(Topic ID: 230065)

Gottlieb Dragon roll-over scoring issue

By Matty80

5 years ago



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#1 5 years ago

Hi folks!
First I just wanted to say on my first post, what a great forum this is and how much you guys have helped me already with info you've provided to others. So thank you all and keep up the good work!

Now to my problem that I can't seem to find an answer for and it's got me stumped!

I've been getting a gottlieb dragon up and running and doing a restore on it. It's all back and working but for some reason, when you roll over the "D" roll-over target, it gives you the full 5x multiplier.

According to the score card, roll-over scoring is meant to be;
1 roll-over = 2x multiplier
Combination of 2 rollovers = 3x multiplier
Combination of 3 rollovers = 4x multiplier
And all 4 = 5x multiplier

But as soon as I activate either lower or upper "D" rollovers, I get 5x multiplier without any other rollovers activated.

Hoping someone can share some insight and help a newb brother out.

Cheers all

#2 5 years ago

Check your switch matrix. Run the switch test, press the D rollover, either position. If it's not working right, you might see it call out 4-5 different switch numbers that correspond with the rest of the rollovers (which would cause it to roll right to 5X) and possibly other switches.

If it's that, you might have a bad diode, or one of the logic chips controlling the switch matrix being bad, either from static shock or battery damage to the MPU. Mostly easy fixes unless there's battery damage to the MPU as part of it, at which point any fix might be temporary.

#3 5 years ago

Thanks so much for the reply Lynn.
This is the first SS I've worked on with no prior electronics experience so I'm learning as I go so thanks for the help.
Yes when I run the switch matrix test for the "D" roll-over, it did what you said and listed all the switches on A1J7-14 (Inc switch 25 which I can't find listed in the manual). Tested the diode in that circuit on the mpu board and it was showing voltage both ways so I'm guessing that's bad. I also tested a few others for cross reference and there's about 3 doing the same thing while others show voltage only one way. Is it reliable to test diodes in line or do they need to be removed from the circuit for reliable testing? And yes, there is battery damage to the mpu so I may be fighting a losing battle

#4 5 years ago
Quoted from Matty80:

Thanks so much for the reply Lynn.
This is the first SS I've worked on with no prior electronics experience so I'm learning as I go so thanks for the help.
Yes when I run the switch matrix test for the "D" roll-over, it did what you said and listed all the switches on A1J7-14 (Inc switch 25 which I can't find listed in the manual). Tested the diode in that circuit on the mpu board and it was showing voltage both ways so I'm guessing that's bad. I also tested a few others for cross reference and there's about 3 doing the same thing while others show voltage only one way. Is it reliable to test diodes in line or do they need to be removed from the circuit for reliable testing? And yes, there is battery damage to the mpu so I may be fighting a losing battle

The nonexistent switch matches exactly with what I was seeing myself; it's a switch that logically can exist, but physically does not. When we had it with Solar Ride, it would walk through the rollovers/drop targets, then a logical switch past that, but is unpopulated in the physical switch matrix.

Go ahead and replace the diodes, and see if that fixes the issue first. You can usually test those in circuit; transistors and capacitors are more the ones that you can't test in circuit without the circuit affecting the readings.

If that doesn't work, replace the 74xx series logic on the board above those connectors. It's OK to use sockets with the replacements. That should fix it, either temporarily (if the battery alkalines weren't neutralized correctly when the battery was removed, which is actually quite likely) or permanently, and might be helpful in testing. And yes, if the alkalines weren't neutralized correctly, you're going to have a losing battle with the switch matrix.

I know TNT Amusements (toddtuckey) was selling an undamaged System 1 MPU for $125 on this site, you can always check with him to see if he's still got it for sale, the boards are pretty much interchangeable across all 16 machines as long as you plug in the ROM chip you have. Otherwise, you can go for a NiWumpf, Pascal Janin, or even a LISY1 if you're into programming your own ruleset.

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