November 11, 1976 HR-1680 Bulletin No: S/S Receiver HR-1680-1 No VFO Output Several L30 [PN 40-1859] coils have been found with the color dot on the wrong lug. The color dot should be on the coil center tap lug. Q.A. is checking all kits and parts stock. -------------------------------------------------------------------------------------------------------------------- November 11, 1976 HR-1680 Bulletin No: S/S Receiver HR-1680-2 No VFO Output When mounting the VFO capacitor to the capacitor mounting bracket, 6-32 X 1/4 screws must be used. If 6-32 X 3/8 screws are used they will short out to the stator plates of the VFO capacitor. A good indication that this might be the case is a low voltage, below 1.5V, across ZD301. -------------------------------------------------------------------------------------------------------------------- November 18, 1976 HR-1680 Bulletin No: S/S Receiver HR-1680-3 Trimmer Capacitor [PN 31-76] NLA When C139, C146 on the front end circuit board requires replacement, use [PN 31-85]. ------------------------------------------------------------------------------------------------------------------- November 24, 1976 HR-1680 Bulletin No: S/S Receiver HR-1680-4 Audio Gain Decreases When Sharp Pulses Are Received *******This Bulletin Superceded by HR-1680-6******* -------------------------------------------------------------------------------------------------------------------- January 6, 1977 HR-1680 Bulletin No: S/S Receiver HR-1680-5 IF Oscillation + + + + Information not yet available + + + + -------------------------------------------------------------------------------------------------------------------- February 21, 1977 HR-1680 Bulletin No: S/S Receiver HR-1680-6 IF Oscillation *******Supercedes HR-1680-4******* + + + + Information not yet available + + + + -------------------------------------------------------------------------------------------------------------------- March 7, 1977 HR-1680 Bulletin No: S/S Receiver HR-1680-7 Fuse F201 Blows When Servicing Audio/Regulator Circuit Board + + + + Information not yet available + + + + -------------------------------------------------------------------------------------------------------------------- March 22, 1977 HR-1680 Bulletin No: S/S Receiver HR-1680-8 Receiver Front End Stability + + + + Information not yet available + + + + -------------------------------------------------------------------------------------------------------------------- May 13, 1977 HR-1680 Bulletin No: S/S Receiver HR-1680-9 Front End Oscillates *****Superceded by HR-1680-10***** + + + + Information not yet available + + + + -------------------------------------------------------------------------------------------------------------------- July 8, 1977 HR-1680 Bulletin No: S/S Receiver HR-1680-10 Front End Oscillates *****Supercedes HR-1680-9***** + + + + Information not yet available + + + + -------------------------------------------------------------------------------------------------------------------- July 24, 1978 HR-1680 Bulletin No: S/S Receiver HR-1680-11 Preselector Drifts The preselector may drift off resonance, usually about one minute after a band change. This is most noticeable on the 40 meter band. To solve this problem install a 10 kilohm resistor [PN 6-103-12] in parallel with C114 and C115. This provides a DC return path for diodes D105 through D108. Make this change only when necessary. ---------------------------------------------------------------------------------------------------------------- May 7, 1979 HR-1680 Bulletin No: S/S Receiver HR-1680-12 8.65 MHz Bandpass Filter Won't Adjust Properly Change the 10 pf cefamic capacitor at C143 to a 5-25 pf trimmer capacitor [PN 31-85]. This component will fit directly. ------------------------------------------------------------------------------------------------------------------- July 30, 1979 HR-1680 Bulletin No: S/S Receiver HR-1680-13 No AGC When Case Bottom Installed This may be caused by the left-front foot screw touching terminal strip CK (junction of R5 and R6). To correct, bend terminal strip toward front of unit. -------------------------------------------------------------------------------------------------------------------- February 8, 1980 HR-1680 Bulletin No: S/S Receiver HR-1680-14 Sweep Aligning the 8.65 Bandpass Filter + + + + Information not yet available + + + + -------------------------------------------------------------------------------------------------------------------- February 8, 1980 HR-1680 Bulletin No: S/S Receiver HR-1680-15 S Meter Reads S9 or Pins for Most Signals + + + + Information not yet available + + + + -------------------------------------------------------------------------------------------------------------------- October 21, 1980 HR-1680 Bulletin No: S/S Receiver HR-1680-16 Audio Oscillations and Pilot Lamp Dims When Tuning a Strong Station + + + + Information not yet available + + + + -------------------------------------------------------------------------------------------------------------------- November 25, 1980 HR-1680 Bulletin No: S/S Receiver HR-1680-17 Tantalum Capacitor Change + + + + Information not yet available + + + + -------------------------------------------------------------------------------------------------------------------- August 28, 1981 HR-1680 Bulletin No: S/S Receiver HR-1680-18 R7 Control Change + + + + Information not yet available + + + + -------------------------------------------------------------------------------------------------------------------- August 28, 1981 HR-1680 Bulletin No: S/S Receiver HR-1680-19 IC201 Regulator Change + + + + Information not yet available + + + + -------------------------------------------------------------------------------------------------------------------- October 25, 1982 HR-1680 Bulletin No: S/S Receiver HR-1680-20 Schematic Correction - Diode Numbers D2 and D4 Interchanged + + + + Information not yet available + + + + -------------------------------------------------------------------------------------------------------------------- That's all that is shown for the HR-1680 (1966-89). Hopefully one of these days I will be able to talk those that have the years we are missing to lend them to me so they can be posted for all to use. Enjoy! 73 de Joe W7LPF/4 [NNN0KUU] QWCA - SOWP - NCVA - FISTS - RCC Gordonsville, Va 22942 [Orange Co]