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Is your Williams ROM board giving you problems?


 

The best way to diagnose a ROM board is by removing all ROM chips and getting the minimum amount of ROMs needed (listed below) to boot up the game to an error screen. After you have an error code on the screen add one ROM chip at a time. In order to see an error message on the screen you need at very least a working CPU board and a working ROM board with the following good ROM chips installed. The first thing that needs to be done is replace the 40 pin ribbon cable, see this page for details: Replacing your ribbon cable

 

For Defender game:
Rom # If missing or bad
Rom #3 (needed for selftest) blue or purple jail bars and all 4 LEDs on
Rom #7 rug pattern repeats itself with #1&3 LED on
Rom #8 after 2nd rug sweep you'll see a blue screen then repeats itself
Rom #10 same as ROM #7 symptom
Rom #11 same as ROM #8 symptom

(above picture is from Bob Roberts website)

**Note: ROM #5 is not used**

For Stargate game:
Rom # If missing or bad
Rom #2 white screen with correct error code on the ROM board
Rom #8 rug test and error code on LED then repeats itself
Rom #9 same as ROM #8 symptom
Rom #12 (needed for selftest) jail bars flashing then very slow backwards semi looking rug test

All Stargate ROM chips are 2532

 

For Robotron or Joust games:
Rom # If missing or bad
Rom #6 rug pattern repeats itself
Rom #7 rug pattern repeats itself
Rom #10 rug pattern repeats itself
Rom #11 after 2nd rug sweep you'll see a blank screen
Rom #12 (needed for selftest) red and white jail bars

All Robotron and Joust ROM chips are 2732

 

For Sinistar game:
Rom # If missing or bad
Rom #6 rug pattern repeats itself
Rom #7 rug pattern repeats itself
Rom #10 rug pattern repeats itself
Rom #11 (needed for selftest) after 2nd rug sweep you'll see a blank screen
Rom #12 red and white jail bars

All Sinistar ROM chips are 2732