Dolby Laboratories CP65 manual 12 AND, Repeat, A-ChainAlignment Procedures, Action, Indication

			4-16
			A-Chain Alignment Procedures
b. Optical Preamplifier Adjustments
Step		Action		Indication
No.
14
			RTA
Cat. No. 240
			IN
Proj. 1	Status
RV101	Gain	L
RV102 hf
RV201	Gain	R
RV202 hf
TP501 L tp			X
	L	SIGNAL
		PRESENT	Y
	R
TP502 R tp
RV301 Gain		L
RV302 hf		R
RV401 Gain			SCOPE	dB
RV402 hf
Proj. 2	Status			+10

TP503 GND

+5

INTO	✓
FOCUS

0

REPEAT 12 AND 13 –5

OUT OF

FOCUS X

–10

.05 .1 .2 .4 .8 1.6 3.15 6.3 12.5 kHz

15

dB +10

+5

	✓									0
Cat. No.
240A										–5
										–10
	.05	.1	.2	.4	.8	1.6	3.15	6.3	12.5	kHz
Proj. 1
GAIN
Lt										dB
hf										+10
GAIN
Rt
hf
Lt tp										+5

	Lt	X
signal										0
present
	Rt
Rt	tp									–5
GAIN
Lt	hf									–10
GAIN		.05	.1	.2	.4	.8	1.6	3.15	6.3	12.5 kHz
Rt	hf
Proj. 2										dB
gnd
										+10

+5

X0

–5

–10

.05 .1 .2 .4 .8 1.6 3.15 6.3 12.5 kHz

4-17

A-Chain Alignment Procedures

b. Optical Preamplifier Adjustments

Notes

Disconnect the RTA from the left test point and connect it to the right test point TP502 R. Then repeat Steps 12 and 13. NOTE: The azimuth and high frequency response must be the same at both the left and right test points. If results are not similar, it may be necessary to remove the lens and check for oil or contamination or a degraded slit. Replace the lens, if necessary. Do not proceed to the next step until the outputs at both the left and right test points are similar.

Appendix B shows the effects of slit geometry on frequency response.

The test in this step is performed both at the right and left channel test points of the Cat. No. 240A card.

The frequency response must be within 1 dB to at least 12 kHz. Adjust the L hf and R hf potentiometers on the Cat. No. 240A card for the most extended high frequency response without “peaking.” If these adjustments do not improve the frequency response, the problem may be a degraded slit or damage to the lens.