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Model 8642A/B Service
Procedure Guide
COMMENT
When looking at the instrument, some of the mechanical procedures may
seem intuitively obvious. There are, however, some hidden problems. We
strongly recommend that you read through an entire procedure before
performing any of the steps in these mechanical procedures.
Procedure Paragraph
Introduction 8-1
Tools 8-2
Open/Close Front Panel (Except Option 002) 8-7
Open/Close Front Panel (Option 002 Only) 8-8
Remove/Replace Al Module 8-10
Remove/Replace LCD Display 8-11
Replace LCD Lamps 8-12
Remove/Replace A2 Module 8-9
Remove/Replace Top Cover 8-3
Remove/Replace A3 Module 8-5
Remove/Replace A4 Module 8-6
Remove/Replace A4 Module 8-25
Remove/Replace RF Modules (A6, A7, A9, All-14, A16, A19) 8-4
Module Disassembly (A6, A7, A9, Al 1-14, A16, A19) 8-21
Remove Printed Circuit Assemblies 8-22
Replace Printed Circuit Assemblies 8-23
Remove/Replace Right Side Cover 8-13
Remove/Replace A17 Module 8-14
Remove/Replace Rear Bottom Cover 8-15
Remove/Replace A18 Module 8-16
Remove/Replace A20 Module 8-17
Remove/Replace Fan (Bl) 8-19
Remove/Replace A5 Ribbon Cables 8-20
Remove/Replace Module Feedthrough Filter Network 8-24
Remove/Replace A8 Oscillator (Option 001 Only) 8-18
rev.i3JUN86 8B-1
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. Service Model 8642A/B
8-1. INTRODUCTION \ ^
This section contains mechanical procedures required for service of the HP 8642A/B Synthesized
Signal Generator. The instrument should be serviced in an electrostatic discharge protected
environment. For your safety, read the warnings and cautions in the General Information sec
tion of this manual before performing the assembly/disassembly procedures.
NOTE
Unless otherwise noted, the directions "left" and "right"
given in the instructions are referenced as though you are
looking at the instrument from the front panel.
The first page of this section, PROCEDURE GUIDE, is a quick reference for locating the para
graph in which the removal and replacement procedures for each module/assembly can be found.
8-2. TOOLS
Most screws used in instrument are Torxhead screws. They require a torque driver and Torxhead
bits for proper removal and installation.
To avoid damage, do not exceed the following torque limits:
Torque limit for 4 mm screws: 2.2 Nm. (Use bit T15)
Torque limit for 3 mm screws: 1.5 Nm. (Use bit T10)
Two bits are located in tool pouch sent with the Operating Manual.
To set torque limit of wrench, remove cover from end of handle. Lift the key to the vertical
position and turn clockwise to increase torque setting, or turn counter-clockwise to decrease
torque setting. Align hairline on clear bulb of wrench shaft with the desired setting. Push the
key back to the flat position (a very slight turn in either direction may be necessary for key to
lock into place).
Also included in the tool pouch are two module extender posts.
An RF connector wrench is located above fan on right inner wall of center rear bracket. A fuse
extraction/insertion tool is located on top of rear frame under the power supply cover.
8B-2 rev.I3JUN86
Model 8642A/B Service
r> 3. Loosely secure A 5 and insulator to front brace with seven screws. When all seven screws
are in place, tighten each one.
CAUTION
Cables W14 and W15 must be properly dressed into notch
provided in left controller guide . Improperly dressed cables
can be punctured by screws when securing guide and
bracket to frame.
4. Dress W14 (08642-60010) and W15 (08642-60011) flush against left side of
instrument. Mount left (black) controller guide over the cables with two panhead screws.
Mount the left guide metal bracket with two flathead screws.
5. Replace two screws in right (white) controller guide.
6. Reconnect all cables. (Refer to diagram on inside of instrument Top Cover for cable
connections.)
7. Position the modulation shield into the front frame and loosely secure with seven screws.
When all screws are in place tighten each one.
r~\ 8. Replace A 2 Module. (Refer to paragraph 8-9.)
