Panaplex display history

[Jules Richardson]

On 05/30/2015 05:00 PM, Brent Hilpert wrote:
> If you look closely at the displays, esp. at an angle to the glass, you
> can see the anode coating on the inside surface of the glass. If you see
> a red/brownish non-uniform discoloration in that coating, or
> discoloration around the ends of the segment bars, or some black spots
> on the segment bars, that can be an indication of 'burning' or 'wear'.
> Not sure how bad it has to get before it's a failure/problem, or how
> long it might last once that begins to appear.

I'll give that a go. So far I've not noticed any like that, just the usual 
slightly-hazy appearance which every such display I've ever seen has.

> There should be nice high-voltage drivers on those boards too.

Yes, I'm missing the wiring harnesses and the interface boards which hooked 
up to the pump mechanicals, but I've got the driver ICs for the displays, a 
complete PSU, a second PSU board, and one of the Z80-based logic boards.

If the wiring was obvious (it's probably not) then it's possible that I 
could hook everything up and that there may be some sort of test mode to 
drive all the digits at once, which would save desoldering failed 
displays/drivers for reuse. We'll see.

> No, I never saw gas pumps with LED displays. As I recall, gas pumps
> around here went from mechanical to Beckman GD displays sometime in the
> mid-70s, then transitioned to LCD in the late-80s/early-90s. So pumps in
> Britain never saw the gas-discharge display generation?

I don't remember them over in the UK, just mechanical displays being 
replaced by LCD.  Although Nixies were used over in the UK, these types of 
7-seg GD displays seemed much rarer generally.

I just noticed yesterday (now that I knew what to look for) that one of the 
little old gas stations in town has pumps of the same style as the ones 
which I think these boards came from, so I'll go take a look at them when I 
get a chance (and maybe ask who owns them - I don't know if a gas station 
typically buys their pumps outright, or if they're leased from another 
company along with a maintenance contract)

> Speaking of old display technology, as someone who has been collecting
> NIXIE and other-display-type equipment for many years, the NIXIE clock
> craze of the past few years has been a bit of a surprise. And now that
> crowd has discovered the other old display types such as the 7-segment
> incandescent Numitron & minitron displays, which are quite rare. If you
> want a display technology that was obsolete almost from the day it was
> introduced that would be it.
>
> If I ever get around to building a NIXIE clock, I was going to try
> putting a motion detector in it to turn the display on/off for the sake
> of longevity of the displays.

I'm very tempted to completely over-engineer a clock, just for the heck of 
it: using one of my Nixie-based voltmeters for the display portion, keeping 
it intact and sticking it in a small rack along with some sort of old 
computer to drive it (either directly via the rear-panel interface, or via 
a D/A convertor). The computer would have 'net access, so if I could 
find/compile/write an NTP client for it, it would be perfect.

It would be way too power-hungry to just leave running all the time, of 
course, but it would be kind of goofy to see. For an alarm, well I know 
someone who has a 6V police siren from an old cop car... ;-)

cheers

Jules