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Marconi Instruments P4428 Technical Manual

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Technical
Manual
THERMAL CAMERA
P4428
© Marconi Applied Technologies Limited
This report, which is released on the
understanding that the Company's
proprietary rights therein are recognised
and that it is solely for the information of
the recipient, must not be copied either as
a whole or in part, or disclosed to any
third party or used as the basis for the
manufacture or sale of apparatus, without
prior written permission from the Company.
8720A-4

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Summary of Contents for Marconi Instruments P4428

  • Page 1 Technical Manual THERMAL CAMERA P4428 © Marconi Applied Technologies Limited This report, which is released on the understanding that the Company’s proprietary rights therein are recognised and that it is solely for the information of the recipient, must not be copied either as...

  • Page 2: Table Of Contents

    CONTENTS FRONT FOLD Section 1 General Descriptions Page Picture of Complete P4428 Brief Specification 2 - 4 Operating and Technical Descriptions 5 - 13 Internal Assembly Details 14 - 18 Batteries 19 - 23 Camera Disassembly and Tube replacement 24 - 25...
  • Page 3 P4428 Pyroelectric Vidicon Camera Complete with Voltage Stabiliser Unit - 1 -...
  • Page 4 Specification SPECIFICATION 1. Camera The camera has been designed to operate in the hostile conditions encountered in a fire-fighting environment. Weight 3.0Kg (camera including muff and harness) Material Case - Polycarbonate Harness - Nylon Muff PVC/Nylon flame retardant - felt liner Visor Neoprene Immersion...
  • Page 5 Specification Temperature Resolution 200 lines per picture height for a temperature difference of 2EC (Chopped) - 1EC (Panned). Lens The lens has a hard anti-reflection coating and may be cleaned as necessary with an appropriate soft cloth. Focal length 18mm, f/0.8 Angle of View Spectral Response 8 to 14µm...
  • Page 6 Specification 2. Voltage Stabiliser Mechanical Weight 0.5Kg (less batteries) Material Polycarbonate Electrical Input 9.5 to 15 volts Output 8.7V @ 400mA D.C. P4428K Voltage Stabiliser - 4 -...

  • Page 7: Operating And Technical Descriptions

    Operating and Technical Descriptions P4428 GENERAL DESCRIPTION The P4428 hand -held thermal imaging camera uses the P8092 pyroelectric vidicon, and provides a thermal television picture in the 8 to 14 micron radiation band. It is enclosed in a sealed injection moulded polycarbonate case and is intended for use in fire-fighting applications.

  • Page 8: Operating And Technical Descriptions

    Operating and Technical Descriptions MECHANICAL SPECIFICATION 2.1. Dimensions Camera: 27cm x 17cm dia. (excluding pistol grip and visor) Voltage Stabiliser Unit: 18cm x 6.5cm x ll.5cm 2.2. Weight Camera: (including harness, muff, visor and pistol grip) 3.0kg Voltage Stabiliser Unit: (less batteries) 0.5kg 2.3.
  • Page 9 Operating and Technical Descriptions COMPLETE SET UP FOR NEW TUBE 6.l. Replacing Tube See Appendix 2. 6.2. Gl and Pedestal Control Adjustments These controls are adjusted using the values of I G4 (BEAM) and I G4 (BEAM + PEDESTAL) pre-determined for each tube during factory test to obtain a specific value of pedestal current.
  • Page 10 Operating and Technical Descriptions OPERATING FACILITIES AND ADJUSTMENTS 7.1. Electrode Supplies Pre-set controls are located on the scan board. G2 Fixed voltage 175 volts G3 Pre-set for 80 volts (RV109) iii) G4 Fixed voltage 135 volts G1 Variable from 0 to -60 volts (RV111) Target (CPS) Pre-set to 0 volts 7.2.
  • Page 11 Operating and Technical Descriptions 7.8. Flicker Suppressor The flicker suppressor is a digital field store, used to eliminate flicker between alternate fields in 'chop' mode. Adjustments are provided for clock frequency (RV209), RAM input-output data phase (RV210) [not required on SMT version], alternate -line interlace (RV212) and store vertical position (RV211).
  • Page 12 Operating and Technical Descriptions 8.4. Video Processing Two stages of amplification are used with a combined gain of approximately 25. The first stage utilises an LM733 [NE592] video amplifier which has a gain of 5 and also acts as a phase splitter giving outputs of both positive and negative phase.
  • Page 13 Operating and Technical Descriptions The store is arranged as 128 x 256 bytes of 6 bits each. This corresponds to an array of 128 picture elements in each of 256 of the 288 lines in each field. This array is placed centrally on the screen by delaying in both line and field directions.
  • Page 14 Operating and Technical Descriptions 8.8. Motor Control (Scan Board) The shutter motor blade completes one revolution for one frame of video. The dc motor is locked in phase with the scanning beam by comparing field drive (divided by two) with a pulse from a light sensor and creating a feedback loop using a phase locked loop circuit.
  • Page 15 Operating and Technical Descriptions 8.11. Magnetic Focus A current regulator, V105, Q113, is used to supply the focus current, the value of which is set by control RV116. 8.12. Target Discharge Under adverse overload conditions it is possible that the tube target may become positively charged and the tube cease to function.

