after around 150, which meant that it cannot be relied on.

First duty was to open and clean it up thoroughly, which I did. It had collected dust all over to the extent possible!

how to fix voltage stabilizer

how to repair voltage stabilizer

Then looked for the trouble maker, which I found as dry solder on the wire connected to the relay, which looked like just wound on the contact instead of soldering. After cleaning and soldering it, the relay worked properly. Anyhow, I reworked on this stabilizer from in to out, by re-soldering and tightening the screws wherever the wires were fastened with screws. Replaced the two electrolytic capacitors as the readings were far out of range (both ESR and capacitance).

fixing voltage stabilizer

The circuit used one diode DS5 and one transistor C547B. The Stabilizer indeed had been handled by another technician long back, as I could make it out from a few solder spots and replacement of this transistor. But why was the relay wire just wound on the contact instead of soldering, is something that baffled me. Perhaps to make sure that it goes back for another service?!

servicing voltage stabiliser

After finishing the work, I connected a 100W bulb as load and checked. It worked perfectly.

This stabilizer used only one relay, which meant that there was only cut off and no boost/buck like many others, which used two relays and corresponding winding wires in the primary. So, this was a very old design.

voltage stabilizer fix by India Repairman

As the customer was not using the meter, she (a widowed old lady living alone) did not want it to be replaced. I checked the input/output in the meter after pressing the bell button and selecting the switch to that point. Here is what I saw:

voltage stabilizer repair by India Repairman

These are the two capacitors that I changed, which taped to its cabinet when giving delivery to the customer.

bad capacitor in voltage stabilizer

Anyhow, satisfaction never failed to get added to its collection bag!

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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You may check on his previous repair article below:




  1. Waleed Rishmawi

    November 7, 2020 at 3:39 pm

    very interesting to the finest details repair. I just love it. thanks for sharing. have a blessed day

    • Parasuraman S

      November 9, 2020 at 4:32 pm

      Many thanks!

  2. Albert van Bemmelen

    November 7, 2020 at 6:25 pm

    If you ever have made or copied the circuit of such a refridgerator stabilizer I'm interested. Because unlike the units also used in Humberto's country Cuba, we here in Europe do not know about having or using these devices. Mainly because our provider powerline net is very stable and it almost never is unstable or results in a power failure.

    • Humberto

      November 8, 2020 at 11:59 am

      In my country so voltage as frequency are not very stable. It´s a pity!

      • Albert van Bemmelen

        November 8, 2020 at 5:56 pm

        I know dear Humberto. And I still kept the information of your refrigerator circuit you published in one of your repair articles on my hdd backup somewhere. Of which the photos as you know were not detailed enough to make up their values to draw the exact circuit.

    • Parasuraman S

      November 9, 2020 at 4:33 pm

      Ok. I will bear in mind! Many thanks!

  3. Yogesh Panchal

    November 7, 2020 at 7:40 pm

    This unit may have gone to ground fill if not found safe hands for tackle.
    well done sir.

    • Parasuraman S

      November 9, 2020 at 4:34 pm

      Many thanks!

  4. JG"Joe"Ayala

    November 7, 2020 at 9:53 pm

    Interesting article! I never heard of such device here in Central Florida. Never the less, it was educational. Thanks for sharing our experience.

    • Parasuraman S

      November 9, 2020 at 4:35 pm

      Many thanks!

  5. Henrique J. G. Ulbrich

    November 8, 2020 at 1:05 am

    Of course, using voltage stabilizers is generally a mistake. They bother more than help in most cases. Mainly in the case reported here: only one relay to switch the outputs, which means a poor/very limited correction range. Most people use voltage stabilizers thinking that´s correct, but in many cases is the contrary. When jumping from one condition to the other, the relay contacts suppress the output voltage for some milliseconds. On applying the "corrected" voltage again after this short period, there is a possibility to occur inrush currents, depending on the characteristics of the equipment being supplied. If the equipment power supply is of an SMPS type, on applying again the voltage (when the relay completes its work), there is an NTC at the input of the SMPS that, due to be hot, presents very low resistance, favouring the creation of a high inrush current that is generally too heavy for the SMPS circuits. This switched power supply might be affected, which would not happen if the stabilizer is not used. The question: does this old lady really need to use this stabilizer? The majority of electric supply companies worldwide generally provide a relatively stable voltage, dismissing the use of any extra stabilizer.

    • Parasuraman S

      November 9, 2020 at 4:36 pm

      Very true! Many thanks!

  6. Humberto

    November 8, 2020 at 11:59 am

    Good repair of this old stabilizer. When I was a child, CROWN was a brand with great prestige in my country. There were Tape Recorders, Radios, Radio Cassette Recorders, Walk Man (later), etc

    • Parasuraman S

      November 9, 2020 at 4:37 pm

      Many thanks! Love to recall such old times!


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