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BK Precision 1795 Instruction Manual
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BK Precision 1795 Instruction Manual

High current power supply
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B PRECISION
K
®
Instruction Manual
Model 1795 High Current Power Supply

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Summary of Contents for BK Precision 1795

  • Page 1 B PRECISION ® Instruction Manual Model 1795 High Current Power Supply...
  • Page 2 Limited Two Year Warranty B & K Precision Corp. warrants to the original purchaser that its product and the component parts therof, will be free from defects in workmanship and materials for a period of two years from the data of purchase. B &...

  • Page 3: Table Of Contents

    TABLE OF CONTENTS SECTION PARTICULARS PAGE NO. GENERAL INFORMATION SPECIFICATIONS INSTALLATION OPERATING INSTRUCTIONS SERVICE INSTRUCTIONS PART LIST SCHEMATICS CIRCUIT DIAGRAMS...

  • Page 4: General Information

    GENERAL INFORMATION DESCRIPTION : The 1795 High Current Regulated D.C. Power Supply is completely solid and suitable for bench operation or standard 19" rack operation. It is a well regulated constant voltage / constant current supply which delivers 0-64V at 0-15Amps and can be adjusted continuously throughout the output range.

  • Page 5: Specifications

    SECTION - 2 SPECIFICATIONS OUTPUT VOLTAGE 0-64V DC continuously variable with coarse and fine voltage controls. LOAD CURRENT 0-15 Amp max., continuously variable with coarse and fine controls. CONSTANT VOLTAGE MODE REGULATION LINE Less than ± 0.01% ± 2mV for ±10% change in line voltage.

  • Page 6: Installation

    INSTALLATION INITIAL INSPECTION : As soon as the power supply 1795 unit is unpacked, inspect for any damage that may have occurred during transit. Save all packing material until inspection is completed. If any damage is found, notify the carriers immediately. Our authorised representatives should also be notified.
  • Page 7 230V Mains Operation at the Input of EMI Filter located at bottom side of the unit. REPACKAGING FOR SHIPMENT : To ensure safe shipment of the power supply 1795 unit, it is recommended that the package designed for the unit be used. The original packaging material is reusable.

  • Page 8: Operating Instructions

    SECTION - 4 OPERATING INSTRUCTIONS TURN ON SETTING PROCEDURE : following procedure describes the use of controls and indicators for Constant Voltage and Constant Current Mode of Operation. CONSTANT VOLTAGE (CV) MODE : a. Set ‘POWER ON’ Switch & keep the OUTPUT ON/OFF switch to OFF position ( b.
  • Page 9 Positive or negative voltage can be obtained from this supply by grounding either one of the output terminals or one end of the load. Always use two leads to connect load to the supply, regardless of where the setup is grounded. This will eliminate any possibility of the output current return paths through the power source ground which would damage the line cord plug.
  • Page 10 OUTPUT CAPACITANCE : Internal capacitor C3 ( L1791-FP-CNT-0603 PCB ) connected across the output terminals of the power supply, helps to supply high current pulses of short duration during constant voltage operation. Any capacitance added externally will improve the pulse current capability, but will decrease the safety provided by the constant current circuit.
  • Page 11 OPERATORS SAFETY SUMMARY The general safety information in this part of the summary is for both operating & servicing personnel. Specific warnings and cautions will be found throughout the manual where they apply, but may not appear in this summary. TERMS IN THIS MANUAL : CAUTION : Statements identify conditions or practices that could result in...
  • Page 12 USE THE PROPER FUSE : To avoid fire hazard, use only fuse of the correct type, voltage rating and current rating as specified in the parts list for your product. For 115V operation 20A, For 230V operation 10A Slow blow. Refer fuse replacement to qualified service personnel.

