29 Jul
2012
29 Jul
'12
10:05 a.m.
On 07/29/2012 08:18 AM, David Riley wrote:
On Jul 29, 2012, at 5:37 AM, Camiel Vanderhoeven
wrote:
It can also be due to insufficient load in the case of switch mode power
supplies.
That supply want a minimum of 10% load (10% of full current and on both the
12V and 5V lines).
Allison
The measurements were taken with the power
distribution board and
minimum load module plugged in; I don't want to plug any other modules
in while the power looks like this. Is there any documentation
available on this power supply? Or, does anyone have an idea as to
what's going on here? The 6 Hz frequency strikes me as odd...
Looks like
"motorboating" to me; low-frequency oscillations due to a
feedback loop in the power supply forming a relaxation oscillator.
In my tube amps (which is where I usually see that), it's often a
result of the power supply's output impedance being too high. A
failing cap is often to blame; check your output caps?
- Dave