HP 5334B Universal Counter Display Question - "OFL" - Page 1
Forum section: electronics / testgear

author: xrunner
author_rank: Super Contributor
timestamp: October 26, 2015, 07:24:53 pm
content: What does this mean if the display changes to this -"OFL"There doesn't appear to be anything wrong, and it passes all self-tests and measures correctly, but if I take a measurement, and leave the instrument alone for something like 15 minutes or so (while the last frequency measurement is still on the display,but the external source is off), the frequency measurement on the display changes to display just "OFL".If I just turn on the external source, the display again measures the frequency OK immediately. I have scoured the manual and can not find a single mention of the meaning of "OFL". I wonder if it's some kind of time-out if the trigger goes away ... I have no idea.Thanks for any help.

author: Vgkid
author_rank: Super Contributor
timestamp: October 26, 2015, 07:29:29 pm
content: Overflow, i guess. I dont have accesd to the manual on my phone, for the 5335 I do...

author: xrunner
author_rank: Super Contributor
timestamp: October 26, 2015, 07:30:37 pm
content: Quote from: Vgkid on October 26, 2015, 07:29:29 pmWhat's "overflowing"?

author: saber63
author_rank: Newbie
timestamp: October 28, 2015, 05:22:48 am
content: I am interested in this as well, as i have a 5334b on its way.In looking over the manual's I never found any mention of "OFL" either!That includes the service manual... (links in case anyone needs umhttp://www.ko4bb.com/manuals/index.php?dir=HP_Agilent/HP_5334_Universal_Counter)

author: Electro Fan
author_rank: Super Contributor
timestamp: October 28, 2015, 06:57:12 am
content: various interpretations of OL and OFLOLOverloadOver LimitOut of LimitsOpen Loop (Ohms?)Open Circuit?OFLOverflowhttp://www.veris.com/docs/Installs/196manual.pdfNOTE: If diode reads 0 in both directions, diode isshorted. If diode reads OFL in both directions, diodeis open.

author: xrunner
author_rank: Super Contributor
timestamp: October 28, 2015, 12:33:27 pm
content: Quote from: saber63 on October 28, 2015, 05:22:48 amI found it mentioned in the manual for an HP 8562E spectrum analyzer -http://exodus.poly.edu/~kurt/manuals/manuals/HP%20Agilent/HP%208562E%20Service.pdfExamples -QuoteandQuoteIt displayed OFL the other day a few times, but hasn't done it since. It doesn't display "ERROR" or anything else - just "OFL" at the left side of the display. It only appeared when the input signal went away, and only after 10 to 15 minutes. It never appeared when the input signal was there. As soon as the input signal appeared, the "OFL" went away and it worked just fine. It's strange that a display indication isn't mentioned in the user or service manual. That is strange for HP.

author: edpalmer42
author_rank: Super Contributor
timestamp: October 28, 2015, 07:55:39 pm
content: It sounds like it's a benign condition rather than a failure. Similar to a high impedance DMM that overflows if the input is left open.The manual says that the maximum period and time interval is 1000 seconds i.e. 16.666 minutes. I suspect that 1000 seconds is also the maximum length of time that the unit will wait for a trigger.Ed

author: Vgkid
author_rank: Super Contributor
timestamp: October 28, 2015, 09:28:18 pm
content: Similiar issue for me.i was measuring thr 60hz mains frequency, disconnected the external 10Mhz, and all of a sudden it would a few Ghz as mains frequency. Impressive, but look at the schematics to see how it determines where the freq reference comes from.

author: xrunner
author_rank: Super Contributor
timestamp: October 28, 2015, 09:53:53 pm
content: Quote from: edpalmer42 on October 28, 2015, 07:55:39 pmLooks like it's something to do with what you said. I did two tests - I had channel C count a 20 MHz signal then I removed the signal. I waited for 17 minutes (to go longer than 1000 seconds) and then re-connected the signal. The display flashed "OFL" very quickly then started counting again (sometimes it just flashes OFL). Then I removed the signal again and waited for only 15 minutes then re-connected the signal - it did not flash OFL.So your answer was very insightful - thanks.Still - it's odd that the documentation would not even mention the instrument might display "OFL" so people would not freak out when they can't find it in the manual.