Editing Osborne Executive Troubleshooting Guide (section)

== Component-level Tests & Voltage Table ==

Use the following test points to confirm system health:

{| class="wikitable styled-table"
! Test Point !! Expected Voltage !! Notes
|-
| Mainboard +5V rail || +5.0 V DC (±5%) || Logic supply for all ICs
|-
| Mainboard +12V rail || +12.0 V DC (±10%) || Drives, CRT, some logic
|-
| Mainboard -5V rail || -5.0 V DC (±10%) || DRAM bias (4116/4164)
|-
| Z80 pin 6 (Clock) || ~4 MHz square wave || Essential for CPU operation
|-
| Z80 pin 26 (Reset) || Low → High at power-on || Should pulse low then high
|-
| 6845 CRTC pin 21 (HSYNC) || 15.7 kHz pulse || Confirms video timing
|}

If any voltage is missing, recap the PSU and check associated regulators and diodes.