Eight Ball Deluxe
Bally, 1981I am working on an Eight Ball Deluxe and the million comma on player one is stuck on during gameplay. What components drive this/need to be replaced? I looked on PinWiki and could only find specifics about the number segments, not the commas.
Thanks
Is it a Bally display or a Stern Display?
Something in the recesses of my mind tells me the comma on 7 digit Stern displays was select-able on their boards. And the Stern displays were a common replacement back in the day as they are pin compatible with Bally.
I moved the display to the 4 player position and the comma remained lit, even though the display read "00". The display is a Bally display.
Update:
I replaced Q22, CR1, CR2, and a new chip/socket. Same problem 
I clipped one leg of Q22 and both commas disappear. What else could be wrong?
Thanks
Looking at the schematic, I see the following resistors on the "comma" path:
- R60 (1.5K) - My thought is starting with this one since it's tied to the MPS-A42 and ground
- R61 (1.5K)
- R62 (300K)
- R63 (150K)
Could any of these resistors be causing the comma issue? All other segments are working on every digit, so I don't know what else it could be.
Quoted from MrBally:Sounds like a bad glass. Try swapping the glass between a known good display and the problem display to isolate the problem.i
Nope, not a bad glass............."I clipped one leg of Q22 and both commas disappear."
At the Bally service schools held in the late '70's, a bad glass with an internal short was demonstrated to light all of the particular segments on the glass. With a working display, the bad glass was simply held up to the display and carefully all legs of the glass were tension pressed to the exposed legs passing through the bottom of the pcb. You have to be really careful doing the test this way which is why I suggested swapping two display glasses.
I had a very similar issue with my 7 digit display in a Skateball. Both commas would light when the scoring showed "00" before gameplay started. It ended up being a long process of troubleshooting, but in the end it was the zener diode VR1.
You may want to check the voltages on both sides of this diode - there should be about 100-110 volt difference. In my case, there was no difference in voltage - the zener was shorted. Replacing VR1 solved the problem.
Quoted from pinplayer01:It ended up being a long process of troubleshooting, but in the end it was the zener diode VR1. You may want to check the voltages on both sides of this diode - there should be about 100-110 volt difference. In my case, there was no difference in voltage - the zener was shorted. Replacing VR1 solved the problem.
I will check this out. I did not replace VR1 when I replaced CR1, CR2, U1 and Q22.
VR1 is a 1N3045A Zener Diode (110V) in the manual. Are there other Zener Diodes that will work? NTE5097A? It's rated at 100V, 1W, instead of 110V.
Thanks
I had to rebuild the solenoid driver board high voltage section since adjusting the POT did not change the voltage at TP2. The voltage measured 230VDC. After I rebuilt the HV section and dialed the voltage back down to around 170VDC, the million comma no longer comes on when the thousands comma is lit (which is how it should be since the current high score is set at 830,000 to see if the display is working properly). Is it possible that the high voltage from the driver board was overpowering the signal to the millions comma?
I believe you have a bad glass or one on the way out. However, since it is working with the proper 190 volts, no worries. Eventually internal arcing will take place with the lower voltage. No estimate how long. It could be another 25-30 years....
I have a similar problem with the million comma on one of my 7 digit displays. I swapped the display with another one to prove it was the display itself. In my case however the problem is intermittent. One moment the display is working fine and the comma is correctly either shown or not depending on the score and then the next moment the comma shows up when it shouldn't and it also appears brighter and distorted. You can also see the problem appear when the comma should be shown anyway, because of the extra brightness and distortion of the comma at those times.
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