Fuse F6 blows on Gottlieb Force II - system 80

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mbudman
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Fuse F6 blows on Gottlieb Force II - system 80

Post by mbudman »

Hello,

Fuse F6 (slow blow 8 amp) blows immediately on power on for a Gottlieb Force II system 80 pin. System says this is for the solenoids. As I am new to this (system 80) anyone have any suggestions?

Thanks,

Mark

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sylvain
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Re: Fuse F6 blows on Gottlieb Force II - system 80

Post by sylvain »

This typically means that:
- you probably have at least one coil that is burned/shorted, or a missing (or disconnected) diode across its lugs;
- its associated drive transistor is shorted on the driver board;
- MPU-Driver harness connector needs to be checked.

You will need to fix - with the machine powered OFF:
- find and replace the bad coil(s) - under the playfield and in the cabinet/head (knocker, etc.)
and make sure the diode and wiring are properly installed/connected on the new/proper replacement coil;
- replace the drive transistor(s) on the driver board;
- replace the fuse with a proper fuse rating for F6 (8A Slow Blow indeed).

Plus also need to perform, before powering-up the machine after above repairs:
- check the MPU-Driver harness for any broken, weak or corroded pins inside the housings at both ends - especially if there had been
corrosion on the original MPU at some point. Replace pins as necessary, or the whole harness;
- Ensure the finger connectors on the MPU and Driver boards are clean and not corroded where the MPU-Driver harness connects;
- Perform the ground mod, including adding the extra +5V and ground wires on that MPU-Driver harness.

Good luck!
-Sylvain.
Looking for Bally Star-Jet, Capersville or 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 over 35 years.
Serious and fun hobby, powerful nostalgia !

mbudman
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Posts: 299
Joined: Thu Oct 04, 2012 11:33 pm
Location: Montreal

Re: Fuse F6 blows on Gottlieb Force II - system 80

Post by mbudman »

Thanks Sylvain. Your advice is always A1.

Best,

Mark

mbudman
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Joined: Thu Oct 04, 2012 11:33 pm
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Re: Fuse F6 blows on Gottlieb Force II - system 80

Post by mbudman »

I have made some progress. After speaking with R.A.B., based on some of the symptoms, he suggested that I check the tilt switch. It was not set right and I fixed it, so now I am sort of able to start a game.

Fuse F6 still blows (instantly with a lot of current), but I am able to add credits, and have the score go to single digit zero when I press the credit button. Cannot add additional players.

However, nothing works - no sound, no scoring, no flippers, nothing at all.

There are pop bumper boards that are supposed to be under the playfield and they are not there. Looks like someone tried ot wire the system so it works without these boards (although who knows if it was done correctly). Different color wires are jumped / connected together.

One flipper coil (upper) and one pop bumper coil are coated in black soot. These could the problem coils.

Sylvain, are you certain the coils require diodes The are a few diode boards under the playfield. Are these diode boards not used instead of diodes on the coils?


Test sequence does not work.

Thanks,

Mark

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sylvain
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Re: Fuse F6 blows on Gottlieb Force II - system 80

Post by sylvain »

Mark,

The small germanium diodes on boards inside the cabinet and under the playfield in those System 80 Gottliebs
are low power signal diodes used in the switch matrix. 5V from/to the MPU. Nothing to do with coils.

Separately, each coil needs a 1N400x (such as 1N4004, 1N4005, ... 1N4007) 1A silicon diode across its lugs
to protect against back voltage spike upon turn OFF of the drive transistor. Without that diode installed there,
the drive transistor would be damaged at 1st turn on/off and would short again due to uncontrolled high-back voltage.

In fact, if you look, all existing coils in that machine *should* have such a 1A silicon diode across its lugs already.

BTW, your suspect coil is probably that burned pop-bumper coil. Disconnect one of its wire and see if it stops F6 from blowing.

Regards,
-Sylvain.
Looking for Bally Star-Jet, Capersville or 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 over 35 years.
Serious and fun hobby, powerful nostalgia !

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