Subject: Gottlieb sound speech board adjustments Re: Q*Bert sound-board pots
Date: Tue, 19 Sep 2000 20:07:41 -0400
From: "Dave Hollister" <arcade@dotnow.com>
Newsgroups: rec.games.video.arcade.collecting

Here is a proceedure from a Gottlieb tech bulletin* for adjusting the early sound speech boards (as used in pins Mars, Volcano, Black Hole etc. and early vids). You are supposed to turn all dip switches on, plug the board into a test fixture, and install test roms (anyone have these rom images?).

I've gotten good results without having the test roms or a test fixture.

Get out your oscilloscope & set it to Vert. 5V/div [I think this is a typo. I use 2V/div for the first two adjustments.], dc coupled, Horiz. 2Ms/Div, internal trigger.

Monitor U22 pin 6 and adjust R13 so the signal doesn't flatten at the top

Monitor U21 pin 6 for a sawtooth signal and adjust R6 for signal amplitude of 3 to 5 volts peak to peak

Monitor pin 7 on the edge connector & set scope to Vert. 5v/division. Adjust R15 so the signal doesn't flatten out at the top and bottom (a little flattening at the bottom is ok). Then with the scope set to vert. 5v/div & horiz. 2 mSec/div adjust R6 for 6.8 divisions between the two large peaks. This one is fun to play with. Then adjust R16 so the signal doesn't flatten out at the top or bottom

That's what they say anyway. You can fool around with the settings and get some interesting variations in the speed and pitch of what I call the "swedish chef" voice (from the muppet show).

Dave Hollister

* volume 2, issue number 8 of the Gottlieb publication "On Target" from September 1981.

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