Black Hole
Gottlieb, 1981Hi everyone,
I need to do the system 80 ground mods on my Black Hole. It has a Rottendog power supply and Ni-Wumph MPU and driver board. Does anyone have any information about how to do the ground mods on these boards? Any advice, pictures or links would be greatly appreciated.
The problem wasn't with the boards -- the problem was with the connections to the boards (except for the multi ground driver boards). A single point of ground should always be provided to each board. For some reason, very few people provide this 20cent ground connection. If connectors are original or old, you may need to add a wire to the ground somewhere on the board.
Thanks for the reply
I meant to ask: where do you attach the ground wire to each of these boards? There's lots of advice out there about where to attach the ground wires to the original boards but I can't find any information about where to attach them to the Rottendog power supply and Ni-Wumpf MPU and driver board.
Pinwikki has pictures of the ground mods.
http://www.pinwiki.com/wiki/index.php?title=File:GTB_Sound_Speech_ground_Upgrade.JPG
Thanks for the replies everyone but none of these responses deal with how to do the ground mods on aftermarket boards.
I'm going to go back to original boards anyhow.
Quoted from solarvalue:Thanks for the replies everyone but none of these responses deal with how to do the ground mods on aftermarket boards.
I think you're the one misunderstanding - the mods are not ON the boards, it's on the connectors to the boards, which are still obviously in place for the new boards too.
If there were a ground issue on the boards wouldn't you expect it to be fixed on the design of your brand new aftermarket boards? 
You should only need to make sure the harness connection between MPU and driver board is correct - just buy a new harness already assembled ksarcase has them for $35. Do the ground mod for the original sound board. Solder a ground wire from P2 pin 2 or 5 and connect to ground. Pin 2 and 5 are connected by a solder trace so either will work.
Quoted from Otaku:I think you're the one misunderstanding - the mods are not ON the boards, it's on the connectors to the boards, which are still obviously in place for the new boards too.
If there were a ground issue on the boards wouldn't you expect it to be fixed on the design of your brand new aftermarket boards?
Sorry, my post above was not meant to be snarky in anyway, I was just trying to further the discussion in case anyone else has the same problem later on.
As I understand it, the original problem was that there was only a single connection between the cabinet ground and circuit board ground and this was located on the power supply. The ground path then ran through the connectors to the other boards, which is also problematic. The ground mods provide new connections between the ground plane of each of the other boards directly to the cabinet ground. I imagine that to ensure more reliable operation, the ground plane on each of the aftermarket boards still has to be connected directly to the cabinet ground, otherwise it is still dependent on the ground path through the connectors to the power supply. My question was where on each of the aftermarket boards can this connection be made, since they are surely different to the recommended connection points on the original boards.
Quoted from solarvalue:Sorry, my post above was not meant to be snarky in anyway, I was just trying to further the discussion in case anyone else has the same problem later on.
As I understand it, the original problem was that there was only a single connection between the cabinet ground and circuit board ground and this was located on the power supply. The ground path then ran through the connectors to the other boards, which is also problematic. The ground mods provide new connections between the ground plane of each of the other boards directly to the cabinet ground. I imagine that to ensure more reliable operation, the ground plane on each of the aftermarket boards still has to be connected directly to the cabinet ground, otherwise it is still dependent on the ground path through the connectors to the power supply. My question was where on each of the aftermarket boards can this connection be made, since they are surely different to the recommended connection points on the original boards.
No "snark" taken. 
I've never seen this mod done before, but if you've done the connector mod with new pins you should be good to go, the other thing is really unnecessary as long as the connector is done and the other pins are re-pinned.
Linking the ground to the cabinet ground would just be another path to ground, nothing really "better" about it that what you already have. Perhaps it was an issue with the traces leading back to the connector not being beefy enough (I've seen this with arcade machines), and would assume it's fixed on the newer boards. No more preventative measures required, in my opinion!
I am looking for a set of LED displays for a Gottlieb System 1. Just tired of "rejuvinating" the original displays via the old re burning the filament method that does not work on any of more than 24 or so original displays. They last for about a day, and that's it - dark again! Boston Pinball Company is out of them and they don't know when or if they will crank out another batch.
Hey solarvalue I had exactly the same question. I have both ni-wumpf mpu and driver boards in a Haunted House and have been doing the ground mods in the last few days.
I added an extra ground in the connector between the 2 boards but was also going to add an extra ground straight to the mpu board. The ni-wumpf has a hole just near the A1J1 connector and I was going to add a ground there.
No idea what to do about the driver board though!
Good work. In the end I converted my game back to the original boards and sold the after-market boards.
Quoted from Jlescher19:I am looking for a set of LED displays for a Gottlieb System 1. Just tired of "rejuvinating" the original displays via the old re burning the filament method that does not work on any of more than 24 or so original displays. They last for about a day, and that's it - dark again! Boston Pinball Company is out of them and they don't know when or if they will crank out another batch.
Oh dear... still sold out and no word of more?
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