Archived from groups: rec.games.video.arcade.collecting (More info?)
Asteroids repair log:
Monitor working.
Problem on board.
Problem: No picture. Spot killer on.
Checked Y output. Voltage was fluctuating around like normal.
Checked X output. Stuck. Not fluctuating.
Used a logic probe to check activity at both DAC's D11, B11 pin 15.
Y DAC was pulsing, X DAC was not.
Checked input pins 1-10 on both DAC's
Same activity on both chips.
Solution: Replaced X DAC at D11.
Game working now.
Moral: You don't always need a scope to diagnose a bad DAC
Google search words:
Asteroids blind out digital analog converter Atari AD561J 40715
picture blank screen stuck
Dan in Denver
Click here for my current auctions
http://tinyurl.com/68o72
www.classicarcaderesource.com
Asteroids repair log:
Monitor working.
Problem on board.
Problem: No picture. Spot killer on.
Checked Y output. Voltage was fluctuating around like normal.
Checked X output. Stuck. Not fluctuating.
Used a logic probe to check activity at both DAC's D11, B11 pin 15.
Y DAC was pulsing, X DAC was not.
Checked input pins 1-10 on both DAC's
Same activity on both chips.
Solution: Replaced X DAC at D11.
Game working now.
Moral: You don't always need a scope to diagnose a bad DAC
Google search words:
Asteroids blind out digital analog converter Atari AD561J 40715
picture blank screen stuck
Dan in Denver
Click here for my current auctions
http://tinyurl.com/68o72
www.classicarcaderesource.com
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