RESTORATION OF A WHIRLPOOL INDUCTION COOKER-NX2002 TO CONTINUE ITS SERVICE
This induction cooker (hereinafter referred to as IC for brevity) was brought to me by a regular customer mentioning that it was lying neglected in the attic. Having known and also experienced the efforts that I put in to revive almost dead devices, he wanted me to try to bring it back to life. As you can see from the pictures above, the IC had enough dust, dirt and cobwebs inside apart from rust formations, which got cleaned up thoroughly as usual. Since the IGBT was found short, I did not apply the power and went ahead with my revival plan already practiced several times in the past.
The values shown by black fixed capacitors and high watt resistors are as shown below:
The 820K 1% tolerance resistors were showing 852K and 825K which definitely will affect the voltage sensor circuit. The dropping resistors connected in series should ultimately give DC good feedback of around 2.7V to the uController for proper functioning. The value of the black fixed capacitor was 5uF; but it showed 2.586 reaching a shorting condition, because of which the IGBT could have blown.
I replaced all the defective components (IGBT too) as well as the electrolytic capacitors as usual. Rusted jumper wires were also replaced along with a few fixed caps on the control panel as well as main board. The press to on switches were replaced due to rust formations. The fan was replaced as it was sluggish in spite of lubrication. Both the boards were retouched with fresh solder and cleaned thoroughly. The 820K was achieved by series of resistors as I was not having it in stock. Let us have a look of all these:
The last two snaps are that of the uController and Panel controller. After all these exercises. I assembled the boards keeping it on the table and applied power. I was glad to see that it had got back its life. So assembled the IC and tested it with a pan of water. Also used it in my kitchen for a couple of days.
Last picture would also show you the 8050/8550/18VZener/Diodes/IN4148 etc. replaced as preventive maintenance.
Mission accomplished which qualified the utmost satisfaction to gain entry into the 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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