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> Rejuvinating Vfd's?
Posted: February 08, 2011 01:01 am
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All pumped up about these 70's handheld game VFDs at the moment. Got me thinking - i've got a couple of (milti digit 7 segment, typical of clocks) VFD's that have dimmed with age. I assume this is the filament and not the phosphor? Think they can be rujuvinated? Maybe driving the nuts out of them for a few seconds (I've done this by accident and the filaments are tougher than you'd expect) with or without some sort of HV bias?

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Posted: February 08, 2011 09:55 am
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I mistakenly commented on this in the other thread, but I'm thinking it's probably phosphor death. Cooking the filament for a while to boil some.. fresh oxide or whatnot, can't hurt though. I'd think running it with higher grid/segment voltage and/or fil voltage should buy it some more brightness for the remainder of it's life, though...

I think anything in a portable video game ain't gonna have many miles on it though. Those things must have sucked batteries like a... well, you know.

Probably more useful to keep an ear to the ground for dead microwaves and VCRs, and yank the VFDs from them. Or hell, they ain't much new.


the ones with a lot of segments and digits are kind of a pain to operate though..
If you end up picking something up maybe we can go in together and save some shipping.. although shipping in canada ain't exactly cheap any more is it...

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Posted: February 08, 2011 02:38 pm
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i lean toward emission drop if the overall brightness of the display is low .
depending on the exact construction of the vfd , low brightness in spots can be attributed to a drop in emission (depletion rather than poisoning) and/or phosphor contamination .

boiling the filament by raising the voltage 20-30% for about a half hour may help the emission ... however ...
there is not much meat to those thoriated tungsten filaments .
for their diameter and temperature (even lower than the old 1 and 3 volt "radio" tubes) they put out a fair amount of emission .
there may not be much "reserve" to/left in them .

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Posted: February 08, 2011 06:12 pm
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Jim, I have a bunch of VFDs from old nukers & VCRs. Want them? I will never use them.

Trouble rather the tiger in his lair, than the sage among his books.
For to you, kings & armies are things mighty & enduring.
To him, mere toys of the moment, to be overturned at the flick of a finger.

Fortuna favet fortibus.
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