Specifications

ManualsBrandsShure ManualsAmplifierSR10

apply. As in conventional full-range operation, the

second

HIGH and LOW FREQ lnput Jacks may be

used for additional, parallel-connected

biamplified

SR108's.

BASIC OPERATING HINTS

Should any difficulty be encountered in SR108 ope-

ration, the problem may often be traced to some

simple source such as an

er.ror in interconnection.

The following is offered as a basic guide to problems

of this sort.

Symptom:

SR108 is "dead" (no output)

Check: 1. Check inputs and outputs of all equip-

ment driving

SR108.

2. Check interconnecting cables and con-

nectors.

3. Check to see that LOUDSPEAKER OP-

ERATION Switch position corresponds to

desired operating mode.

Symptom: Poor or no high-frequency output (normal

low-frequency output)

Check:

1. Check setting of LOUDSPEAKER OPER-

ATION Switch.

2. If symptom appears only when LOUD-

SPEAKER OPERATION Switch is in

BI-

AMP position, check output of equipment

driving high-frequency drivers.

Check high-frequency response of pro-

gram material.

Symptom: Poor or no low-frequency output (normal

high-frequency output)

Check: 1. If symptom appears only when LOUD-

SPEAKER OPERATION Switch is in

BI-

AMP position, check output of equipment

driving low-frequency speakers.

2. Check low-frequency response of pro-

gram material.

SERVICE

INSTRUCTIONS

Speaker Servicing

1. To measure dc resistance of high-frequency

driver assembly (LOUDSPEAKER SWITCH in any

position), first remove speaker cables. Remove

10 Phillips head screws securing upper rear

panel to enclosure. Remove panel and discon-

nect wiring harness

(PI) from its socket (J7)

on printed circuit board (see Figure

M).

Un-

solder high-frequency driver leads from inductor

L2 and measure dc resistance of high-frequency

driver assembly

(LS7-LS10). Total dc resist-

ance of assembly should be between 12.5 and

14.5 ohms.

To measure dc resistance of each high-fre-

quency driver

(LS7-LSlO), remove five bolts se-

curing high-frequency driver assembly support

bracket

(318" and 9/16" socket wrench may be

used) and remove bracket. Do not permit

high-

frequency driver assembly to drop when bracket

is removed. Carefully withdraw high-frequency

driver assembly (drivers and throat adapter as-

sembly) from compartment. Disconnect one lead

between the four high-frequency drivers. Meas-

ure resistance of each high-frequency driver

voice coil. Each driver should measure between

12.5 and 14.5 ohms. Replace any defective

drivers as described in High-Frequency Driver

Replacement.

2. If above tests do not locate defective high-fre-

quency driver, check for voice coil rubbing or

binding by driving each driver with a test signal

(4V

max.) from a sweep oscillator and amplifier

covering the frequency range from 2600 to

10,000

Hz.

WARNING

Sound pressure levels generated by this

test may be damaging to your hearing. Aim

drivers away from listeners and toward

sound-absorbent material (curtains, blanket,

etc.). Carefully adjust test signal amplitude

to avoid unnecessarily high sound pressure

levels for prolonged periods.

Sound from high-f requency drivers should be

clean and free from buzzes or rattles which may

indicate driver failure. Replace any defective

drivers as described in High-Frequency Driver

Replacement.

To measure dc resistance of low-frequency

speakers, connect an ohmmeter between tip

and sleeve connections of FULL-RANGE

lnput

Jacks J1 or J2 (LOUDSPEAKER OPERATION

Switch in -4, -2,

0 or +2 position), or be-

tween tip and sleeve connections of LOW

FREQ/

BlAMP OPERATION lnput Jacks J3 or J4 (LOUD-

SPEAKER OPERATION Switch in BlAMP posi-

tion). The FULL-RANGE resistance reading

should be between 11.25 and 13.35 ohms, and

the BlAMP reading should be between 11.25

and 12.75 ohms. Readings outside these limits

indicate possible low-frequency speaker failure.

To measure dc resistance of each low-frequency

speaker

(LS1-LSG), remove 26 Phillips head

screws securing lower rear panel to enclosure.

Remove rear panel and rest it on floor, taking

care not to stress input jack wiring. Using ohm-

meter, measure resistance of each low-frequency

speaker coil. A clicking sound will be made by

a "good" speaker when ohmmeter is connected

or disconnected. Each low-frequency speaker

should measure between 7.5 and 8.5 ohms with

speaker leads disconnected. Replace any speak-

ers found defective.

If above tests do not locate defective low-fre-

quency speaker, check for voice coil rubbing or

binding by first disconnecting lead between two

top low-frequency speakers. Set sweep oscilla-

tor and amplifier to produce test signal (8V max.)

and sweep each speaker over the frequency

range of 50 to 2600 Hz.