Hi,
My Keithley 2100 DMM (please do NOT post to this thread about how the 2100 sucks, blah, blah... for the price it is a really nice 6 1/2 digit meter, that has a GUI that is somewhat lacking) started throwing up an occasional error on startup. It would say AT SPEC MODE, and then if you went through the menus to errors you would see ERR +509.
Apparently this error is a problem with the filter caps.
From the Keithley forum, posted by Keithley employee:
Error +599 is an error that involves on of the power supply filter capacitors.
This capacitor becomes faulty and the 3.3V supply is now up to 7V.
The symptom is shown on the display as
"AT SPEC mode DSP version:XX"
And the beeper continuously beeps.
Solution is to send in for service)calibration charge only) as this is a known issue.
So this is a known issue... Fun! This is what happens when you put trash "Stone" brand capacitors into a piece of test equipment.
Well, mine is a few years old and bought off eBay; so there is no warranty. So I fixed it myself.
Before and after pics:
Look at the tops of those crappy Stone capacitors!
My new Nichicons were a little larger. I will silicone them after a few days of use to make sure all is well.