Two Round Service Done ON V-Guard Induction Model VIC-400 & Also Case Of VIC-07V1
This induction cooker was brought to me with the complaint that it gets on, but does not heat up. The device had enough dust and dirt inside, which was as expected:
I used to wonder how such home appliances collect so much of dust and dirt. Even if the cleaning done in the house could cause displacement and settlement elsewhere, and if these fall within the catchment area of the cooling fans, it will get sucked in, I have seen such dust and dirt even in devices which do not have a cooling fan. Just think how much of these particles are reaching our lungs!!! What does our body do with these free deposits???
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After finishing the routine thorough internal cleaning, I carried out the blind replacement of all electrolytic capacitors, being my first step in restoring any electronic devices. Then the next step was to replace the 2N3904/2N3906/8050 transistors, 78L05 regulator, 18V Zener, suspected high watt resistors, IN4148 and other suspected diodes. Then carried out retouch of both the boards after scraping the varnish on solder joints with a metal brush, lest it should cause bad contacts. While replacing the 2N3906, I noticed that the new batch of transistors is different from the one in the board had:
If we are not aware and careful about such variations done by the manufacturers without following the international standards, we will end up in bitter soup!
After finishing the refurbishing work, I cleaned the boards thoroughly using IPA and inspected them under a 10X lens looking for any SPR-made mistakes such as soldering jumping over to the next track or component. There were two such breaches, which I rectified. Then reassembled the boards, kept the top on the coil and a pot with water in it and applied power to check whether the device was getting on and found the function was normal:
As you see from the above pictures, the water got boiled at 1300, drawing a current of about 6A which was a good sign.
I fit the panel back, closed the cover without fixing screws and transferred it to my kitchen, remembering to take away ours before keeping this in that place. I am repeating the caution not to keep one induction cooker on another even though the bottom one is disconnected as the pulses pass through the coil in the bottom that will blow the IGBT, which happened to me before. (https://jestineyong.com/caution-never-keep-one-induction-cooker-on-another-for-testing-alesson-learnt/) The cooker was tested for three days and found to be working very well. Then I fixed the bottom cover with screws and delivered it to the customer’s home as I was passing by that for another TV work. The cooker was connected in their kitchen and tested for proper function before I left from there. Though it looked as though the case was closed, in came the complaint after a couple of days stating that the cooker was showing E6 error. I went to their home and checked the AC voltage and found it to be normal. Then checked the vessels used, which were also compliant. So, picked it up and brought home to carry out further investigations. The suspicion was on the vessel sensor. When I did a cold check, got a reading of 85K in the digital multimeter. The normal reading is around 70 to 72K.
Replaced it and tried, but even then the E6 error was being shown. The next suspicion was on the 500 Ohms potentiometer. I replaced it and also a couple of high watt resistors as these could vary in value on load. Then the cooker worked very well, and I tested in very high setting also (maximum temperature). The ampere reading was also well within the limits:
Once again the cooker was delivered to the customer and checked at their premises and found to be working well.
Following are the pictures of the components replaced in the first round and second round:
Though I am keeping my fingers crossed and hoping that it would not make an ‘about-turn’, the satisfactions need not have to wait in the rain (it is rainy season here!) and therefore were allowed entry to the collection bag.
ADDENDUM – CASE OF A SIMPLE JOB DONE IN YET ANOTHER V-GUARD INDUCTION COOKER MODEL VIC-07V1
As though to provide some solace was the entry of this Induction Cooker which came in after the above complicated case. This was brought to me with the same complaint; i.e. getting on, but not heating. When I powered it, it was not showing any error code also. I opened the cooker and cleaned the inside, which was not as bad as the earlier one:
The cause for failure was visibly clear as I saw the 5uF 250V AC capacitor burst, picture of which is given in the second image above to save space. After cleaning and checking the board generally, I replaced the capacitor and applied power.
The cooker got on and also heated up the water kept on top in the vessel. As the cooker was not very old, the board looked in good shape and the customer was having only a low budget, I checked the cooker for two days in our kitchen, and passed its function. Mission accomplished with a record replacement of only one capacitor in this, which caused the production of a satisfaction that gained entry again in the same collection bag!
This article was prepared for you by Parasuraman Subramanian from India. He is 76 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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