Plasma ball.

viperrwk

you can line up the leads to a mounted working display and see if if it lights up. Don't blame me if something bad happens in the process.

I have plama ball somewhere..... i should find it and see if it really works.

http://www.amazon.com/Plasma-Ball-Inch-Battery-Operated/dp/B00PPFQ08G/ref=sr_1_2

Input voltage has no bearing, its the output voltage that is kicked up to the high voltage range to make a plasma ball look cool.

Most of them are just 5 or 12v

I thought they used step-up transformers and operated at HV. I guess 5-12v makes more sense. A plastic ball + HV on a consumer product would not be a good idea.

Which reminds me, I have to revive my DIY Tesla coil project at some point. Way too many projects started and never finished....I hate my project shelf right now....

This is the alternative for non-mounted glass. Nonetheless the plasma ball is the best solution since you can test both mounted and unmounted displays.

Working 7 digit display tested with plasma ball

This is a mounted 7 digit display. I tested this in a RK and it worked fine though the glass needs to be remounted to the board with double sided tape. You can easily see the segments getting excited and if you move the display across the ball you'll see different segments light up.

Non-working 7 digit display tested with plasma ball

This is another display i tested in the same machine with only this display hooked up. I had nothing on the display and you can see the plasma ball does not excite any of the segments.

This is a cheap plasma ball like the one Andrew linked to. Runs off a 12v wall wart. Kids love it too.

viperrwk

I am going to have to find my plasma ball and bust out the box of unknown displays. neat

I just ordered one to test a bunch I have. Great tip! Thanks Viper

I justified buying it right now cause my 3 year old will get a kick out of it. Doubles as a legit toy for a kid.

I just tried it with some Bally 6 digit displays.

I could not get any segments to light.

I guess a different animal.

Same glass is used in both Bally and Williams. Depending on the strength of the Plasma ball and it's batteries you might have to get it really close to get them to light. I have used this technique on Bally, Williams, Zaccaria, Atari, Data East displays as well as small, med and large DMD's. If a segment lights (or usually just the edges around the perimeter of the glass) you usually have a good glass. Nothing showing up is usually a bad glass, but not always.

Not a great toy for a 3 year old. I know this because I have gone through 3 of these globes (and am currently without one) due to my kids wanting to turn it on when I am not home.

would display show anything if held near the other displays
or held near a plasma tv screen ??? if you dont have a plasma ball

My plasma ball is maybe 4" globe and is corded. It is likely 10 years old. I am getting more confident that the display is junk but like I mentioned I get no segment glow on any of the good glasses so. I guess not all plasma balls work. Just my luck.