Monitor gets repiared – planned obsolescence or not

The concept of planned obsolescence (or built-in obsolescence) is not new at all.

Electrolytic capacitors are -intentionally or not- the common cause cause of defect in power supplies these days. The other components these circuits consist of just do not age in this scale, but also not THAT predictable. You may make a mistake when routing the board and put them near a particularly warm spot – or someone did write just that in the specification. (No engineer wilfully designs such a weak spot.) And on the bill of material a capacitor with a higher temperature- or voltage rating is just cents above the one that will fail certainly after three to four years.

Samsung monitors and TV sets are infamous for their failing power supplies. Yes, they were produced in enormous numbers, so a lot of them will inevitably fail – and they were built to a price, but look at the circuit board below: it’s PERFECT! Immaculate. Every detail of it -solder mask, contact areas, milled grooves, the traces for the high currents, …- just EVERYTHING has been cautiously and properly thought through. Chances that they really made a mistake in placing the capacitors or calculating their lifespan are vanishingly low. And if they wanted to save every cent possible: why are there two layers of silkscreen!?

If you like Dave Jones and his manner of expression, you may want to watch EEVblog #347 – Bad Cap LCD Monitor Repair.

Unlike Dave I did not go dumpster diving, but my SyncMaster 225BW took longer and longer to properly power up. So to me it was clear that I had to replace the storage capacitors of one of the low voltage rails…

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Opening the case and folding away the power supply PCB there were brown marks on an insulating sheet – so there was no doubt which components got too hot for too long. The (predetermined) breaking points did their jobs – the tops were convex.

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Searching my collection I found some fitting replacements (at least same capacity, voltage and temperature, but not higher or thicker). Desoldering on this pure THT PCB is really easy – if your iron has enough power to heat up those large copper planes quickly. To let this last long enough don’t forget to clean away the flux afterwards.

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Buying a new monitor woul have been nice – one matching the resolution of our TV set, which is connected to the same PC, finally. But throw away the wohle device, just because two tiny components fail? No way!

(Original post: http://www.metalforum-owl.de/viewtopic.php?f=21&t=138&start=200#p57513, August 13th 2013)

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