Here are some simple steps you can take to narrow down the problem:
1) When you first turn the game on you should hear a slight popping sound in the speaker. This tells you that the following things are working:
A: getting power to the soundboard
B: speaker is working
C: sound pot is working
D: output stage on the soundboard is working (IC1)
If you think your volume pot is bad remove the connector IOJ4 on the soundboard and run a jumper across pins 1 and 2. This will act as if your volume is turned all the way up.
2) Press the test button located on your soundboard. If you hear sound you will know that the following things are working on the soundboard:
A: 6802/6808 CPU chip (IC9)
B: 6821 PIA chip (IC10)
C: ROM chip (IC12)
D: 6810 (IC11) and the rest of the output stage
3) If you hear sound when you go through the self test on the screen menu you will know that the following things are working on the soundboard:
A: ROM board and cable between ROM and soundboard are good (a bad cable will produce the wrong sounds).
B: Buffer chips (IC5) on the soundboard and everything after the 6821 PIA is good.
4) If you hear sound but it is distorted and/or the wrong sound is coming out of the speaker, check the following things on the soundboard:
A: Check your jumpers and voltages
B: ROM board (very unlikely but possible a bad 6821 on the ROM board) and cable between ROM and soundboard
C: Buffer chips on the soundboard and/or 6821 PIA
D: Sound ROM chip or socket is bad
E: TDA2002 output is bad
F: Some of the caps are bad mainly in the output stage of the soundboard
5) No sound but you can hear popping sound when to play with the volume pot:
A: Check your 2 Fuses on the SND board. These are 4Amp fuses.
B: Check for 5vDC on the SND board. Test pin 4 should read 5vDC; test pin 3 is ground. Also check the 12vDC and -12vDC (or-5vDC) at the IOJ1 plug.
C: If you don't have the 5vDC check the BR1 on the SND board.
D: If all your voltages check out and your jumpers are set correctly then it's probably a bad 6802/08, 6821, 6810 or ROM chip on the SND board.
6) No sound and you don't hear any popping sound when you play with your volume pot:
A: If all the above steps check out make sure you have the W1 jumper installed. This jumper (wire or 1ohm resistor) is removed for games with speech boards.
B: Check your IC1 TDA2002 output amp.
Other helpful hints on the soundboard:
1) If you're hooking up a switching power supply and don't have a -12vDC for your soundboard you can use a -5vDC from the switching PS.
2) Williams has 2 basic soundboards; a square shaped soundboard commonly found in most Williams games of the time and a rectangular shape soundboard commonly found in older Defender or system 4-6 pinball games. As long as the jumpers are set correctly, both of these will work in any game as long as you don't need a speech board. If you need a speech board, use the newer square shaped soundboard with a 40pin header (IOJ5).
3) If you need jumper settings check Dave's website in the UK @: robotron-2084
This is what the old type (rectangular) Williams soundboard looks like:
Here is a picture of the newer (square) Williams soundboard:
The different video sound ROM chips for Williams games are:
|Chip Marking||Type of Chip (EPROM)||Game|
|Rom #3||2532||Robotron (2084)|
|Rom #6||?||Black Knight (pinball)|
|Rom #7||?||Gorga (pinball)|
|Rom #8||?||Alien Poker (pinball)|
|Rom #9||2532||Sinistar (upright or front in cockpit)|
|Rom #10||2532||Sinistar (cockpit rear)|
(if you have any inputs for #6-#8 please email me, thanks)