711 Charger Service Manual 711 UNIVERSAL DESK CHARGER 711380 Rev. D Welch Allyn Medical Division 4341 State Street Road P.O.
D escri pti on EC N # D ate A pproved 711380 A New Release of Uni versal C harger S ervi ce Manual 5-43820 10/09/01 DK 711380 B Update per E C N 5-43926 11/09/01 711380 C Update per E C N 5-44417 03/12/02 DK 711380 D Update per E C N 5-44590 05/06/02 DK P art N o R ev DK Drawings and/or illustrations and/or part numbers contained in this document are for reference purposes only. For current revisions call the Welch Allyn Customer Service phone number listed in Section 1 page 3.
Contents PAGE Section 1: General Information 1.1 About the Universal Desk Charger ............................................................................... 1 1.2 Block Diagram ............................................................................................................. 1 1.3 Hardware Electrical Specifications ............................................ ...................................... 2 1.4 Help Information ......................................................................
The universal desk charger electrical circuitry is designed to provide a safe (if not optimal) trickle charge profile for all Welch Allyn handles. It is intended to replace the 71110 Desk Charger. However, the major improvements over the 71110 that directly affect the electrical design are: 1. It is intended to operate from an AC power source from 100V to 275V. Along with a standard IEC connector, this will be an international unit.
1.3 Hardware Electrical Specifications 1.3.1 Absolute Maximum Ratings Input Voltage Range: 100VACRMS to 240VACRMS, 50Hz or 60HZ. Peak Input Voltage: 275VACRMS (limited by LM317T max voltage spec and transformer design) It is only guaranteed to maintain SELF internal voltages up to 240V, which is its highest rated input.
All service and repairs must be performed by fully trained and properly equipped personnel, using genuine replacement parts and correct procedures. Failure to do so will invalidate the 1 year new product warranty. 1.4 Help Information Customer Service Welch Allyn, Inc. 4341 State Street Road, PO Box 220 Skaneatles Falls, NY 13153-0220 U.S.A. Telephone 1-800-535-6663 When calling, refer to the model number on the bottom of the Universal Charger.
1.6 Safety Warnings Read and understand all safety warnings and service notes printed in this Service Manual and the Operator’s Manual part number 711137. Use hospital grade plugs only. Green power light indicates that main power is connected to the appliance. Only authorized Welch Allyn Service Centers can perform service. This product complies with current required standards for electromagnetic interference and should not present problems to other equipment nor is it affected by other devices.
2.1.1 Inspect shipping package and product for damage. Make a record of possible shipping damage. 2.1 Incoming Inspection 2.2.1 Tools required for service: Phillips screw driver, repair test handle T17814. 2.2 Required Tools 2.3 Incoming Operational Test NOTE: Any Welch Allyn rechargable handle can be substituted for the T17814 repair test handle. 2.2.2 The repair test handle, Tool# T17814, can be ordered from Welch Allyn by calling Customer Service at 800-535-6663. 2.1.
3.1 Trouble Shooting 3.1.1 Green LED not on. Use a known good power cord. Replace the power cord if this fixes the problem. Check Fuses If fuses are OK, then replace printed circuit board. 3.1.2 Amber charge LED not on. Insert a Welch Allyn rechargeable handle in charging well or T17814 repair test handle. If the amber charge light still does not come on, then replace printed circuit board. 6 WELCH ALLYN UNIVERSAL DESK CHARGER SERVICE MANUAL 711380 REV.
4.1.1 Base Housing Removal/Installation Removal Remove the 4 screws holding the base housing to the cover housing. If a new base housing is required: Clean the label and foot recesses on the new base housing with isopropyl alcohol and allow them to dry. Install a new model label in its recess as shown below. 4.1 Repair and Disassembly Observe all ESD precautions Observe all ESD Precaution Install 4 new feet in their corresponding recesses Stamp the new base housing with the original date of manufacture.
