Parts List, Fixed Resistor, 261 or | Agilent Technologies 2948

Model 8904A

Instrument Changes

NOTE

It ispossible that the 22 gauge black wire may break while replacing the new ground wire. If it does, strip 8 mm (5116 inch) of insulation from it and properly wrap and solder it to a second new lug.

10.Replace the screw in the standoff, inserting the screw through the lug with the black wire first and then through the lug with the new ground wire. Tighten the screw.

11.Put the main wiring harness next to the standoff and secure both together with a gray cable tie (HP 1400-0249). Cut off the excess tie wrap lead. Make sure the box on the tie wrap is toward the inside of the instrument.

12.Replace the top cover and make a quick check of the operation of the instrument.

7-8. MODIFICATION FOR OUTPUT OVERVOLTAGE PROTECTION IMPROVEMENT

(Serial Prefix 2747A and below)

The output overvoltage protection circuit of the HP 8904A Multifunction Synthesizer has a potential problem. On instruments with serial prefix 2747A and below, excessive leakage in four clamp diodes (A3CR415 to A3CR418) shifts the trip point of the circuit to a voltage too high to protect the output against inadvertent application of high reverse voltage.

No failures due to this problem have been observed, but all instruments with serial prefix 2747A and below should be modified.

Modify the instruments as directed below. (Refer to Service Sheet SS4 for schematic and component locator.)

1.Order the parts listed in the table below.

2.Replace diodes A3CR15 through A3CR18 with part number 1901-0880.

3.Replace A3R494 and A3R95 (1780s1) with part number 0698-0085 (26100).

4.Replace A3R491 and A3R493 (34.8 kR) with part number 0757-0199 (21.5 k0).

5.If the instrument has Option 002, a second output, the same modification should be made to the A10 assembly.

Parts List

I	HPPartNumber~~	1 CD	I Qty* I	Description	I
	0698-0085	0	2	Fixed Resistor, 261OR
	0757-0199	3	2	Fixed Resistor, 21.5 kR
I	1901-0880	7	4	Diode
I	* If the instrument has Opt 002, order twicethis quantity.				I

rev.15DEC89

Firmware Updates/Hardware Modifications

7-13

Image 61

Agilent Technologies 2948 Modification for Output Overvoltage Protection Improvement, Parts List, Fixed Resistor, 261 or

