
Replacing the two bulbs in the meter for the 651S1.
I have just finished replacing the two 6 Volt, type 328, miniature bulbs in my 651S1.
The procedure is:
(1) Remove meter by unscrewing four small screws that hold the compression
mounts for the meter.
(2) Use a small screw driver to separate separate the slot/grove holds the
meter cover. This is on the back of the meter. Do not remove any screws
on the back of the meter.
(3) Snap the front cover off the meter.
(4) Remove two screws that hold the white plastic meter dial. Slide the
dial out from under the meter pointer.
(5) Remove two screws from the white bezel that has two holes for the two
bulbs.
(6) If this white bezel is glued to the black plastic carefully seperate
it from the meter using an exacto knife. Watch out for damaging the meter
pointer.
(7) Set the meter on its back and lift out the bulb holder. Remove the
two screws at the back of the holder.
(8) You can now replace the bulbs.
(9) Reverse the process to preplace the meter.
KF4FOR
Work:P.A. Bernhardt Home: Paul Bernhardt, KF4FOR
Code 6794 5704 Ridge View Dr.
Naval Research Laboratory Alexandria, VA 22310
Washington, DC 20375
Tel: 202-767-0196 703-960-9656
FAX: 202-767-0631
Changing the displays in the unit.
Service bulletins
651S-1 General Purpose HF Receiver
PUB NO. NOTE DATE DESCRIPTION
SB 1 10/1/72 Reduction of 450-kHz Leakage From Synthesizer Reference Board A11
SB 2 6/6/73
Change 1
10/15/73 Reduction of Noise Level
SB 3 7/15/73 Add Keep-Alive Frequency Memory Function
SB 4 7/15/73 Extend Comma and Decimal Lamp Life in Frequency Display
SB 5 12/15/74 Minimize TCU Circuit Card Response to Data Link Noise and
Failure
SB 6 3/1/75 Reduce Intermodulation Level
SB 7 2/7/75 Reduce Internal Spurious Signals
SB 8 12/27/74 Allow Remote Control Operation With RS-232C Serial Control Interface
Card A9
SB 9 2/15/75 Increase Life of Display Tubes
SB 10 12/31/75
Revised
8/2/76
4/1/77 Replacing Display Tubes With LED Plug-in Assemblies
SB 11 Not Issued
SB 12 5/1/78
Revised
7/1/78 Replacing Nonprocurable Integrated Circuits
SB 13 10/1/80 Replace Nonprocurable Parts
SB 14 11/1/80 Reduce 100-kHz Sidebands
SB 15 5/1/81 Prevent Invalid Monitor Responses From the HF Receiver
SB A 11/1/73 Change DCFE Filter Switching Diode
SB C 1/15/78 Supply KAV Power to DCFE
651S-1A General Purpose HF Receiver
PUB NO. NOTE DATE DESCRIPTION
SB 1 7/15/73 Extend Comma and Decimal Lamp Life in Frequency Display
SB 2 6/6/73
Change 1
10/15/73 Reduction of Noise Level
SB 3, 4 Not Issued
SB 5 12/15/74 Minimize TCU Circuit Card Response to Data Link Noise and Failure
SB 6 3/1/75 Reduce Intermodulation Level
SB 7 Not issued
SB 8 12/27/74 Allow Remote Control Operation With RS-232C Serial Control Interface
Card A9
SB 9 2/15/75 Increase Life of Display Tubes
SB 10 12/31/75
Revised
8/2/76
4/1/77 Replacing Display Tubes With LED Plug-in Assemblies
SB 11 Not Issued
SB 12 5/1/78
Revised
7/1/78 Replacing Nonprocurable Integrated Circuits
SB 13 10/1/80 Replace Nonprocurable Parts
SB 14 11/1/80 Reduce 100-kHz Sidebands
SB A 11/1/73 Change DCFE Filter Switching Diode
651S-1B General Purpose HF Receiver
PUB NO. NOTE DATE DESCRIPTION
SB 1 - 5 Not Issued
SB 6 3/1/75 Reduce Intermodulation Level
SB 7 - 9 Not Issued
SB 10 12/31/75
Revised
8/2/76
4/1/77 Replacing Display Tubes With LED Plug-in Assemblies
SB 11 7/27/76 Prevent Premature Fuse Failure
SB 12 5/1/78
Revised
7/1/78 Replacing Nonprocurable Integrated Circuits
SB 13 10/1/80 Replace Nonprocurable Parts
SB 14 11/1/80 Reduce 100-kHz Sidebands
SB 15 5/1/81 Prevent Invalid Monitor Responses From the HF Receiver