keithley meter giving trouble..

[Ranjini]

I am using two keithley 6487 through labview to scan the voltage for an ion beam deflector. recently one of them started showing cmpl on the front panel ocomp also flashes. all the probes i opened and run it through frontpanel. still the problem persists. tried to update the firmware and it failed to complete updating .

can any one give any clue why this happens. the interlock connector is proper.

this is not a question directly linked with labview but i could not find any other active forum to post the problem. i apologise.

pls help me to recover it.

thanking you

ranjini

[Francois Normandin]

Hi Ranjini,

Here's the Source Manual Reference manual extract (page 3-18) for your condition:

http://www.keithley.com/products/locurrhir...487/Documents#6

Compliance indication

At any time, it is possible that the voltage source will go into compliance (current limit

reached). Should this situation occur, the OCOMP annunciator (Output Compliance) will

flash and the displayed voltage value for readings of less than 6½ digits will alternate

between showing the value and displaying "CMPL". If you are in a menu where the voltage

source value is not shown on the right-most four characters of the display, only the

flashing OCOMP annunciator will be shown.

It seems you're out-of-range. Maybe check the range of this 6487. If both 6487 should be the same range, verify both are set the same.

[sENS:VOLT:RANG? + CURR:RANG?] It could also be a current-limit if you're using the voltage source (SOUR:VOLT:RANG? + CURR:RANG?), but if you're measuring voltage (sense), that is not the case.

Hope this helps.

[Ranjini]

Dear normandinf,

i follow the manual refrence and already understood the meaning of compliance. we have seen this conditions many times when the current measured is more than the set range. but now the problem is we are not connecting any voltage source and no current is flowing. still it says cmpl. that means it may be shorted inside the instrument somewhere???

we have written the program to configure both the 6487 and they are same and functioning fine so far.

i hope u have understood the problem. and thanks a lot for a quick reply.

waiting for ur reply

thanking you

ranjini

QUOTE (normandinf @ Jun 21 2008, 06:43 PM)

Hi Ranjini,

Here's the Source Manual Reference manual extract (page 3-18) for your condition:

http://www.keithley.com/products/locurrhir...487/Documents#6

Compliance indication

At any time, it is possible that the voltage source will go into compliance (current limit

reached). Should this situation occur, the OCOMP annunciator (Output Compliance) will

flash and the displayed voltage value for readings of less than 6½ digits will alternate

between showing the value and displaying "CMPL". If you are in a menu where the voltage

source value is not shown on the right-most four characters of the display, only the

flashing OCOMP annunciator will be shown.

It seems you're out-of-range. Maybe check the range of this 6487. If both 6487 should be the same range, verify both are set the same.

[sENS:VOLT:RANG? + CURR:RANG?] It could also be a current-limit if you're using the voltage source (SOUR:VOLT:RANG? + CURR:RANG?), but if you're measuring voltage (sense), that is not the case.

Hope this helps.

[Francois Normandin]

Sorry, I didn't want to seem patronizing. Most people posting these kind of requests on LAVA didn't look in the manual prior to asking the question. Since it's not the case here, my apologies.

I think your equipment is probably damaged. Do you know if there were any surges before the equipment began to be faulty? I had a similar experience with a Keithley Electrometer (K6517) where a student shorted the high voltage source (1000V) to the current measurement (uA range, no protections). The first time, the equipment protected itself (probably through some capacitive protection) and the compliance error disappeared the next day, everything coming back to normal as if it never happened. We were not so lucky the second time (a year later...) and we had to send the unit to Keithley for repairs.

If you're confident about opening the case (warranty issues maybe?), then you can check for ground faults. There is usually a grounded metallic casing on the acquisition board to protect the user from high voltages when he sneaks in. When the short happened in our lab, that case became permanently at -300V! If you can find such a faulty behavior, then there would be no doubt about the way to proceed next.

Good luck...

[Ranjini]

Thank you normandinf, for sharing your experience .

in our 6487 , the voltage source part behaves strangely . when i start the instrument, the source shows -8 V. but if i switch on voltage source and cross -8 v then it shows the actual voltage and then i can increase it to zero or even positive. may be as u say it is damaged. ( dissaponited :headbang: my experiments is waiting for the instrument ).

i have written to keithley .

thanking you

ranjini