Williams sync

RobMcRaf

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Donor 10 years: 2013, 2015-2022, 2024
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Saltbreez working with RobMcRaf

Williams Rev B Stargate/Joust/Robotron MPU has horiz sync issues. Pin 11 of 4A show a busted up pattern on the O-scope as opposed to a known working MPU. Replaced chip 3A; Pattern of 4A-11 cleaned up significantly, however, STILL not horiz syncing to 2 known good monitors...


Any ideas?

Thanks,

Saltbreez
 
Next board Stargate Rev D.

Troubleshooting a Stargate board (Rev D).

Inital symptom: When power is applied, monitor displays a dim salmon color. Got through troublshooting chart to checking the Clock Gen Ckt. (chips 7G & 4D). Clock was present at output of 7G, but not present at 4D (pin 9). Also, 6809 running hot (even when changed) and clock detected bleeding through onto the Vcc +5v bus. We attempted to place a 10uF cap to remove the signal. Didnt work. The board continues to show no response beyond basic clock generation.

Replaced chip 4D (7474) in the middle of this effort.

Open to suggestions.
 
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