Service manual

Assembly
Removal and
Replacement
This section contains the procedures for removal and installation of major
assemblies. Read the Safety Summary at the front of this manual before servicing
the instrument.
Warning Hazardous voltages exist on the power supply, CRT, and the display
sweep board. To avoid electrical shock, adhere closely to the following
procedures. Also, after disconnecting power cable, wait at least three
minutes for capacitors on the power supply and sweep boards to
discharge before servicing this instrument.
Caution Never remove or install any assembly with the instrument power ON. Component
damage can occur.
Caution The effects of ELECTROSTATIC DISCHARGE may damage components. Use
grounded wriststraps and mats when servicing the System Assembly Board.
Removal and
Replacement of
System Assembly
Board
1. Disconnect pod cables from rear of instrument.
2. Disconnect power cable.
3. Remove ten screws securing top cover. Remove top cover.
4. Disconnect disk drive cable from disk drive.
5. Remove two screws securing disk drive to power supply. Remove disk drive
by sliding assembly out front panel of instrument.
6. Remove two retaining pins securing power supply to chassis. Slide power
supply out far enough to gain unobstructed access to power supply cables.
7. Disconnect power supply line input and DC output cables. Remove power
supply.
8. Disconnect video sweep cable, BNC trigger cables, disk drive cable,
keyboard cable, fan cable, power supply DC output cable, and HP-IB cable
from system board.
9. Remove eight screws securing rear panel to chassis. Remove rear panel.
10. Remove RS-232 ESD ground spring from RS-232 connector.
11. Carefully place instrument in a front-panel-down position (or on its side) and
remove eight screws securing system board to chassis (on underside of
instrument).
12. Carefully slide system board out rear of instrument.
13. Carefully slide new system board through rear of instrument.
HP 1650B/1651B Service
Service Manual 6-17