Galaxian is watchdogging

JDGJr

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Donor 4 years: 2012, 2016, 2019, 2024
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I'm running a new CPU and a known working ROM daughterboard, but the CPU is resetting constantly. Wait is high. This board has two 8304s installed in 9b and 5k.

I've replaced the 2101 RAMs, but not the others.
I've checked the ROM images and the continuity from legs of the CPU and ROMs to the back of the PCB (including from the daughterboard). Legs have been clean as needed, before testing.

I've read about shorting the 'watchdog pads', but have no idea what I'm looking for on the board. EDIT: found the pads on the main PCB, near the top/right corner of the daughterboard.

Any pointers on how to determine what is causing the CPU to reset?

thanks
 
Last edited:
Can someone detail how to use the test ROM? does it plug into the daughter card (bottom socket is marked 'U'), or into the main board without mounting the daughter card?
 
Found the 7404 @ 6E was bad. Replacing it allowed the board to start (CPU stopped resetting) and it now plays!

The test ROM plugs into 7F after removing the daughterboard.
 
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