Section V Model 240A
Paragraphs 5-38 to 5-41
5-38. WAVEFORMS. nal signal generator that is accurately calibrated, it
is possible to identify birdies accurately. This tech-
5-39. Waveforms of 240A circuit operation in the nique is particularly useful when calibrating the high
sweep mode are illustrated adjacent to the schematic frequency ranges, where adjustment range exceeds
of the associated circuits. Waveform test points are the largest marker interval of 2.5 Mc.
identified on the schematics with a number inside a
triangle; e.g., v.
24DA SWEEP
, nPE , GENERATOR
5-40. MARKER AMBIGUITY. SIGNAL GENERATOR
r (OR GRID DIP OSCILLATOR)
5-41. Because of the extremely wide sweep range
and the possibility of gross missdjustment of linearity )UT
WEEP
particularly on the 35-75 and 75-120 Mc ranges, it is COMPOSITE SIGNAL OUT
possible to interpret the marker birdies incorrectly. PAD
If any doubt exists as to marker interpretation, make -OR
an equipment connection as shown in Figure 5-5. By
injecting signals from a grid-dip oscillator or exter- Figure 5-5. Setup for Pip Identification
Table 5-5. Trouble-Shooting Chart
Symptom Possible Cause Correction
With the equipment connected to a Fuse defective. Replace fuse F601.
suitable 115-volt source and Power
Pilot light defective. Replace pilot light Ds601.
Switch I'ON17, pilot light does not
light. Primary winding or filament sec- Check continuity of transformer
ondary winding of power trans- T601 and replace if defective.
former open.
~~
Vacuum tube filaments do not I Defective vacuum tube. Check vacuum tube and replace if
light. defective.
Primary winding or secondary
windings of filament trans- Check continuity of transformer
former open. T603 and/or T604.
Defective volt age stabilizer . Check continuity of T602.
~~ ~
Vacuum tube filaments of V202, Defective selenium rectifier Check rectifier bridge CR602 and
203, and 205 do not light. or capacitor. capacitor C605 and replace if de-
fective.
Fuse F601 blows repeatedly after Vacuum tube rectifier, filter Remove rectifier V605. If fuse
power is applied. capacitors, power transformer does not blow, check C601 and
or voltage stabilizer defective. C602 for possible shorts. If nor-
mal, check V605. If normal, check
continuity of T601 and T602.
~~ ~
Filaments light but no plate Vacuum tube rectifier defective. Check V605 and replace if defective.
voltage.
Filter choke defective. Check continuity of L601 and re-
place if defective.
Filter capacitor defective. Check C601 and C602 for possible
shorts and replace if defective.
No -75 DC voltage. Defective silicon diode. Check CR601 and replace if defec-
tive.
Defective capacitors. Check C603 and C604 for possible
shorts.
I Defective filter choke. Check L602.
5 -6 |
ACEC
