Magic smoke out of fridge

When fridge got me popping sound and display turned black, I realized that 10 years old Whirlpool went out of service. My “damn it” comment was quickly followed by my wife: “You are going abroad next week! What we do now?”.  Considering subtle smell of magic smoke I felt next to fridge’s back, I knew any repair shop will simply get me new control module, and these are overpriced, sometimes nearly 1/3 of appliance cost. The choice was easy: fix it or get a new fridge, next day.

Blown power switcher IC

Blown power switcher IC

Smelly control module

Smelly control module

Getting control module out of its tight compartment was a nightmare. As soon as I opened it it was obvious there was tiny explosion inside: I found plastic top chipped off the integrated circuit. Close inspection of PCB got me interesting view of micro-crater in the IC itself.

One thread on electronics forum described that issue as typical failure: electrolytic caps drying over time led to shorting circuitry and blowing out TNY268 relying on these caps. This scenario matched perfectly my aged fridge. I simply needed to replace switcher IC and few caps. Tricky part was that I needed to fix it as quickly as possible – no time for making online order and waiting a week when I am back home and can rework PCB. I rushed to local shops a bit hopeless as these days they in-stock availability is just a tiny fraction of components usually needed in repairs or daily work etc. And indeed I could not get this chip in DIL thru-hole casing anywhere. I bought SMD version and DIL socket to make a prothesis. Excessive plastic was cut off to ease soldering SMD part to DIL socket and finally I could mount such hybrid on PCB. 

SMD part soldered to DIL socket

SMD part soldered to DIL socket

Barely visibly broken resistor

Barely visibly broken resistor

Late Friday’s afternoon I could test controller board just to discover it does not work. What an irritating feeling. Short break got me a bit of energy to walk the board again. Desoldering and checking neighbour parts one by one let me discover broken power resistor. Close look revealed tiny crack on the bottom, hard to spot without disassembly. No charred marks, what a bastard :)

As soon as I got this bloke replaced my fridge starded again. Woohoo! Few hours or work, $10 spent on parts and gas, around $200 saved on repair or at least $600 on new appliance. Now I just need to convince my lady that this saving is my pocket money.

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