The 8643A is a decent 1GHz (2G optional) signal generator. I’ve repaired mine (video on YT) a few years ago. Additional information and resources on the hpwiki here

Capacitor replacement list #

I replaced a number of capacitors in my unit’s power supply boards : mainly RIFA film caps, some LXF series caps (notoriously leaky) and a few others for good measure.

Note, my unit was not defective due to bad PSUs (they were fine), but a shorted tantalum cap in the A8 module. I replaced it and other decoupling tants with aluminium-polymer caps which are very low ESR and hopefully more robust against high inrush current. PSU recapping was preventative.

PSU 1: NFS40-7624 (single output 24VDC)                                                          
																			 
desig             val                dims                PN                   notes               
																			 
c6                22u 35V            H6 dia6.5 p4        50ML22MEFC8X5        
c15,16,17         330u 35V           H20 dia10 p5        stock (UPW1H331)     LXF                 
																			 
PSU 2: NFS96-7630 (multi output +5, +15, -15, +36)                                                             
																			 
C25               2n2 250VAC Y       L13 W3 H6 P10 rect  R413F12204000M       RIFA                
C11,12,18,24      100u 50V           H16 D10 P5          MAL214651101E3       LXF                 
C19,20,21,23      2200u 16V          H30 D13 P5          EEU-FK1C222          LXF                 
C7                47n 300VAC/630DC Y L18 W7 H13 P15 rect MKP1J024704C00KSSD   RIFA                
C15,26            1000u 35V          H30 D13 P5          MAL217050102E3       LXF                 
C8,17,27          47u 50V            H12 D6 P2.5         50YXG47MEFC6.3X11    KME                 
																			 
A8: STD MOD/NSM OSC , 08644-61003, SN 3538A03206                                                             
																			 
C407              100u/10V tant                          RNS1A101M            decoupl rail        
C405,406,221,222  22u/25V tant                           RNS1E220MDN1         decoupl rail        
C205,208,213,216  22u/25V tant                                                FB opamp, not replac
C211,212          22u/25V tant                                                decoupl rail        
L402              10uH MS14046-4                         1537-36K