Installation guide

Troubleshooting
Troubleshooting Assembly Level Problems
1-43
600 Post Regulators
• If the +5.2 VD, +3.4 VDY, and ± 15 V supplies are good on the J34 connector pins indicated:
a. Remove the W27 ribbon cable from J1 of the A21 YTO Driver (Option UNJ or Option 506).
b. Measure the +5.2 VD, +3.4 VDY, and ± 15 V on the appropriate pins of the W27 ribbon cable.
— If the voltages are good, replace the A21 YTO Driver (Option UNJ or Option 506).
(Refer to “A21 YTO Driver (Option UNJ or Option 506) and A22 Coupler (Option 506)” on
page 2-50.)
— If the voltages are bad:
a. Remove the W27 ribbon cable from the J34 connector on the A23 Motherboard.
b. On W27, ohm the appropriate pins from one end of the cable to the other.
— If the pins on W27 measure good (indicated as zero ohms), replace the A23 Motherboard.
(Refer to “A23 Motherboard” on page 2-52.)
— If the pins on W27 measure bad (indicated as infinite ohms), replace the W27 cable.
• If the +5.2 VD, +3.4 VDY, and ± 15 V supplies are bad on the J34 connector pins indicated:
a. Check the origin of the supply.
— If the supply voltage is good at the origin, replace the A23 Motherboard.
(Refer to “A23 Motherboard” on page 2-52.)
— If the supply voltage is bad at the origin, troubleshoot the problem using that assembly's
troubleshooting procedure.
601 DACs Test
• If the +32 V, +5.2 V, and
−5.2 V supplies are good on the J34 connector pins indicated:
a. Remove the W27 ribbon cable from J1 of the A21 YTO Driver (Option UNJ or Option 506).
b. Measure the +32 V, +5.2 V, and
−5.2 V supplies on the appropriate pins of the W27 ribbon cable.
— If the voltages are good, replace the A21 YTO Driver (Option UNJ or Option 506).
(Refer to “A21 YTO Driver (Option UNJ or Option 506) and A22 Coupler (Option 506)” on
page 2-50.)
— If the voltages are bad:
a. Remove the W27 ribbon cable from the J34 connector on the A23 Motherboard.
b. On W27, ohm the appropriate pins from one end of the cable to the other.
— If the pins on W27 measure good (indicated as zero ohms), replace the A23 Motherboard.
(Refer to “A23 Motherboard” on page 2-52.)
— If the pins on W27 measure bad (indicated as infinite ohms), replace the W27 cable.
• If the +32 V, +5.2 V, and
−5.2 V supplies are bad on the J34 connector pins indicated:
a. Check the origin of the supply.
— If the supply voltage is good at the origin, replace the A23 Motherboard.
(Refer to “A23 Motherboard” on page 2-52.)
— If the supply voltage is bad, troubleshoot the problem using that assembly's procedure.