6 Jun
2005
6 Jun
'05
12:52 p.m.
From: "Dwight K. Elvey" <dwight.elvey at amd.com>
Sent: Monday, June 06, 2005 2:09 PM
In this particular case I would disagree. The Imsai is fairly well filtered
and I would expect less ripple, if there is much ripple I would suspect bad
caps or poor connections of the caps.
Of course when these caps fail you usually know it all the way down the
street ;-)
Randy
www.s100-manuals.com
From: ard at
p850ug1.demon.co.uk
Hi
For this particular test, using DC coupled is probably
best. As Dave mentions, you just don't want the voltage
on the unregulated 8 volt line to drop below 7 volts.
It can tolerate a relatively large ripple.
Dwight By the way, the power supply, so far, has tested
fine. I'm going to look
for any ripple with the scope later today. I've never done that test --
should I DC or AC couple the scope for that test?
AC coupled. That's really what AC coupling is for -- you want to ignore
the steady DC level (of several volts) and look at the (hopefully) much
smaller AC ripple on top of it. To do that you need to turn up the Y
sensitivity on your 'scope, and unless you have a differential comparator
input or something, you won't be able to keep the trace on-screen with DC
coupling.
Don't worry too much about ripple on an S100 supply. The S100 supply is
not regulated -- the regulators are on each of the boards (the 8V input
is designed to be regulated down to 5V, etc). The regulators should take
care of small amounts of ripple on the backplane supply lines.
-tony