  • Page 16: Internal Assembly Details

    Internal Assembly Details Viewing Lens Scan Board Elapsed Time Indicator Iris Motor P4428 Internal View (A) - 14 -...
  • Page 17 Internal Assembly Details Head Amp Video Board Shutter Blade Shutter Sensor P4428 Internal View (B) - 15 -...
  • Page 18 Internal Assembly Details Viewing Lens Monitor Shutter Sensor Iris Motor Shutter Blade P4428 Internal View (C) - 16 -...
  • Page 19 Internal Assembly Details Pevicon Tube Base Tube TubeClamp Yoke Adjustment Yoke Fixing Screws Yoke Neoprene Gasket Video to Scan Board Connector P4428 Internal View (D) - 17 -...
  • Page 20 Internal Assembly Details Shutter Blade Retaining Screws (4) Iris Motor Shutter Motor Shutter Sensor Germanium Lens Iris Limit Switches Iris Drive Belt P4428 Internal View (E) - 18 -...

  • Page 21: Batteries

    Batteries BATTERIES There are two battery cartridges for the P4428, the P4428B (white or red label) which is intended for disposable primary cells and the P4428R (black label) which is supplied with rechargeable cells. 10.1 Using Primary batteries Only Alkaline Manganese chemistry AA cells will give the specification operational time.
  • Page 22 Batteries 10.2 Using Rechargeable Batteries The rechargeable battery cartridge P4428R contains 10 NiCd ‘AA’ cells of 600mAh capacity. The cartridge should be recharged using the cartridge container type P4428CA and charger unit type P4428UA. The charger is a 50mA constant current charge requiring 14 to 16 hours for a full charge of an empty set of cells.
  • Page 23 Batteries - 21 -...
  • Page 24 Batteries 10.4 Additional Instructions for Replacing the Battery Fuse Follow instructions on changing the batteries up to and including step 3. Remove the two batteries covering the fuse slot identified by the ‘fuse’ label. Using the battery cartridge wrench provided (attached to the cap lanyard) unscrew the central contact on the bottom of the battery pack.
  • Page 25 Batteries - 23 -...
  • Page 26 Camera Disassembly CAMERA DISASSEMBLY Camera Case Removal Remove the harness and the main part of the insulation muff. Disconnect the voltage stabiliser unit by unplugging the in-line connector situated by the pistol grip. Hold the camera with the lens uppermost, depress the front plate and rotate the breech ring clockwise to unlock the case.
  • Page 27 Camera Disassembly R.F. Screen Earth Tag (Shown unsoldered) Breech Ring Locating Notch Case Front Locating Screws Internal R.F.Screen P4428 Case Removal Diagram (Shown without muff and harness) - 25 -...

  • Page 28: Modification Record

    Mod 2 Video Processing to ESA 56493BA (November 1984) Mod 3 Video Processing to ESA 56493BA Fitted with P4428/3 scan and P4428/3 video boards. Electrically identical to Mod 2. (August 1985) Mod 4 Modification to sample video for iris on alternate fields only.

  • Page 29: Modification Record

    Modification Record Mod 8 Monitor tube change from 40CB4M to 40JB4. Resistor changes to suit new monitor:- R111 – Wire Link R112 – 15MΩ R113 – 10MΩ R144 – 5M6Ω In some later cases the heater requires a resistor in parallel (P104 pin 3 to pin 6) to obtain the correct split between Pevicon and CRT.

  • Page 30: Primary Fault Check Procedures

    SECTION 2 FAULT FINDING AND SETUP PRIMARY FAULT CHECK PROCEDURE The following checklists should aid fault finding on the P4428 camera to enable simple faults to be remedied and if necessary complete boards changed. After a board or tube change the camera must be...
  • Page 31 Fault Check Procedures If the faults exhibited by the camera do not fit into those listed in the checklists or if advice is required before major board change work is undertaken, please contact the factory or agent, stating the serial number and fault symptoms. Marconi Applied Technologies will be pleased to advise and assist.
  • Page 32 Fault Check Procedures Checklist 3 Remove camera from case, connect to external PSU (refer to page 32). At this point there should be a picture with circular blanking on the internal monitor. If not start checklist 5. Use the following instruction sets to determine the type of picture :- The picture is :- Almost white but still responds to some images.
  • Page 33 Fault Check Procedures Checklist 4 Unplug voltage stabiliser from camera, connect external supply (refer page 32). Check current consumption. If greater than 0.1A start voltage stabiliser checklist page 59 rear fold. Plug voltage stabiliser into camera. Check current consumption of camera. If greater than 0.5A refer to Factory. Checklist 5 Plug in external monitor.
  • Page 34 Fault Check Procedures Removing Camera Case (See also Diagram Page 25) Remove the harness and the main part of the insulation muff. Disconnect the voltage stabiliser unit by unplugging the in-line connector situated by the pistol grip. Hold the camera with the lens uppermost, depress the front plate and rotate the breech ring clockwise to unlock the case.
  • Page 35 Electrical Setup P4428 CAMERA ELECTRICAL SETUP PROCEDURE Items in square brackets are the differences for the new SMT boards Before switching on turn G1 pot RV111 anti-clockwise [clockwise] and pedestal pot RV110 clockwise [anticlockwise]. Select pan mode. Turn flicker suppressor off by setting RV212 fully anticlockwise.
  • Page 36 Electrical Setup Reduce circular blanking sizeRV206 and adjust circle shape RV207 (monitor raster set to 3:4 ratio). The circle should be 34.7µs wide and 15.8ms or 13.4ms high (625/525 TV systems respectively) Check video at L201 [TP5] and adjust the shading controls to achieve as flat a signal as possible, in both line and field rates (RV202, RV205 field and RV203,RV201 line).

  • Page 37: Yoke Assembly

    Electrical Setup Adjust brightness and contrast of internal monitor (RV107 and RV106). Check and adjust optical focus by moving yoke assembly. Check yoke rotation. Check LED battery indicators. Adjust RV115 for offset and R114 for range [no adjustment]. Rail drop out point should be below 9.2V.