Bally Eight Ball (Bally, 1977) VFD issue

[yaypinball]

Greetings!

I have a '77 Bally Eight Ball that has had a display that has gone wonkers.. After sitting for about a year, I plugged the machine back in and it booted right up - came back 20 minutes later and the Player 1 display is extremely bright on all digits and is only partially readable because everything ends up looking like an 8.

I've seen where a bad transistor will cause 1 digit to go bright but what could cause the whole display brighten up? Before I go down the road of rebuilding the display, I want to make sure it isn't a voltage / driver issue so any suggestions are greatly appreciated.

Thanks!

I'll try to attach a picture later on.

 

[Philly_pa]

Have you tried placing the faulty "Player 1 display" in another player's position, like player 3 or 4?

Like wise, place Player 2, 3 or 4's diaplay in the player 1 position.

This will tell you if the problem is with the individual display or the circuit leading to a specific player's display.

 

[pinballdaveh]

the display voltage regulator is on the solenoid driver board. TP2 is the display output. to get at it you may have to remove the safety plastic. to test use a dmm set to the highest dc voltage range. adjust voltage to 180-190 volts using RT1 adjustment. if voltage isnt adjustable and voltage output is near 230 volts, transistors may be shorted and voltage is un-regulated. on a display that is bright with all 8's check for cracked solder connections on male pins, the display decoder/driver chip may be bad, or the display glass may be bad. new 6 digit display glasses are availible from marco at $40.00 .

 

[yaypinball]

Thanks folks - I've been pretty bad about checking my email (work has owned me for the last month) but year end freeze is coming up in 2 weeks so hopefully I'll get some time to look further.

More to come (hopefully!)