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Ludlum Measurements 4901P Instruction Manual

Pancake gm hand & shoe monitor
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LUDLUM MODEL 4901P
PANCAKE GM
HAND & SHOE MONITOR
April 2024
Serial No. 289679 and Succeeding
Serial Numbers

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Summary of Contents for Ludlum Measurements 4901P

  • Page 1 LUDLUM MODEL 4901P PANCAKE GM HAND & SHOE MONITOR April 2024 Serial No. 289679 and Succeeding Serial Numbers...
  • Page 2 LUDLUM MODEL 4901P PANCAKE GM HAND & SHOE MONITOR April 2024 Serial No. 289679 and Succeeding Serial Numbers...

  • Page 3: Table Of Contents

    Table of Contents 1. INTRODUCTION ............................ 1 2. SPECIFICATIONS ........................... 3 3. USER OPERATION ..........................5 ........................ 5 SSEMBLY AND ISASSEMBLY Assembly Procedure ........................... 5 Disassembly Procedure ........................6 ..........................6 PERATIONAL HECK ............................ 7 ADIATION HECK 4. DESCRIPTION OF CONTROLS AND FUNCTIONS ................9 5.
  • Page 4 Annual Calibration Verification Procedure ..................23 ..........................24 ROUBLESHOOTING ........................25 EPAIR AND ALIBRATION 8. RECYCLING ............................26 9. PARTS LIST ............................27 HVPS B 53) ......................27 OARD RAWING LED D 4) ....................29 RIVER OARD RAWING 60) ......................30 OARD RAWING LED D...

  • Page 5: Introduction

    Model 4901P Hand & Shoe Monitor Section Introduction The Model 4901P Beta/Gamma Hand & Shoe Monitor is intended for use as a medium-level beta and gamma contamination monitor. There are four count channels in the standard configuration, monitoring the palms of each hand and the soles of each shoe.
  • Page 6 Model 4901P Hand & Shoe Monitor Model 4901P Hand and Shoe Monitor Ludlum Measurements, Inc. Page 2 April 2024...

  • Page 7: Specifications

    Model 4901P Hand & Shoe Monitor Section Specifications pancake-type, halogen-quenched GM Detectors: 1.7 ±0.3 mg/cm mica Window: energy dependent Energy Response: Background Count Rate: 200-250 cpm Hands: 250-300 cpm Shoes: Detector Effeicnecy (4π): Hands: 12% for 12% for 3% for...
  • Page 8 Model 4901P Hand & Shoe Monitor Background Update Interval: adjustable from 1 to 99 minutes. A background count will take place if the machine is not in use at every interval specified by this timer. Background accumulation will be forced within this interval Force Update: of time if an automatic accumulation has not been made.

  • Page 9: User Operation

    Model 4901P Hand & Shoe Monitor Section User Operation Assembly and Disassembly The vertical sections of the hand detector are now shipped detached from the foot detector section. Four screws (8-32X1/2 inch) are used to reattach the vertical sections. A connector is used to distribute power/signals to and from the detectors and main electronics.

  • Page 10: Disassembly Procedure

    Check that the unit returns to normal service (READY LED will light) after the 60-second update interval has expired. Disassembly Procedure Turn the power OFF to the Model 4901P and remove the power cord from the receptacle. Place the unit on a workbench or other suitable work area.

  • Page 11: Radiation Check

    This check verifies that the instrument is turned on, that the settings are appropriate, and that the system alarms when the detectors are exposed to excess radiation (above background level). Ludlum Measurements suggests that this operational check be performed after setup and before use.
  • Page 12 Model 4901P Hand & Shoe Monitor removed before the count is complete. • Once count is complete, the green CHECK OK light or the read ALARM light will turn on. Smaller red lights will turn on with the ALARM light to indicate the location of the alarm.

  • Page 13: Description Of Controls And Functions

    All of the microprocessor RAM is transferred to flash memory when this button is pushed. Any changes made to variables only change the current microprocessor RAM. If the Model 4901P is turned off prior to saving changes, these changes are lost. To save parameter changes, press the SAVE button before turning the Model 4901P off.
  • Page 14 The SHORT COUNT LED stays on for the alarm hold time or until the hand switches are re-activated. A short count resets the count time. If no hand switch is sensed during the short count time, then the Model 4901P goes back to the ready state lighting the READY LED.

