24 Aug
2014
24 Aug
'14
5:11 p.m.
On 08/24/2014 04:27 PM, dwight wrote:
It would seem my guess was wrong. It seems to be the
regulator.
Herb seems to think it's a good idea to replace old linear regulators on
S100 boards as a matter of course as well. Given that the "knee" in the
7805 (according the Fairchild data sheet) occurs at about 2.2A and then
*slowly* drops back down (e.g. limits current to 2A at a 15V
differential, which has the regulator dumping 30W in heat), it's
probably not a bad idea. Many vendors either didn't heatsink those
TO220 packages or exceeded the ratings quite routinely.
Makes me grateful for switching regulators like the LM2678 that makes
for a cool 5A design. I think someone even makes retrofits for the 78xx
and 79xx series.
--Chuck