I have fielded two dozen pieces of equipment with 2x16 VFD from Noritake. These are on 24/7 and they were shipped over a 4 year period starting in 2000. In normal state, there are 4 digits always turned on on the first line. The other digits are rarely turned on. The displays start being noticeably darker after 2 years and barely usable after 3-4 years. The digits that are not normally used seem to last much longer but they eventually get darker, just at a much slower rate. It may be due to contamination rather than the filament itself wearing out. By now, most have been replaced at least once, with a different part number because the old one has become obsolete.
Didier KO4BB On April 11, 2015 11:37:49 AM CDT, Chuck Harris <[email protected]> wrote: > From visual inspection, the filaments in these >vacuu-fluroescent displays look like bare wire, >which would make them some sort of doped tungsten >alloy.. which doesn't really ever wear out. > >The only problems I have ever seen is due to >phosphor fatigue. The display stops glowing >on whichever digit is on all the time... and >you see this as unequal brightness between the >digits. > >I have never seen a vacuum fluorescent display >just fade away in any reasonable time. They >seem to go for years and years. I have alarm >clocks and ovens, and microwaves with these >displays some of which have been glowing for >around 40 years now, and still going strong. > >I have seen vacuu-fluorescent displays that >have gone dark, and found that the reason is >the filament supply has quit...usually due to >a bad electrolytic capacitor. > >-Chuck Harris > >Don@True-Cal wrote: >> The 3458A DISP? command, rather entered from the front panel or via a >GPIB Command is not adequately discussed in the User's Manual IMO. >There are four numeric values 0,1,2 & 3 plus the ability to enter a >string value as mentioned below. All four values are supported via the >GPIB, but only 0,1 &2 are valid modes for the front panel DISP? command >- the front panel DISP? 3 seems to be accepted and interpreted the same >as DISP? 1 (On). The value 0 (Off) seems somewhat pointless and simply >places dashes across the display. The value 1 (On) is the default and >normal mode. The value 2 (Msg) displays control messages only. These >three modes would obviously offer no help to prolonging display life >since the display filament would need to remain on. The interesting >DISP? 3 (Clr) is the one in question rather is removes power to the >display filament providing some help for display life. I'm not sure >without actually getting inside and testing if filament voltage is >present or not. Checking t > h >e >> schematics for a display filament voltage interrupter might also >be a clue, but would still be firmware dependent. I use Agilent VEE for >3458A control and plotting and have provided a dynamic display control >using DISP? 0-3 modes and I often leave the display in mode 3 (Clr) for >long plot cycles (sometimes weeks). In this mode, the display is >completely blank, including no enunciator (sampling) indicators at all. >My hope is that the display filaments are off. Anyone know for sure? >> >> Don >> >> -----Original Message----- >> From: volt-nuts [mailto:[email protected]] On Behalf Of new >> Sent: Saturday, April 11, 2015 12:09 AM >> To: [email protected] >> Subject: [volt-nuts] dark display for 3458 >> >> Hi, again... >> >> Now that I have the keysight connection expert running my two sick >3458s, I don't need to look at data on the displays. To keep them from >burning out, I wanted to turn them off. >> >> I found a workaround of: >> >> DISP 0,' (16 spaces) .' >> >> This put a period on the bottom of the blank screen and moves it 16 >spaces to the right..... >> right off the screen! >> >> So now the display is dark and only shows things like the 'err' >message. >> >> QUESTION - will this kill the 3458 or its display somehow? >> >> Willy >> _______________________________________________ >> volt-nuts mailing list -- [email protected] To unsubscribe, go to >https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there. >> >> _______________________________________________ >> volt-nuts mailing list -- [email protected] >> To unsubscribe, go to >https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there. >> >_______________________________________________ >volt-nuts mailing list -- [email protected] >To unsubscribe, go to >https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >and follow the instructions there. -- Sent from my Motorola Droid Razr HD 4G LTE wireless tracker while I do other things. _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
