VS1 Troubleshooting Manual
Responding to alarms
Page 1-36
Issue 10.0 2018-10-29
Pre-amp/IPA PWB replacement
See Figure
MD-2
in the Mechanical Drawings section (Section 6) of this manual.
1. Remove the transmitter’s bottom cover. Retain hardware for re-installation.
2. Unsolder and remove the six solder connections to the pre-amp/IPA PWB (A5). They
include two white, 16 AWG wires (to pads D and E), two tinned copper jumpers (to pads B
and C), a white coaxial cable (to pads A and G) and two 20 AWG links (to pads F and H).
3. Remove the two M3 screws, Belleville and flat washers securing each of the clamps that
secure FETs Q1 and Q2 to the heat sink.
4. Remove the four M3 screws securing the pre-amp/IPA PWB to the heat sink, noting one of
the securing screws also holds thermistor RT1 in place (see Figure MD-2). Temporarily
move RT1 and its associated wiring to allow removal of the pre-amp/IPA PWB.
5. Remove the pre-amp/IPA PWB from the heat sink, noting the orientation.
6. Clean the heat sink surface with a soft cloth and non-abrasive grease remover.
Do not
use
any material that may scratch the heat sink surface.
7. Obtain the replacement NAPA28B pre-amp/IPA PWB from the station spares kit, if
purchased.
8. Spread a small amount of thermal compound (Nautel Part # HAG39, from the station
spares kit), in a thin, even layer, on the bottom surface of the pre-amp/IPA PWB palette
and
on the top and bottom of the RT1 tab, removed in
Step 4
. Use thermal compound to cover
the threads on the M3 screw that secures RT1 in
Step 8
.
9. Secure the pre-amp/IPA PWB on the heat sink using the four screws removed in
Step 5
,
noting the correct orientation. Re-install thermistor RT1 under one of the securing screws.
Do not tighten the four screws at this time.
NOTE:
FETs are static sensitive. Handle the PA PWB in a static protected manner.
CAUTION:
When securing FET hardware, you can damage the FET case if you fully tighten one
screw while the other is loose. Avoid this by alternately tightening the two screws.
Summary of Contents for VS1
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Page 8: ...VS1 Troubleshooting Manual Page viii Issue 10 0 2018 10 29...
Page 56: ...VS1 Troubleshooting Manual Responding to alarms Page 1 48 Issue 10 0 2018 10 29...
Page 84: ...VS1 Troubleshooting Manual Wiring connector lists Page 4 6 Issue 10 0 2018 10 29...
Page 102: ...Issue 10 0 2018 10 29 MD 7 Figure MD 7 NAPA23 03A PA PWB C16 R13 R12 C5 C8...
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