VOGONS


First post, by xbit

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Any idea what this small heat sink is cooling? And I'm wondering if its supposed to get as hot as it does. Like VERY hot. I almost want to put some thermal paste and a tiny fan on it <g>

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Reply 1 of 4, by gerwin

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xbit wrote on 2023-02-24, 00:42:

Any idea what this small heat sink is cooling? And I'm wondering if its supposed to get as hot as it does. Like VERY hot. I almost want to put some thermal paste and a tiny fan on it <g>

It converts supplied 5 Volt to 3,x Volt for the processor, when configured to do so. It is the voltage regulator.
On both my 486 motherboards I added a slighly larger heatsink to this VRM, to lower the temperature slightly. But such modifications may interfere with larger add-in cards in the nearby slots.

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Reply 3 of 4, by rasz_pl

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>what this small heat sink is cooling?

linear regulator

> And I'm wondering if its supposed to get as hot as it does. Like VERY hot.

Yes. Linear regulators are, to put it simply, just resistors radiating away the input/output difference (dropped voltage). Very inefficient as you can imagine. Whatever the power 3V CPU uses that regulator will eat additional ~50% while being significantly smaller.

> I almost want to put some thermal paste and a tiny fan on it

do you have the urge to mount additional radiators in your car? or modify the thermostat? after all coolant easily hits 100C! 😀
Linear regulators are designed to operate at those temperatures just fine. Dont worry about it.

>One thing I noticed is it bends very easy. So, something to be carful with i'm sure.

yes, dont bend it 😜 Ideally radiator should have its own leg or lie flat on the side. Looking at https://theretroweb.com/motherboards/s/lucky- … r-ls-486e-rev:d Lucky Star went that route in later revision. Of course this would only matter in mobile applications where constant movement has a potential of stressing the part beyond its limits - this is why big capacitors (heavy part on small two legs) tend to be glued down with white snot in power supplies.

Open Source AT&T Globalyst/NCR/FIC 486-GAC-2 proprietary Cache Module reproduction