Contents

Innovating the HPWay Agilent Technologies Copyright@ HEWLETT-PACKARD Company Multifunction Synthesizer Regulatory Information Safety Considerations Safety Considerationsfor this Instrument Product Markings Contents Reu.200CT88 Service cont’d Section Introductionto this Section Replaceable Parts ListReference Designationsand Abbreviations Used in this Manual How to Order Replaceable Parts List Updating Manual Updates Nable 6-1.Reference Designations AccessAbbreviations 1 ALC Abbreviations 2 Rev.01JUL91 Replaceable PartsDescription Number Code HPPart Description Number Mfr- Mfr. Part Number Code Fible 6-3.Replaceable PartsCAPACITOR-FXD22PF +-5% Poovdc CER 0+-30 Not Assigned Designation Number Reference HP Part Description Mfr Reference HP Part Description Designation Number Rev.1 7MAY88 Me 6-3. Replaceable PartsReference HP Part Designation Number Not Assigned Connector Spin M Post Type DIODE-SWITCHING 80V 200MA 2NS DO45CONNECTOR-RFSMC M PC 5 W H M CONNECTOR-RF SMC M PC W H M Reference Mfr HP Part Description Cable 6-3.Replaceable PartsRESISTOR-TRMR 1K 10% C TOP-ADJ 17-TRN RESISTOR-TRMR20K 10% C TOP-ADJ 17-TRN 0698-3430 Mfr. Part Number Description Mfr Rev.17MAY88 IC OP AMP Prcn 8-DIP-C PKG Transistor Array 16-PIN Plstc DIPIC Instm Ampl CUR 10-DIP-P PKG IC OP AMP LOW-BIAS-H-IMPD 8-DIP4 PKG HPPart Description Nble 6-3. Replaceable Parts L e 6-3. Replaceable Parts A10 Ble 6-3.Replaceable Parts Miscellaneous PartsHPPart Designation Number Code Reference HPPart Description Mfr Rnftsund Plstem DOME-HD .125DIA Deck AssyRIVET-BUND PL-STEM DOME-HD .125DIA RIVET-BUND Plstem Domehd .125DIA Not Separaretlyreplaceable PANEL, Front AYKeypad Punched Shield Display QW. Description Reference HPPart Designation Number Qty.Description Designation Code Mfrm Mfr. Part Number Code Lbble 6-3. Replaceable PartsOrder by Description IZZ-9 Main Deck Assembly Top, 2923A and above Model 8904A Main Deck Assembly Bottom Main Deck Assembly Bottom, Option 006 2948A and above Reu.30NOV89 Front Panel Assembly, 2923A and above Rent Panel Assembly, Option 006 2948A and above Reu.30NOV89 Rear Panel Assembly Rear Panel Assembly, Option 005 2948A and above Rev.30N0 Rev.ZSSEP88 Covers, Labels, and ROMs Output Cables 1 Output Cables, Option 005 29484 and above 2 Rev.30N0V89 Table of Contents Rev.15DEC89 Option ConversionsNumber 2942A and below Titled Hardware Modifications Instrument ModificationsRevision 22987A with HP 08904-8701 0 as A2U12 FRONT-TO-REAR-PANELOUTPUT Conversion Description Modification ProcedureParts Required Tools Required Operation Verification Fl Channel Config Description REAR-TO-FRONT-PANELOUTPUT ConversionRev.15DEC89 Rear-to-Front-Panel Output Conversion Fl Channel Config Ront Panel Output Hardware Output Cable Routing ALL Options Rev.01JUL91 Firmware UpdatesBardware Modifications Firmware Updates A2U12 and A2U13Different function Serial Prefix 2737A and below Modification for Possible Ground Wire Shock Hazard Firmware Updates/Hardware Modifications Parts Location Shown with Power Supply Removed Firmware Updates/Hardware Modifications Ground Wire Wrapping Modification for Output Overvoltage Protection Improvement Parts ListHPPartNumber ~~ Qty Description Fixed Resistor, 261 or Cabinet Parts Color Change Modification for Potential Power Supply Short Reu.15DEC89 Firmware UpdatesIHardwareModifications 1. Modificationfor Front Panel Assembly Removing the Front Panel Installingthe Front Panel Dont-Panel Assembly, 2923A and above Section Service A3 or A10 Output Assembly Phase Synchronization Option Before Applying Power Safety ConsiderationsHOW the Section is Organized Iwarning Schematic Symbology and Schematic Diagram Notes Service TOOLS, HELPS, and Information Pin of socket Schematic Diagram Notes 1 Schematic Diagram Notes 2 Schematic Diagram Notes 3 Digital Symbology Reference Information Llzble 8-1.Schematic Diagram Notes 4 Combinational Logic Symbols and Functions Schematic Diagram Notes 5 Schematic Diagram Notes 6 Digital Symbology Reference Information Only with D-type flip-flops Gate and Dependency-Binary Schematic Diagram Notes 7 Miscellaneous Llable 8-1.Schematic Diagram Notes 8of Schematic Diagram Notes 9 Service Active Levels Schematic Diagram Notes 10 Enable Schematic Diagram Notes 11 What the Multifunction Synthesizer Can Do Principles of Operation OverallHow Waveforms Are Generated Channel a Generating Staircases in the Phase Accumulator Output of the Phase Adder for P=O, 1, Further Digital Waveform Processing with Options Pulse Phase @PHASE FreouencyFreouency SUM Pulse Level Interrelationshipof the Circuit Assemblies Analog Waveform ProcessingReu.15DEC89 Principles of Operation Overall Synthesizer PASSY- t General A2 Digital Assembly Digital-to-Analog Converter Service Sheet A3 Output Assembly Service Sheets 1 through GeneralTrack-and-Hold Circuit Service Sheet Simplified Diagram of the Sampler Drive 10.Simplified Diagram of the Sampler Amplifier Audio Amplifier Service Sheet Low-Pass Filters Service SheetSine X/X CompensationService Sheet 12, and 24 dB Attenuators Service Sheet Floating Output Amplifier Service Sheet Floating Amplifier Driver and On/Off Switch Service SheetOvervoltage Protectionand Output Circuits Service Sheet Rev.15DEC89 Troubleshooting General Troubleshooting General Procedure A2 Digital Assembly to A3 or A10 Output Assembly InterfaceEquipment 1. How to Access A3 in Instruments Equipped with Option Serial Prefix Troubleshooting Digital/Output Interface Period Fl Channel Config Pin Frequency Hz Fl Channel Config A3/A10 Connection Function A3 Key Sequence A10 Key SequenceIC Pin Level F3 Memory Map Access Pin Clocks A10J1 and J5 Miscellaneous Control Fl Keyboard Check A2 Digital Assembly to A1 Keyboard Assembly Interface Pin Key Pressed Response lTL AMPTD, Wave Form Key Sequence Annunciator Status IC on A2 Pin Level lTL F3 Memory Map Access Description A2 Digital Assembly to A5 Display Assembly Interface A3 or A10 Output Assembly Troubleshooting Phase Synchronization Phase Synchronizationoption HP 8904A Opts After keying in 8 7, the display should be IFirmware Revision 18387A Serial No HP 8904A Opts 02/01 IFirmware Revision 18387A Serial No After keying in 4 8, the display should be Begin again at step Troubleshooting Memory Backup Battery 48.1 HOW to Replace the Memory Backup BatteryTools and Supplies Parts Troubleshooting Memory Backup Battery 48.3 Rev.15DEC89 Troubleshooting Memory Backup BatteryPage N a 12.4. Line Voltage Wiring Harness R300 A3 Component Coordinates 1 L0nA Current Source Ipower Supply Conditioners Comp A3 Component Coordinates 2 Ss2 On the A3 schematicRev.28MAR89 31901 N3AILlO ONV I813IldIll3 JJOlfl3 dWHS 15.Service Sheet Information Component Locator Rev.28MAR89 54.1 Changes Ampto Instrument Settings Measure Aooitions I T I a L Instrument SettingsCoup OUT K2A Component Coordinates 1 + a 56.1 Ss4 Ss4 A6 Schematic and Component locator Ss5 0 A3/A10 Output Assembly