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A few weeks ago I picked up this awesome older Sony CRT, saving it from certain death. Here it is, a 27" Trinitron KX-M270 monitor circa 1986. Still fires right up and works flawlessly, save for some slight geometry funkiness and a noisy flyback for the first 30-45 seconds of operation.



Initially I popped off the back and gave it quick blast from an air compressor at work, but today I finally had some spare time to fully dismantle the chassis in order to remove the decades of dust with some brushes and a can of compressed air. Unfortunately, on the underside of the board many of the solder joints around the flyback and other components adjacent to it are heavily corroded. Some of it almost seems burnt.



Looking at the top of the board in the same area, the PCB itself seems to be saturated with a brownish liquid (bottom left of photo below - you can see where the stain begins). At first I thought may have been soda, but the affected area is located underneath the tube when the chassis is slid into place where no liquids could reach it from outside the case. This is about as clean as I could get it without using isopropyl or anything of the sort.



Like I said, the set seems to function just fine as is and I'm sure I'm being needlessly anal-retentive about it. Seeing that it won't be stored in any adverse environmental conditions from now on, I'm wondering if this is one of those "if it ain't broke" situations. Could this corrosion cause problems in the future if not addressed?

You did right blowing off all the dust. Leave the surface corrosion alone, you might damage the components and traces if you try to clean that. Likley stored in the garage by the previous owner, just keep the TV indoors.

Yep, the previous owner was clearing out some CRTs and other old tech that were being stored on the unfinished side of his basement for the better part of a decade. Thanks for easing my mind. I'm amazed at how well this thing still works considering the components are all original and pushing 30+ years.

The noise you hear when you turn on the system could be faulty capacitors, also brown gunk will often be a leaking component like resistor or capacitor. Look to see if any capacitors are leaking, or swelling - if so, replace them. Check solder joints, if any have become loose resolder them (you can get cold solder joints sometimes on old equipment).

Uhh that's not corrosion on those solder joints, that's solder flux.