  • Page 13: Service Instructions

    If there is any question about the correct function or operation of any control, see the Operating Instructions section. 5.2.3 SYSTEM AND ASSOCIATED EQUIPMENT: Before trobleshooting the 1795, check for proper input fuse as per part list is intac. Check the line voltage at the power source before connecting the mains cord is rated for the correct input voltage.
  • Page 14 checked by substituting a new component for it ( or one which has been checked previously). However, be sure that circuit conditions are not such that a replacement transistor might also be damaged. If substitute transistors are not available, use a dynamic tester. Static-type testers are not recommended, since they do not check operation under simulated operating conditions.
  • Page 15 5.3.6 If Fuse blows, connect the unit through a variable AC Source with a current meter and monitor the current at no load. If the current is very high (more than 2 ampere or so ) load, check for Bridge Rectifier short or shorted Diode, or Secondary Winding short, etc 5.3.7 If output voltage or current DPM's are not reading, check for loose connections especially in crimping, soldering, of Connectors.
  • Page 16 5.4.3 VOLTAGES AT VARIOUS PINS OF IC LM324 IS AS FOLLOWS ( IC-101 ) :- IC PIN NO. VOLTAGES & CHECK CONDITIONS PIN1 0V ( WHEN V POT KEPT AT MIN. POSITION IN CV MODE ) PIN1 +5V ( WHEN V POT KEPT AT MAX. POSITION IN CV MODE ) PIN2 &...
  • Page 17 5.5.2 ORDERING PROCEDURE : When ordering replacement parts from B+K Inc. please include the following minimum information : Power Supply Type ( 1795 B+K ). Power Supply Serial Number ( For example, 03080001 ). A description of the part ( if electrical include the circuit number ).
  • Page 18 CAUTION Static discharge can damage any semiconductor component in this instrument. This instrument contains electrical components that are susceptible to damage from static discharge. Static voltages of 1KV to 30KV are common in unprotected environments. Observe the following precautions to avoid damage : Minimize handling of static-sensitive components.

  • Page 19: Part List

    FAULT FINDING PROCEDURE ( A ) FUSE BLOWS FUSE BLOWS Is Line Voltage OK ? Adjust Proper Line Voltage. Is Fuse Rating OK ? Insert proper rating Fuse. Is Mains Transformer Tapping OK ? Adjsut the Tap according to required voltage. Are Power Diodes Connected on Heat Sink Short ? Replace the Damaged Diodes.
  • Page 20 ( B ) UNREGULATED O/P VOLTAGE UNREGULATED O/P VOLTAGE Is IC LM324 OK ? Replace the IC. Is Voltage Pot Open OR Replace the Voltage Pot and Pot Wire is Reaching PCB ? Ensure proper continuity with the PCB Are Mosfets OK ? Replace the Damaged Mosfet.
  • Page 21 ( C ) NO OUTPUT VOLTAGE. NO O/P VOLTAGE Is IC LM324 OK ? Replace It. Is Voltage Pot Short ? Replace It. Is Voltage Selection Preset Open ? Replace It. Are Zener Diodes Z1 & Z2, Preset VR1 on Preg. PCB OK ? Replace It.
  • Page 22 ( D ) NO DPM INDICATION. NO DPM INDICATION Is Display Completely Blank ? Is Continuity between IC7805 & DPM OK ? Does Display shows only Ensure proper Continuity. dot Indication ? Is Continuity between IC7905 & Ensure proper Continuity. DPM's OK ? Is Continuity between ANGD &...
  • Page 23 ( E ) DPM NOT READ ( 000 ). DPM NOT READ ( V & I ) ( 000 ) Is DPM IC 707 OK ? Replace It. Does Hi and Low Wire Ensure proper Continuity. Reach DPM's ? IC TL431 OK ? Replace It.

