Did you do the ground mods to EVERYTHING?

You can't really get started until you have done so.

Did you print out this?

http://arcadecontrols.com/files/Manuals/Black%20Hole%20-%20Haunted%20House%20Repair%20Guide.pdf

+1

Another excellent guide here:
http://www.flippers.com/gottlieb_ground_cures.html

What amazes me is how many people disregard the mandatory ground updates. They only take an hour or so to do and don't require much more than a little wire and some basic soldering skills.
Do these before putting additional time and money into your game!

With the new Rottendog MPU, Driver Board, and Power Supply do you still need to ground everything?

Just a newbie question...

Thanks.

Yes, the ground upgrades are ESSENTIAL.

When you have done those, next you check the condition of the Molex pins in the all the connectors. You need to understand that connectors have an insertion life of 25 insertions. That's it - twenty-five! Anything after that is a bonus.

So, replacing pins is a common occurrence in any repair shop or experienced home repair person.

The guides are there for a reason.

John :-#)#
www.flippers.com

Yes. Primary reason is the Gottlieb, unlike Bally and Williams who used the shield inside the head as a common ground plane, decided to use the interconnect cables to provide ground to the logic.

So the ground needed for say solenoid circuits on the driver board,,, comes from the interconnect cable from the MPU. The MPU gets its ground through the cable to the power suppply. And to compound things most of these are simple fingers on modules and not trifurcon style power connections.... P/S->MPU->Driver is the path...

Soooooooooo,,, ANY impedance introduced in the ground path manifests itself in ground current the causes thing like solenoid drivers to be partially turned on constantly. Doing things like slow baking coils, transistors and oh yeah increasing the impedance of the ground connection which causes a run away environment....

Only real way to fix it, hard ground everything back to a common point with real wire.

FWIW, my HH is rock solid. I did all the ground fixes, replaced the big orange cap in the cab (you did that right??), modified the VUK and installed 2.5SB fuses in holder in front of all playfield reset coils.

For more reading on System 80, there's also this;

http://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_80

Steve