System 80 Display Extra Segment Lit

On a Pink Panther (6 digit) I have a single display that the h segment (the 1) lights up whenever the g (middle horizontal line) is lit. I followed the UDN6118 test instructions listed here: https://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_80#UDN6118_and_Other_Display_Logic_Chip_Failures on Z1 and everything was as expected. I also tested for shorts between pins 3 & 4 on the glass and 7 & 8 on the connector.

The problem moves with the display.

Anyone have any other ideas? The display doesn't show any evidence of shorted or broken filaments.

#3 3 years ago

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Quoted from Isochronic_Frost:
Following, I had a hell of a time with this too and I ended up replacing it with another display. Still have the old one incase someone figures it out some day!

Can you tell me what you tried?

#4 3 years ago

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Rechecked the UDN and looked at the connections coming into it and into the glass. Nothing stands out and there are no shorts that I can detect.

I was inspecting the glass closely and I noticed some discoloration on the g segment on the 100s and 10s digit.

2021-03-30 18.39.45 (resized).jpg2021-03-30 18.39.50 (resized).jpg

The other digits look fine
2021-03-30 18.39.58 (resized).jpg

#5 3 years ago

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Chris Hibler helped me out on facebook but here is the answer:

I pulled Z1 as there really is only 2 places this issue can be since it moves with the display. I socketed Z1 and put it back in but with pin 11 pulled. This is the driver for the h segment. The logic being if the chip is shorted then the segment cannot be lit, if the segment is lit then the glass is shorted.

Put it in my Joker Poker to test and sure enough the segment was lit. Bad glass is the culprit.

2021-03-31 07.43.59 (resized).jpg

Post last edited 3 years ago: “added image”

#7 3 years ago

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Quoted from G-P-E:
Always disappointing to see parts that are no longer available (e.g. display) go TU. Now save those 6118s for future use!

Already harvested. I saw someone selling a lot of glass the other day including some gottlieb but he wants to sell the whole batch

#9 3 years ago

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Quoted from Isochronic_Frost:
Good to know.
I’ll have to check but my glass is probably bad too. I’ll hang on to it because it is playable. It’s annoying to look at but it’s not like these displays are falling from the sky anymore

Big daddy has some rebuilds for $59

#11 3 years ago

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Quoted from frenchmarky:
Would the rejuvenation trick of applying extra voltage to it have any possibility of 'clearing', burning off etc. whatever is shorting the segment?

I don't think so, the filaments stand above the segments and don't touch. Recharging them removes resistance to make the segments brighter. I think this would make the short worse.

#14 3 years ago

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