Black Hole Controlled lamp stuck on help

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jim43bob
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Black Hole Controlled lamp stuck on help

Post by jim43bob »

Hi everyone!
Hoping someone can help me out with a lamp problem
Lamp on #1 rollover is stuck on.
It's L41 driven by Q42.
I've checked the transistor ( getting 1400 on E to B and 800 on B to C) which are the same readings I get on the others.
On Z11 which drives it I'm getting .7 to .9 with a DMM when checking pins 2-7 and 9-15 and .3 checking pins 1 and 16
With a logic probe I'm getting a high to low signal for the #2 and #3 rollovers when in attract mode but just a steady high signal for the # 1 ( pin 7 on Z11)
I just don't know where to go from here.
Getting ready to move in spring and have to get rid of most of my pins and am not letting it go until it's back to 100%

Any help appreciated!

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sylvain
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Re: Black Hole Controlled lamp stuck on help

Post by sylvain »

From your readings and observations, it appears Z11 is probably defective and would need to be replaced (install a socket too).
In attract mode, are the input pins 4,5,12,13 toggle high/low on Z11, as seen on your Logic probe?
(if not, issue could be harness/connector).

Given sometimes transistors test good with a DMM, but do not work correctly in-circuit, I would replace Q42 first just in case,
as it is easier to replace a transistor compared to a chip due to the number of pins involved. Plus a potential bad transistor
might also rarely impact the voltage on its base, thus impacting the voltage reading on the drive source Z11 pin 7.
...Then replace Z11 if a good new Q42 replacement does not solve the issue.

Good luck!
-Sylvain.
Looking for Bally Star-Jet, The Wiggler, Williams Magic City, Grand Lizard, Swords of Fury, 1986 Pinstar Gamatron, and a few others.
Collecting & repairing electro-mechanical and solid state pinball machines with quality and care for 40+ years already.
Serious and fun hobby, powerful nostalgia !

jim43bob
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Re: Black Hole Controlled lamp stuck on help

Post by jim43bob »

Thanks Sylvain! Will change transistor first, Outside of the one lamp locked on everything else is working great.
It's the little things that drive me crazy, but you have to expect it from a 40 year old Gottlieb I guess!
Could I be testing the inputs to Z11 wrong? When I put probe on pins 4,5,12 and 13 the probe was flickering and chirping away.
I had it set to TTL and using the same +5VDC and common from the test pins on the power supply. Should I be using some other supply for the logic probe???

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sylvain
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Re: Black Hole Controlled lamp stuck on help

Post by sylvain »

jim43bob wrote: Sat Dec 19, 2020 11:20 pm Could I be testing the inputs to Z11 wrong? When I put probe on pins 4,5,12 and 13 the probe was flickering and chirping away.
I had it set to TTL and using the same +5VDC and common from the test pins on the power supply. Should I be using some other supply for the logic probe???
That is fine. The 4 pins 4,5,12 and 13 are toggling, so the inputs of Z11 are fine, no single input line is stuck high or low.
One output (pin 7) appears stuck. Please let us know later if Q42 or Z11 replacement fixes the stuck lamp issue.
Looking for Bally Star-Jet, The Wiggler, Williams Magic City, Grand Lizard, Swords of Fury, 1986 Pinstar Gamatron, and a few others.
Collecting & repairing electro-mechanical and solid state pinball machines with quality and care for 40+ years already.
Serious and fun hobby, powerful nostalgia !

jim43bob
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Posts: 35
Joined: Sat Nov 10, 2012 1:23 pm
Location: Simcoe,Ontario
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Re: Black Hole Controlled lamp stuck on help

Post by jim43bob »

Just want to let everyone know it was in fact Z11 gone bad. Replaced it after ordering from Dave Astill.
Many thanks go out to Sylvain for his wealth of knowledge!
Getting ready to move and have to thin the herd, will be sad to see Black Hole go but did not want to post it unless it was working 100%

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