Model 405C Sect.IV Page 3
4-7 NEUTRALIZING THE AMPLIFIER When lubricating the stepping switch, it is important
1) Remove bottom dust cover. to apply the right amount of lubricant. Too much
can be as bad as not enough. To assure the proper
amount, the term "dip" will be used as a guide. To
2) Set line voltage to 115 volts. turn instrument on, obtain one "dip" of lubricant, dip the brush into the
and allow 5-minutes warm up.
lubricant, then wipe the brush against the side of
3) Set RANGE switch to AUTOand SAMPLING con- the bottle to remove the drop that forms at the end
trol to maximum but not to EXT. of the brush. In most cases one dip will be enough
to lubricate several parts. Brush the lubricant
lightly over the parts. Do not scrub the brush on
4) Connect direct short across 405C INPUT.
the parts because such action usually results in too
5) Adjust Amp Neut control C10 to set readout to much lubricant on the first part and too little on the
+. 000. This control is mounted on socket of V3. others .
During manufacture the undercut portion of the
wiper shaft is filled with ANG-3-A grease, and a
4-a ~OSA-~SC ADAPTER ADJUSTMENT small portion of this grease is applied to the end
The only adjustment required by the 405A-95C of the shaft opposite the mounting hub before the
shaft is assembled into the hub. This lubrication
Digital Recorder Adapter is the adjustment of the is good for the life of the switch and needs repla-
staircase voltages for range indication on the @ cing only when the wiper assembly is replaced.
Model 560A Digital Recorder. Proceed as follows:
1) Connect Adapter to Recorder only and turn Re-
A. EXPOSING THE SWITCH FOR LUBRICATION
corder on.
1) Remove stepping switch cover. See Figure 4-4.
2) Adjust R302 (A) and R308 (B) in Adapter until
voltages at pins 1 and 4 of P301A are +169 and
-1-119 respectively. Use the 405C to measure the 2) Remove nuts that hold stepping switch mounting
bracket to deck.
voltages, for they should be set as close as pos-
sible to their correct values. 3) Remove screws holding switch to bracket and
remove bracket.
4-9 STEPPING SWITCH MAINTENANCE 4) Lift switch up through deck. You may have to
remove relay K2 to make room. Reverse proce-
The stepping switch should be kept clean and well dure to replace switch.
lubricated. Inspect the switch according to the
schedule below and add lubricant or clean and re-
lubricate as necessary.
B. LUBRICATING THE STEPPING SWITCH
1) After 30,000 revolutions or three months, which- The lubricating points for the stepping switch
ever is first. are shown in Figure 4-1.
2) After each additional 150, 000 revolutions or
six months, whichever is more frequent. 4-10 TUBE AND DIODE REPLACEMENT
A. TUBE REPLACEMENT
To obtain the best results from 'maintenance lubri-
In many cases of instrument malfunction, the
cation, first wipe the parts as clean as possible. cause is a weak or defective tube. Locate the
If the switch is excessively dirty, clean it with a trouble as nearly as possible and'check the tubes
high-quality cleaner such as xylene which does not
leave a film upon evaporation. in the suspected circuits.
A lubrication kit consisting of three types of lubri- The best tube checker is the circuit in which a tube
cant, each in a small bottle, is included with your must operate. Check tubes by substitution and re-
instrument. Each bottle has a geometric figure place the original one if a newone does not restore
(and the switch manufacturer's specification num- proper circuit operation. However, if circuit con-
ber) on it for easy identification in the lubrication dition (burned resistor, etc. ) indicates that the
procedure below. Each bottle cap has attached to original tube may be shorted or otherwise mechan-
it the type of brush best suited for the particular ically defective, check the tube on a "tube tester"
lubricant. before returning it to the circuit.
00518- 1 |
ACEC
HEWLETT-PACKARD
