Nautel VS300 Troubleshooting Manual

Also see for VS300: Quick start guide Installation manual Operation and maintenance manual Preinstallation manual Troubleshooting manual

Nautel VS300 Troubleshooting Manual Manual pdf 41 page image

VS300 Troubleshooting Manual Responding to alarmsIssue 10.0 2019-01-18 Page 1-332. Using a digital multimeter, check the continuity between each drain lead of the FET(positive meter probe) and the metal flange of the FET (negative meter probe).– If the measurement is open circuit, the PA PWB is OK and does not requirereplacement. Continue troubleshooting and suspect a problem with an associatedPWB.– If the measurement is not open circuit, replace the PA PWB (see “PA PWBreplacement” on page 1-31).–Pre-amp PWB replacementSee Figure MD-1 in the Mechanical Drawings section (Section 6) of this manual.1. Remove the transmitter’s top cover. Retain hardware for re-installation.2. Unsolder and remove the six solder connections to the pre-amp PWB (A5). Theyinclude a white, 24 AWG wire (to pad A), a white, 16 AWG wire (to pad B), and twocoaxial cables (to pads C and D and F and G).3. Remove the two M3 screws, Belleville and flat washers securing the clamp that securesFET Q1 to the heat sink.4. Remove the four M3 screws securing the pre-amp PWB to the heat sink.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 notuse any material that may scratch the heat sink surface.7. Obtain the replacement NAPA27A pre-amp PWB from the station spares kit, ifpurchased.8. Spread a small amount of thermal compound (Nautel Part # HAG39, from the stationspares kit), in a thin, even layer, on the bottom surface of the pre-amp/IPA PWBpalette.NOTE:FETs are static sensitive. Handle the pre-amp PWB in a static protected manner.