OBSERVE ALL ESD PRECAUTIONS 4.1.3 Fuse Replacement: Remove base housing as described above. Remove PCB as described above. Pry the two fuses out of the brackets on the IEC connector that is attached to the PCB. Insert the new fuses into the brackets on the IEC connector. Reinstall the PCB as described above. Reinstall the base housing as described as above. 8 WELCH ALLYN UNIVERSAL DESK CHARGER SERVICE MANUAL 711380 REV.
APPENDIX A Detailed Description Theory Input The Input provides a power entry module, transformer, bridge rectifier, and sufficient bulk capacitance to assure 200 mA operation under low line conditions. The full wave bridge consists of four 1N4004 rectifier diodes. The bulk filter capacitor is 1000 uF, 50V. Since the rectified voltage cannot exceed 40V (LM317 limitation), and the transformer cannot exceed 25VACRMS (per agency) the design has a safe margin.
APPENDIX A In the actual circuit, there is another resistor between The Output and Adj. This is necessary for proper operation of the voltage limit circuit, which will be discussed below. However, it should be noted here that this resistor will have essentially no effect on the operation of the basic current limit circuitry as described, since the current out of the Adj pin is very low. Transformer Headroom - The maximum trip point (shutdown voltage) of the Simba handle is 5.06V.
APPENDIX A LED The LED section detects the current limit condition to indicate that a charge is in process. This requires one Yellow LED per charge well. There is also a green LED’s that simply indicate that power is on. Green Power On Indicator LED The green LED is powered from a constant current source. The constant current source uses three PNP transistors, two pass transistors (required to handle worst case power) and one sense transistor.
Yellow Charge indicator LEDs Each yellow LED is meant to show that a particular well is charging. The yellow LED is on when the current limit is active. To do this, the base – emitter junction of a PNP transistor is placed across the battery charger current limit sense resistor. Whenever the voltage drop across the current limit sense resistor exceeds .6V, the transistor is turned on, and power is supplied to the LED. Coincidentally, .6V is roughly ½ of the LM317 adjust voltage (1.25V).
APPENDIX B 1 8 2 3 7 4 5 6 Ref Part Number 1 711101-1 COVER, DESK CHARGER, PRINTED 2 711096-502 PC BOARD ASSY 3 711104 BASE, DESK CHARGER 4 495083 RUBBER FEET 5 711074 MDL LABEL,711 SERIES,DESK CHGR 6 106124-48 SCREW,#8 PLASTITE,.625L,PH 7 236706-3107 FUSE- INTERNATIONAL 8 761076-0 POWER CORD, DETACH.(DOM/JAPAN) 8 761076-2 POWER CORD-DETACH (EUROPEAN) 8 761076-4 POWER CORD-DETCHBL (U.
APPENDIX C T RA NS FO R M E R , DE SK C H AR G ER 8 7 6 5 2 1 1 GND_POW ER D2 1N4004 ACOUT2 2 J1 SCREW 2 3 1 C1 1 0 0 0 u F, 5 0 V + D4 1N4004 1 4 2 3 +V R A W J2 SCREW 1 4 2 3 J3 SCREW +V R AW 2 3 J4 SCREW 2 1 4 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 +V R AW 1 D3 1N4004 D1 1N4004 A C IN L E T, IE C 3 2 0 C O N N E C T O R 1 ACOUT1 2 F2 1 T1 2 3 4 1 F1 3 AC IN1 2 GND_ESD 1 AC IN2 2 PE1 R1 2 O N LED SE N SE 1 3 1 Q1 2N4403 1 1 4 9 .
APPENDIX C +V R AW Q 11 2N4403 1 3 1 R 14 + L E D 11 Y E LLO W 1 2 1 3 01 R 12 20 2 VO TA B VROUT1 2 4 1 VI ADJ U 11 LM 3 17 3 1 2 VRADJ1 2 R 11 3 01 2 L E D 11 YELLOW LEDC TL1 2 2 R 13 1 50 1 1 1 2 3 1 2 3 2 J12 R V 11 TR AN SG UA R D , 18V 2 J13 C 11 0 .1 u F 1 2 3 1 2 3 J 11 C E N T E R C O N TA C T S P R IN G, P O S IT IV E 1 1 +CHARGE1 1 +CHARGE1 D 11 1 N 46 92 (6.