  • Page 24: Schematics

    ( F ) UNIT NOT TAKE CURRENT. UNIT NOT TAKE CURRENT Is Current Set Preset R21 OK ? Replace It. Is Current Pot Short ? Replace It. Is Wiring Related to Ensure proper Continuity. Current Pot OK ? Are Load Terminals connected properly with Nut inside Unit ? Ensure proper Terminal Contact.
  • Page 25 ( G ) UNIT DIRECTLY GOES TO CC. UNIT DIRECTLY GOES TO CC Is Shunt Resistor open OR Replace Shunt Resistor Dry Soldered ? if necessary. Is IC LM324 OK ? Replace It. Is Current select Preset Replace It. R21 Open ? Is Remote Sense Terminal Pressed ? Ensure Remote Sense Switch is...
  • Page 26 ( H ) NO CURRENT CONTROL. NO CURRENT CONTROL Is Current Pot Open ? Replace it. Are Wires related to Current Pot OK ? Ensure proper Connectivity. Check the Current Potentiometer. It might be Open. Check all Wires related to Current Potentiometer. ( I ) POOR LINE REGULATION.
  • Page 27 ( J ) POOR LOAD REGULATION. POOR LOAD REGULATION Load Terminal Nut inside Unit might be Loose. Is there any Oscillation Reduce Resistor R6 ( 2.2K ) on in CV Mode ? F/Panel PCB until Oscillation dies OUT. If Oscillation still Prevail reduce R9 to 2K on F/Panel PCB.
  • Page 28 ( L ) EXTERNAL PROGRAMMING NOT OK. EXTERNAL PROGRAMMING NOT OK Is Pot connected across INT Ensure 5K Pot connected & COM OK ? between INT and COM Terminal. Is there proper Continuity between PROG Terminal and O/P +Ve ? Ensure proper Connectivity.
  • Page 29 SECTION - 6 PART LIST & SCHEMATICS L1791-FP-CNT-0603 PCB ASSY Reference Part Reference Part Designator Description Designation Description RESISTORS 500E(3206F) Not Used 100E 100E(3206F) Not Used 100E(3206F) R30* 360E R31* 360E 100E(3206F) Not Used 1K, 10W 100K Short 1.5K 3.3E Short 100E 330K...
  • Page 30 L1791-FP-CNT-0603 PCB ASSY Reference Part Reference Part Designator Description Designation Description CONNECTORS J2.54 - 3MSL, 3 PIN SIL 2.54mm ST LOCK MALE J2.54 - 3FSL, 3 PIN SIL 2.54mm ST LOCK FEMALE CLAMPS SINGLE PUSH SWITCH MTG. CLAMP DOUBLE PUSH SWITCH MTG. CLAMP DOUBLE PUSH SWITCH MTG.

  • Page 31: Circuit Diagrams

    PS-PREG-1791-0503 PCB ASSLY Reference Part Reference Part Designator Description Designation Description TRANSISTORS BC 109 BC 557 MPSA12 BC 547 BC 557 ZENERS 4.7V, ½W 10V, ½W PRESET 5K ( 3206F ) HOR TRANSFORMER EE25 PULSE TX. Z-DPM/01 REV - 01 X 2 Reference Part Reference...
  • Page 32 PS-AUX-DC-L1791-0503 PCB ASSLY Reference Part Reference Part Designator Description Designation Description CAPACITORS 470µF/35V, ELE 100nF, 50V, DISC 47µF/35V, ELE 470µF, 35V, ELE 10µF/35V, ELE 470µF, 35V, ELE 10µF/35V, ELE 220µF, 35V, ELE 100nF/50V, DISC C12 100nF, 50V, DISC Not Used 100nF, 50V, DISC Not Used 10µF, 35V, ELE...
  • Page 33 FRONT PANEL ASSLY Reference Part Reference Part Designator Description Designation Description 5K, WWPOT 500E, WWPOT 1K, WWPOT 50E, WWPOT SWITCH 20A/250V ON/OFF SWITCH 7. MAIN CHASSIS ASSLY Reference Part Designator Description RESISTOR 4.7K/2W, MOR 0.025E / 25W SHUNT DIODES U30D40C (30AMP/400V DUAL DIODE) CAPACITORS 10 X 4700µF, ELE 1µF / 250V AC CAP X 2...
  • Page 37 BOTTOM VIEW OF MODEL : 1790 / 1791...
  • Page 38 FRONT PANEL CONTROL PCB OF 1790 / 1791...
  • Page 39 POWER MODULE PCB OF 1790 / 1791...
  • Page 40 PRE REGULATOR / AUX. P/S PCBs 1790 / 1791...
  • Page 41 Service Information Warranty Service : Please return the product in the original packaging with proof of purchase to the below address. Clearly state in writing the perfor- mance problem and return any leads, connectors and accessories that you are using with the device. Non-Warranty Service : Please return the product in the priginal packag- ing to the below address.
  • Page 42 B PRECISION ® B & K PRECISION CORP. SN: 480-808-9-001 22820 Savi Ranch Parkway Printed in India Yorba Linda, CA 92887 (M-00285) www.bkprecision.com...