  • Page 15: Safety Considerations And Warning Markings

    Pollution Degree 2 (as defined by IEC 644) Cleaning Instructions and Precautions The Model 4901P may be cleaned externally with a damp cloth, using only water as the wetting agent. Do not immerse the instrument in any liquid. Observe the following precautions when cleaning: 1.
  • Page 16 If the wrong power converter is used, the instrument and/or power converter could be damaged. The Model 4901P is marked with the following symbols: PROTECTIVE CONDUCTOR TERMINAL (per IEC 417, No. 5019) – designates the central grounding point for the safety ground. This symbol is visible inside the chassis.

  • Page 17: Electrical Safety Precautions

    Model 4901P Hand & Shoe Monitor Electrical Safety Precautions • Do not expose the unit to rain or an environment where it may be splashed by water or other liquids, as doing so may result in fire or electric shock.

  • Page 18: Setup

    Model 4901P Hand & Shoe Monitor Section Setup This section gives instructions on how to use the keys to set up the instrument. Examples of keystroke sequences are given for each parameter. For information on using the instrument to make a radiation check, see Section 7.
  • Page 19 Model 4901P Hand & Shoe Monitor Individual Alarms The individual channel alarms are left hand, right hand, left foot, and right foot (LH, RH, LF, and RF). If the counts are greater than, or equal to, the count alarm set point for an individual channel during the count time, then the individual alarm LED (LH, RH, LF, RF) activates.

  • Page 20: Setup Background Menu

    Model 4901P Hand & Shoe Monitor High Background Alarms Set the high background parameters to preclude nuisance alarms from varying backgrounds. For backgrounds near 100 counts per minute, choose 175. Set both the LH/RH and LF/RF high-background set points. Setup Background Menu Access the SETUP menu: •...

  • Page 21: Setup Time Menu

    Model 4901P Hand & Shoe Monitor Setup Time Menu This menu sets the count time and alarm hold time. The alarm hold time also applies to the SHORT COUNT LED. To access the SETUP TIME menu: • With READY displayed on the LCD.

  • Page 22: Setup Volume Menu

    Setup Volume Menu The volume menu sets only the ALARM volume. The Model 4901P emits a beeping sound after various events (mode change, parameter change, etc.). This beeping volume is always at the maximum and is not adjustable.

  • Page 23: Read Menu

    • Press the EXIT key to exit back to the ALARMS menu. Read Time Menu This menu reads all the time parameters of the Model 4901P. The user cannot change these values from this menu. To access the READ TIME menu: •...

  • Page 24: Read Volume Menu

    • Press the EXIT key to exit back to the VOLUME menu. Read Volume Menu This menu reads all of the volume parameters of the Model 4901P. The user cannot change these values from this menu. To access the READ VOLUME menu: •...
  • Page 25 Model 4901P Hand & Shoe Monitor To access the PASSWORD menu: • With READY displayed on the LCD. • Press SELECT once to select the setup menu. SETUP menu appears. • Press SELECT once to execute the setup menu. ALARMS menu appears.

  • Page 26: Calibration Menu

    Model 4901P Hand & Shoe Monitor Calibration Menu The Cal Menu has two choices: Display of Hands Count Data Selecting this mode provides a one-second updating display of the current count from the hand detectors (in counts per second). This mode is used for setting or checking the threshold level and as a general diagnostic using a pulser or source counts from the detectors.

  • Page 27: Calibration And Troubleshooting

    Section Calibration and Troubleshooting Calibration Procedure General The Model 4901P was set up for 80 mV sensitivity and 900 Vdc operation for GM type detectors. Equipment 1. Ludlum Model 500 pulser or equal 2. High-impedance voltmeter or high-voltage measurements (10 megohm) 3.

  • Page 28: Troubleshooting

    Model 4901P Hand & Shoe Monitor Trouble Shooting The block diagram of the Model 4901P can be thought of as four detectors connected to a multi-counter main board. All detectors operate from a single, high-voltage power supply (HVPS). This supply is located on the main electronics chassis just below the main board.

  • Page 29: Repair And Calibration

    Model 4901P Hand & Shoe Monitor power-down and up cycle. Caution!: To avoid electrical shock, ensure that the instrument is off for at least one minute before touching the connections. Repair and Calibration To return an instrument for repair or calibration, provide sufficient packing material to prevent damage during shipment.

