Fluke 5700A/5720A Odd Problem

Started by Hawaii596, 12-21-2009 -- 11:54:05

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Hawaii596

12-21-2009 -- 11:54:05
If it's down, we'll have to send it out for repair anyway; but wondering if anyone may have seen this problem on a 5720A (this one is a 5700A/EP - with the 5720A upgrade)....

DC volts > or = to 100 VDC I got an overload trip with nothing connected.  I seem to recall seeing this problem before.  I switched over to another station; but just for the heck of it, recycled the power on the problem unit and tried no load (nothing connected to output terminals) 100 VDC and it works fine.  The GROUND to GUARD strap is connected.

I don't have the time to deal with it at the moment; and so was wondering if anyone has seen this.  One little detail (I think) is that it was used on GPIB with MetCal previously.  Maybe some oddball little setting during that use??

I'm leaning toward something defective in hardware.  I'll try leaving it set for 0 mVDC for a while and then re-trying the 100 VDC to see if the symptoms come back.  For the moment, just wanted to poll in case anyone has experience in this one.
"I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind."
Lord Kelvin (1824-1907)
from lecture to the Institute of Civil Engineers, 3 May 1883

Bryan

#1
12-21-2009 -- 12:24:03
Have you run the self diagnostics?  Does it run @ say 50V or other level within the 22-220 Valt range?   Diagnostic will likely point to failure A14/A15/A16, one or all.

sgtcory

#2
12-26-2009 -- 15:57:14
Just flipping through the manual. . .  Are you using external sensing?

From the manual :
5. 69

"If external sense is enabled and there is no signal at the SENSE terminals, an error condition occurs.  The 5720A responds to this error condition by reverting to standby mode and generating a limit error. "

I'm not sure if the overload would show up as a limit error, but reading further - it might :

"When an overload condition occurs, both the 5200A and the 5270A calibrators generate a limit error.  This limit error causes the 5700A/5720A Series II to revert to standby mode, unlike the 5200A, which remains in operating mode when overload occurs. "

Which would imply (as far as I can tell), that an overload is a limit error.

Thought I would share it - just in case  :wink:
Cory
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