9. Close front panel. (Refer to paragraph 8-7: Except Option 002, paragraph 8-8: Option
002 only.)
10. Replace A3 and A4 Modules. (Refer to paragraph 8-5 and 8-6.)
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rev.!3JUN86 8B-45
Model 8642A/B Service
.^""""N The On-Site Service Kit contains many tools needed to service the instrument. (See Table 9-1 for
contents of kit.)
Other tools required but not contained in the kit are:
2 pt. Pozidrive screwdriver.
1 pt. Pozidrive screwdriver
6.0 mm open end wrench.
Small flathead screwdriver.
Small needlenose pliers
Small diagonal cutters
Soldering/Desoldering tools
Tools not included in the kit which are called for in the procedures are printed in italics.
8-3. TOP COVER
Removal Time: 2 min
Replacement Time: 2 min
Tools Required: Pozidrive screwdriver.
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To Remove: Top Cover
1. Remove four rear feet from rear frame of instrument by removing screw in each foot.
2. Loosen screw in middle of rear edge of top cover. This is a captive screw (attached to top
cover). Loosening it will cause cover to push away from front frame.
3. Slide top cover toward rear of instrument to disengage and lift and away. The cover has
a tight fit and may need to be worked loose.
To Replace: Top Cover
1. Place cover onto top of instrument making sure that the cover fits into the grooves on
the top of the side covers. Slide cover toward front of instrument while applying a slight
downward pressure to front edge of cover. Guide into slot in top of front frame. The
cover has a tight fit and may need to be worked forward.
2. When screw on rear edge of cover is in contact with rear frame tighten it. The cover
should move forward as the screw is tightened.
3. Replace four feet on rear frame, one screw in each.
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rev.!3JUN86 8B-3
Service Model 8642A/B
8-25. MODULE: A5
Removal Time: 2 min
Replacement Time: 2 min
Tools Required: Pozutrive screwdriver, torque driver Torxhead bits
To Remove
1. Remove top cover. (Refer to paragraph 8-3.)
2. Remove A3 and A4 Modules. (Refer to paragraph 8-5 and 8-6.)
3. Open front panel (refer to paragraph 8-7: except Option 002, paragraph 8-8: Option 002
only).
4. Remove A2 Module. (Refer to paragraph 8-9.)
5. Remove seven screws in modulation shield (metal plate behind A 2). Pull shield out of
instrument.
6. Remove left (black) controller guide metal mounting bracket (two screws).
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7. Remove two screws in left (black) controller guide.
8. Turn instrument on its side and remove four screws on rear edge of front bottom cover.
Pull cover toward rear panel to disengage from front frame.
9. Remove two screws holding left (black) controller guide to bottom of A 5 Module and pull
guide out of instrument.
10. Remove two screws on far right side holding right (white) controller guide.
11. Disconnect all cables from A 5 Module.
12. Remove seven panhead screws securing board to brace. DO NOT remove six flathe&d
screws visible through holes in center section of AS Module.
13. Pull Module out through bottom of instrument.
To Replace
1. Push AS Module into instrument through bottom of instrument and align with front
brace. Be sure front brace insulator is in place behind A 5.
2. Plug HP-IB Cable (W12) into bottom left corner of A5 at A5J20 and A5J21. Red stripe
on cable faces front panel. Dress Wl2 between standoffs on side of frame.
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8B-44 rev.l3JUN86
Service Model 8642A/B
8-4. RF MODULES: A6, A 7, A9, A l l - 1 4 , A16, A19
Removal Time: 4 min
Replacement Time: 8 min
Tools Required: RF connector wrench
To locate module, refer to drawing on inside of instrument top cover.
To Remove: A6, A7, A9, A l l - 1 4 , A16, A19
1. Remove top cover (Refer to paragraph 8-3.)
2. Reroute obstructing coax cables around ends of module. (These are cables lying across the
top of module that would hinder lifting of module from the instrument.
3. Use RF connector wrench provided in the instrument to disconnect intermodular cables
from the module being removed. (These are cables which connect the module to other
parts of the instrument, including ribbon cables.)