Editing Atari 600XL Troubleshooting Guide (section)

=== Voltage Test Points ===
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[[File:Atari 600XL (photo).jpg|thumb|right|300px|Atari 600XL. Source: Wikimedia Commons.]]

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|+'''Primary Voltage Test Points'''
|-
! Test Point !! Expected Voltage !! Tolerance !! Notes
|-
| +5V rail (Pin 40 of CPU / U1) || +5.0V DC || ±0.25V || Main logic supply — measure directly at the CPU VCC pin
|-
| +5V rail (Pin 24 of ANTIC / U7) || +5.0V DC || ±0.25V || Verify supply reaches custom chips
|-
| +5V rail (Pin 28 of POKEY / U19) || +5.0V DC || ±0.25V || POKEY supply — also affects keyboard scanning
|-
| +5V rail (Pin 20 of GTIA / U4) || +5.0V DC || ±0.25V || GTIA supply
|-
| GND (any ground pin) || 0V || — || Reference ground
|-
| +5V at power connector || +5.0V DC || ±0.1V || Measure at the barrel jack before board insertion
|}

{{Warning|'''Always verify the power supply output BEFORE connecting it to the computer.''' Voltages above +5.5V can destroy the 6502C, ANTIC, GTIA, and POKEY. These custom chips are irreplaceable.}}