Bally and Stern (77-84) are just plug and play. You can buy a single led replacement display from a Pinball Life, but it’ll be cheaper to repair it. You can buy all the needed components at Great Plains Electronics.

Yes. Unlike e.g. Williams EE, the displays of your Bally EE are independant. There is no "Master display" or something like that.

It might look a little strange with different types of displays, but technically spoken, that's no problem.

Did that before on my EBD so the games could go on while I was repairing the original and had no plasma spare part at hand.

If it's Player 1 that's failing, you might as well interchange it with player 4 for a quick repair and make your pinball a 3-player-version

Eight Ball was a six digit game.
Or did you mean Eight Ball Deluxe which was a seven digit game?
Suggest to put the LED display at the credit/ball in play display position and move that original one to player 1 so all the player displays are plasmas and look the same.

There's no technical reason why you can't mix and match. However, the appearance may differ a bit between the LED and original plasma displays.

As long as the plasma display isn't seriously burnt up, the PCB can usually be repaired for a few dollars of electronics components.

A section on display repair: https://www.pinwiki.com/wiki/index.php?title=Bally/Stern#Display_problems

Sometimes, individuals/suppliers also sell repaired plasma displays.

Yes, you can sometimes buy individual LED displays or a full set of them. However, I just did a quick check on a couple brands, and currently, I'm not really seeing individual LED displays for sale--just mostly full sets.

Pinitech, wolffpac, pinscore, and xpin are brands that are currently available. It looks like pinitech and wolffpac are only offering DIY kits (meaning, you solder everything together yourself, rather than buy a plug & play ready display).

That could be a connectivity issue. Usually because of cracked solder joints on the header pins, tarnished header pins, or tarnished/damaged connector pins--or a combination of all three.

The segments are lit, but vary in brightness across the display. One side might be bright, while the other is dim. Although usually with these displays, outgassing doesn't happen very much. It's usually either sealed, or the glass is broken.

One of the other main issues is black spots in the display segments, or burnt areas in the segments. Those aren't fixable. You either use the displays as-is, or replace the glass, or replace the entire display.

Missing digits/segments are *usually* fixable, since that's typically a logic, connectivity, or power issue. But sometimes it can be a a problem in the glass itself.

These kits are inexpensive, easy to assemble and match pretty well.

https://pinside.com/pinball/forum/topic/wolffpac-6-digit-display-kit-review

Tipps repairing these displays

- first resolder the connectors and recrimp the plugs.
Then:
- Missing digits or missing segments -> there is al easy-to-follow instruction available, which transistor needs to be replaced*
- Nonsense displayed? BCD-to-7-segment-decoder is only a few cent, try replacing
- nothing to see at all? You might loose - the glass is not reparable.

* https://pinwiki.com/wiki/index.php?title=Bally/Stern#Display_problems

Re-solder all those pin connectors on your displays and you should be golden!