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b. Optical Preamplifier Adjustments |
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Step | Action | Indication |
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No. |
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12 |
| OSCILLOSCOPE TRACES |
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✓
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| RT |
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Cat. No. 240A |
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Proj. 1 Status |
| IN |
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RV101 Gain | L |
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RV102 hf |
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RV201 Gain | R |
| x |
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RV202 hf |
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TP501 L tp | SIGNAL | X | Out of phase | |
L |
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| PRESENT | Y |
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R |
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TP502 R tp |
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RV301 Gain | L |
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RV302 hf | R |
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RV401 Gain | SCOPE |
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RV402 hf |
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Proj. 2 Status |
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TP503 GND |
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| MODE |
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| x | Incorrect azimuth |
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13
dB +10
+5
INTO | ✓ |
FOCUS |
0
OUT OF
FOCUS X
.05 |
| .1 |
| .2 |
| .4 |
| .8 |
| 1.6 |
| 3.15 |
| 6.3 |
| 12.5 |
| kHz |
RTA DISPLAY
b. Optical Preamplifier Adjustments
Notes
Remove the Cat. No. 97 film and thread and play the pink noise on the Cat. No. 69 film (emulsion away from screen). Connect the RTA to the left test point TP501 L on the Cat. No. 240A.
Switch the oscilloscope to the X/Y mode and adjust the azimuth of the projector optics for the narrowest diagonal trace. (Blooming at the ends of the trace may be caused by improper lighting of the edges of the optical tracks. If necessary, repeat steps 8 and 9 above, or step 5 on page
xx
Not enough light | Uneven light on cell |
on one channel |
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Then, while observing the trace on the RTA, adjust the focus of the sound track lens for the best high frequency response. The trace shown in the example is ideal; merely attempt to obtain the best response. The azimuth and focus adjustments interact so you must repeat Steps 12 and 13 until no further adjustments are required.