  • Page 30: Recycling

    To this end, Ludlum Measurements, Inc. strives to supply the consumer of its goods with information regarding reuse and recycling of the many different types of materials used in its products.

  • Page 31: Parts List

    Model 4901P Hand & Shoe Monitor Section Parts List Reference Description Part Number Model 4901P Hand UNIT Completely Assembled & Shoe Monitor Model 4901P Hand & Shoe Monitor 48-3009 BOARD Assembled HVPS 5436-042 HVPS Board, Drawing 436 x 53 C001 10µF 20V 04-5655 CAPACITORS C002 1µF 35V...
  • Page 32 Model 4901P Hand & Shoe Monitor Reference Description Part Number Q001 2N70022L 05-5840 TRANSISTORS Q002 PQ05SZ11 05-5858 Q121 2N7002L 05-5840 Q131 MTD10N05E 05-5839 Q211 PQ20VZ51 05-5863 Q221 MMBT3904T 05-5841 Q222 MMBT4403L 05-5842 Q223 TIP120 05-5782 DIODES CR021-CR022 1N4007 07-6274 CR031-CR032...

  • Page 33: Led Driver Board (Drawing 420 X 4)

    Model 4901P Hand & Shoe Monitor Reference Description Part Number R212 165K 1/8W 1% 12-7877 R213 22.1K 1/8W 1% 12-7843 R214 1.27K 1/8W 1% 12-7902 R215 33.2K 1/8W 1% 12-7842 R221 22.1K 1/8W 1% 12-7843 R222 4.75K 1/8W 1% 12-7858...

  • Page 34: Main Board (Drawing 215 X 60)

    Model 4901P Hand & Shoe Monitor Reference Description Part Number BOARD Assembled Main 5215-087 Main Board, Drawing 215 x 60 C101 68µF 6.3V 04-5654 CAPACITORS C201 68µF 6.3V 04-5654 C211 0.1µF 50V X7R 04-5663 C231 0.01µF 50V X7R 04-5664 C301 2700µF 35V E...
  • Page 35 Model 4901P Hand & Shoe Monitor Reference Description Part Number R402 10 OHM 1/8W 1% 12-7836 R403 10K 1/8W 1% 12-7839 R431 10K 1/8W 1% 12-7839 R501 10K 1/8W 1% 12-7839 R503 73.2K 1/8W 1% 12-7895 R504 10K 1/8W 1%...

  • Page 36: Led Display Board (Drawing 420 X 226)

    Model 4901P Hand & Shoe Monitor Reference Description Part Number CRYSTALS Y311 MICRO 6.144 MHZ 01-5262 TRANSFORMERS T401 MODEL 177 AUDIO 4275-083 LED Display Board, BOARD Assembled LED Display 5420-226 Drawing 420 x 226 CAPACITORS 68µF 10V 04-5654 0.01 µF 25V...

  • Page 37: Interconnect Board (Drawing 420 X 178)

    Model 4901P Hand & Shoe Monitor Reference Description Part Number 10µF 10V 04-5757 0.1µF 25V 04-5744 10µF 10V 04-5757 0.001µF 2kV 04-5838 RK7002AT116 05-931 TRANSISTORS RESISTORS 100K 100mW 1% 12-7082 21.5K 250mW 1% 12-7001 0 OHM 12-8013 10K 100mW 1%...
  • Page 38 Model 4901P Hand & Shoe Monitor Reference Description Part Number CONN-640456-2 MTA100 13-8073 CONNECTORS CONN-640456-4 MTA100 13-8088 CONN-1-640456-4 MTA100 13-8141 CONN-640456-2 MTA100 13-8073 CONN-640456-5 MTA100 13-8057 CONN-640456-3 MTA100 13-8081 CONN-1-640456-1 MTA100 13-8059 CONN-640456-5 MTA100 13-8057 MISCELLANEOUS DS01 UNIMORPH TEC-3526-PU 21-9251 Ludlum Measurements, Inc.

  • Page 39: Drawings And Diagrams

    Model 4901P Hand & Shoe Monitor Section Drawings and Diagrams Panel and Plate Assembly Drawings Main Chassis Front Panel, Drawing 420 x 171 Front Panel LED, Drawing 420 x 170 Schematics and Component Layouts HVPS Board, Drawing 436 x 53...

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